Pharmacology Module 1

A hospitalized AIDS patient is receiving antiret-roviral 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 microbiology laboratory (C) Results of a Gram stain are available (D) Results of antibacterial susceptibility tests are available (E) Specimens have been taken for laboratory tests and examination

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

More than 90% of this drug is excreted in the urine in intact form. Because its urinary solubility is low, patients should be well hydrated to prevent nephrotoxicity. Which drug is described? (A) Acyclovir (B) Efavirenz (C) Indinavir (D) Trifluridine (E) Zidovudine

(A) Acyclovir

A young woman is brought to a hospital emergency department with intense abdominal pain of 2 days duration. The pain has spread to the right lower quadrant and is accompanied 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 appropriate 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 drug active against anaerobes should be included in the antimicrobial drug regimen (B) Cultures are pointless because this is probably a mixed infection (C) Empiric antibiotic therapy of abdominal sepsis should always include a third-generation cephalosporin (D) Gram stain of the blood would provide positive identification of the specific organism involved in this infection (E) The combination of ampicillin and gentamicin provides good coverage for all likely pathogens

(A) A drug active against anaerobes should be included in the antimicrobial drug regimen

The most appropriate treatment of gonorrhea in this patient is (A) A single intramuscular dose of ceftriaxone (B) Amoxicillin orally for 7 d (C) Procaine penicillin G intramuscularly as a single dose plus oral probenecid (D) Meropenem orally for 7 d (E) Vancomycin intramuscularly as a single dose

(A) A single intramuscular dose of ceftriaxone

Which statement about vancomycin is accurate? (A) Active against methicillin-resistant staphylococci (B) Bacteriostatic (C) Binds to PBPs (D) Inhibits transpeptidation (E) Oral bioavailability

(A) Active against methicillin-resistant staphylococci

A 52-year-old man (weight 70 kg) is brought to the hospital emergency department in a confused and delirious state. He has had an elevated temperature for more than 24 h, dur-ing 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 findings include elevated protein, decreased glucose, and increased neutrophils. 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) Cefoxitin (C) Ceftriaxone (D) Fosfomycin (E) Vancomycin

(A) Ampicillin

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) Antibiotic treatment throughout hospitalization will prevent nosocomial infections (B) Likely pathogens include anaerobes, enteric Gram-negative bacteria, and group B streptococci (C) Prophylaxis with antimicrobial drugs has efficacy in this type of surgical procedure (D) This drug will not be effective against anaerobes (E) Without prophylaxis, the infection rate following this procedure exceeds 5% under optimal conditions

(A) Antibiotic treatment throughout hospitalization will prevent nosocomial infections

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 dif-ficulty, and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expecto-rated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work had 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 inter-actions if the drug prescribed were (A) Azithromycin (B) Clindamycin (C) Doxycycline (D) Erythromycin (E) Vancomycin

(A) Azithromycin

Your 23-year-old female patient is pregnant and has gonorrhea. 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 admit-ted to the hospital with malaise, chills, and high fever. A blood culture 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) Ceftriaxone (C) Meropenem (D) Oxacillin (E) Ticarcillin plus clavulanic acid

(A) Aztreonam

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

A 45-year-old homeless man presents to the emergency depart-ment with fever, weight loss, and a productive cough. Chest x-ray shows right apical infiltrate and TB is suspected. He is started on empiric INH, rifampin, and pyrazinamide. The pri-mary reason for the use of drug combinations in the treatment of this patient's TB is: (A) Delay or prevent the emergence of resistance (B) Ensure patient compliance with the drug regimen (C) Increase antibacterial activity synergistically (D) Provide prophylaxis against other bacterial infections (E) Reduce the incidence of adverse effects

(A) Delay or prevent the emergence of resistance

Which statement about "once-daily" dosing with aminoglycosides is accurate? (A) Dose adjustment is important in renal dysfunction (B) It is inconvenient for outpatient treatment (C) Extra nursing time is required for drug administration (D) Often more side effects than multiple (conventional) dosing regimens (E) It results in underdosing

(A) Dose adjustment is important in renal dysfunction

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 dur-ing 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 produces 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 4 antitubercular drugs (B) Hospitalize the patient and start treatment with rifampin (C) Prescribe isoniazid for prophylaxis and send the patient home to await culture results (D) Provide no drugs and send the patient home to await culture results (E) Treat the patient with isoniazid plus rifampin

(A) Hospitalize the patient and start treatment with 4 antitubercular drugs

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

Concerning quinupristin-dalfopristin, which statement is accurate? (A) Active in treatment of infections caused by E faecalis (B) An effective drug in treatment of multidrug-resistant streptococcal infections (C) Bacteriostatic (D) Hepatotoxicity has led to FDA drug alerts (E) Increase the activity of hepatic drug-metabolizing enzymes

(B) An effective drug in treatment of multidrug-resistant streptococcal infections

A 10-year-old American girl presented to the emergency department with fever, chills, lethargy, and sple-nomegaly. She had recently returned from Nigeria, where she had spent 3 weeks with her grandparents. She had previously received all standard childhood immunizations but no prophylactic travel medications because her parents had returned to Nigeria several times previously without any medical problems. Laboratory examination reveals low hematocrit and platelet count and elevated creatinine. Blood smear reveals parasites in the erythrocytes and a diagnosis of falciparum malaria is made. This patient should immediately receive (A) Artemether plus lumefantrine (Coartem) (B) Artesunate (C) Pentamidine (D) Primaquine (E) Stibogluconate

(B) Artesunate

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

(B) Azithromycin

Which antibacterial agent appears to be the safest to use in the pregnant patient? (A) Amikacin (B) Azithromycin (C) Ciprofloxacin (D) Erythromycin (E) Tetracycline

(B) Azithromycin

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

(B) Benzalkonium chloride

A 27-year-old pregnant patient with a his-tory 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) Amoxicillin (B) Cefoperazone (C) Ciprofloxacin (D) Trimethoprim-sulfamethoxazole (E) Vancomycin

(B) Cefoperazone

Which of the following statements about beta-lactam antibiotics is most correct? (A) Cephalexin and other first-generation cephalosporins cross the blood-brain barrier (B) Ceftriaxone and nafcillin are both eliminated mainly via biliary secretion (C) Instability of penicillins in gastric acid does not limit their oral absorption (D) Renal tubular reabsorption of amoxicillin is inhibited by probenecid (E) Ticarcillin has limited activity against several Gram-negative rods

(B) Ceftriaxone and nafcillin are both eliminated mainly via biliary secretion

A patient with AIDS has a CD4 count of 45/μL. He is being maintained on a 3-drug regimen of indinavir, didanosine, and zidovudine. For prophylaxis against opportunistic infections, he is also receiving cidofovir, fluconazole, rifabutin, and trimethoprim-sulfamethoxazole. The drug most likely to suppress herpetic infections and provide prophylaxis against CMV retinitis in this patient is (A) Fluconazole (B) Cidofovir (C) Indinavir (D) Rifabutin (E) Trimethoprim-sulfamethoxazole

(B) Cidofovir

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

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

(B) Decreased accumulation of the drug in the food vacuole

A 30-year-old male patient who is HIV-positive and symptomatic has a CD4 count of 250/μL and a viral RNA load of 15,000 copies/mL. His treatment involves a 3-drug antiviral regimen consisting of zidovudine, didanosine, and ritonavir. The patient is taking acyclovir for a herpes infection and ketoconazole for oral candidiasis. He now complains of anorexia, nausea and vomiting, and abdominal pain. His abdomen is tender in the epigastric area. Laboratory results reveal an amylase activity of 220 U/L, and a preliminary diagnosis is made of acute pancreatitis. If this patient has acute pancreatitis, the drug most likely to be responsible is (A) Acyclovir (B) Didanosine (C) Ketoconazole (D) Ritonavir (E) Zidovudine

(B) Didanosine

Oral formulations of this drug should not be used in a preg-nant AIDS patient because they contain propylene glycol. One of the characteristic adverse effects of the drug is hyper-pigmentation on the palms of the hands and soles of the feet, especially in African-American patients. (A) Amprenavir (B) Emtricitabine (C) Efavirenz (D) Fosamprenavir (E) Zalcitabine

(B) Emtricitabine

A 14-year-old patient has experienced severe headache and double vision for a month. His temperature is 38.6°C (101.5°F). His CSF culture was positive for cryptococcal antigen. Which of the following drugs would be appropriate to treat this patient systemically (not intrathecally)? (A) Amphotericin B (B) Fluconazole (C) Itraconazole (D) Ketoconazole (E) Nystatin

(B) Fluconazole

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) Griseofulvin (C) Ketoconazole (D) Itraconazole (E) Nystatin

(B) Griseofulvin

A hospitalized AIDS patient is receiving antiret-roviral drugs but no antimicrobial prophylaxis. He develops sepsis with fever, suspected to be caused by a Gram-negative bacillus. If amikacin 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 hematotoxic (E) Is rapidly metabolized by the liver

(B) Has a narrow therapeutic window

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 dur-ing 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 produces 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) Dyspnea, flushing, palpitations, and sweating may occur after ingestion of tyramine-containing foods (B) In fast acetylators, lower maintenance doses are necessary (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%

(B) In fast acetylators, lower maintenance doses are necessary

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

(B) Melarsoprol

A 65-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) Ampicillin (B) Ofloxacin (C) Sulfadiazine (D) Trimethoprim (E) Vancomycin

(B) Ofloxacin

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, which is often irreversible (C) Ototoxicity is reduced if loop diuretics are used to facili-tate the renal excretion of aminoglycoside antibiotics (D) Reduced blood creatinine is an early sign of aminoglycoside nephrotoxicity (E) Skin reactions are very rare following topical use of neomycin

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

A 34-year-old patient is febrile (39.5°C [103.1°F]), with a white blood cell count that has risen from 8500 to 20,000/mm3. The ICU attending physician is concerned about a bloodstream infection and decides to treat with empiric combination ther-apy directed against Pseudomonas aeruginosa. The combination therapy includes tobramycin. 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

(C) Cause misreading of the code on the mRNA template

A 52-year-old man (weight 70 kg) is brought to the hospital emergency department in a confused and delirious state. He has had an elevated temperature for more than 24 h, dur-ing 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 findings include elevated protein, decreased glucose, and increased neutrophils. Treatment of this patient should be initiated immediately with intravenous administration of (A) Amoxicillin (B) Cephalexin (C) Ceftriaxone plus vancomycin (D) Nafcillin(E) Piperacillin

(C) Ceftriaxone plus vancomycin

A 52-year-old man (weight 70 kg) is brought to the hospital emergency department in a confused and delirious state. He has had an elevated temperature for more than 24 h, dur-ing 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 findings include elevated protein, decreased glucose, and increased neutrophils. Resistance of pneumococci to penicillin G is due to (A) Alterations in porin structure (B) Beta-lactamase production (C) Changes in chemical structure of target penicillin-binding proteins (D) Changes in the d-Ala-d-Ala building block of peptido-glycan precursor (E) Decreased intracellular accumulation of penicillin G

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

A 4-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. She 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) Azithromycin (C) Chloramphenicol (D) Doxycycline (E) Erythromycin

(C) Chloramphenicol

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 dif-ficulty, and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expecto-rated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work had 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 erythromycin, she should (A) Avoid exposure to sunlight (B) Avoid taking supplementary iron tablets (C) Decrease her intake of caffeinated beverages (D) Have her plasma urea nitrogen or creatinine checked before treatment (E) Temporarily stop taking loratadine

(C) Decrease her intake of caffeinated beverages

A 72-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 daily total of 200 mg (C) Decrease the dosage to 180 mg every 8 h (D) Discontinue amikacin and switch to gentamicin (E) Maintain the patient on the present dosage and test auditory function

(C) Decrease the dosage to 180 mg every 8 h

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 dif-ficulty, and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expecto-rated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work had 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) Ampicillin (B) Clindamycin (C) Doxycycline (D) Linezolid (E) Vancomycin

(C) Doxycycline

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 dur-ing 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 produces 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, pyrazinamide, rifampin (D) Isoniazid, pyrazinamide, rifampin, streptomycin (E) PAS, pyrazinamide, rifabutin, streptomycin

(C) Ethambutol, isoniazid, pyrazinamide, rifampin

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 H pylori (D) Is active against methicillin-resistant strains of staphylococci (E) Is active against strains of streptococci that are resistant to erythromycin

(C) Has greater activity against H pylori

A 10-year-old boy has uncomplicated pulmonary tuberculosis. 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 test of 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) Polyarthralgia is a potential adverse effect of the drugs the boy is taking (E) The potential nephrotoxicity of the prescribed drugs warrants periodic assessment of renal function

(C) His 3-year-old sibling should receive INH prophylaxis

Which of the following statements about the clinical uses of the aminoglycosides is accurate? (A) Effective in the treatment of infections caused by anaerobes such as Bacteroides fragilis (B) Gentamycin is used with ampicillin for synergistic effects in the treatment of enterococcal endocarditis (C) In the treatment of a hospital-acquired infection caused by Serratia marcescens, netilmicin is less effective than streptomycin (D) Often used as monotherapy in the empiric treatment of life-threatening bacterial infections (E) Aminoglycosides are well absorbed after oral administration

(C) In the treatment of a hospital-acquired infection caused by Serratia marcescens, netilmicin is less effective than streptomycin

Which statement about the mechanisms of action of antiviral drugs is accurate? (A) Acyclovir has no requirement for activation by phosphorylation (B) Ganciclovir inhibits viral DNA polymerase but does not cause chain termination (C) Increased activity of host cell ribonucleases that degrade viral mRNA is one of the actions of interferon-α (D) The initial step in activation of foscarnet in HSV-infected cells is its phosphorylation by thymidine kinase (E) The reverse transcriptase of HIV is 30-50 times more sensitive to inhibition by fosamprenavir than host cell DNA polymerases

(C) Increased activity of host cell ribonucleases that degrade viral mRNA is one of the actions of interferon-α

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

(C) Infections due to Pneumocystis jirovecii

Immunofluorescent microscopic examination of fluid expressed from the penile chancre of this patient revealed treponemes. Because he appears to be infected with Trepo-nema 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

(C) Inject intramuscular benzathine penicillin G

A 28-year-old man living on the East Coast was transferred by his employer to 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) Flucytosine (C) Itraconazole (D) Micafungin (E) Terbinafine

(C) Itraconazole

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

(C) Ketoconazole

A 10-year-old American girl presented to the emergency department with fever, chills, lethargy, and sple-nomegaly. She had recently returned from Nigeria, where she had spent 3 weeks with her grandparents. She had previously received all standard childhood immunizations but no prophylactic travel medications because her parents had returned to Nigeria several times previously without any medical problems. Laboratory examination reveals low hematocrit and platelet count and elevated creatinine. Blood smear reveals parasites in the erythrocytes and a diagnosis of falciparum malaria is made. The patient should have received prophylaxis for the prevention of malaria; what prophylactic regimen would have been most appropriate? (A) Artesunate (B) Chloroquine (C) Mefloquine (D) Quinidine (E) Tetracycline

(C) Mefloquine

Which statement about the fluoroquinolones is accurate? (A) Antacids increase their oral bioavailability (B) Contraindicated in patients with hepatic dysfunction (C) Fluoroquinolones are drugs of choice in a 6-year-old child with a urinary tract infection (D) Gonococcal resistance to fluoroquinolones may involve changes in DNA gyrase (E) Modification of moxifloxacin dosage is required in patients when creatinine clearance is less than 50 mL/min

(D) Gonococcal resistance to fluoroquinolones may involve changes in DNA gyrase

A 26-year-old woman was treated for a suspected chlamydial infection at a neighborhood clinic. She was given a pre-scription for oral doxycycline to be taken for 14 d. Three weeks later, she returned to the clinic with a mucopurulent cervicitis. 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 azithromycin (D) Treat her in the clinic with an intravenous dose of amoxicillin (E) Write a prescription for oral erythromycin for 10 d

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

An adult patient (weight 80 kg) has bacteremia suspected to be due to a Gram-negative rod. Tobramycin is to be administered 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 = 30 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

(D) 600 mg

Tetracyclines are the drugs of choice for Rocky Mountain spotted fever and Lyme disease. The mechanism of antibacte-rial action of tetracycline 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

A 30-year-old male patient who is HIV-positive and symptomatic has a CD4 count of 250/μL and a viral RNA load of 15,000 copies/mL. His treatment involves a 3-drug antiviral regimen consisting of zidovudine, didanosine, and ritonavir. The patient is taking acyclovir for a herpes infection and ketoconazole for oral candidiasis. He now complains of anorexia, nausea and vomiting, and abdominal pain. His abdomen is tender in the epigastric area. Laboratory results reveal an amylase activity of 220 U/L, and a preliminary diagnosis is made of acute pancreatitis. In the further treatment of this patient, the drug causing the pancreatitis should be withdrawn and replaced by (A) Atazanavir (B) Cidofovir (C) Foscarnet (D) Lamivudine (E) Ribavirin

(D) Lamivudine

Which of the following statements about interferon-α is false? (A) At the start of treatment, most patients experience flu-like symptoms (B) Indications include treatment of genital warts (C) It is used in the management of hepatitis B and C (D) Lamivudine interferes with its activity against hepatitis B (E) Toxicity includes bone marrow suppression

(D) Lamivudine interferes with its activity against hepatitis B

A 55-year-old man 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 cardiac arrhythmia. 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

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) Ciprofloxacin (C) Erythromycin (D) Nitrofurantoin (E) Tetracycline

(D) Nitrofurantoin

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

(D) Nystatin

JT is a 14-year-old patient who is diagnosed with otitis media, requiring amoxicillin. The primary mechanism of antibacte-rial action of amoxicillin involves inhibition of (A) Beta-lactamases (B) Cell membrane synthesis (C) N-acetylmuramic acid synthesis (D) Peptidoglycan cross-linking (E) Transglycosylation

(D) Peptidoglycan cross-linking

Which compound is the safest drug to use topically to treat scabies and pediculosis? (A) Benzoyl peroxide (B) Chlorhexidine (C) Lindane (D) Permethrin (E) Silver sulfadiazine

(D) Permethrin

A 10-year-old American girl presented to the emergency department with fever, chills, lethargy, and sple-nomegaly. She had recently returned from Nigeria, where she had spent 3 weeks with her grandparents. She had previously received all standard childhood immunizations but no prophylactic travel medications because her parents had returned to Nigeria several times previously without any medical problems. Laboratory examination reveals low hematocrit and platelet count and elevated creatinine. Blood smear reveals parasites in the erythrocytes and a diagnosis of falciparum malaria is made. If the girl recovers from the acute falciparum attack but a month later develops P vivax malaria, what drug or drugs should be given to eradicate schizonts and latent hypnozoites in the liver? (A) Artesunate (B) Dapsone (C) Halofantrine (D) Primaquine (E) Quinine

(D) Primaquine

Which statement about the actions of antimicrobial agents is false (A) Metronidazole has activity against C difficile (B) Neonatal gonococcal ophthalmia can be prevented by silver nitrate (C) Polymyxins act as cationic detergents to disrupt bacterial cell membranes (D) Resistance to nitrofurans emerges rapidly, and there is cross-resistance with sulfonamides (E) Salicylic acid has useful antidermatophytic activity when applied locally

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

A patient with AIDS has a CD4 count of 45/μL. He is being maintained on a 3-drug regimen of indinavir, didanosine, and zidovudine. For prophylaxis against opportunistic infections, he is also receiving cidofovir, fluconazole, rifabutin, and trimethoprim-sulfamethoxazole. The dose of indinavir in this patient may need to be increased above normal. This is because (A) Fluconazole slows gastric emptying (B) Ganciclovir increases the renal clearance of indinavir (C) Gastric absorption is inhibited by fluconazole (D) Rifabutin increases hepatic drug metabolism (E) Sulfamethoxazole increases indinavir plasma protein binding

(D) Rifabutin increases hepatic drug metabolism

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

(D) Rifampin

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) Choose an antibiotic based on drug susceptibility of the cultured organism (B) Initiate a two-drug regimen of INH and pyrazinamide (C) Prescribe rifabutin because it prevents the development of MAC bacteremia (D) Start treatment with the combination of azithromycin, ethambutol, and rifabutin (E) Treat with trimethoprim-sulfamethoxazole

(D) Start treatment with the combination of azithromycin, ethambutol, and rifabutin

37-year-old woman with leukemia was undergoing chemotherapy with intravenous antineoplastic drugs. During treatment, she developed a systemic infection from an opportunistic pathogen. There was no erythema or edema at the catheter insertion site. A white vaginal discharge was observed. After appropriate specimens were obtained for culture, empiric antibiotic therapy was started with gentamicin, nafcillin, and ticarcillin intravenously. 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 griseofulvin (B) Continue current antibiotics and start amphotericin B (C) Stop current antibiotics and start itraconazole (D) Stop current antibiotics and start amphotericin B (E) Stop current antibiotics and start terbinafine

(D) Stop current antibiotics and start amphotericin B

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

(D) Sulfadiazine

A 40-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 moderate abdominal pain and tenderness. His cur-rent 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 appropri-ate drug to use in this patient is (A) Ampicillin (B) Doxycycline (C) Norfloxacin (D) Sulfasalazine (E) Trimethoprim-sulfamethoxazole

(D) Sulfasalazine

The primary mechanism of resistance of Gram-positive organisms to macrolide antibiotics including erythromycin is (A) Changes in the 30S ribosomal subunit (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

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

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) Pentamidine (D) Tinidazole (E) TMP-SMZ

(D) Tinidazole

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

(D) Toxoplasmosis

A hospitalized AIDS patient is receiving antiret-roviral drugs but no antimicrobial prophylaxis. He develops sepsis with fever, suspected to be caused by a Gram-negative bacillus. 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 the treatment of (A) Cryptococcal meningitis with amphotericin B and flucytosine (B) Coliform infections with sulfamethoxazole and trimethoprim (C) Enterococcal infections with rifampin and vancomycin (D) Pseudomonal infections with carbenicillin and gentamicin (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

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

Which statement about the clinical use of sulfonamides is correct? (A) Cannot be used topically for treatment of chlamydial infections of the eye (B) Effective as sole agents in the treatment of prostatitis C) Effective in Rocky Mountain spotted fever (D) In some bacterial strains resistance occurs via reduced PABA formation (E) Reduced intracellular uptake is a mechanism of sulfonamide resistance in some bacterial strains

(E) Reduced intracellular uptake is a mechanism of sulfonamide resistance in some bacterial strains

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) Flucytosine (C) Nystatin (D) Voriconazole (E) None of the above

(E) None of the above

Which antiseptic promotes wound healing? (A) Cetylpyridinium chloride (B) Chlorhexidine (C) Hexachlorophene (D) Phenol (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 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) Ketoconazole (D) Terbinafine (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 cefoxitin (B) Intravenous third-generation cephalosporin (C) Oral amoxicillin (D) Oral ciprofloxacin (E) Oral erythromycin and neomycin

(E) Oral erythromycin and neomycin

Which statement about antitubercular drugs is accurate? (A) Antimycobacterial actions of streptomycin involve inhi-bition of arabinosyltransferases (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

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

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

(E) Skin rash

Which statement about ciprofloxacin is accurate? (A) Antagonism occurs if used with dihydrofolate reductase inhibitors (B) Ciprofloxacin is active against MRSA strains of staphylococci (C) Most "first-time" urinary tract infections are resistant to ciprofloxacin (D) Organisms that commonly cause ear infections are highly resistant (E) Tendinitis may occur during treatment

(E) Tendinitis may occur during treatment

Which statement is accurate regarding the antibacterial action of the aminoglycoside amikacin? (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 inhibi-tory concentration (E) The drug continues to exert antibacterial effects even after plasma levels decrease below detectable levels

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

A 76-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 injected intramuscularly and the patient should be sent home (B) Analgesics should be prescribed, but antibiotics should be withheld pending microbiological results (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 imipenem-cilastatin (E) The patient should be hospitalized and treatment started with gentamicin plus ticarcillin

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

A young woman is brought to a hospital emergency department with intense abdominal pain of 2 days duration. The pain has spread to the right lower quadrant and is accompanied 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 appropriate 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

A 55-year-old man 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 cardiac arrhythmia. 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 gentamicin but has much weaker activity in combination with penicillin against enterococci. (A) Amikacin (B) Erythromycin (C) Netilmicin (D) Spectinomycin (E) Tobramycin

(E) Tobramycin

In an accidental needlestick, an unknown quantity of blood from an AIDS patient is injected into a resident physician. The most recent laboratory report on the AIDS patient shows a CD4 count of 20/μL and a viral RNA load of greater than 107 copies/mL. The most appropriate course of action regard-ing treatment of the resident is to (A) Determine whether HIV transmission has occurred by monitoring the patient's blood (B) Treat with a single high dose of zidovudine (C) Treat with full doses of zidovudine for 4 weeks (D) Treat with single doses of zidovudine and indinavir (E) Treat with zidovudine plus lamivudine plus ritonavir for 4 weeks

(E) Treat with zidovudine plus lamivudine plus ritonavir for 4 weeks

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) Levofloxacin (C) Linezolid (D) Sulfamethoxazole (E) Trimethoprim

(E) Trimethoprim

Which statement about antiprotozoal drugs is most 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, block-ing replication (E) Trimethoprim-sulfamethoxazole is the drug of choice for Pneumocystis jirovecii pneumonia

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

A 27-year-old nursing mother is diagnosed as suffering from genital herpes. She has a history of this viral infection. Previously, she responded to a drug used topically. Apart from her current problem, she is in good health. Which drug to be used orally is most likely to be prescribed at this time? (A) Amantadine (B) Foscarnet (C) Ritonavir (D) Trifluridine (E) Valacyclovir

(E) Valacyclovir

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) Ceftriaxone (D) Piperacillin (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) Amoxicillin (B) Chloramphenicol (C) Doxycycline (D) Levofloxacin (E) Vancomycin

(E) Vancomycin