Pharmacology Block 4

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A hospitalized AIDS patient is receiving anti- retroviral drugs but no antimicrobial prophylaxis. He develops sepsis with fever, suspected to be caused by a gram-negative bacillus. Antimicrobial treatment of this severely immune-depressed patient should not be initiated before (A) Antipyretic drugs have been given to reduce body temperature (B) Infecting organism(s) have been identified by the micro-biology laboratory (C) Results of a Gram stain are available (D) Results of antibacterial drug susceptibility tests are available (E) Specimens have been taken for laboratory tests and examinations

(E) Specimens have been taken for laboratory tests and examinations

Which parasite is susceptible to niclosamide? (A) Ascaris lumbricoides (B) Echinococcus granulosus (C) Fasciola hepatica (D) Necator americanus (E) Taenia solium

(E) Taenia solium

A 21-year-old woman from Southeast Asia has been staying with family members in the United States for the last 3 mo and is looking after her sister's preschool children during the day. Because she has difficulty with the English language, her sister escorts her to the emergency department of a local hospital. She tells the staff that her sister has been feeling very tired for the last month, has a poor appetite, and has lost weight. The patient has been feeling somewhat better lately except for a cough that pro- duces a greenish sputum, sometimes specked with blood. With the exception of rales in the left upper lobe, the physical examination is unremarkable and she does not seem to be acutely ill. Laboratory values show a white count of 12,000/μL and a hematocrit of 33%. Chest x-ray film reveals an infiltrate in the left upper lobe with a possible cavity. A Gram-stained smear of the sputum shows mixed flora with no dominance. An acid-fast stain reveals many thin rods of pinkish hue. A preliminary diagnosis is made of pulmonary tuberculosis. Sputum is sent to the laboratory for culture. Which statement concerning the possible use of isoniazid (INH) in this patient is false? (A) A lower maintenance dose than usual is required in a patient from Southeast Asia (B) Flushing, sweating, dyspnea, and palpitations may occur after ingestion of tyramine-containing foods (C) Peripheral neuritis may occur during treatment (D) The patient should take pyridoxine daily (E) The risk of the patient developing hepatitis from INH is less than 2%

(A) A lower maintenance dose than usual is required in a patient from Southeast Asia

Which statement about vancomycin is accurate? (A) Active against methicillin-resistant staphylococci (B) Bacteriostatic (C) Binds to penicillin-binding proteins (PBPs) (D) Hepatic metabolism (E) Oral bioavailability

(A) Active against methicillin-resistant staphylococci

A malnourished 12-year-old child who lives in a rural area of the southern United States presents with weakness, fever, cough, abdominal pain, and eosinophilia. His mother tells you that she has seen long, thin worms in the child's stools, sometimes with blood. A presumptive diagnosis of ascariasis is confirmed by the presence of the ova of A lumbricoides in the stools. However, microscopy also reveals that the stools contain the eggs of Necator americanus. The drug most likely to be effective in the treatment of this child is (A) Albendazole (B) Diethylcarbamazine (C) Ivermectin (D) Niclosamide (E) Praziquantel

(A) Albendazole

Interactions between this drug and cell membrane compo- nents can result in the formation of pores lined by hydrophilic groups present in the drug molecule. (A) Amphotericin B (B) Flucytosine (C) Griseofulvin (D) Itraconazole (E) Terbinafine

(A) Amphotericin B

A 52-year-old man (weight 70 kg) is brought to the hospital emergency department in a confused and deliri- ous state. He has had an elevated temperature for more than 24 h, during which time he had complained of a severe headache and had suffered from nausea and vomiting. Lumbar puncture reveals an elevated opening pressure, and cerebrospinal fluid find- ings include elevated protein, decreased glucose, and increased neutrophils. Gram stain of a smear of cerebrospinal fluid reveals gram-positive diplococci, and a preliminary diagnosis is made of purulent meningitis. The microbiology report informs you that for approximately 15% of S pneumoniae isolates in the com- munity, the minimal inhibitory concentration for penicillin G is 20 mcg/mL. If this patient had been 82 years old and the Gram stain of the smear of cerebrospinal fluid had revealed gram-positive rods resembling diphtheroids, the antibiotic regimen for empiric treatment would include (A) Ampicillin (B) Aztreonam (C) Cefazolin (D) Fosfomycin (E) Meropenem

(A) Ampicillin

A 27-year-old pregnant patient with a history of pyelonephritis has developed a severe upper respiratory tract infection that appears to be due to a bacterial pathogen. The woman is hospitalized, and an antibacterial agent is to be selected for treatment. Which antibacterial agent appears to be the safest to use in the pregnant patient? (A) Azithromycin (B) Clarithromycin (C) Kanamycin (D) Sulfadiazine (E) Tetracycline

(A) Azithromycin

Once weekly administration of which of the following anti- biotics has prophylactic activity against bacteremia caused by M avium complex in AIDS patients? (A) Azithromycin (B) Clarithromycin (C) Ethambutol (D) Kanamycin (E) Rifabutin

(A) Azithromycin

Your 23-year-old female patient is pregnant and has gonor- rhea. The medical history includes anaphylaxis following exposure to amoxicillin. The most appropriate drug to use is (A) Azithromycin (B) Cefixime (C) Ceftriaxone (D) Ciprofloxacin (E) Doxycycline

(A) Azithromycin

A 36-year-old woman recently treated for leukemia is admitted to the hospital with malaise, chills, and high fever. Gram stain of blood reveals the presence of gram-negative bacilli. The initial diagnosis is bacteremia, and parenteral antibiotics are indicated. The records of the patient reveal that she had a severe urticarial rash, hypotension, and respiratory difficulty after oral penicillin V about 6 mo ago. The most appropriate drug regimen for empiric treatment is (A) Aztreonam (B) Cefazolin (C) Imipenem (D) Nafcillin (E) Ticarcillin plus clavulanic acid

(A) Aztreonam

A traveler in a geographical region where chloroquine-resistant P falciparum is endemic used a drug for prophy- laxis but nevertheless developed a severe attack of P vivax malaria. Which drug should be used for oral treatment of the acute attack of P vivax malaria but does not eradicate exoerythro- cytic forms of the parasite? (A) Chloroquine (B) Mefloquine (C) Primaquine (D) Pyrimethamine-sulfadoxine (E) Quinidine

(A) Chloroquine

A patient with AIDS has an extremely high viral RNA titer. While blood is being drawn from this patient, the syringe is accidentally dropped, contaminating the floor, which is made of porous material. The best way to deal with this is to (A) Clean the floor with a 10% solution of household bleach (B) Clean the floor with soap and water (C) Completely replace the contaminated part of the floor (D) Neutralize the spill with a solution of potassium permanganate (E) Seal the room and decontaminate with ethylene oxide

(A) Clean the floor with a 10% solution of household bleach

Methenamine salts are used as urinary antiseptics. The reason they lack systemic antibacterial action is that they are (A) Converted to formaldehyde only at low pH (B) Metabolized rapidly by hepatic drug-metabolizing enzymes (C) More than 98% bound to plasma proteins (D) Not absorbed into the systemic circulation after oral ingestion (E) Substrates for active tubular secretion

(A) Converted to formaldehyde only at low pH

The primary reason for the use of drug combinations in the treatment of tuberculosis is to (A) Delay or prevent the emergence of resistance (B) Ensure patient compliance with the drug regimen (C) Increase antimycobacterial activity synergistically (D) Provide prophylaxis against other bacterial infections (E) Reduce the incidence of adverse effects

(A) Delay or prevent the emergence of resistance

All of the following statements about the clinical uses of the aminoglycosides are accurate EXCEPT (A) Effective in the treatment of infections caused by Bacteroides fragilis (B) Gentamicin is used with ampicillin for synergistic effects in the treatment of enterococcal endocarditis (C) Netilmicin is more likely to be effective than strepto- mycin in the treatment of a hospital-acquired infection caused by Serratia marcescens (D) Often used in combination with cephalosporins in the empiric treatment of life-threatening bacterial infections (E) Owing to their polar nature, aminoglycosides are not absorbed after oral administration

(A) Effective in the treatment of infections caused by Bacteroides fragilis

Which helminthic infection does not respond to treatment with praziquantel? (A) Hydatid disease (B) Opisthorchiasis (C) Paragonimiasis (D) Pork tapeworm infection (E) Schistosomiasis

(A) Hydatid disease

A student studying medicine at a Caribbean university develops fever, chills, and diarrhea resulting from S mansoni, and oxamniquine is prescribed. Which statement about the proposed drug therapy is accurate? (A) If the patient has a history of seizure disorders, hospitalization is recommended during treatment (B) It is not effective in the late stages of the disease (C) Oxamniquine is safe to use in pregnancy (D) The drug blocks GABA receptors in trematodes (E) The drug is also effective in tapeworm infections

(A) If the patient has a history of seizure disorders, hospitalization is recommended during treatment

If ampicillin and piperacillin are used in combination in the treatment of infections resulting from Pseudomonas aeruginosa, antagonism may occur. The most likely explanation is that (A) Ampicillin is bacteriostatic (B) Ampicillin induces beta-lactamase production (C) Autolytic enzymes are inhibited by piperacillin (D) Piperacillin blocks the attachment of ampicillin to penicillin-binding proteins (E) The 2 drugs form an insoluble complex

(B) Ampicillin induces beta-lactamase production

A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise, which have lasted 3 or 4 d. She appears to have some respiratory difficulty, and chest examination reveals rales but no other obvious signs of pulmo- nary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expectorated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work has similar symptoms to those she is experiencing. The patient has no history of serious medical problems. She takes loratadine for allergies and supplementary iron tablets, and she drinks at least 6 cups of caffeinated coffee per day. The physician makes an initial diagnosis of community-acquired pneumonia. A 5-d course of treatment for community-acquired pneumonia would be effective in this patient with little risk of drug interactions if the drug prescribed were: (A) Ampicillin (B) Azithromycin (C) Clindamycin (D) Erythromycin (E) Vancomycin

(B) Azithromycin

A 33-year-old man was seen in a clinic with a complaint of dysuria and urethral discharge of yellow pus. He had a painless clean-based ulcer on the penis and nontender enlarge- ment of the regional lymph nodes. Gram stain of the urethral exudate showed gram-negative diplococci within polymorpho- nucleocytes. The patient informed the clinic staff that he was unemployed and had not eaten a meal for 2 days. The most appropriate treatment of gonorrhea in this patient is (A) Ampicillin orally for 7 d (B) Ceftriaxone intramuscularly as a single dose (C) Procaine penicillin G intramuscularly as a single dose plus oral probenecid (D) Tetracycline orally for 5 d (E) Vancomycin intramuscularly as a single dose

(B) Ceftriaxone intramuscularly as a single dose

Infections caused by gram-negative bacilli have occurred when this cationic surfactant has been used as a skin antiseptic. (A) Acetic acid (B) Cetylpyridinium chloride (C) Hexachlorophene (D) Merbromin (E) Thimerosal

(B) Cetylpyridinium chloride

A 52-year-old man (weight 70 kg) is brought to the hospital emergency department in a confused and deliri- ous state. He has had an elevated temperature for more than 24 h, during which time he had complained of a severe headache and had suffered from nausea and vomiting. Lumbar puncture reveals an elevated opening pressure, and cerebrospinal fluid find- ings include elevated protein, decreased glucose, and increased neutrophils. Gram stain of a smear of cerebrospinal fluid reveals gram-positive diplococci, and a preliminary diagnosis is made of purulent meningitis. The microbiology report informs you that for approximately 15% of S pneumoniae isolates in the com- munity, the minimal inhibitory concentration for penicillin G is 20 mcg/mL. Resistance of pneumococci to penicillin G is due to: (A) Beta-lactamase production (B) Changes in chemical structure of target penicillin- binding proteins (C) Changes in porin structure (D) Changes in the D-Ala-D-Ala building block of peptido- glycan precursor (E) Decreased intracellular accumulation of penicillin G

(B) Changes in chemical structure of target penicillin- binding proteins

A 2-year-old child is brought to the hospital after ingesting pills that a parent had used for bacterial dysentery when traveling outside the United States. The child has been vomiting for more than 24 h and has had diarrhea with green stools. He is now lethargic with an ashen color. Other signs and symptoms include hypothermia, hypotension, and abdominal distention. The drug most likely to be the cause of this problem is (A) Ampicillin (B) Chloramphenicol (C) Clindamycin (D) Doxycycline (E) Erythromycin

(B) Chloramphenicol

A 24-year-old woman has returned from a vacation abroad suffering from traveler's diarrhea, and her problem has not responded to antidiarrheal drugs. A pathogenic gram-negative bacillus is suspected. Which drug is most likely to be effective in the treatment of this patient? (A) Amoxicillin (B) Ciprofloxacin (C) Sulfacetamide (D) Trimethoprim (E) Vancomycin

(B) Ciprofloxacin

A 55-year-old patient with a prosthetic heart valve is to undergo a periodontal procedure involving scaling and root planing. Several years ago, the patient had a severe allergic reaction to procaine penicillin G. Regarding prophylaxis against bacterial endocarditis, which one of the following drugs taken orally is most appropriate? (A) Amoxicillin 10 min before the procedure (B) Clindamycin 1 h before the procedure (C) Erythromycin 1 h before the procedure and 4 h after the procedure (D) Vancomycin 15 min before the procedure (E) No prophylaxis is needed because this patient is in the negligible risk category

(B) Clindamycin 1 h before the procedure

Which statement about "once-daily" dosing with amino- glycosides is not accurate? (A) Convenient for outpatient therapy (B) Dosage adjustment is less important in renal insufficiency (C) Less nursing time is required for drug administration (D) Often less toxic than conventional (multiple) dosing regimens (E) Underdosing is less of a problem

(B) Dosage adjustment is less important in renal insufficiency

A 27-year-old pregnant patient with a history of pyelonephritis has developed a severe upper respiratory tract infection that appears to be due to a bacterial pathogen. The woman is hospitalized, and an antibacterial agent is to be selected for treatment. Assuming that the physician is concerned about the effects of renal impairment on drug dosage in this patient, which drug would not require dosage modification in renal dysfunction? (A) Amikacin (B) Erythromycin (C) Ofloxacin (D) Trimethoprim-sulfamethoxazole (E) Vancomycin

(B) Erythromycin

A 28-year-old man living on the East Coast was transferred by his employer to central California for several months. On his return, he complains of having influenza-like symptoms with fever and a cough. He also has red, tender nodules on his shins. His physician suspects that these symptoms are due to coccidioidomycosis contracted during his stay in California. Which is the drug of choice if this patient is suffering from persistent lung lesions or disseminated disease caused by Coccidioides immitis? (A) Amphotericin B (B) Fluconazole (C) Ketoconazole (D) Micofungin (E) Terbinafine

(B) Fluconazole

If the aminoglycoside gentamicin is used in the treatment of this patient, monitoring of serum drug level may be advised because the drug (A) Does not penetrate into cerebrospinal fluid (B) Has a narrow therapeutic window (C) Is antagonized by beta-lactam antibiotics (D) Is metabolized by hepatic enzymes (E) Is hematotoxic

(B) Has a narrow therapeutic window

Which statement about fluconazole is accurate? (A) Does not penetrate the blood-brain barrier (B) Has the least effect of all azoles on hepatic drug metabolism (C) Is an inducer of hepatic drug-metabolizing enzymes (D) Is highly effective in the treatment of aspergillosis (E) Oral bioavailability is less than that of ketoconazole

(B) Has the least effect of all azoles on hepatic drug metabolism

A 21-year-old woman from Southeast Asia has been staying with family members in the United States for the last 3 mo and is looking after her sister's preschool children during the day. Because she has difficulty with the English language, her sister escorts her to the emergency department of a local hospital. She tells the staff that her sister has been feeling very tired for the last month, has a poor appetite, and has lost weight. The patient has been feeling somewhat better lately except for a cough that pro- duces a greenish sputum, sometimes specked with blood. With the exception of rales in the left upper lobe, the physical examination is unremarkable and she does not seem to be acutely ill. Laboratory values show a white count of 12,000/μL and a hematocrit of 33%. Chest x-ray film reveals an infiltrate in the left upper lobe with a possible cavity. A Gram-stained smear of the sputum shows mixed flora with no dominance. An acid-fast stain reveals many thin rods of pinkish hue. A preliminary diagnosis is made of pulmonary tuberculosis. Sputum is sent to the laboratory for culture. At this point, the most appropriate course of action is to (A) Hospitalize the patient and start treatment with isoniazid plus rifampin (B) Hospitalize the patient and start treatment with 4 anti- mycobacterial drugs (C) Prescribe isoniazid for prophylaxis and send the patient home to await culture results (D) Prescribe no drugs and send the patient home to await culture results (E) Treat the patient with isoniazid plus rifampin

(B) Hospitalize the patient and start treatment with 4 anti- mycobacterial drugs

An adult patient (weight 60 kg) has bacteremia suspected to be due to a gram-negative rod. Tobramycin is to be admin- istered using a once-daily dosing regimen, and the loading dose must be calculated to achieve a peak plasma level of 20 mg/L. Assume that the patient has normal renal function. Pharmacokinetic parameters of tobramycin in this patient are as follows: Vd = 20 L; t1/2 = 3 h; CL = 80 mL/min. What loading dose should be given? (A) 100 mg (B) 200 mg (C) 400 mg (D) 600 mg (E) 800 mg

Regarding the toxicity of aminoglycosides, which statement is accurate? (A) Gentamicin and tobramycin are the least likely to cause renal damage (B) Ototoxicity due to amikacin and gentamicin includes vestibular dysfunction that is often irreversible (C) Ototoxicity is reduced if loop diuretics are used to facilitate aminoglycoside renal excretion (D) Skin reactions are rare with use of topical neomycin (E) With traditional dosage regimens, the earliest sign of nephrotoxicity is a reduced blood creatinine

(B) Ototoxicity due to amikacin and gentamicin includes vestibular dysfunction that is often irreversible

Regarding the mechanism of action of aminoglycosides, the drugs (A) Are bacteriostatic (B) Bind to the 50S ribosomal subunit (C) Cause misreading of the code on the mRNA template (D) Inhibit peptidyl transferase (E) Stabilize polysomes

A 52-year-old man (weight 70 kg) is brought to the hospital emergency department in a confused and deliri- ous state. He has had an elevated temperature for more than 24 h, during which time he had complained of a severe headache and had suffered from nausea and vomiting. Lumbar puncture reveals an elevated opening pressure, and cerebrospinal fluid find- ings include elevated protein, decreased glucose, and increased neutrophils. Gram stain of a smear of cerebrospinal fluid reveals gram-positive diplococci, and a preliminary diagnosis is made of purulent meningitis. The microbiology report informs you that for approximately 15% of S pneumoniae isolates in the com- munity, the minimal inhibitory concentration for penicillin G is 20 mcg/mL. Treatment of this patient should be initiated immediately with intravenous administration of (A) Ampicillin-sulbactam (B) Cefazolin (C) Cefotaxime plus vancomycin (D) Nafcillin (E) Ticarcillin

A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise, which have lasted 3 or 4 d. She appears to have some respiratory difficulty, and chest examination reveals rales but no other obvious signs of pulmo- nary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expectorated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work has similar symptoms to those she is experiencing. The patient has no history of serious medical problems. She takes loratadine for allergies and supplementary iron tablets, and she drinks at least 6 cups of caffeinated coffee per day. The physician makes an initial diagnosis of community-acquired pneumonia. If this patient were to be treated with the macrolide erythromycin, she should: (A) Avoid exposure to sunlight (B) Avoid taking supplementary iron tablets (C) Decrease her intake of caffeinated beverages (D) Discontinue loratadine temporarily (E) Have her plasma urea nitrogen or creatinine checked before treatment

A 50-kg patient with creatinine clearance of 80 mL/min has a gram-negative infection. Amikacin is administered intra- muscularly at a dose of 5 mg/kg every 8 h, and the patient begins to respond. After 2 d, creatinine clearance declines to 40 mL/min. Assuming that no information is available about amikacin plasma levels, what would be the most reasonable approach to management of the patient at this point? (A) Administer 5 mg/kg every 12 h (B) Decrease the dosage to a daily total of 200 mg (C) Decrease the dosage to 125 mg every 8 h (D) Discontinue amikacin and switch to gentamicin (E) Maintain the patient on the present dosage and test auditory function

A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise, which have lasted 3 or 4 d. She appears to have some respiratory difficulty, and chest examination reveals rales but no other obvious signs of pulmo- nary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expectorated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work has similar symptoms to those she is experiencing. The patient has no history of serious medical problems. She takes loratadine for allergies and supplementary iron tablets, and she drinks at least 6 cups of caffeinated coffee per day. The physician makes an initial diagnosis of community-acquired pneumonia. Regarding the treatment of this patient, which of the following drugs is most suitable? (A) Amoxicillin (B) Clindamycin (C) Doxycycline (D) Linezolid (E) Vancomycin

Which statement about ciprofloxacin is accurate? (A) Active against most MRSA strains of staphylococci (B) Antagonism occurs if it is used with inhibitors of dihydrofolate reductase (C) During treatment, tendinitis and even tendon rupture may occur (D) Most "first-time" urinary tract infections are resistant to ciprofloxacin (E) Organisms associated with middle ear infections are highly resistant

Which statement about the clinical use of sulfonamides is false? (A) Active against C trachomatis and can be used topically for the treatment of chlamydial infections of the eye (B) Are not effective as sole agents in the treatment of prostatitis (C) Effective in Rocky Mountain spotted fever in patients allergic to tetracyclines (D) Resistance can occur in some strains of bacteria because of increased production of PABA (E) Some resistant bacterial strains exhibit decreased intra- cellular accumulation of sulfonamides

Which statement about the fluoroquinolones is accurate? (A) Afluoroquinoloneisthedrugofchoicefortreatmentofan uncomplicated urinary tract infection in a 7-year-old girl (B) Antacidsincreasetheoralbioavailabilityoffluoroquinolones (C) Gonococcal resistance to fluoroquinolones may involve changes in DNA gyrase (D) Modification of moxifloxacin dosage is required in patients when creatinine clearance is less than 50 mL/min (E) The fluoroquinolones are contraindicated in patients with hepatic dysfunction

Which drug is least likely to be effective in the treatment of esophageal candidiasis if it is used by the oral route? (A) Clotrimazole (B) Fluconazole (C) Griseofulvin (D) Itraconazole (E) Nystatin

Clarithromycin and erythromycin have very similar spectra of antimicrobial activity. The major advantage of clarithromycin is that it (A) Does not inhibit hepatic drug-metabolizing enzymes (B) Eradicates mycoplasmal infections in a single dose (C) Has greater activity against M avium-intracellulare complex (D) Is active against methicillin-resistant strains of staphylococci (E) Is active against strains of streptococci that are resistant to erythromycin

A 10-year-old boy has uncomplicated pulmonary tubercu- losis. After initial hospitalization, he is now being treated at home with isoniazid, rifampin, and ethambutol. Which statement about this case is accurate? (A) A baseline auditory function test is essential before drug treatment is initiated (B) His mother, who takes care of him, does not need INH prophylaxis (C) His 3-year-old sibling should receive INH prophylaxis (D) The patient may develop symptoms of polyarthralgia caused by rifampin (E) The potential nephrotoxicity of the prescribed drugs warrants periodic assessment of renal function

Which statement about imipenem is accurate? (A) Active against methicillin-resistant staphylococci (B) Has a narrow spectrum of antibacterial action (C) In renal dysfunction, dosage reduction is necessary to avoid seizures (D) Is highly susceptible to beta-lactamases produced by Enterobacter species (E) Is used in fixed combination with sulbactam

Metronidazole is not effective in the treatment of (A) Amebiasis (B) Infections due to Bacteroides fragilis (C) Infections due to Pneumocystis jiroveci (D) Pseudomembranous colitis (E) Trichomoniasis

A 33-year-old man was seen in a clinic with a complaint of dysuria and urethral discharge of yellow pus. He had a painless clean-based ulcer on the penis and nontender enlarge- ment of the regional lymph nodes. Gram stain of the urethral exudate showed gram-negative diplococci within polymorpho- nucleocytes. The patient informed the clinic staff that he was unemployed and had not eaten a meal for 2 days. Immunofluorescent microscopic examination of fluid expressed from the penile chancre of this patient revealed treponemes. Because he appears to be infected with Treponema pallidum, the best course of action would be to: (A) Administer a single oral dose of fosfomycin (B) Give no other antibiotics because drug treatment of gonorrhea provides coverage for incubating syphilis (C) Inject intramuscular benzathine penicillin G (D) Treat with oral tetracycline for 7 d (E) Treat with vancomycin

1. A missionary from the United States is sent to work in a geographic region of a Central American country where Onchocerca volvulus is endemic. Infections resulting from this tissue nematode (onchocerciasis) are a cause of "river blindness," because microfilariae migrate through subcutane- ous tissues and concentrate in the eyes. Which drug should be used prophylactically to prevent onchocerciasis? (A) Albendazole (B) Diethylcarbamazine (C) Ivermectin (D) Oxamniquine (E) Suramin

Which drug causes muscle paralysis in nematodes by enhancing the actions of GABA? (A) Albendazole (B) Diethylcarbamazine (C) Ivermectin (D) Mebendazole (E) Pyrantel pamoate

A traveler in a geographical region where chloroquine-resistant P falciparum is endemic used a drug for prophy- laxis but nevertheless developed a severe attack of P vivax malaria. The drug taken for chemoprophylaxis was probably (A) Atovaquone (B) Diloxanide furoate (C) Mefloquine (D) Proguanil (E) Quinine

This drug can clear trypanosomes from the blood and lymph nodes and is active in the late CNS stages of African sleeping sickness. (A) Emetine (B) Eflornithine (C) Melarsoprol (D) Nifurtimox (E) Suramin

After a backpacking trip in the mountains, a 24-year-old man develops diarrhea. He acknowledges drinking stream water without purification, and you suspect he is showing symptoms of giardiasis. Because you know that laboratory detection of cysts or trophozoites in the feces can be difficult, you decide to treat the patient empirically with (A) Chloroquine (B) Emetine (C) Metronidazole (D) Pentamidine (E) TMP-SMZ

A 22-year-old man with gonorrhea is to be treated with cefixime and will need another drug to provide coverage for possible urethritis caused by C trachomatis. Which of the fol- lowing drugs is least likely to be effective in nongonococcal urethritis? (A) Azithromycin (B) Clindamycin (C) Nitrofurantoin (D) Ofloxacin (E) Tetracycline

A 48-year-old patient is scheduled for a vaginal hysterectomy. An antimicrobial drug will be used for prophylaxis against postoperative infection. It is proposed that cefazolin, a first-generation cephalosporin, be given intravenously at the normal therapeutic dose immediately before surgery and continued until the patient is released from the hospital. Which statement about the proposed drug management of this patient is not accurate? (A) Enteric gram-negative rods, anaerobes, enterococci, and group B streptococci are likely pathogens (B) In this type of surgical procedure, antimicrobial prophylaxis has documented efficacy (C) Nosocomial (hospital-acquired) infection will be prevented by treatment throughout the period of hospitalization (D) This drug will not be effective against anaerobes (E) Without prophylaxis, the infection rate following this procedure exceeds 5% under optimal conditions

The primary mechanism of antibacterial action of the penicillins involves inhibition of (A) Beta-lactamases (B) N-acetylmuramic acid synthesis (C) Peptidoglycan cross-linking (D) Synthesis of cell membranes (E) Transglycosylation

A 22-year-old South Korean man has recently moved to Minnesota. He has symptoms of clonorchiasis (anorexia, upper abdominal pain, eosinophilia), presumably contracted in his homeland where the Oriental liver fluke is endemic. He also has symptoms of diphyllobothriasis (abdominal dis- comfort, diarrhea, megaloblastic anemia), probably caused by consumption of raw fish from lakes near the Canadian bor- der. Which drug is most likely to be effective in the treatment of both clonorchiasis and diphyllobothriasis in this patient? (A) Ivermectin (B) Niclosamide (C) Praziquantel (D) Thiabendazole (E) Pyrantel pamoate

A traveler in a geographical region where chloro- quine-resistant P falciparum is endemic used a drug for prophy- laxis but nevertheless developed a severe attack of P vivax malaria.5. Which drug should be given later to eradicate schizonts and latent hypnozoites in the patient's liver? (A) Amodiaquine (B) Halofantrine (C) Primaquine (D) Quinine (E) Sulfadoxine

A 37-year-old woman with leukemia was under- going chemotherapy with intravenous antineoplastic drugs. During treatment, she developed a systemic infection from an opportunis- tic pathogen. There was no erythema or edema at the catheter insertion site. A white vaginal discharge was observed. After appro- priate specimens were obtained for culture, empiric antibiotic therapy was started with gentamicin, nafcillin, and ticarcillin intra- venously. This regimen was maintained for 72 h, during which time the patient's condition did not improve significantly. Her throat was sore, and white plaques had appeared in her pharynx. On day 4, none of the cultures had shown any bacterial growth, but both the blood and urine cultures grew out Candida albicans. At this point, the best course of action is to (A) Continue current antibiotics and start amphotericin B (B) Continue current antibiotics and start flucytosine (C) Stop current antibiotics and start amphotericin B (D) Stop current antibiotics and start ketoconazole (E) Stop current antibiotics and start terbinafine

A 37-year-old woman with leukemia was under- going chemotherapy with intravenous antineoplastic drugs. During treatment, she developed a systemic infection from an opportunis- tic pathogen. There was no erythema or edema at the catheter insertion site. A white vaginal discharge was observed. After appro- priate specimens were obtained for culture, empiric antibiotic therapy was started with gentamicin, nafcillin, and ticarcillin intra- venously. This regimen was maintained for 72 h, during which time the patient's condition did not improve significantly. Her throat was sore, and white plaques had appeared in her pharynx. On day 4, none of the cultures had shown any bacterial growth, but both the blood and urine cultures grew out Candida albicans. If amphotericin B is administered, the patient should be pre- medicated with (A) Diphenhydramine (B) Ibuprofen (C) Prednisone (D) Any or all of the above (E) None of the above

(D) Any or all of the above

The mechanism of antibacterial action of doxycycline involves: (A) Antagonism of bacterial translocase activity (B) Binding to a component of the 50S ribosomal subunit (C) Inhibition of DNA-dependent RNA polymerase (D) Interference with binding of aminoacyl-tRNA to bacterial ribosomes (E) Selective inhibition of ribosomal peptidyl transferases

(D) Interference with binding of aminoacyl-tRNA to bacterial ribosomes

Serious cardiac effects have occurred when this drug was taken by patients using the antihistamines astemizole or terfenadine (A) Amphotericin B (B) Fluconazole (C) Griseofulvin (D) Ketoconazole (E) Terbinafine

(D) Ketoconazole

3. Which statement about pyrantel pamoate is accurate? (A) Acts as an antagonist at GABA receptors (B) Equivalent in efficacy to niclosamide in the treatment of tapeworm infections (C) Hepatotoxicity is dose-limiting (D) Kills adult worms in the colon but not the eggs (E) Synergistic with praziquantel in fluke infections

(D) Kills adult worms in the colon but not the eggs

A male patient presents with lower abdominal discomfort, flatulence, and occasional diarrhea. A diagnosis of intestinal amebiasis is made, and E histolytica is identified in his diarrheal stools. An oral drug is prescribed, which reduces his intestinal symptoms. Later he presents with severe dysentery, right upper quadrant pain, weight loss, fever, and an enlarged liver. Amebic liver abscess is diagnosed, and the patient is hospitalized. He has a recent history of drug treatment for a tachyarrhythmia. The preferred treatment that he should have received for the initial symptoms (which were indicative of mild to moderate disease) is (A) Diloxanide furoate (B) Iodoquinol (C) Metronidazole (D) Metronidazole plus diloxanide furoate (E) Paromomycin

(D) Metronidazole plus diloxanide furoate

Which compound is used topically to treat scabies and pediculosis? (A) Benzoyl peroxide (B) Chlorhexidine (C) Mupirocin (D) Permethrin (E) Silver sulfadiazine

(D) Permethrin

Which statement about the actions of antimicrobial agents is false? (A) Daptomycin has activity against strains of staphylococci resistant to vancomycin. (B) Neonatal gonococcal ophthalmia can be prevented by silver nitrate (C) Polymyxins act as cationic detergents to disrupt bacterial cell membranes (D) Resistance to nitrofurantoin emerges rapidly, and there is cross-resistance with sulfonamides (E) Salicylic acid has useful antidermatophyte activity when applied topically

(D) Resistance to nitrofurantoin emerges rapidly, and there is cross-resistance with sulfonamides

Which drug increases the hepatic metabolism of other drugs? (A) Clarithromycin (B) Erythromycin (C) Ketoconazole (D) Rifampin (E) Ritonavir

(D) Rifampin

Which drug is effective in the treatment of nocardiosis and, in combination with pyrimethamine, is prophylactic against Pneumocystis jiroveci infections in AIDS patients? (A) Amoxicillin (B) Ciprofloxacin (C) Clindamycin (D) Sulfadiazine (E) Trimethoprim

(D) Sulfadiazine

A 55-year-old man complains of periodic bouts of diarrhea with lower abdominal cramping and intermittent rectal bleeding. Seen in the clinic, he appears well nourished, with blood pressure in the normal range. Examination reveals moder- ate abdominal pain and tenderness. His current medications are limited to loperamide for his diarrhea. Sigmoidoscopy reveals mucosal edema, friability, and some pus. Laboratory findings include mild anemia and decreased serum albumin. Microbiologic examination via stool cultures and mucosal biopsies do not reveal any evidence for bacterial, amebic, or cytomegalovirus involvement. The most appropriate drug to use in this patient is (A) Amoxicillin (B) Ciprofloxacin (C) Doxycycline (D) Sulfasalazine (E) Trimethoprim-sulfamethoxazole

(D) Sulfasalazine

A young woman is brought to a hospital emer- gency department with intense abdominal pain of 2 d duration. The pain has spread to the right lower quadrant and is accompa- nied by nausea, vomiting, and fever. She arrives at the emergency department with a blood pressure of 85/45, pulse 120/min, and temperature 40°C. Her abdomen has a board-like rigidity with diffuse pain to palpation. Laboratory values include the following: WBC 20,000/μL and creatinine 1.5 mg/dL. After abdominal x-ray films are taken, a preliminary diagnosis of abdominal sepsis is made, possibly resulting from bowel perforation. After appro- priate samples are sent to the laboratory for culture, the patient is hospitalized, and antimicrobial therapy is started with intravenous ampicillin and gentamicin. Regarding the treatment of this patient, which statement is accurate? (A) A Gram stain of the blood would provide positive identification of the specific organism involved in this infection (B) Cultures are pointless because this is probably a mixed infection (C) Empiric antimicrobial therapy of abdominal sepsis should always include a third-generation cephalosporin (D) The antibiotic regimen should include a drug active against anaerobes (E) The combination of ampicillin and gentamicin provides good coverage for all likely pathogens

(D) The antibiotic regimen should include a drug active against anaerobes

A 67-year-old man is seen in a hospital emergency department complaining of pain in and behind the right ear. Physical examination shows edema of the external otic canal with purulent exudate and weakness of the muscles on the right side of the face. The patient informs the physician that he is a diabetic. Gram stain of the exudate from the ear shows many polymorphonucleocytes and gram-negative rods, and samples are sent to the microbiology laboratory for culture and drug susceptibility testing. A preliminary diagnosis is made of external otitis. At this point, which of the following is most appropriate? (A) Amikacin should be administered by intramuscular injec- tion, and the patient should be sent home (B) Analgesics should be prescribed for pain, but antibiotics should be withheld pending the results of cultures (C) Oral cefaclor should be prescribed together with analge- sics, and the patient should be sent home (D) The patient should be hospitalized and treatment started with gentamicin plus ticarcillin (E) The patient should be hospitalized and treatment started with intravenous imipenem-cilastatin

(D) The patient should be hospitalized and treatment started with gentamicin plus ticarcillin

Regarding the clinical use of liposomal formulations of amphotericin B, which statement is accurate? (A) Amphotericin B affinity for these lipids is greater than affinity for ergosterol (B) Less expensive to use than conventional amphotericin B (C) More effective in fungal infections because they increase tissue uptake of amphotericin B (D) They decrease the nephrotoxicity of amphotericin B (E) They have a wider spectrum of antifungal activity than conventional formulations of amphotericin B

(D) They decrease the nephrotoxicity of amphotericin B

Trimethoprim-sulfamethoxazole is established to be effective against which of the following opportunistic infections in the AIDS patient? (A) Cryptococcal meningitis (B) Disseminated herpes simplex (C) Oral candidiasis (D) Toxoplasmosis (E) Tuberculosis

(D) Toxoplasmosis

A 26-year-old woman was treated for a suspected chlamydial infection at a neighborhood clinic. She was given a prescrip- tion for oral doxycycline to be taken for 10 d. Three weeks later, she returned to the clinic with a mucopurulent cervici- tis. On questioning she admitted not having the prescription filled. The best course of action at this point would be to (A) Delay drug treatment until the infecting organism is identified (B) Rewrite the original prescription for oral doxycycline (C) Treat her in the clinic with a single oral dose of cefixime (D) Treat her in the clinic with a single oral dose of azithromycin (E) Write a prescription for oral erythromycin for 10 d

(D) Treat her in the clinic with a single oral dose of azithromycin

A patient with AIDS and a CD4 cell count of 100/μL has persistent fever and weight loss associated with invasive pulmonary disease due to M avium complex (MAC). Optimal management of this patient is to (A) Select an antibiotic based on drug susceptibility of the cultured organism (B) Start treatment with INH and pyrazinamide (C) Treat with rifabutin because it prevents the development of MAC bacteremia (D) Treat with the combination of clarithromycin, ethambutol, and rifabutin (E) Treat with trimethoprim-sulfamethoxazole

(D) Treat with the combination of clarithromycin, ethambutol, and rifabutin

A combination of drugs might be given to this patient to provide coverage against multiple organisms or to obtain a synergistic action. Examples of antimicrobial drug synergism established at the clinical level include (A) Amphotericin B with flucytosine in cryptococcal meningitis (B) Carbenicillin with gentamicin in pseudomonal infections (C) Rifampin with vancomycin in enterococcal infections (D) Trimethoprim with sulfamethoxazole in coliform infections (E) All of the above

(E) All of the above

Risk factors for multidrug-resistant tuberculosis include: (A) A history of treatment of tuberculosis without rifampin (B) Recent immigration from Asia and living in an area of over 4% isoniazid resistance (C) Recent immigration from Latin America (D) Residence in regions where isoniazid resistance is known to exceed 4% (E) All of the above

(E) All of the above

Which statement is accurate regarding the antibacterial action of gentamicin? (A) Antibacterial activity is often reduced by the presence of an inhibitor of cell wall synthesis (B) Antibacterial action is not concentration-dependent (C) Antibacterial action is time-dependent (D) Efficacy is directly proportional to the duration of time that the plasma level is greater than the minimal inhibitory concentration (E) Gentamicin continues to exert antibacterial effects even after plasma levels decrease below detectable levels

(E) Gentamicin continues to exert antibacterial effects even after plasma levels decrease below detectable levels

A 21-year-old woman from Southeast Asia has been staying with family members in the United States for the last 3 mo and is looking after her sister's preschool children during the day. Because she has difficulty with the English language, her sister escorts her to the emergency department of a local hospital. She tells the staff that her sister has been feeling very tired for the last month, has a poor appetite, and has lost weight. The patient has been feeling somewhat better lately except for a cough that pro- duces a greenish sputum, sometimes specked with blood. With the exception of rales in the left upper lobe, the physical examination is unremarkable and she does not seem to be acutely ill. Laboratory values show a white count of 12,000/μL and a hematocrit of 33%. Chest x-ray film reveals an infiltrate in the left upper lobe with a possible cavity. A Gram-stained smear of the sputum shows mixed flora with no dominance. An acid-fast stain reveals many thin rods of pinkish hue. A preliminary diagnosis is made of pulmonary tuberculosis. Sputum is sent to the laboratory for culture. Which drug regimen should be initiated in this patient when treatment is started? (A) Amikacin, isoniazid, pyrazinamide, streptomycin (B) Ciprofloxacin, cycloserine, isoniazid, PAS (C) Ethambutol, isoniazid, ofloxacin, streptomycin (D) Ethionamide, pyrazinamide, rifampin, streptomycin (E) Isoniazid, rifampin, pyrazinamide, ethambutol

(E) Isoniazid, rifampin, pyrazinamide, ethambutol

The primary mechanism of resistance of gram-positive organisms to erythromycin is (A) Decreased activity of uptake mechanisms (B) Decreased drug permeability of the cytoplasmic membrane (C) Formation of drug-inactivating acetyltransferases (D) Formation of esterases that hydrolyze the lactone ring (E) Methylation of binding sites on the 50S ribosomal subunit

(E) Methylation of binding sites on the 50S ribosomal subunit

Neuropathies are more likely to occur with this agent when it is used in patients with renal dysfunction. The drug may cause acute hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. (A) Chlorhexidine (B) Halazone (C) Methenamine (D) Metronidazole (E) Nitrofurantoin

(E) Nitrofurantoin

A 31-year-old man has gonorrhea. He has no drug allergies, but a few years ago acute hemolysis followed use of an anti- malarial drug. The physician is concerned that the patient has an accompanying urethritis caused by C trachomatis, although no cultures or enzyme tests have been performed. Which of the following drugs will be reliably effective against both gonococci and C trachomatis and safe to use in this patient? (A) Cefixime (B) Ciprofloxacin (C) Spectinomycin (D) Sulfamethoxazole-trimethoprim (E) None of the above

(E) None of the above

A 37-year-old woman with leukemia was under- going chemotherapy with intravenous antineoplastic drugs. During treatment, she developed a systemic infection from an opportunis- tic pathogen. There was no erythema or edema at the catheter insertion site. A white vaginal discharge was observed. After appro- priate specimens were obtained for culture, empiric antibiotic therapy was started with gentamicin, nafcillin, and ticarcillin intra- venously. This regimen was maintained for 72 h, during which time the patient's condition did not improve significantly. Her throat was sore, and white plaques had appeared in her pharynx. On day 4, none of the cultures had shown any bacterial growth, but both the blood and urine cultures grew out Candida albicans. Candida is a major cause of nosocomial bloodstream infec- tion. The opportunistic fungal infection in this patient could have been prevented by administration of (A) Caspofungin (B) Fluconazole (C) Nystatin (D) Posaconazole (E) None of the above

(E) None of the above

Which adverse effect occurs with the use of mebendazole during intestinal nematode therapy? (A) Cholestatic jaundice (B) Corneal opacities (C) Hirsutism (D) Peripheral neuropathy (E) None of the above

(E) None of the above

Which antiseptic promotes wound healing? (A) Benzalkonium chloride (B) Chlorhexidine (C) Hexachlorophene (D) Iodine (E) None of the above

(E) None of the above

A 28-year-old man living on the East Coast was transferred by his employer to central California for several months. On his return, he complains of having influenza-like symptoms with fever and a cough. He also has red, tender nodules on his shins. His physician suspects that these symptoms are due to coccidioidomycosis contracted during his stay in California. This patient should be treated immediately with (A) Amphotericin B (B) Caspofungin (C) Terbinafine (D) Voriconazole (E) None of these drugs

(E) None of these drugs

A 48-year-old patient is scheduled for a vaginal hysterectomy. An antimicrobial drug will be used for prophylaxis against postoperative infection. It is proposed that cefazolin, a first-generation cephalosporin, be given intravenously at the normal therapeutic dose immediately before surgery and continued until the patient is released from the hospital.If the patient had been scheduled for elective colonic surgery, optimal prophylaxis against infection would be achieved by mechanical bowel preparation and the use of (A) Intravenous cefotetan (B) Intravenous third-generation cephalosporin (C) Oral ampicillin (D) Oral fluoroquinolone (E) Oral neomycin and erythromycin

(E) Oral neomycin and erythromycin

Plasmodial resistance to chloroquine is due to (A) Change in receptor structure (B) Increase in the activity of DNA repair mechanisms (C) Increased synthesis of dihydrofolate reductase (D) Induction of drug-inactivating enzymes (E) Reduced accumulation of the drug in the food vacuole

(E) Reduced accumulation of the drug in the food vacuole

Which adverse effect is most likely to occur with sulfonamides? (A) Fanconi's aminoaciduria syndrome (B) Hematuria (C) Kernicterus in the newborn (D) Neurologic dysfunction (E) Skin reactions

(E) Skin reactions

Which statement about antitubercular drugs is accurate? (A) Antimycobacterial actions of streptomycin involve inhibition of arabinosyl transferases (B) Cross-resistance of M tuberculosis to isoniazid and pyrazinamide is common (C) Ocular toxicity of ethambutol is prevented by thiamine (D) Pyrazinamide treatment should be discontinued immediately if hyperuricemia occurs (E) Resistance to ethambutol involves mutations in the emb gene

(E) Resistance to ethambutol involves mutations in the emb gene

A 21-year-old woman from Southeast Asia has been staying with family members in the United States for the last 3 mo and is looking after her sister's preschool children during the day. Because she has difficulty with the English language, her sister escorts her to the emergency department of a local hospital. She tells the staff that her sister has been feeling very tired for the last month, has a poor appetite, and has lost weight. The patient has been feeling somewhat better lately except for a cough that pro- duces a greenish sputum, sometimes specked with blood. With the exception of rales in the left upper lobe, the physical examination is unremarkable and she does not seem to be acutely ill. Laboratory values show a white count of 12,000/μL and a hematocrit of 33%. Chest x-ray film reveals an infiltrate in the left upper lobe with a possible cavity. A Gram-stained smear of the sputum shows mixed flora with no dominance. An acid-fast stain reveals many thin rods of pinkish hue. A preliminary diagnosis is made of pulmonary tuberculosis. Sputum is sent to the laboratory for culture. On her release from the hospital, the patient is advised not to rely solely on oral contraceptives to prevent pregnancy because they may be less effective while she is being main- tained on antimycobacterial drugs. The agent most likely to interfere with the action of oral contraceptives is (A) Amikacin (B) Ethambutol (C) Isoniazid (D) Pyrazinamide (E) Rifampin

(E) Rifampin

Questions 2 and 3. A young woman is brought to a hospital emer- gency department with intense abdominal pain of 2 d duration. The pain has spread to the right lower quadrant and is accompa- nied by nausea, vomiting, and fever. She arrives at the emergency department with a blood pressure of 85/45, pulse 120/min, and temperature 40°C. Her abdomen has a board-like rigidity with diffuse pain to palpation. Laboratory values include the following: WBC 20,000/μL and creatinine 1.5 mg/dL. After abdominal x-ray films are taken, a preliminary diagnosis of abdominal sepsis is made, possibly resulting from bowel perforation. After appro- priate samples are sent to the laboratory for culture, the patient is hospitalized, and antimicrobial therapy is started with intravenous ampicillin and gentamicin. If the antibiotic regimen in this patient is modified to include metronidazole (A) Ampicillin should be excluded from the regimen (B) Coverage will be extended to methicillin-resistant staphylococci (C) Gentamicin should be excluded from the regimen (D) Metronidazole should not be administered intravenously (E) The patient should be monitored for candidiasis

(E) The patient should be monitored for candidiasis

2. A nonindigenous person who develops onchocerciasis in an endemic region and receives drug treatment is likely to experience a severe reaction. Symptoms include headache, weakness, rash, muscle aches, hypotension, and periph- eral edema. Which statement concerning this reaction is accurate? (A) Bithionol was prescribed (B) Extensive fluid replacement is essential (C) Symptoms are more intense in indigenous adults than expatriate adults (D) The reaction is due to drug toxicity (E) The reaction is due to killing of microfilariae

(E) The reaction is due to killing of microfilariae

A male patient presents with lower abdominal discomfort, flatulence, and occasional diarrhea. A diagnosis of intestinal amebiasis is made, and E histolytica is identified in his diarrheal stools. An oral drug is prescribed, which reduces his intestinal symptoms. Later he presents with severe dysentery, right upper quadrant pain, weight loss, fever, and an enlarged liver. Amebic liver abscess is diagnosed, and the patient is hospitalized. He has a recent history of drug treatment for a tachyarrhythmia. The drug regimen most likely to be effective in treating severe extraintestinal disease in this patient is (A) Chloroquine (B) Diloxanide furoate plus iodoquinol (C) Emetine plus diloxanide furoate plus chloroquine (D) Pentamidine followed by mefloquine (E) Tinidazole plus diloxanide furoate

(E) Tinidazole plus diloxanide furoate

This drug has characteristics almost identical to those of gen- tamicin but has much weaker activity in combination with penicillin against enterococci. (A) Amikacin (B) Erythromycin (C) Netilmicin (D) Spectinomycin (E) Tobramycin

(E) Tobramycin

Supplementary folinic acid may prevent anemia in folate- deficient persons who use this drug; it is a weak base achieving tissue levels similar to those in plasma (A) Ciprofloxacin (B) Moxifloxacin (C) Sulfacetamide (D) Sulfamethoxazole (E) Trimethoprim

(E) Trimethoprim

Which statement about antiprotozoal drugs is accurate? (A) Chloroquine is an inhibitor of plasmodial dihydrofolate reductase (B) Mefloquine destroys secondary exoerythrocytic schizonts (C) Primaquine is a blood schizonticide and does not affect secondary tissue schizonts (D) Proguanil complexes with double-stranded DNA-blocking replication (E) Trimethoprim-sulfamethoxazole is the drug of choice for Pneumocystis jiroveci pneumonia

(E) Trimethoprim-sulfamethoxazole is the drug of choice for Pneumocystis jiroveci pneumonia

Concerning quinupristin-dalfopristin, which statement is accurate? (A) Active in treatment of infections caused by E faecalis (B) Bacteriostatic (C) Hepatotoxicity has led to FDA drug alerts (D) Induce formation of hepatic drug-metabolizing enzymes (E) Used in management of infections caused by multidrug-resistant streptococci

(E) Used in management of infections caused by multidrug-resistant streptococci

A patient needs antibiotic treatment for native valve, culture- positive infective enterococcal endocarditis. His medical history includes a severe anaphylactic reaction to penicillin G during the last year. The best approach would be treatment with (A) Amoxicillin-clavulanate (B) Aztreonam (C) Cefazolin plus gentamicin (D) Meropenem (E) Vancomycin

(E) Vancomycin

In a patient suffering from pseudomembranous colitis due to C difficile with established hypersensitivity to metronidazole the most likely drug to be of clinical value is (A) Chloramphenicol (B) Clindamycin (C) Doxycycline (D) Levofloxacin (E) Vancomycin

Pharmacology Block 4

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