Pharmacology Rosh Review Extra Questions

In which of the following clinical scenarios would it be appropriate to use nitrofurantoin? A 31-year-old woman with acute complicated cystitis A 42-year-old woman with acute uncomplicated cystitis A 56-year-old woman with pyelonephritis A 72-year-old woman with acute uncomplicated cystitis

A 42-year-old woman with acute uncomplicated cystitis Hint: Nitrofurantoin is an appropriate antibiotic choice for the treatment of acute uncomplicated cystitis. Nitrofurantoin is a nitrofuran antibiotic that is bactericidal in urine. It inactivates bacterial ribosomal proteins and, as a result, disrupts protein synthesis within the bacteria. Its spectrum of activity includes gram-negative bacteria that is often implicated in the development of urinary tract infections, such as Escherichia coli and Enterococci species

Which of the following patients should receive antibiotic treatment? A 32-year-old woman with 10 days of cough with purulent sputum without fever A 54-year-old man with 8 days of worsening nasal congestion and headache A 7-year-old boy with 1 day of ear pain, a bulging tympanic membrane, and no evidence of fever An 83-year-old woman with pyuria and no symptomatic complaints

A 54-year-old man with 8 days of worsening nasal congestion and headache Hint: A 32-year-old woman with 10 days of cough with purulent sputum without fever (A) likely has acute bronchitis. This condition is primarily caused by viral infections and is not effectively treated with antibiotics. A 7-year-old boy with one day of ear pain, a bulging tympanic membrane, and no evidence of fever (C) can be treated for acute otitis media via observation and symptomatic treatment for one to two days prior to initiating antibiotic treatment. Children under age 2 years and older children with a toxic appearance, persistent otalgia > 48 hours, temperature ≥ 102.2°F in the past 48 hours, or those with bilateral acute otitis media or otorrhea should be initially treated with an antibiotic. An 83-year-old woman with pyuria and no symptomatic complaints (D) presents with asymptomatic bacteriuria. This condition is common in elderly patients and is not associated with increased adverse events if untreated. Furthermore, antibiotic treatment in this patient population has not demonstrated a proven benefit.

In which of the following scenarios would prescribing amoxicillin-clavulanate be most appropriate? A child with acute otitis media who failed amoxicillin treatment A man with a diabetic foot infection A woman with an acute exacerbation of chronic obstructive pulmonary disease An adolescent who is a chronic carrier of group A Streptococcus

A child with acute otitis media who failed amoxicillin treatment Hint: Amoxicillin-clavulanate inhibits beta-lactamase-producing Haemophilus influenzae, as well as strains of Staphylococcus aureus. It is most commonly used to treat otitis media, sinusitis, lower respiratory infections, bite wounds, and urinary tract infections (particularly those caused by beta-lactamase-producing Enterobacteriaceae). It is also used as a treatment for otitis media in children who have treatment failure after amoxicillin. A man with a diabetic foot infection (B) has risk factors for Pseudomonas aeruginosa infection. Amoxicillin-clavulanate does not cover this infection. Occasionally, this drug is used for mild infections if infection with Pseudomonas aeruginosa is not a concern. A woman with an acute exacerbation of chronic obstructive pulmonary disease (C) may not require antibiotics. There is an off-label use of amoxicillin-clavulanate in patients with COPDexacerbations that are severe and are being treated for concurrent infection or prophylaxis for pneumonia. Most individuals who are chronic carriers of group A Streptococcus (D) do not require treatment. If treatment is given, amoxicillin without clavulanate can be used

Which of the following is the most active aminoglycoside against respiratory infections caused by Mycobacterium fortuitum? Amikacin Plazomicin Streptomycin Tobramycin

Amikacin Hint: Plazomicin (B) has the most potent activity against Enterobacteriaceae when compared to other aminoglycosides. It often retains activity against Klebsiella pneumoniae carbapenemases or extended-spectrum beta-lactamase-producing Enterobacteriaceae despite the presence of an aminoglycoside-modifying enzyme that inactivates other aminoglycosides. Streptomycin (C) is mainly used as a second-line agent for the treatment of tuberculosis, often used in combination with other agents to prevent the emergence of resistance. It is the first-line treatment of plague and tularemia and can also be used to treat brucellosis. Tobramycin (D) has better activity against Pseudomonas aeruginosa infections. Infections caused by Enterococcus faecium are resistant to tobramycin due to the presence of aminoglycoside-modifying enzymes.

A 17-year-old girl presents with a sore throat and intermittent fever for the past seven days. Her rapid strep is negative. She is started on an antibiotic and returns a few days later with a diffuse, erythematous morbilliform rash. Subsequent testing for mononucleosis is positive. Which of the following antibiotics was she most likely given during her first visit? Amoxicillin Azithromycin Cephalexin Levofloxacin

Amoxicillin Hint: Amoxicillin should not be given to patients with mononucleosis, as this can cause an erythematous, maculopapular rash about 7 to 10 days after the initiation of antibiotics. Patients with mononucleosis who develop a rash while taking amoxicillin are often mislabeled as having a penicillin allergy.

Which of the following medications is safest for the treatment of fungal infections during the first trimester of pregnancy? Amphotericin B Caspofungin Fluconazole Flucytosine

Amphotericin B Hint: Caspofungin (B) is an echinocandin antifungal agent that is not recommended for use in pregnant patients due to the risk of fetal harm. This and other echinocandin medications have been shown to cross the placenta and, at high doses, cause skeletal and visceral changes as well as increased abortion rates. This class of medications carries a pregnancy category C rating. Fluconazole (C) is a triazole antifungal that is contraindicated during pregnancy, particularly the first trimester. Known fetal abnormalities include brachycephaly, abnormal facies, cleft palate, arthrogryposis, and congenital heart disease, among others. Flucytosine (D) is an antifungal that is converted in vivo to fluorouracil. This metabolite is suspected to cause congenital abnormalities in humans while the parent drug has been linked to teratogenic effects in animal studies

A 35-year-old who has AIDS is diagnosed with cryptococcal meningitis, and an antifungal is given empirically. About one hour after the infusion is started, the patient develops fever and chills. Which of the following antifungals is most likely to have caused this reaction? Amphotericin B Fluconazole Flucytosine Itraconazole

Amphotericin B Hint: Common adverse effects include infusion-related reactions, such as fever and chills, that usually occur a few hours after starting intravenous administration. Nephrotoxicity is another common side effect, with renal function usually returning to baseline after the drug is discontinued. Other side effects include hypotension, thrombophlebitis, hypokalemia, hypomagnesemia, anemia, nausea, vomiting, rash, diarrhea, leukopenia, thrombocytopenia, hyponatremia, and chest pain

A 61-year-old man presents to the emergency department with a headache for the past day. He also complains of neck stiffness and subjective fever. Vital signs are T 101.6°F, HR 122 bpm, BP 138/76 mm Hg, RR 20/min, and oxygen saturation 97% on room air. Kernig sign is positive on exam. Lumbar puncture is performed for cerebrospinal fluid analysis. Which of the following antibiotics is indicated to empirically cover Listeria monocytogenes in this patient? Amoxicillin Ampicillin Ceftriaxone Vancomycin

Ampicillin Hint: Ampicillin is used in patients with suspected bacterial meningitis who are neonates or at least 50 years of age to provide empiric coverage against Listeria monocytogenes. Amoxicillin (A) has similar coverage to ampicillin, but it has better oral absorption. Ampicillin can be administered intramuscularly and intravenously, whereas amoxicillin is only available in oral form. Amoxicillin is not used to cover Listeria monocytogenes in patients with meningitis. Ceftriaxone (C) is also part of the empiric regimen in patients with suspected meningitis. Ceftriaxone is a third-generation cephalosporin and provides broad gram-negative coverage. Vancomycin (D) is also part of the empiric regimen in patients with suspected bacterial meningitis. Vancomycin provides broad gram-positive coverage, including methicillin-resistant Staphylococcus aureus.

Which of the following types of pathogens is metronidazole most useful in covering? Anaerobes Fungi Gram-negative enteric pathogens Gram-positive respiratory pathogens

Anaerobes Hint: It is typically used to provide coverage against anaerobes or protozoa. Some of the advantages of using metronidazole include high serum concentrations with oral administration and penetration of the blood-brain barrier. Common clinical uses include treating the following infections: trichomoniasis, bacterial vaginosis, giardiasis, brain abscesses, and Clostridioides difficile colitis infections

Which of the following infections is most often treated with amphotericin B? Aspergillosis Chromoblastomycosis Esophageal candidiasis Tinea capitis

Aspergillosis Hint: Chromoblastomycosis (B) is typically resistant to amphotericin B and is typically treated with itraconazole or terbinafine. Esophageal candidiasis (C) is typically treated with oral fluconazole. Amphotericin B may be used for refractory cases, however, this is an off-label indication for this medication. Tinea capitis (D) is typically treated with griseofulvin. Amphotericin B should be reserved for systemic life-threatening infections and not localized infections.

A 22-year-old woman is seen in the clinic for cough and low-grade fever. She had a gradual onset of malaise, fever, and cough. Cough is productive of scant yellow sputum. She reports associated shortness of breath with the cough and complains of chest soreness. On physical examination, she has a fever of 100.6°F. Lungs are clear to auscultation. A chest radiograph is obtained, which reveals patchy consolidations. You are concerned for pneumonia and would like to choose an antibiotic that provides coverage for Mycoplasma pneumoniae. What is the preferred drug choice for this patient? Amoxicillin Azithromycin Ciprofloxacin Clindamycin

Azithromycin Hint: Amoxicillin (A) is incorrect. Amoxicillin does not provide coverage for atypical pneumonia organisms. Ciprofloxacin (C) is incorrect. Levofloxacin and moxifloxacin are fluoroquinolones that are preferred for upper respiratory infections, but ciprofloxacin does not have good coverage for Streptococcus pneumoniae. Clindamycin (D) is incorrect. Clindamycin does not provide coverage to atypical pneumonia pathogens.

Amphotericin B is best indicated for the treatment of a severe manifestation of which of the following conditions? A) Coccidioidal meningitis B) Disseminated blastomycosis C) Invasive aspergillus D) Oral candidiasis

B) Disseminated blastomycosis Hint: Despite its effective nature in treating a variety of fungal infections, the utility of amphotericin B is hindered by its toxic side effects and it is, therefore, generally reserved for patients diagnosed with severe, life-threatening invasive fungal infections, such as disseminated blastomycosis.

An 8-year-old boy presents with tinea capitis. Which of the following is the recommended first-line treatment? A) Ketoconazole shampoo B) Oral griseofulvin C) Oral itraconazole D) Topical clotrimazole

B) Oral griseofulvin Hint: Griseofulvin is a penicillin derivative used to treat fungal infections caused by Trichophyton spp., Microsporum spp., and Epidermophyton floccosum. Common uses include the treatment of tinea corporis, tinea pedis, tinea cruris, tinea barbae, tinea capitis, and tinea unguium. This medication works by binding to keratin, making it more resistant to fungal infection. The mechanism of action includes inhibition of fungal cell mitosis. Ketoconazole shampoo (A) helps reduce the likelihood of recurrence and may help slow progression of infection, however, this is not effective as a treatment option. Oral itraconazole (C) has been shown to be effective in limited studies, however, there is a greater side effect profile when compared to griseofulvin. More studies are needed before this becomes a more acceptable treatment option. Topical clotrimazole (D) and other topical therapies are not effective since the infection typically involves hair follicles. Topical therapies may miss areas that are infected because of inadequate penetration through the hair.

Which of the following accurately describes bacteriostatic antibiotics? Bacitracin is a bacteriostatic antibiotic Bacteriostatic antibiotics cannot be used to treat urinary tract infections Bacteriostatic antibiotics inhibit bacteria growth Bacteriostatic antibiotics work by killing bacteria

Bacteriostatic antibiotics inhibit bacteria growth Hint: Antibacterial medications are classified as either bacteriostatic or bactericidal. Bacteriostatic agents decrease bacteria reproduction and inhibit growth but do not directly kill bacteria. Bactericidal agents kill bacteria.

Itraconazole is a first-line medication for which of the following conditions? Blastomycosis Cryptococcosis Fusariosis Systemic candidiasis

Blastomycosis Hint: Itraconazole is a triazole antifungal used to treat a variety of mycoses as well as dermatophyte and superficial Candida infections. It is particularly helpful for blastomycosis and histoplasmosis for which it is a first-line medication. This class of medications works by inhibiting ergosterol synthesis which maintains the integrity of the fungal cell membrane. Itraconazole is administered orally with a 55% oral bioavailability and 60-hour elimination half-life with renal, biliary, and fecal routes of excretion. Contraindications to the use of itraconazole include ventricular dysfunction (e.g., congestive heart failure). Multiple drug-drug interactions limit its use; examples of concurrent drugs that contraindicate the use of itraconazole include dofetilide, ergot derivatives, methadone, midazolam, and ticagrelor, among many others. Pregnant women with systemic fungal infections should have serum concentrations monitored closely due to the unpredictable absorption of itraconazole. If possible, alternative medications should be administered for women planning a pregnancy as well as those in the first trimester of pregnancy. Gastrointestinal side effectssuch as nausea, vomiting, diarrhea, and abdominal pain are common with triazole antifungal use. The triad of hypertension, hypokalemia, and peripheral edema has been linked to itraconazole. Similar to other triazole antifungals, itraconazole can result in hepatotoxicity, and liver transaminases should be monitored over the course of therapy.

A 68-year-old, neutropenic patient who is hospitalized and undergoing cancer treatment develops a fever. Which of the following agents would provide coverage against Pseudomonas aeruginosa? A) Azithromycin B) Cefazolin C) Ceftazidime D) Ceftriaxone

C) Ceftazidime Hint: Ceftazidime and cefoperazone are the only third-generation cephalosporins with activity against Pseudomonas aeruginosa. In general, third-generation cephalosporins provide better gram-negative coverage than first- or second-generation cephalosporins and can cross the blood-brain barrier, which allows them to also be used in the treatment of bacterial meningitis. Third-generation cephalosporins are used to treat a variety of infections, including pyelonephritis, pneumonia, gram-negative bacteremia, and meningitis. Ceftazidime is specifically useful due to its coverage of Pseudomonas aeruginosa. In neutropenic patients with severe illness and known or suspected Pseudomonas aeruginosa infection, two agents should be used to provide coverage against Pseudomonas aeruginosa. The typical regimen is a beta-lactam and an aminoglycoside or fluoroquinolone

A 42-year-old woman is diagnosed with mild esophageal candidiasis. Which of the following is the first-line treatment for this infection? A) Intravenous amphotericin B B) Intravenous posaconazole C) Oral fluconazole D) Oral voriconazole

C) Oral fluconazole Fluconazole is an azole antifungal that works by inhibiting the enzyme lanosterol 14-alpha-demethylase from converting to ergosterol. Inhibition of the conversion to ergosterol causes cell membrane dysfunction and cell lysis to occur. Fluconazole is available as an intravenous solution or as an oral formulation. It is used to treat infections caused by endemic mycoses, Cryptococcus spp., and Candida spp. It is most often used to treat candidiasis and cryptococcal meningitis. It is used as first-line therapy in treating esophageal candidiasis due to the low cost andhigh efficacy rates. Since fluconazole is primarily hepatically metabolized, contraindications to using fluconazole include administration to a patient with preexisting liver disease. All azole antifungals carry the risk of causing hepatotoxicity. Intravenous amphotericin B (A) is reserved for patients with drug-resistant infections and infections during pregnancy. The side effect profile and toxicity of the drug makes it a less optimal first-line option. Intravenous posaconazole (B) is not indicated for esophageal candidiasis. The oral formulation of this drug has shown efficacy in treating esophageal candidiasis but is reserved for cases that are refractory to fluconazole therapy. Oral voriconazole (D) is as effective as fluconazole in treating esophageal candidiasis, however, it is used as a second-line treatment option because of the greater side effect profile and the risk of more drug-drug interactions.

Which of the following triazole antifungal agents is the most potent and demonstrates the widest spectrum of activity? A) Fluconazole B) Itraconazole C) Posaconazole D) Voriconazole

C) Posaconazole Hint: The most potent triazole antifungals with the widest spectrum of activity are posaconazole and isavuconazole Fluconazole (A), itraconazole (B), and voriconazole (D) are triazole antifungals that are less potent and have a narrower range of activity than posaconazole. Fluconazole is commonly used for yeast infections while itraconazole is used for aspergillosis, blastomycosis, histoplasmosis, and oral and esophageal candidiasis. Voriconazole is a first-line treatment for invasive aspergillosis.

A 52-year-old man who is undergoing a bone marrow transplant develops invasive aspergillosis for the second time and cannot tolerate treatment with amphotericin B. He is then treated with voriconazole but shows no signs of improvement. Which of the following drugs should be added in addition to voriconazole in cases of refractory invasive aspergillosis? Caspofungin Fluconazole Griseofulvin Terbinafine

Caspofungin Hint: It can also be used as combination therapy with drugs such as amphotericin B and voriconazole for invasive aspergillosis in patients who have failed monotherapy and have refractory cases, such as the patient above. It is also used as empiric therapy for febrile neutropenia

Which of the following is a first-generation, parenteral cephalosporin? Cefazolin Cefepime Ceftriaxone Cefuroxime

Cefazolin Hint: There are two oral first-generation cephalosporins currently available in the United States: cephalexin and cefadroxil. The only parenteral first-generation cephalosporin currently available is cefazolin.

A 29-year-old pregnant woman presents to the emergency department complaining of severe right lower quadrant pain. Abdominopelvic ultrasound reveals a healthy fetus at 8 weeks gestation and an inflamed, noncompressible appendix measuring 7 mm in diameter with no sign of rupture. In addition to metronidazole, which of the following antibiotics is the best choice for perioperative prophylaxis in this patient? Cefepime Cefoxitin Clindamycin Vancomycin

Cefoxitin Hint: Cefoxitin is a parenteral second-generation cephalosporin antibiotic indicated for use in perioperative prophylaxisof surgical wound infection. Cefoxitin has good activity against gram-positive organisms, including methicillin-susceptible Staphylococcus aureus, as well as good activity against Enterococcus. Cefoxitin is indicated for the prevention of surgical infection for the following procedures: appendectomy, biliary tract surgery, small intestine surgery, colorectal surgery, and hysterectomy Cefoxitin is pregnancy category B and is safe for use in pregnant and nursing women

A 28-year-old woman presents to the clinic complaining of a sore spot on her arm for one week. On exam, there is an erythematous, tender, 3 cm pustule on the extensor surface of her lower arm with regional lymphadenopathy. The pustule is draining, and a culture of the fluid reveals gram-positive cocci in clusters. Which of the following antibiotics is the best choice for this patient, who has no known drug allergies? Cefepime Cephalexin Ciprofloxacin Clarithromycin

Cephalexin Hint: The patient in the above vignette has a skin infection due to gram-positive organisms, most likely Staphylococcus aureus. For most skin and skin structure infections, beta-lactam antibiotics are appropriate first-line treatment choices. The cephalosporins, as a class, are antibiotics with a beta-lactam ring that are developed from the fungus Cephalosporium. Five generations of cephalosporins exist. First-generation cephalosporins include cephalexin, cefadroxil, and cefazolin. These agents have good activity against most gram-positive organisms but poor activity against most gram-negative organisms. Cefepime (A) is a fourth-generation parenteral cephalosporin with moderate activity against gram-positive organisms and good activity against gram-negative organisms. For this reason, and for ease of administration and better cost profile, cephalexin is a better choice for the patient in the above vignette. Ciprofloxacin (C) is a fluoroquinolone with good activity against gram-negative bacteria. Ciprofloxacin is indicated in the treatment of lower urinary tract infections, abdominal infections, bacterial sinusitis, infectious diarrhea, chronic bacterial prostatitis, bone and joint infections, gonococcal infections, nosocomial pneumonia, anthrax, and plague. Ciprofloxacin can also be used to treat skin and skin structure infections, but a cephalosporin is a better choice for the patient above. Potentially serious side effects of ciprofloxacin include tendonitis, tendon rupture, peripheral neuropathy, and central nervous system effects. Clarithromycin (D) is a macrolide antibiotic used primarily for the treatment of Helicobacter pylori infection, mycobacterial infection, acute maxillary sinusitis, and exacerbation of chronic bronchitis. Clarithromycin may also be used for tonsillitis, skin and skin structure infections, and community-acquired pneumonia

Gray baby syndrome is a condition that results when there is toxicity from which of the following antibiotics? Chloramphenicol Daptomycin Linezolid Tigecycline

Chloramphenicol Hint: Chloramphenicol should not be used to treat infants due to the risk of developing chloramphenicol toxicity or "gray baby syndrome." Due to the inability of the neonatal kidneys and liver to excrete chloramphenicol and its metabolites, vasomotor collapse can occur resulting in a gray discoloration of the skin. The infant may present with lethargy, gray cyanosis, pallor, and abdominal distention and tenderness. It can also develop from maternal exposure during pregnancy and lactation due to its ability to cross the placenta and enter the breast milk. Gray baby syndrome is fatal if left untreated. This syndrome is preventable, since there are other antibiotics that can be used instead if needed

A 60-year-old woman presents to the emergency department with flank pain, dysuria, and fever. She has costovertebral angle tenderness on exam. Which of the following is the best empiric antibiotic for this condition? Amoxicillin Ciprofloxacin Fosfomycin Nitrofurantoin

Ciprofloxacin Hint: Fluoroquinolones are a broad-spectrum class of bactericidal antibiotics Amoxicillin (A) should not be used as a first- or second-line agent in the treatment of urinary tract infections. Fosfomycin (C) is one of the first-line agents in the treatment of acute cystitis. It can be administered as a single dose, however, it cannot be used to treat pyelonephritis as it does not achieve adequate tissue levels outside of the bladder. Nitrofurantoin (D) is another first-line agent for cystitis. It also cannot be used for pyelonephritis because like fosfomycin it does not achieve adequate tissue levels outside of the bladder.

A 23-year-old otherwise healthy woman presents with right calf pain after playing soccer earlier today. She is diagnosed with an Achilles tendon rupture. She exercises regularly and has been playing soccer every week for several years. She had a urinary tract infection a few weeks ago and was prescribed an antibiotic for seven days. Which of the following antibiotics is associated with tendon ruptures? Amoxicillin-clavulanate Azithromycin Ciprofloxacin Doxycycline

Ciprofloxacin Hint: Fluoroquinolones have several black box warnings because they are associated with tendonitis and tendon rupture, peripheral neuropathy, and central nervous system effects (e.g., hallucinations, insomnia, convulsions, psychosis, confusion, anxiety, and depression). Other serious side effects include renal impairment, hypoglycemia, phototoxicity, retinal detachment, and Clostridioides difficile-associated diarrhea

A 45-year-old man with a history of HIV and severe sulfa allergy presents with productive cough and dyspnea for three weeks. His CD4 count is 150 cells/m3. A chest X-ray shows bilateral infiltrates. Which of the following is the most appropriate therapy in addition to primaquine? Clarithromycin Clindamycin Telithromycin Trimethoprim-sulfamethoxazole

Clindamycin Hint: Clarithromycin (A) is a macrolide derived from erythromycin by the addition of a methyl group. It inhibits bacterial protein synthesis by binding to the 50S ribosomal RNA. Clarithromycin, like erythromycin, is active against strains of gram-positive organisms (pneumococci, streptococci, staphylococci, and corynebacteria), atypical bacteria (Mycoplasma pneumoniae, Chlamydia trachomatis, C. psittaci), mycobacteria (Mycobacterium kansasii, M scrofulaceum), and gram-negative organisms (Neisseria, Bartonella henselae, Bordetella pertussis). Clarithromycin is more active against Mycobacterium avium complex than erythromycin. Telithromycin (C) is a ketolide, a semisynthetic derivative of erythromycin. Telithromycin has limited clinical use and is active against Streptococcus pyogenes, S.pneumoniae, Staphylococcus aureus, Moraxella catarrhalis, and several macrolide-resistant strains. Improved activity of telithromycin against macrolide-resistant strains is due to the structural modification that renders it a poor substrate for efflux pump-mediated resistance. Trimethoprim-sulfamethoxazole (D) is a synergy between trimethoprim, which inhibits enzymes of the folic acid pathway, and sulfamethoxazole, which disrupts bacterial folic acid production and growth. Trimethoprim-sulfamethoxazole is effective in treating a variety of infections, including shigellosis, systemic salmonella infections, urinary tract infections, prostatitis, and some nontuberculous mycobacterial infections. It is considered a first-line agent for treating P. jiroveci pneumonia in a patient with HIV. However, the patient in the vignette has a severe sulfa drug allergy, which is a contraindication to its use.

25-year-old man presents to the emergency department after a dog bit his hand while he was walking in the park. Since he has a penicillin allergy, he is prescribed oral clindamycin and told to follow up at the wound clinic in 24-48 hours. Which of the following is a black box warning for clindamycin? Anaphylaxis Clostridioides difficile-associated diarrhea Stevens-Johnson syndrome Thrombocytopenia

Clostridioides difficile-associated diarrhea

A 62-year-old woman, who was recently treated with steroids for an asthma exacerbation, presents with mild thrush. Which of the following treatment options would be best? Clotrimazole troches Itraconazole capsules Nystatin suspension Oral fluconazole

Clotrimazole troches Hint: Itraconazole capsules (B) should not be used for the treatment of oropharyngeal candidiasis. The capsules are less effective than itraconazole solution due to the variability in the absorption rate. Nystatin suspension (C) is an acceptable treatment option but has been shown to have inferior rates of efficacy compared with oral clotrimazole. Oral fluconazole (D) is typically reserved for more advanced cases of oropharyngeal candidiasis. For mild cases of thrush, oral clotrimazole is the preferred treatment. Oral fluconazole carries the risks of QT prolongation and hepatotoxicity.

A 19-year-old man, currently in college, presents to the emergency department, brought by his roommate, for high fever and confusion. He had been reporting a headache and neck discomfort prior to becoming altered. You obtain past medical history from the patient's mother over the phone, who reveals that he was never vaccinated. On physical examination, he is photophobic, toxic-appearing, and febrile to 102.7°F. He is not oriented to place and is generally slow to respond. Nuchal rigidity is noted. He has positive Kernig and Brudzinski signs. You suspect bacterial meningitis. In addition to beginning vancomycin, which other antibiotic would be appropriate to administer empirically? A) Ampicillin B) Cefazolin C) Ceftazidime D) Ceftriaxone

D) Ceftriaxone Hint: Ceftriaxone is an appropriate antibiotic to administer in the treatment of bacterial meningitis. Ceftriaxone is a third-generation cephalosporin antibiotic. It works to inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins. It has good penetration throughout the body, particularly in the cerebrospinal fluid. It is broad-spectrum, covering gram-positive and gram-negative pathogens. Its indications include bacteremia, osteomyelitis and other joint infections, Neisseria gonorrhoeae (treatment of choice), intra-abdominal infections, community-acquired pneumonia, otitis media, bacterial meningitis, pelvic inflammatory disease, complicated cystitis, and surgical prophylaxis. It is available in intramuscular and intravenous forms. Side effects include eosinophilia, diarrhea, thrombocythemia, increased transaminases, and potential anaphylaxis/hypersensitivity reaction. It is considered pregnancy category B and is used to treat pregnant women with Neisseria gonorrhoeae and Lyme disease. Ceftriaxone should not be given with any calcium-containing solutions in neonates as it can result in lung and kidney damage, as well as hyperbilirubinemia.

A 25-year-old man presents to the clinic for testing. He states he has been involved with high-risk sexual behavior and wants to be tested "for everything." A rapid plasma reagin is positive and is confirmed with a fluorescent treponemal antibody absorption. He has no known allergies. Which of the following is the first-line treatment for this diagnosis? A) Azithromycin B) Ceftriaxone C) Doxycycline D) Penicillin G

D) Penicillin G Hint: Penicillin G is in the penicillin family of drugs and is the first-line treatment for syphilis. It is a beta-lactam antibiotic. Beta-lactam antibiotics inhibit bacterial growth through inactivating enzymes involved in cell wall synthesis. Azithromycin (A) should only be used if there is documented resistance or failure of the other available treatments. The beta-lactam antibiotics are typically more effective at treating syphilis. Ceftriaxone (B) is effective but not preferred due to the multiple intravenous doses or intramuscular injections that are required over 10 to 14 days. Doxycycline (C) is also effective, but the dosing schedule makes it less optimal. The dosing for doxycycline is twice daily for 14 days, which decreases potential compliance and increases treatment failure rates.

Which of the following antibiotics may be responsible for tooth discoloration in pediatric patients? Azithromycin Ceftriaxone Doxycycline Metronidazole

Doxycycline Hint: The tetracycline class of antibiotics has also been associated with tooth discoloration and abnormalities in bone development when used in children less than 8 years of age. In pregnant women, there is risk of abnormal teeth discoloration and growth or bone development in the fetus.

Cephalexin is indicated for the treatment of which of the following infections? Ecthyma Intra-abdominal abscess Neisseria meningitidis infection Traveler's diarrhea

Ecthyma Hint: Cephalexin is indicated in the treatment of impetigo and ecthyma, which are generally caused by the gram-positive organism Staphylococcus aureus. Off-label indications for cephalexin usage include endocarditis prophylaxis and joint infections. Cephalexin can also be used as an alternative agent in the treatment of cellulitis, erysipelas, cystitis, and streptococcal pharyngitis

Which of the following is inhibited by the antifungal fluconazole? Beta(1,3)-D-glucan production Cell mitosis Ergosterol production Lanosterol 14-alpha-demethylase production

Ergosterol production Hint: Echinocandins inhibits the synthesis of beta(1,3)-D-glucan (A). Griseofulvin is an antifungal that works by inhibitingfungal cell mitosis (B). Fluconazole does not inhibit lanosterol 14-alpha-demethylase (D) but prevents it from converting to ergosterol.

Which of the following conditions would penicillin V potassium most commonly be prescribed to treat? Actinomycosis Animal bite wound Erysipelas Urinary tract infection

Erysipelas Hint: Penicillin V potassium is a derivative of penicillin G, however, it is more stable in acidic environments, which allows it to be dosed orally, whereas penicillin G is for parenteral use only.This medication is active against gram-positive and gram-negative cocci, as well as most anaerobes and gram-positive rods. Currently, labeled indications for penicillin V potassium include fusospirochetosis, pneumococcal infections, rheumatic fever, and staphylococcal and streptococcal infections (including erysipelas)

A 65-year-old man presents with multiple episodes of foul-smelling watery diarrhea that started three days ago, accompanied by severe cramping abdominal pain, nausea, anorexia, and low-grade fever. He was treated with clindamycin two weeks ago for left lower leg cellulitis. Toxigenic culture for Clostridioides difficile is positive for both toxin and organism. Which of the following macrolides is the preferred agent for treating this patient? Azithromycin Clarithromycin Erythromycin Fidaxomicin

Fidaxomicin Hint: Azithromycin (A), clarithromycin (B), and erythromycin (C), like fidaxomicin, are macrolides. They are often active against gram-positive organisms (especially pneumococci, streptococci, staphylococci, and corynebacteria), atypical organisms (Mycoplasma, Chlamydia), mycobacteria, and gram-negative organisms (Neisseria spp., Bordetella pertussis, Bartonella henselae, and Haemophilus influenzae). Azithromycin is highly active against Chlamydia spp. and can be used to treat sexually transmitted infections caused by Chlamydia. Clarithromycin has more activity against Mycobacterium avium complex than erythromycin. Erythromycin is used traditionally in the treatment of corynebacterial infections (diphtheria, Corynebacterium sepsis, erythrasma) and respiratory, neonatal, ocular, or genital chlamydial infections. Unlike fidaxomicin, these macrolides do not have coverage against Clostridioides difficile, and as a result, they cannot be used to treat the patient in the vignette above.

Which of the following medications should be administered with amphotericin B to treat severe cryptococcal meningitis? Anidulafungin Fluconazole Flucytosine Voriconazole

Flucytosine Hint: Anidulafungin (A) is an echinocandin used to treat systemic and subcutaneous Candida infections such as esophageal or invasive candidiasis. It is not effective in the treatment of cryptococcal meningitis. Fluconazole (B) is a triazole antifungal commonly used to treat dermatophyte and Candida infections. While it does have activity against Cryptococcus neoformans, the pathogen responsible for cryptococcal meningitis, it is not used in conjunction with amphotericin B and is instead used as a monotherapy after the induction phase of treatment. This treatment is known as consolidation therapy. Additionally, it is not the first-line regimen for severe cases of this disease. A second-generation triazole, voriconazole (D) has increased utility against invasive aspergillosis, esophageal candidiasis, and invasive candidiasis compared to other triazole antifungals. This medication is not appropriate for the treatment of cryptococcal meningitis.

A 23-year-old man who is HIV-positive and taking a daily dose of trimethoprim-sulfamethoxazole presents with macrocytic anemia. Which of the following is a side effect of this antibiotic that may cause his anemia? Folate deficiency Hemolysis Vitamin B12 deficiency Vitamin D deficiency

Folate deficiency Hint: Adverse effects include anorexia, nausea, vomiting, vertigo, seizure, peripheral neuritis, erythema multiforme, hyperkalemia, rash, urticaria, renal insufficiency, hyperkalemia, hyponatremia, and folate deficiency (which can manifest as macrocytic anemia). More serious reactions include Stevens-Johnson syndrome, toxic epidermal necrolysis, agranulocytosis, aplastic anemia, and, rarely, hepatic necrosis

A 29-year-old woman presents to the office with concerns regarding burning sensation when urinating. She has been experiencing dysuria for the past two days. She notes going to the bathroom more often and more urgently. She is afebrile. On physical examination, she has suprapubic tenderness but no costovertebral angle tenderness. She is not pregnant and has no known allergies. Which of the following drug choices would be appropriate to initiate in this patient Amoxicillin-clavulanate 500 mg orally twice daily for five days Ciprofloxacin 250 mg orally twice daily for three days Ertapenem 1 g intramuscular injection for one dose Fosfomycin 3 g orally for one dose

Fosfomycin 3 g orally for one dose Hint: Fosfomycin is an appropriate antibiotic choice for patients presenting with acute uncomplicated (simple) cystitis. Amoxicillin-clavulanate (A) is incorrect. Amoxicillin with clavulanic acid is appropriate for uncomplicated cystitis if patients cannot take one of the first-line agents (nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin). Ciprofloxacin (B) is incorrect. Ciprofloxacin should only be used for uncomplicated cystitis if a patient cannot take any of the first-line drugs or a second-line beta-lactam. Ertapenem (C) is incorrect. Ertapenem can be used for complicated cystitis.

Which of the following aminoglycosides has the least potent activity against Enterobacteriaceae? Amikacin Gentamicin Plazomicin Tobramycin

Gentamicin

Which of the following side effects is most commonly associated with the administration of oral fluconazole? Elevated liver function enzymes Headache Nausea QT prolongation

Headache Hint: The most common side effect associated with fluconazole is headache. Other side effects include dizziness, skin rash, nausea, and abdominal pain. Serious side effects, such as QT prolongation or hepatic dysfunction, can occur with the administration of fluconazole, however, these occur less commonly

Which of the following disease processes is the use of miconazole indicated for? Aspergillosis Oropharyngeal candidiasis Seborrheic dermatitis Tinea capitis

Hint: Miconazole is an azole antifungal. It is an imidazole derivative. The mechanism of action of this medication is inhibition of the biosynthesis of ergosterol which leads to damage of the fungal cell wall membrane. It is most often used to treat a variety of candidal infections (including oropharyngeal candidiasis), however, it can be used topically to treat other fungal infections such as tinea corporis, cruris, and pedis Aspergillosis (A) is typically treated with voriconazole if a monotherapy regimen is selected. Seborrheic dermatitis (C) is managed with topical ketoconazole as a first-line therapy. Tinea capitis (D) is typically treated with an oral antifungal, such as griseofulvin, since topical treatments are difficult to apply to the scalp.

A 66-year-old man presents to the clinic with severe diarrhea. He was treated with clindamycin during a recent hospitalization. Stool studies show that a toxin-producing organism is causing the infection. Which of the following is the best treatment for the most likely diagnosis? Ciprofloxacin Intravenous vancomycin Metronidazole Oral vancomycin

Hint: clostridioides difficile is an anaerobic and gram-positive bacillus bacterium that is spore-forming, toxin-producing, and can colonize and infect the human intestinal tract after antibiotic therapy has altered the normal gut flora. Ciprofloxacin (A) is a fluoroquinolone antibiotic. Fluoroquinolones are one of the most likely antibiotic classes to cause Clostridioides difficile infection and are not used in the treatment of Clostridioides difficile infection. Metronidazole (C) is an antibiotic that is considered a second-line agent for Clostridioides difficile infection. Patients with fulminant Clostridioides difficile infection are treated with oral vancomycin and parenteral metronidazole. However, oral vancomycin is first-line treatment for both nonsevere and severe Clostridioides difficile infection. Intravenous vancomycin (B) has no effect on Clostridioides difficile colitis since the antibiotic is not excreted appreciably into the colon during the short course of antibiotic administration.

A 21-year-old man with history of primary generalized epilepsy is admitted to the hospital for recurrent urinary tract infections. He was evaluated by his primary care provider for flank pain and fever. He was given ciprofloxacin in the outpatient setting, but his condition worsened. His urine culture reveals Enterococcus faecalis resistant to multiple drug therapies, including vancomycin. Sensitivity revealed susceptibility to carbapenem antibiotics. Which of the following carbapenem antibiotics has an increased risk of lowering the seizure threshold? Doripenem Ertapenem Imipenem Meropenem

Imipenem Hint: Imipenem is known to cause a decrease in the seizure threshold and should not be used in individuals with a history of seizures or those at high risk of seizure. Imipenem is a carbapenem antibiotic with a broad spectrum of antibiotic activity. It is effective against gram-negative bacteria such as Haemophilus influenzae, Neisseria gonorrhoeae, and Pseudomonas aeruginosa. It is also effective against anaerobic bacteria and gram-positive organisms (Enterococcus faecalis and Listeria monocytogenes). Indications include bacterial septicemia, bone and joint infections, gynecologic and intra-abdominal infections, skin and soft tissue infections, and complicated urinary tract infections

A 16-year-old boy presents with multiple round patches with central clearing and raised scaly borders that appeared a few days ago on his upper torso. He is on the wrestling team at his high school. He is prescribed naftifine 1% cream. Which of the following best describes the mechanism of action of this drug? Inhibition of fungal mitosis Inhibition of glucan synthase Inhibition of squalene epoxidase Inhibition of sterol demethylase

Inhibition of squalene epoxidase Hint: Naftifine is a drug in the class of allylamine antifungals, and although its exact mechanism of action is unknown, it appears to work by inhibiting an enzyme called squalene epoxidase, which interferes with sterol biosynthesis in the fungal cell wall

A 56-year-old man diagnosed with esophageal candidiasis is given an infusion of caspofungin intravenously. Which of the following best describes the mechanism of action of this drug? Inhibits fungal cell wall synthesis Inhibits fungal mitosis Inhibits fungal nucleic acid synthesis Inhibits fungal plasma membrane stability

Inhibits fungal cell wall synthesis Hint: Inhibition of fungal mitosis (B) is the mechanism of action of griseofulvin, which is used to treat dermatophytosis. Inhibition of fungal nucleic acid synthesis (C) is the mechanism of action of flucytosine, an antifungal that is used to treat serious Candida and Cryptococcus infections. Inhibition of fungal plasma membrane stability (D) is the mechanism of action of amphotericin B, which causes fungal cell death by forming pores in the cell membrane.

A 33-year-old man with extensive, persistent tinea corporis returns to the clinic after failing topical antifungal treatment. He is given a prescription for griseofulvin. Which of the following best describes the mechanism of action of this drug? Inhibits fungal cell wall synthesis Inhibits fungal mitosis Inhibits fungal nucleic acid synthesis Inhibits fungal plasma membrane stability

Inhibits fungal mitosis Hint: Inhibition of fungal cell wall synthesis (A) is the mechanism of action of echinocandins, such as caspofungin, that specifically inhibit the enzyme glycan synthase. Inhibition of fungal nucleic acid synthesis (C) is the mechanism of action of flucytosine, an antifungal that is used to treat serious Candida and Cryptococcus infections. Inhibition of fungal plasma membrane stability (D) is the mechanism of action of amphotericin B, which causes fungal cell death by forming pores in the cell membrane.

An 8-year-old girl with a history of asthma presents with white patches on her tongue that began two days ago. She uses an inhaler daily to control her asthma. On physical exam, the patches are easily scraped off. She is prescribed nystatin oral suspension. Which of the following best describes the mechanism of action of this drug? Inhibits fungal cell wall synthesis Inhibits fungal mitosis Inhibits fungal nucleic acid synthesis Inhibits fungal plasma membrane stability

Inhibits fungal plasma membrane stability Hint: Nystatin is a drug in the class of polyene antifungals, which work by binding to sterols in the fungal plasmamembranes, causing membrane instability Inhibition of fungal cell wall synthesis (A) is the mechanism of action of echinocandins, such as caspofungin, which is used to treat Candida infections and aspergillosis. Inhibition of fungal mitosis (B) is the mechanism of action of griseofulvin, which is used to treat dermatophytosis. Inhibition of fungal nucleic acid synthesis (C) is the mechanism of action of flucytosine, an antifungal that is used to treat serious Candida and Cryptococcus infections.

Which of the following best describes the mechanism of action of ketoconazole? Binds to ergosterol altering cell membrane permeability Inhibits fungal cell mitosis Inhibits the conversion from lanosterol to ergosterol Inhibits the synthesis of beta(1,3)-D-glucan

Inhibits the conversion from lanosterol to ergosterol Hint: Amphotericin B binds to ergosterol altering cell membrane permeability (A) and eventually causes cell lysis and death. Griseofulvin is a penicillin derivative that inhibits fungal cell mitosis (B). Caspofungin is an echinocandin that inhibits the synthesis of beta(1,3)-D-glucan (D).

A 23-year-old man is diagnosed with bacterial pneumonia and is prescribed a fluoroquinolone. Which of the following is the mechanism of action for this drug class? Interferes with bacterial cell membrane synthesis Interferes with bacterial protein synthesis Interferes with DNA replication Interferes with RNA synthesis

Interferes with DNA replication Hint: Interferes with bacterial cell membrane synthesis (A) is incorrect because this is the mechanism of action of antibiotics such as penicillin and cephalosporins. Interferes with bacterial protein synthesis (B) is incorrect because this is the mechanism of action of antibiotics such as tetracyclines and aminoglycosides. Interferes with RNA synthesis (D) is incorrect because this is the mechanism of action of rifampin.

A 23-year-old man is prescribed minocycline for acne vulgaris after multiple failed topical treatments. Which of the following is the mechanism of action of this medication? Interferes with bacterial cell membrane synthesis Interferes with bacterial DNA synthesis Interferes with bacterial protein synthesis Interferes with bacterial RNA synthesis

Interferes with bacterial protein synthesis Hint: Interferes with bacterial cell membrane synthesis (A) is incorrect because this is the mechanism of action of antibiotics such as penicillin and cephalosporins. Interferes with bacterial DNA synthesis (B) is incorrect because this is the mechanism of action of fluoroquinolones and metronidazole. Interferes with bacterial RNA synthesis (D) is incorrect because this is the mechanism of action of rifampin.

A 33-year-old man is prescribed neomycin to take orally before he undergoes a colon surgery. Which of the following describes the mechanism of action of this drug? Interferes with bacterial cell membrane synthesis Interferes with bacterial DNA synthesis Interferes with bacterial protein synthesis Interferes with bacterial RNA synthesis

Interferes with bacterial protein synthesis Hint: Interferes with bacterial cell membrane synthesis (A) is incorrect because this is the mechanism of action of antibiotics such as penicillin and cephalosporins. Interferes with bacterial DNA synthesis (B) is incorrect because this is the mechanism of action of fluoroquinolones and metronidazole. Interferes with bacterial RNA synthesis (D) is incorrect because this is the mechanism of action of rifampin.

Which of the following is the mechanism of action of erythromycin? Interferes with bacterial cell wall synthesis Interferes with bacterial DNA synthesis Interferes with bacterial protein synthesis Interferes with mycolic acid synthesis

Interferes with bacterial protein synthesis Hint: Interferes with bacterial cell wall synthesis (A) is incorrect because this is the mechanism of action of penicillins and cephalosporins. Interferes with bacterial DNA synthesis (B) is incorrect because this is the mechanism of action of fluoroquinolones. Interferes with mycolic acid synthesis (D) is incorrect because this is the mechanism of action of isoniazid.

What is the mechanism of action of sulfonamides? Interferes with bacterial cell wall synthesis Interferes with folic acid synthesis Interferes with mycolic acid synthesis Interferes with protein synthesis

Interferes with folic acid synthesis Hint: Sulfonamides are a class of bacteriostatic antibiotics that work by inhibiting folic acid synthesis, which bacteria need to synthesize DNA Interferes with bacterial cell wall synthesis (A) is incorrect because this is the mechanism of action of antibiotics such as penicillins and cephalosporins. Interferes with mycolic acid synthesis (C) is incorrect because this is the mechanism of action of isoniazid. Interferes with protein synthesis (D) is incorrect because this is the mechanism of action of fluoroquinolones and metronidazole.

Anidulafungin is an appropriate treatment for which of the following conditions? Blastomycosis Coccidioidomycosis Cryptococcal meningitis Invasive candidiasis

Invasive candidiasis Hint: Anidulafungin is approved for the treatment of invasive candidiasis, esophageal candidiasis, and other systemic and subcutaneous forms of Candida infections. Additionally, this and other echinocandins can be used in combination with voriconazole for the initial treatment of invasive aspergillosis or with lipid-formulation amphotericin B for salvage therapy of this condition

A 40-year-old woman has histoplasmosis and is being treated with an antifungal drug. After weeks of therapy, she develops adrenal insufficiency. Which of the following drugs is associated with adrenal insufficiency? Fluconazole Itraconazole Ketoconazole Voriconazole

Ketoconazole

Which of the following is the first-line treatment for tinea versicolor? Fluconazole Griseofulvin Ketoconazole Zinc supplements

Ketoconazole Hint: Fluconazole (A) is typically used in the treatment of candidiasis. It is not available in topical formulations and, therefore, is not indicated in the treatment of tinea versicolor. Griseofulvin (B) is an oral formulation that is most often used to treat tinea infections. It is most often used for tinea capitis since topical applications are not amenable to the scalp. Zinc supplements (D) are not a treatment for tinea versicolor however zinc pyrithione is an option for the treatment of tinea versicolor.

Against which of the following pathogens is aztreonam effective? Actinomyces israelii Bacteroides fragilis Klebsiella pneumoniae Stenotrophomonas maltophilia

Klebsiella pneumoniae Hint: Actinomyces israelii (A) is incorrect. A. israelii is a gram-positive rod and thus is not susceptible to monobactam antibiotics. Bacteroides fragilis (B) is incorrect. While B. fragilis is a gram-negative rod, it is an obligate anaerobe and, thus, is not susceptible to aztreonam. Stenotrophomonas maltophilia (D) is incorrect. S. maltophilia is a gram-negative rod but is resistant to multiple antibiotics, including aztreonam. Because of this, trimethoprim-sulfamethoxazole is the drug of choice.

Which of the following conditions is dicloxacillin most commonly used to treat? Erysipelas Lactational mastitis Streptococcal pharyngitis Urinary tract infection

Lactational mastitis Hint: Dicloxacillin is mostly active against penicillinase-producing staphylococci, which is the labeled indication for this drug's use, in contrast to other penicillins that are not effective against Staphylococcus aureus. Currently, it is used to treat skin and soft tissue infections and is commonly used to treat lactational mastitis Erysipelas (A) is caused by beta-hemolytic Streptococcus and not penicillinase-producing staphylococci. The most appropriate first-line treatment for erysipelas is oral or intravenous penicillin. Streptococcal pharyngitis (C) is caused by Streptococcus pyogenes not staphylococci, therefore, the first-line treatment is penicillin. Urinary tract infections (D) can be caused by a host of varying organisms or sometimes multiple organisms at once, however, dicloxacillin is not often recommended for treatment since the most common causative organism is E. coli.

What would be the preferred drug choice for Enterococcus infections that are resistant to vancomycin? Chloramphenicol Linezolid Oritavancin Quinupristin-dalfopristin

Linezolid Hint: Linezolid is approved by the FDA for the treatment of vancomycin-resistant Enterococcusinfections. Linezolid is active against both Enterococcus faecium and Enterococcus faecalis. Linezolid is effective in the treatment of urinary tract infections, bacteremia, and meningitis that are caused by vancomycin-resistant Enterococcus

Which of the following best describes the minimum inhibitory concentration of a drug? Ability of the drug to kill bacteria within a serum sample Concentration of the drug that kills an organism Diameter of the zone of inhibition Lowest concentration of the drug that will slow organism growth

Lowest concentration of the drug that will slow organism growth Hint: Ability of the drug to kill bacteria within a serum sample (A) is the serum bactericidal activity test. This test is often helpful in patients with endocarditis to assess whether a drug will be effective or not. Concentration of the drug that kills an organism (B) is the minimum bactericidal concentration. This test is done by taking the solution from the tubes used in the minimum inhibitory concentration assay, plating them and then incubating the plates to demonstrate the concentration of the drug that kills bacteria and does not allow any growth. Diameter of the zone of inhibition (C) is a method of measuring antibiotic effectiveness that is done by the disk diffusion method. Disks that contain antibiotics are plated with bacteria. The zones around the antibiotic disks that do not grow bacteria are measured, and these are the zones of inhibition used to create antibiotic sensitivity results.

A 24-year-old man with diabetes mellitus presents with a fever, nuchal rigidity, and altered mentation. He was diagnosed with malignant otitis externa a week ago and was started on antibiotic therapy. He did not take medication as directed because he could not afford it. Physical exam reveals positive Kernig and Brudzinski signs. The cerebrospinal fluid analysis shows elevated WBCs, increased protein, and reduced glucose. Gram stain of cerebrospinal fluid demonstrates motile gram-negative rods. Which of the following agents is most likely to be effective based on the most likely causative organism? Cefazolin Cefuroxime Fosfomycin Meropenem

Meropenem Hint: Cefazolin (A) is a first-generation cephalosporin that has strong activity against gram-positive cocci including staphylococci and streptococci. However, it has poor activity against P. aeruginosa and, hence, will not be effective in treating the patient in the vignette. Cefuroxime (B), a second-generation cephalosporin, has activity against Klebsiellaspp. and has extended gram-negative coverage. It can be used to treat community-acquired pneumonia. Although it crosses the blood-brain barrier, it is not effective in treating meningitis, especially that caused by P. aeruginosa and, thereby, should not be used in this patient. Fosfomycin (C) is a bacterial cell wall synthesis inhibitor. It is active against gram-positive and gram-negative organisms. The active drug is excreted by the kidneys, with urinary concentration exceeding minimum inhibitory concentrations for most urinary tract pathogens. Thus, it is very effective for treating uncomplicated urinary tract infections caused by Pseudomonas aeruginosa, Klebsiella spp., Proteus spp., or Escherichia coli. It does not have activity against Acinetobacter.

Which of the following fluoroquinolones has increased activity against gram-positive organisms, particularly Streptococcus pneumoniae? Ciprofloxacin Enoxacin Moxifloxacin Norfloxacin

Moxifloxacin Hint: Moxifloxacin is a fluoroquinolone that inhibits DNA gyrase and topoisomerase II and IV, bacterial enzymes that are essential for maintaining the superhelical structure of DNA. Moxifloxacin has an improved activity against gram-positive organisms (particularly Streptococcus pneumoniae and Staphylococcus). It may also have some gram-negative coverage but is not as active as ciprofloxacin Ciprofloxacin (A) and enoxacin (B) have excellent gram-negative activity and moderate to good activity against gram-positive organisms. Additionally, they have good coverage against methicillin-susceptible Staphylococcus aureus but not methicillin-resistant S. aureus. Ciprofloxacin is particularly effective against Pseudomonas aeruginosa. Norfloxacin (D)is the least active of the fluoroquinolones against both gram-positive and gram-negative organisms. Its minimum inhibitory concentration (i.e., the lowest concentration of the drug needed to prevent visible growth of microorganisms) is approximately four- to eightfold higher than those of ciprofloxacin

Which of the following beta-lactam antibiotics provides coverage against beta-lactamase-producing Staphylococcus aureus? Amoxicillin Nafcillin Penicillin V Vancomycin

Nafcillin Hint: Amoxicillin (A) and penicillin V (C) are not resistant to beta-lactamase. Vancomycin (D) is not a beta-lactam antibiotic. However, vancomycin is frequently used to provide empiric coverage against methicillin-resistant Staphylococcus aureus.

For which of the following conditions is the antifungal nystatin commonly prescribed? Aspergillosis Candidemia Tinea corporis

Oropharyngeal candidiasis Hint: It is used to treat oropharyngeal candidiasis and intestinal candidiasis and is taken orally as a "swish and spit" or "swish and swallow" solution. It is also used to treat vulvovaginal candidiasis and cutaneous candidiasis.

An 80-year-old man presents to the emergency department with lethargy and altered mental status. He is found to have a urinary tract infection caused by Pseudomonas aeruginosa and is started on an aminoglycoside. Which of the following side effects is associated with this class of medications? Ototoxicity Peripheral neuropathy Tendon rupture Thrombocytopenia

Ototoxicity Hint: Side effects of aminoglycosides include renal toxicity, which can be reversible, and vestibular and auditory toxicity, which is often irreversible. Vestibular damage manifests as vertigo and ataxia

A 28-year-old woman presents to the office with concerns of increased vaginal discharge. She describes it as thin, milky discharge with a fishy odor. She denies dysuria, dyspareunia, or vaginal irritation. She has a positive whiff-amine test and clue cells are noted on wet mount. What patient education is important to provide the patient when prescribing her the preferred treatment for her condition? It has not been associated with Stevens-Johnsons syndrome It is safe to use with disulfiram Patients must avoid drinking alcohol while taking the medication Patients often report a fruity taste while taking the medicine

Patients must avoid drinking alcohol while taking the medication Hint: Patients taking metronidazole should be instructed to avoid concurrent ingestion of alcohol and propylene glycol as it can result in disulfiram-like reactions

A patient is administered caspofungin for the treatment of esophageal candidiasis. Which of the following adverse reactions should the patient be made aware of prior to administration? Alopecia Cardiac dysrhythmias Nephrotoxicity Phlebitis at the infusion site

Phlebitis at the infusion site

A 24-year-old man is diagnosed with Chlamydia trachomatis infection. He has an allergy to macrolides. He is prescribed doxycycline. Which of the following side effects is consistent with this drug? Acute kidney injury Muscle cramping Peripheral neuropathy Photosensitivity

Photosensitivity

A 22-year-old man who is otherwise healthy presents to the emergency department with 48 hours of right lower quadrant abdominal pain associated with nausea and vomiting. On exam, he is tender to palpation at McBurney point. CT of the abdomen and pelvis shows a fluid collection in the right lower quadrant and perforated appendicitis is suspected. Which of the following is the best empiric antimicrobial regimen? Amoxicillin and azithromycin Clindamycin and metronidazole Levofloxacin Piperacillin-tazobactam

Piperacillin-tazobactam Hint: The patient in this vignette has perforated appendicitis. The bacterial flora in the appendix is similar to the flora of the colon, and it includes gram-negative rods and anaerobic organisms. Piperacillin-tazobactam is a combination of an antipseudomonal penicillin (piperacillin) and a beta-lactamase inhibitor (tazobactam). Beta-lactamase inhibitors inhibit beta-lactamases produced by some organisms, which expands the spectrum of activity of the penicillin when the two are combined Amoxicillin and azithromycin (A) is incorrect as these do not provide coverage of gram-negative Enterobacteriaceae or anaerobes, which are both needed for empiric coverage of intra-abdominal infections, such as perforated appendicitis. The combination of a beta-lactam antibiotic, such as amoxicillin, and azithromycin is frequently used to treat community-acquired pneumonia in an outpatient setting. However, it does not provide gram-negative coverage against Enterobacteriaceae. Clindamycin and metronidazole (B) is incorrect. Although metronidazole covers anaerobic organisms, this regimen does not adequately cover gram-negative Enterobacteriaceae. Levofloxacin (C) is a fluoroquinolone antibiotic. Levofloxacin does not provide enough coverage against anaerobic organisms to be used as a single antibiotic regimen in the empiric treatment of intra-abdominal infections.

Which of the following statements best describes the mechanism of action of sulbactam when combined with ampicillin? Binds to DNA gyrase and DNA topoisomerase IV Binds to the 30S subunit of the bacterial ribosome Prevents peptide bond formation, inhibiting protein synthesis Protects from inactivation by beta-lactamases

Protects from inactivation by beta-lactamases Hint: Fluoroquinolones work by binding to DNA gyrase and DNA topoisomerase IV (A). Tetracycline antibiotics work by entering the cell wall and binding reversibly to the 30S subunit of the ribosome (B). Prevention of peptide bond formation, inhibiting protein synthesis (C) is the mechanism of action of a lincosamide antibiotic such as clindamycin.

A 42-year-old woman with a history of depression and hypertension presents with a cough and fever. A chest radiograph confirms community-acquired pneumonia. She is currently taking citalopram and lisinopril. She is prescribed clarithromycin. Which of the following adverse effects would you be most concerned for? Diarrhea Nausea QT prolongation Renal failure

QT prolongation Hint: Gastrointestinal side effects are common with macrolide drugs and consist of loose stools, nausea, and abdominal cramping. All macrolides carry the risk of QT prolongation and should not be used in patients with a history of prolonged QT, those taking other drugs that prolong the QT interval

A 60-year-old woman has a worsening skin abscess with surrounding cellulitis caused by methicillin-resistant Staphylococcus aureus and is started on antibiotic therapy. She develops arthralgia-myalgia syndrome. Which of the following drugs was she started on? Azithromycin Clindamycin Quinupristin-dalfopristin Tetracycline

Quinupristin-dalfopristin Hint: Quinupristin-dalfopristin is a combination of two streptogramins including quinupristin (streptogramin B) and dalfopristin (streptogramin A), and the combination acts by inhibiting bacterial protein synthesis. Quinupristin-dalfopristin is active against gram-positive cocci including multidrug-resistant strains of streptococci, penicillin-resistant strains of Streptococcus pneumoniae, methicillin-susceptible and -resistant strains of staphylococci, and Enterococcus faecium. Major adverse reactions associated with quinupristin-dalfopristin include infusion-related events, such as infusion site pain, and an arthralgia-myalgia syndrome Azithromycin (A) is a semisynthetic derivative of erythromycin active against Mycobacterium avium complex and Toxoplasma gondii. It is known to prolong QT interval due to its effect on potassium ion channels, which can, in turn, lead to torsades de pointes. It is associated with a small risk of cardiac death but is not known to cause an arthralgia-myalgia syndrome. Clindamycin (B) is a chlorine-substituted derivative of lincomycin, an antibiotic that is elaborated byStreptomyces lincolnensis. Common adverse reactions of clindamycin include diarrhea, nausea, skin rashes, impaired liver function, and neutropenia. Administration of clindamycin is considered a risk factor for diarrhea and colitis due to Clostridioides difficile. Adverse reactions associated with tetracycline (D) include nausea, vomiting, diarrhea, Clostridioides difficile-associated colitis, tooth discoloration and enamel dysplasia, hepatic impairment, renal tubular acidosis, and nephrotoxicity. Tetracycline is not associated with an arthralgia-myalgia syndrome.

A 45-year-old woman with a history of methicillin-resistant Staphylococcus aureus presents with worsening left lower leg cellulitis. She was seen two weeks ago for left lower leg redness, warmth, and tenderness consistent with cellulitis and was started on cephalexin. A week later, she returned with a 4 cm abscess with extensive surrounding redness. An incision and drainage were performed, and foul-smelling purulent material was expressed and cultured. Culture revealed gram-positive cocci in clusters. She was then started on vancomycin. She now has a low-grade fever, nausea, worsening redness, and streaking up the left leg. Which of the following agents is indicated at this time? Bacitracin Cycloserine Teicoplanin Telavancin

Telavancin Hint: Bacitracin (A) is a cyclic peptide obtained from Bacillus subtilis that inhibits bacterial cell wall formation. Although it is active against gram-positive microorganisms, it is highly nephrotoxic when administered systemically and, hence, is only used topically. Cycloserine (B) inhibits bacterial cell wall formation and is active against many gram-positive and gram-negative organisms. It is used almost exclusively to treat tuberculosis caused by Mycobacterium tuberculosis that is resistant to first-line agents. Teicoplanin (C) is a glycopeptide that has a similar mechanism of action and spectrum of activity as vancomycin. It is used in Europe but has not been approved in the United States.

A 45-year-old man presents to the office complaining of thickened toenails that have gotten increasingly difficult to trim. Physical exam reveals multiple toenails that are yellow with some that have separated from the nail bed. He is given a prescription for an antifungal to be used for the next three months and is told to come back in one month to have his liver function tests monitored. Which of the following drugs was most likely prescribed to this patient? Amphotericin B Griseofulvin Itraconazole Terbinafine

Terbinafine Hint: Oral terbinafine is the drug of choice for the treatment of onychomycosisbut may also be used to treat tinea capitis. It is most active against Trichophyton and may also be effective against Candida, Epidermophyton, and Scopulariopsis. Its topical form can be used to treat tinea pedis, tinea corporis, tinea cruris, and tinea versicolor. Amphotericin B (A) is a drug that is used for very serious fungal infections and is given intravenously. It is not used to treat onychomycosis. Griseofulvin (B) is a second-line agent for the treatment of onychomycosis but is not commonly used because it requires a very long duration of treatment for this condition (6 to 12 months). Itraconazole (C) is an alternative treatment for onychomycosis and can cause liver damage as well, but since it is not a first-line treatment, it is not the best answer in this case.

What is the most common adverse effect when posaconazole is administered intravenously? Headache Hypertension Peripheral edema Thrombophlebitis

Thrombophlebitis Hint: The most common adverse reactions include thrombophlebitis when given intravenously, gastrointestinal upset, headache, peripheral edema, and musculoskeletal pain Headache (A) is a side effect of posaconazole but occurs less commonly than thrombophlebitis occurs when it is given intravenously through a peripheral venous access point. Hypertension (B) and hypotension have both been reported as adverse effects after administration of this drug, however, this occurs less commonly than thrombophlebitis. Peripheral edema (C), particularly lower extremity edema, may occur after administration of this medication. It is generally associated with the oral form of this medication and occurs less commonly than thrombophlebitis occurs with intravenous administration.

Which of the following drugs is known to treat community-acquired pneumonia caused by methicillin-resistant, vancomycin-intermediate, and vancomycin-resistant strains of Staphylococcus aureus as well as Chlamydia spp.? Demeclocycline Doxycycline Minocycline Tigecycline

Tigecycline Hint: Tigecycline has a very broad spectrum of activity. It has demonstrated activity against severalgram-positive and -negative bacteria including methicillin-resistant staphylococci. It is also effective against vancomycin-intermediate and vancomycin-resistant S. aureus, penicillin-susceptible and -resistant enterococci including vancomycin-resistant strains, gram-positive rods, Enterobacteriaceae, multidrug-resistant strains of Acinetobacter spp., both gram-positive and gram-negative anaerobes, Rickettsiae, Chlamydia spp., and Legionella pneumophila. Indications for tigecycline use include community-acquired pneumonia (caused by Streptococcus pneumoniae, Legionella pneumophila, or Haemophilus influenzae) with concurrent bacteremia, complicated intra-abdominal infections (caused by Escherichia coli, Enterobacter cloacae, Staphylococcus aureus, or Bacteroides fragilis), and complicated skin and skin structure infections (caused by E. coli, E. cloacae, or S. aureus)

A 35-year-old man presents to the urgent care with a superficial partial thickness burn. He is treated with bacitracin to prevent infection. Which of the following describes the route of administration and coverage of bacitracin? Oral administration and gram-negative coverage Oral administration and gram-positive coverage Topical administration and gram-negative coverage Topical administration and gram-positive coverage

Topical administration and gram-positive coverage Hint: Bacitracin is a topical peptide antibiotic used to prevent infection from minor skin wounds including superficial burns. The mechanism of action is based on bacitracin interfering with cell wall synthesis. It provides coverage against gram-positive organisms, such as streptococci, pneumococci, and staphylococci. Systemic absorption of bacitracin is rare.

A 34-year-old man with a history of human immunodeficiency virus presents to the clinic for evaluation. He lost his health insurance last year and has not been receiving regular care. He has not been on any antiretroviral medications in the past 12 months secondary to cost. His CD4 count is 122 cells/microL. In addition to beginning antiretroviral therapy at this time, what other clinical intervention would be most appropriate to prevent the development of Pneumocystisjirovecii pneumonia? Atovaquone Clindamycin-primaquine Prednisone Trimethoprim-sulfamethoxazole

Trimethoprim-sulfamethoxazole Hint: Trimethoprim-sulfamethoxazole is used in aerobic gram-positive and gram-negativeinfections. It is effective against methicillin-resistant Staphylococcus aureus and is used in many infections contracted by immunocompromised individuals, such as Serratia marcescens, Pneumocystis jirovecii, and infectious diarrhea. Additionally, it is used in chronic obstructive pulmonary disease exacerbations, urinary tract infections, epididymitis, and prostatitis.

What is the black box warning for the antifungal drug flucytosine? May cause hepatotoxicity May cause QT prolongation Use with extreme caution in patients with congestive heart failure Use with extreme caution in patients with renal impairment

Use with extreme caution in patients with renal impairment Hint: Adverse effects of this drug include nausea, vomiting, and diarrhea. More serious effects include reversible neutropenia, thrombocytopenia, bone marrow suppression, hepatic dysfunction, and severe enterocolitis. Flucytosine has a black box warning that advises using extreme caution when treating patients with renal impairment since it is mainly excreted via the kidneys

A 65-year-old man presents with multiple episodes of watery diarrhea that started two days ago. His diarrhea is associated with severe cramping abdominal pain, nausea, fever, and anorexia. He was treated with clindamycin two weeks ago for left lower leg cellulitis. Physical exam shows severe hypotension, tachycardia, abdominal distention, and fever. Laboratory studies are remarkable for leukocytosis, elevated creatinine, and hypoalbuminemia. Radiographic examination of the abdomen reveals accordion sign. Which of the following is the preferred agent for treating this patient? Dalbavancin Teicoplanin Telavancin Vancomycin

Vanc Hint: The patient in the vignette has pseudomembranous colitis, most likely caused by gram positive, spore-forming Clostridioides difficile, resulting from prior antibiotic therapy using clindamycin. Vancomycin is a water-soluble glycopeptide antibiotic produced by Streptococcus orientalis and Amycolatopsis orientalis and is active only against gram-positive bacteria. It inhibits cell wall synthesis

A 56-year-old woman presents to the emergency department via ambulance after being discovered confused and febrile by her family. She underwent a total knee replacement within the past week. Her blood pressure is 84/56 mm Hg upon arrival. She is noted to be tachycardic and febrile to 102.7°F. You are concerned for bacteremia and decide to administer an intravenous antibiotic that provides coverage for methicillin-resistant Staphylococcus aureus. During the infusion, she develops flushing; redness of her neck, face, and torso; and itching. What medication is most commonly responsible for her reaction? Linezolid Oxacillin Quinidine gluconate Vancomycin

Vancomycin Hint: Red man syndrome is a rate-dependent infusion reaction that occurs with the first administration of vancomycin. Patients should be monitored upon initial infusion to evaluate for the development of red man syndrome, which involves erythema, pruritus, and flushing confined to the upper body. It is not an allergic reaction. Should it occur, the rate of infusion should be decreased. Additional adverse effects include anaphylaxis, nephrotoxicity, ototoxicity, neutropenia (with prolonged use), and drug rash with eosinophilia and systemic symptoms

A 32-year-old man with candidemia is admitted to the hospital and treated intravenously with an antifungal. Over the next several days, he experiences worsening blurred vision and photophobia. For which of the following drugs are visual disturbances a common side effect? Amphotericin B Flucytosine Naftifine Voriconazole

Voriconazole Hint: Voriconazole is a broad-spectrum drug in the triazole class of antifungal medications. Triazoles work by inhibiting fungal cytochrome P450 and sterol C-14 alpha-demethylation, which decreases ergosterol synthesis, disrupts fungal cell membrane function, and increases membrane permeability. Voriconazole is the first-line agent for treatment of invasive aspergillosis. It is also used to treat candidemia, esophageal candidiasis, and other serious fungal infections, such as those caused by Scedosporium apiospermum and Fusarium species. The most common adverse effects are visual changes that can manifest as blurred vision, photophobia, color perception changes, and increased or decreased visual acuity. Other visual disturbances, such as optic neuritis and papilledema, have also been reported. Other side effects include tachycardia, hypertension, hypotension, vasodilation, peripheral edema, fever, chills, headache, hallucinations, dizziness, rash, pruritus, photosensitivity, hypokalemia, hypomagnesemia, nausea, vomiting, diarrhea, jaundice, and xerostomia. More serious side effects include thrombocytopenia, hepatotoxicity, and acute renal failure.

A patient presents to the clinic with a diagnosis of invasive aspergillus. Which of the following antifungals is best indicated for treatment of this condition? Amphotericin B Fluconazole Flucytosine Voriconazole

Voriconazole Hint: Voriconazole is a second-generation triazole with enhanced activity against Aspergillus and Candida species. With this expanded spectrum of activity, voriconazole has become the first-line treatment for invasive aspergillosis, esophageal candidiasis, and invasive candidiasis.

Which of the following is the most common side effect associated with erythromycin? Diarrhea Photosensitivity QT prolongation Vomiting

`Diarrhea Hint: Gastrointestinal effects consist of diarrhea, vomiting, nausea, and abdominal cramping. Diarrhea is the most common of the gastrointestinal side effects. All macrolides carry the risk of QT prolongation and should not be used in patients with a history of prolonged QT