PreTest Self-Assessment and Review (Pretest Series) - 12th Ed PDF

Anti-Infectives Antibacterials Antivirals Antimycobacterials Antiprotozoals Antifungals Questions DIRECTIONS: Each item contains a question or incomplete statement that is followed by several responses. S...

Anti-Infectives Antibacterials Antivirals Antimycobacterials Antiprotozoals Antifungals Questions DIRECTIONS: Each item contains a question or incomplete statement that is followed by several responses. Select the one best response to each question. 409. A patient on antimicrobial therapy develops the following signs and symptoms that ultimately are found to be drug-induced: cough, dyspnea, and pulmonary infiltrates; neutropenia and bleeding tendencies; and pares- thesias. Which of the following is the most likely cause of this patient’s symptoms? a. Amoxicillin b. Azithromycin c. Ciprofloxacin d. Isoniazid e. Nitrofurantoin 410. A patient with an opportunistic infection with Pneumocystis carinii is receiving a combination of sulfamethoxazole (SMZ) and trimethoprim (TMP). Which of the following statements describes best the mechanism by which this combination exerts its desired effects—and does so better than if just one of the drugs was administered? a. The combination exerts significant antiviral activity, thereby reducing the risk of opportunistic P. carinii infections during antiviral therapy with other medications b. The SMZ permeabilizes bacterial cell walls, allowing better penetration of the TMP c. They inhibit sequential steps in bacterial synthesis of tetrahydrofolic acid d. TMP inhibits production of resistance factors (“R-factors”) directed against SMZ e. TMP kills gut flora that otherwise would reduce oral bioavailability of the SMZ 381 Copyright © 2007 by The McGraw-Hill Companies, Inc. Click here for terms of use. 382 Pharmacology 411. Ticarcillin is relatively unique among all the penicillins because it poses a greater risk of a relatively unique side effect or adverse response. Which of the following best summarizes what that unique unwanted effect is? a. Acute renal failure b. Bronchoconstriction, bronchospasm, asthma c. Fever, arthralgia, and other signs of a lupus-like syndrome d. Hypertension, hypervolemia, and bleeding e. Inducing penicillinase and causing resistance 412. A 39-year-old man with aortic insufficiency and a history of multiple antibiotic resistance is given a prophylactic intravenous dose of antibiotic before surgery to insert a prosthetic heart valve. As the antibiotic is being infused, the patient becomes flushed over most of his body. Which of the following antibiotics is most likely responsible? a. Erythromycin b. Gentamicin c. Penicillin G d. Tetracycline e. Vancomycin 413. A patient develops antibiotic-associated pseudomembranous colitis (AAPMC) in response to drug therapy. Which of the following was the most likely cause of this severe problem? a. Amoxicillin b. Azithromycin c. Clindamycin d. Metronidazole e. Trimethoprim plus sulfamethoxazole (TMP-SMZ) 414. A 35-year-old woman complains of itching in the vulval area. Hanging- drop examination of the urine reveals trichomonads. Which of the follow- ing is the preferred treatment for the trichomoniasis? a. Doxycycline b. Emetine c. Metronidazole d. Pentamidine e. Pyrimethamine  Anti-Infectives 383 415. A 75-year-old man has a fever of 104°F. He develops a cough that produces blood-tinged sputum with gram-positive cocci in clusters. A chest x-ray shows increased density in the right upper lobe. Which of the following penicillins is likely to fail to treat this infection adequately? a. Cloxacillin b. Dicloxacillin c. Nafcillin d. Oxacillin e. Ticarcillin 416. A patient will be started on primaquine to treat active Plasmodium vivax malaria, specifically to target the hepatic forms of the parasite. Before you administer the drug you should screen the patient to assess their rela- tive risk of developing a relatively common and severe adverse response to the drug. Which of the following best summarizes what that risk is? a. Cardiac conduction disturbances b. Hemolytic disease c. Nephrotoxicity d. Retinopathy e. Seizures, convulsions 417. A 50-year-old man with Type 2 diabetes develops an otitis from which Pseudomonas organisms are cultured. Topical therapy with polymyxin B is effective. Which of the following best explains the drug’s mechanism of action? a. Disrupts membrane permeability b. Forms reactive products that interfere with DNA replication c. Inactivates bacterial protein sulfhydryl groups d. Inhibits cell-wall synthesis e. Inhibits protein synthesis by binding to tRNA 418. A 27-year-old woman has just returned from a trip to Southeast Asia. Over the past 24 h she has developed shaking, chills, and a temperature of 104°F. A blood smear reveals Plasmodium vivax. Which of the following agents should be used to eradicate the extraerythrocytic phase of the organism? a. Chloroguanide b. Chloroquine c. Primaquine d. Pyrimethamine e. Quinacrine 384 Pharmacology 419. A jaundiced 1-day-old premature infant with elevated free bilirubin is seen in the premature baby nursery. The mother had received an antibi- otic combination for a urinary tract infection (UTI) 1 week before delivery. Which of the following is the most likely cause of the baby’s kernicterus? a. A fourth-generation cephalosporin b. An aminopenicillin (e.g., amoxicillin) c. Azithromycin d. Erythromycin e. A sulfonamide f. A tetracycline 420. A sputum culture of a 65-year-old man with pneumonia is positive for β-lactamase-positive staphylococci. Which of the following is the best choice for penicillin therapy in this patient? a. Ampicillin b. Carbenicillin c. Oxacillin d. Penicillin G e. Ticarcillin 421. A young boy presents with an infestation of Taenia saginata (tape- worm). Which of the following is the most appropriate drug to administer for treating this helminth problem? a. Ceftriaxone b. Chloroquine c. Mebendazole d. Niclosamide e. Primaquine 422. A 40-year-old man is HIV-positive with a cluster-of-differentiation-4 (CD4) count of 200/mm3. Within 2 months he develops a peripheral white blood cell count of 1000/mm3 and hemoglobin of 9.0 mg/dL. Which of the following drugs most likely caused the hematologic abnormalities? a. Acyclovir b. Dideoxycytidine c. Foscarnet d. Rimantadine e. Zidovudine  Anti-Infectives 385 423. An 86-year-old man complains of cough and blood in his sputum for the past 2 days. On admission, his temperature is 103°F. Physical examina- tion reveals rales in his right lung, and x-ray examination shows increased density in the right middle lobe. A sputum smear shows many gram-positive cocci, confirmed by sputum culture as penicillinase-producing Staphylococ- cus aureus. Which of the following antibiotics would be best to administer? a. Ampicillin b. Carbenicillin c. Mezlocillin d. Oxacillin e. Ticarcillin 424. When considering all the main antibacterial drugs that work by inhibiting protein synthesis in one way or another, virtually every one exerts bacteriostatic actions. Which of the following drugs differs from all the rest because the usual consequence of therapeutic serum levels is bac- tericidal, rather than mere inhibition of bacterial growth and replication? a. Aminoglycosides b. Clindamycin c. Erythromycins d. Linezolid e. Tetracyclines 425. A patient with AIDS is treated with a combination of agents, one of which is zidovudine. Which of the following enzymes or replicative processes is the main target of this antiviral drug? a. Nonnucleoside reverse transcriptase b. Nucleoside reverse transcriptase c. RNA synthesis d. Viral particle assembly e. Viral proteases 386 Pharmacology 426. A 39-year-old woman with a history of recurrent urinary tract infec- tions develops a new infection. Culture of a urine sample indicated that the offending organism is Escherichia coli. She receives therapeutic doses of ciprofloxacin. Symptoms disappear as the offending bacteria are destroyed. Which of the following is the main bacterial process or enzyme that was inhibited by levofloxacin? a. Cell-wall synthesis b. Protein synthesis c. Folic acid synthesis d. Topoisomerase II (DNA gyrase) e. DNA polymerase 427. Chloramphenicol is an effective antibiotic, but significant toxicity limits use of the drug, particularly in newborns and infants. Which of the following is the major and most common toxic reaction to this drug, and is the one that severely restricts its use, regardless of the patient’s age? a. Aplastic anemia b. Hepatotoxicity c. Interstitial nephritis d. Pulmonary fibrosis e. Torsades de pointes or ventricular fibrillation 428. A patient with AIDS, being treated with multiple antiviral and immunosuppressive drugs, develops an opportunistic infection caused by P. carinii. Which of the following drugs are we most likely to use to treat the pulmonary infection caused by this protozoan? a. Carbenicillin b. Metronidazole c. Nifurtimox d. Penicillin G e. Pentamidine  Anti-Infectives 387 429. A 25-year-old woman with an upper respiratory tract infection caused by Haemophilus influenzae is treated with trimethoprim-sulfamethoxazole. She responds well in a matter of days after starting this TMP-SMZ therapy. Which of the following bacterial processes is inhibited by this combination, and accounts for the antibacterial effects? a. Cell-wall synthesis b. Protein synthesis c. Folic acid synthesis d. Topoisomerase II (DNA gyrase) e. DNA polymerase 430. A man who has been at the local tavern, drinking alcohol heavily, is assaulted. He is transported to the hospital. Among various findings is an infection for which prompt antibiotic therapy is indicated. Given his high blood alcohol level, which of the following antibiotics should be avoided because of a high potential of causing a serious disulfiram-like reaction that might provoke ventilatory or cardiovascular failure? (Assume that were it not for the alcohol consumption, the antibiotic prescribed would be suit- able for the infectious organisms that have been detected.) a. Amoxicillin b. Cefoperazone or cefotetan c. Erythromycin ethylsuccinate d. Linezolid e. Penicillin G 431. Members of the rifamycin antibiotic family (e.g., rifampin) are involved in a significant number of drug interactions. Which of the follow- ing summarizes best the pharmacodynamic or pharmacokinetic mecha- nism by which the rifamycins cause these problems? a. Displace other drugs from their plasma protein-binding sites b. Induce resistance to many other drugs by stimulating antibody formation c. Induce the hepatic microsomal drug-metabolizing enzymes d. Markedly increase glomerular filtration rates and excretion of the interactants e. Reduce oral absorption and bioavailability of many drugs via a pH-dependent action in the stomach 388 Pharmacology 432. A 43-year-old woman is recovering from major surgery, following discharge from the hospital, in an assisted-care facility. She develops fever, rales, dyspnea, cough, and purulent sputum. Results of a chest radiograph indicate bilateral pulmonary infiltrates. We send blood and sputum sam- ples to the clinical pathology lab for culturing, but now must turn our attention to what we believe is community-acquired pneumonia caused by antibiotic-resistant pneumococci. We want to start empiric antibiotic ther- apy until culture results are available. Which of the following drugs would be best for this initial therapy? a. Amoxicillin b. Cefazolin c. Erythromycin d. Levofloxacin e. Penicillin G f. Vancomycin 433. Blood and sputum cultures taken in a critically ill 26-year-old woman indicate the presence of MRSA—methicillin-resistant Staphylococ- cus aureus. Which of the following drugs is most likely to be effective in treating this infection? a. Amoxicillin plus clavulanic acid b. Clindamycin c. Erythromycin d. Trimethoprim-sulfamethoxazole (TMP-SMZ) e. Vancomycin 434. Compared with most other cephalosporins, the administration of cefmetazole, cefoperazone, or cefotetan is associated with a higher incidence of an adverse response that is particularly dangerous for some patients. Which of the following states best what that rather unique adverse response is? a. Acute heart failure b. Acute renal failure c. Bleeding tendencies in patients taking warfarin d. Hypertension e. Ototoxicity f. Severe allergic reactions in patients with mild penicillin allergies  Anti-Infectives 389 435. A patient with an infectious disease routinely takes their antimicro- bial medication with milk or other dairy products in an attempt to reduce stomach upset from the drug. The antibiotic fails to work adequately because calcium in the milk chelates the drug and reduces its oral bioavail- ability. Which of the following antimicrobial drugs or drug classes was the patient most likely taking? a. Aminoglycoside b. Antimycobacterial drug, specifically isoniazid c. Cephalosporin, first generation d. Cephalosporin, third generation e. Penicillin f. Tetracycline 436. A patient develops profuse, watery diarrhea, fever, abdominal pain, and leukocytosis in response to antibiotic drug therapy. C. difficile infection in the gut is confirmed. Which of the following drugs is the preferred agent for therapy of this antibiotic-associated pseudomembranous colitis? a. Amoxicillin b. Azithromycin c. Clindamycin d. Metronidazole e. Trimethoprim plus sulfamethoxazole 437. Ampicillin and amoxicillin are in the same group of penicillins. However, there are important differences. Which of the following best states how amoxicillin differs from ampicillin? a. Has better oral bioavailability, particularly when taken with meals b. Is effective against penicillinase-producing organisms c. Is a broad-spectrum penicillin d. Does not cause hypersensitivity reactions e. Has great antipseudomonal activity 390 Pharmacology 438. A patient’s history notes a documented severe (anaphylactoid) reac- tion to penicillin. What other antibiotic or class is likely to cross-react and so should be avoided in this patient? a. Aminoglycosides b. Azithromycin c. Cephalosporins d. Erythromycin e. Linezolid f. Tetracyclines 439. A 30-year-old woman develops a severe P. aeruginosa infection. The physician chooses to treat it with amikacin, not with gentamicin. Which of the following statements best describes how amikacin differs from gentamicin? a. Does not require monitoring of blood levels during therapy b. Exerts significant bactericidal effects against anaerobes too c. Has broader spectrum against gram-negative bacilli d. Lacks ototoxic potential e. Protects against typical aminoglycoside nephrotoxicity 440. A 19-year-old being treated for leukemia develops a fever. You give several agents that will cover bacterial, viral, and fungal infections. Two days later, he develops acute renal failure. Which of the following drugs was most likely responsible? a. Acyclovir b. Amphotericin B c. Ceftazidime d. Penicillin G e. Vancomycin  Anti-Infectives 391 441. Penicillins, cephalosporins, and amphotericin B are quite different structurally, and the antimicrobial spectrum of amphotericin B is decidedly different from that of the other agents. Which of the following properties or actions is shared by all three of these drugs or drug groups? a. Act, though various mechanisms, on cell walls or membranes of susceptible organisms b. Contraindicated in immunocompromised patients c. Interact with many drugs by inducing their hepatic metabolism d. Leukopenia (increased white cell counts) is a common side effect e. Nephrotoxicity precludes use in patients with impaired renal function 442. A patient with a P. aeruginosa infection is receiving intravenous gen- tamicin. The aminoglycoside blood levels are well above the minimum inhibitory concentration (MIC), but the clinical response is not satisfactory. A new medication order calls for adding a penicillin, administered in a sep- arate IV line to avoid a physical incompatibility. If this order is carried out, which of the following is most likely to occur? a. The aminoglycoside will inactivate the penicillin b. The aminoglycoside will chemically neutralize and abolish the effects of the penicillin c. The patient is likely to develop Clostridium difficile colitis (superinfection) d. The penicillin will act synergistically with the aminoglycoside e. The penicillin will increase the risk of aminoglycoside nephrotoxicity f. The risk of inducing resistance to both drugs increases dramatically 443. Narrow spectrum penicillins, both penicillinase-sensitive and -resistant, have relatively poor activity against gram-negative bacteria. Which of the following is the main property or characteristic that explains why these microorganisms do not respond well to the penicillins? a. Actively transport any absorbed penicillin back to the extracellular space b. Have an outer membrane that serves as a physical barrier to the penicillins c. Lack a surface enzyme necessary to metabolically activate the penicillins d. Lack penicillin-binding proteins e. Metabolically inactivate these penicillins by mechanisms not involving β-lactamase 392 Pharmacology 444. A 30-year-old man with a 2-year history of chronic renal failure requiring dialysis consents to transplantation. A donor kidney becomes available. He is given cyclosporine to prevent transplant rejection. Which of the following is the most likely adverse effect of this drug? a. Bone marrow depression b. Nephrotoxicity c. Oral and GI ulceration d. Pancreatitis e. Seizures 445. Amantadine, sometimes used in the management of parkinsonism, is also used prophylactically against influenza A infections. Which of the fol- lowing statements best summarizes this drug’s antiviral mechanism of action? a. Causes lysis of infected host cells by release of intracellular lysosomal enzymes b. Inhibits production of viral capsid protein c. Prevents virion release d. Prevents penetration of the virus into the host cell e. Prevents uncoating of viral DNA 446. Streptomycin and other aminoglycosides cause their antimicrobial effects in susceptible organisms by inhibitng protein synthesis. Which of the following is the primary target of these drugs? a. 30S ribosomal subunits b. DNA c. mRNA d. Peptidoglycan units in the cell wall e. RNA polymerase 447. We have a patient with an intraabdominal infection, and Bacteroides fragilis is the main organism found upon culture. Which of the following cephalosporins has the greatest activity against anaerobic bacteria such as B. fragilis? a. Cefaclor b. Cefoxitin c. Cefuroxime d. Cephalexin e. Cephalothin  Anti-Infectives 393 448. You are taking an initial health history from a 22-year-old woman who just moved to your town. She is remarkably fit and healthy, but is wearing two hearing aids for binaural (bilateral) high-frequency hearing loss. You inquire about the possible reason(s) for this. She says she lost most of her hearing after receiving an antibiotic for a severe infection when she was 19, but cannot recall the specific drug. Which of the following drugs was most likely responsible for her hearing loss? a. Aminoglycoside (e.g., gentamicin) b. Cephalosporin, first-generation c. Cephalosporin, third-generation d. Fluoroquinolone (e.g., ciprofloxacin) e. Penicillin 449. A 26-year-old woman with acquired immunodeficiency syndrome (AIDS) develops cryptococcal meningitis. She refuses intravenous medica- tion. Which of the following antifungal agents is the best choice for oral therapy of the meningitis? a. Amphotericin B b. Fluconazole c. Ketoconazole d. Metronidazole e. Nystatin 450. An adult patient is being treated with a parenteral aminoglycoside for a serious Pseudomonas aeruginosa infection. He requires immediate surgery. He is premedicated with midazolam. A dose of succinylcholine is given for intubation, with skeletal muscle paralysis maintained during surgery with pancuronium. Balanced anesthesia is provided with nitrous oxide, isoflu- rane, and oxygen. Which of the following is the most likely outcome of having the aminoglycoside “on board” in the perioperative setting along with all these other drugs? a. Acute hepatotoxicity from an aminoglycoside-isoflurane interaction b. Antagonism of midazolam’s amnestic and sedative effects c. Enhanced aminoglycoside toxicity to host cells d. Increased or prolonged response to neuromuscular blockers e. Reduced risk of catecholamine-induced cardiac arrhythmias 394 Pharmacology 451. A patient with tuberculosis is started on isoniazid (INH) as part of a multidrug regimen. The physician also starts therapy with vitamin B6 at the same time. Which of the following is the main reason for giving the vitamin B6 prophylactically? a. Facilitates INH renal excretion, thereby protecting against nephrotoxicity b. Inhibits metabolism of INH, thereby increasing INH blood levels c. Is a cofactor required for activation of the INH to its antimycobacterial metabolite d. Potentiates the antitubercular activity of the INH e. Prevents some adverse effects of INH therapy 452. One antibiotic is considered very effective in treatment of Rickettsia, Mycoplasma, and Chlamydia infections. It is also used to mange some patients with acne vulgaris lesions. To which of the following drugs does this description apply? a. Bacitracin b. Gentamicin c. Penicillin G d. Tetracycline e. Vancomycin 453. A 45-year-old man with recurrent asthma is being treated with oral theophylline and prednisone, supplemented with an adrenergic bron- chodilator (e.g., albuterol), inhaled “as needed.” He has been exposed to Haemophilus influenzae by a family member and is started on rifampin for prophylaxis against getting the infection himself. Which of the following is the most likely outcome of adding the rifampin? a. Failure of rifampin prophylaxis due to induction of its metabolism by the theo- phylline b. Increased risk of theophylline toxicity c. Loss of asthma control, onset of asthma signs and symptoms d. Rapid development of cholestatic jaundice and liver failure from acute rifampin toxicity e. Sudden sodium and fluid retention, weight gain, from impaired prednisone metabolism  Anti-Infectives 395 454. A 55-year-old man has an infection with Legionella. Assuming no contraindications, which of the following is the drug of choice? a. Chloramphenicol b. Erythromycin c. Lincomycin d. Penicillin G e. Streptomycin 455. We are starting therapy for an established HIV infection in a 28-year- old man. The drugs are ritonavir, saquinavir, zidovudine, and didanosine. We are obviously using two protease inhibitors and two nucleoside reverse transcriptase inhibitors (NRTIs). Which of the following is the main pur- pose of using the ritonavir? a. Help maintain adequate saquinavir levels by inhibiting its metabolism b. Induce the metabolic activation of the NRTIs, which are prodrugs c. Prevent the likely development of hypoglycemia d. Reduce, or hopefully eliminate, saquinavir-mediated host toxicity e. Serve as the main, most active, inhibitor of viral protease in this combination 456. As part of a multidrug attack on a patient’s infection with Mycobac- terium tuberculosis, a physician plans to use an aminoglycoside antibiotic. Which of the following is most active against the tubercle bacillus and seems to be associated with the fewest problems with resistance or typical aminoglycoside-induced adverse effects? a. Amikacin b. Kanamycin c. Neomycin d. Streptomycin e. Tobramycin 396 Pharmacology 457. Such agents as clavulanic acid, sulbactam, or tazobactam are often added to some proprietary (manufactured) penicillin combination prod- ucts. Which of the following is the main reason for including them, or best describes their action? a. Add antibiotic activity against Pseudomonas and many Enterobacter species b. Facilitate antibiotic penetration into the central nervous system and cere- brospinal fluid c. Inhibit cell wall transpeptidases d. Inhibit inactivation of penicillin by β-lactamase-producing bacteria e. Inhibit the normally significant hepatic metabolism of the penicillin f. Reduce the risk and/or severity of allergic reactions in susceptible patients 458. A patient with active tuberculosis is being treated with isoniazid (INH) and ethambutol as part of the overall regimen. Which of the follow- ing is the main reason for including the ethambutol? a. To facilitate entry of the INH into the mycobacteria b. To facilitate penetration of the blood-brain barrier c. To retard the development of organism resistance d. To slow renal excretion of INH to help maintain effective blood levels e. To retard absorption after intramuscular injection 459. A patient has a severe infection caused by anaerobic bacteria. The first-year house officer writes an order for gentamicin. This approach is doomed to fail because aminoglycosides have no activity against anaerobes. Which of the following best explains why anaerobes will be resistant? a. Cannot metabolize the aminoglycosides, which are all prodrugs, to their bacte- ricidal free radical forms b. Cannot oxidatively metabolize aminoglycosides to moieties that are nontoxic to host cells c. Lack molecular oxygen that is a prerequisite for drug binding to the 50S sub- unit of bacterial ribosomes d. Lack the ability to transport aminoglycosides from the extracellular milieu in the absence of oxygen e. Synthesize more and more active resistance factors than do aerobic bacteria  Anti-Infectives 397 460. In patients with hepatic coma, or portal-systemic encephalopathy, decreasing the production and absorption of ammonia from the gastroin- testinal (GI) tract will be beneficial. Which of the following is the antibiotic of choice in this situation and this purpose? a. Cephalothin b. Chloramphenicol c. Neomycin d. Penicillin G e. Tetracycline 461. A child who previously was healthy develops bacterial meningitis. Assuming no specific contraindications, which of the following is the drug of choice? a. Ceftriaxone b. Erythromycin c. Penicillin G d. Penicillin V e. Procaine penicillin 462. A patient is being treated with an antibiotic for a vancomycin-resistant enterococcal infection. They consume an over-the-counter medication con- taining ephedrine and develop a significant spike of blood pressure that leads to a pounding headache. They are transported to the hospital. As part of the workup, blood tests indicate some bone marrow suppression. Which of the following antibiotics is most likely associated with this clinical picture? a. Azithromycin b. Ciprofloxacin c. Erythromycin estolate d. Gentamicin e. Linezolid 398 Pharmacology 463. A 59-year-old woman is diagnosed with tuberculosis (TB). Before prescribing a multidrug regimen, you take a careful medication history because one of the drugs commonly used to treat TB induces some of the microsomal cytochrome P450 enzymes in the liver. Which is the most likely drug? a. Ethambutol b. Isoniazid c. Pyrazinamide d. Rifampin e. Vitamin B6 464. A patient requires an antibiotic that is most effective against P. aerug- inosa. Which of the following is the quinolone of choice? a. Ciprofloxacin b. Enoxacin c. Lomefloxacin d. Norfloxacin e. Ofloxacin 465. A patient has a severe bacterial infection that normally would respond to an oral penicillin or a cephalosporin. However, his chart docu- ments anaphylactoid reactions to both drugs. Which of the following would be the best choice for treating the infection and poses the least risk of cross-reactivity and an allergic response? a. Clotrimazole b. Gentamicin c. Metronidazole d. Tetracycline e. Vancomycin