Sample Questions

Exam #3 Sample Questions Pharmacotherapy 4 April 9, 2015 1. Bordatella pertussis is a gram-negative bacillus that is cultured from the upper airways of a young girl with inflammation and symptoms of upper respiratory infection. Which of the following terms BEST describes the role of this organism in this individual? a. Bordatella pertussis is a commensal organism. b. Bordatella pertussis is a pathogenic organism. c. Bordatella pertussis is a colonizing organism. d. Bordatella pertussis is a synergistic organism. 2. Which of the following is NOT a mechanism by which various microorganisms defeat host defenses against infection? a. Induction of a strong host immune reaction in order to create excessive activity that will eventually exhaust (“burn out”) the immune system. b. Production of exotoxins that facilitate invasion of host tissues and survival inside the host. c. Defeat of proteins of the complement system by inactivation or other means. d. Survival inside host immune cells or escape from the cells after phagocytosis and ingestion. 3. Which of the following statements regarding the role of antimicrobial agents in the treatment of infection is FALSE? a. Antimicrobials limit microbial growth or decrease microbial numbers until the immune system can eradicate the infection through natural means. b. The functional state of the host immune system is often more important in deciding the response to infection than selection of a particular antimicrobial. c. Antimicrobials alone are able to effectively eradicate infection in the majority of patients, with the immune system playing only an adjunctive role. d. Selection of appropriate antimicrobials becomes more important as the host immune system becomes more impaired. 4. Klebsiella pneumoniae is a gram-negative bacillus that is capable of causing a broad range of serious infections in man. Which of the following terms are MOST appropriate for an antibiotic that is able to rapidly reduce numbers of Klebsiella pneumoniae at the site of infection and is relatively specific for activity against this pathogen? a. Bacteriostatic and narrow-spectrum. b. Bactericidal and broad-spectrum. c. Bacteriostatic and broad-spectrum. d. Bactericidal and narrow-spectrum.

5. Which of the following is NOT an important role served by endogenous normal flora? a. Competition with more pathogenic microbes for nutrient sources and space. b. Suppression of local host immune defenses in order to allow colonization by less pathogenic microbes. c. Secretion of substances that inhibit growth of more pathogenic microbes. d. Stimulation of low-level host responses in order to keep the immune system “primed”. 6. Which of the following antimicrobials has the LEAST dependable activity against most methicillin-susceptible Staphylococcus aureus ? a. Moxifloxacin. b. Ceftriaxone. c. Penicillin. d. Nafcillin. 7. Which of the following statements concerning the cephalosporins is FALSE? a. Cefazolin has better activity against Staphylococcus aureus than ceftriaxone. b. Ceftriaxone has better activity against gram-negative aerobes than cefuroxime. c. Cefazolin has better activity against gram-negative aerobes than cefuroxime. d. Cefuroxime has better activity against Staphylococcus aureus than ceftriaxone. 8. Which of the following statements regarding penicillins is TRUE? a. Natural penicillins have excellent activity against both Gram-positive and Gram- negative bacteria. b. Penicillinase-resistant penicillins have excellent activity against both Gram- positive and Gram-negative bacteria. c. Compared to the natural penicillins, the amino-penicillins have similar activity against Gram-positive bacteria but improved Gram-negative activity. d. Common adverse effects of the penicillins include hypersensitivity reactions, rash, and severe nephrotoxicity. 9. Which of the following statements concerning penicillins is FALSE? a. Ureido-penicillins are active against many gram-negative organisms including the Enterobacteriaceae and Pseudomonas aeruginosa . b. Both carboxy-penicillins and ureido-penicillins have activity against streptococci. c. Compared to penicillins alone, penicillin/  -lactamase inhibitor combination agents provide greatly improved activity against staphylococci and anaerobes. d. All  -lactamase-producing gram-negative aerobes are effectively treated with penicillin/  -lactamase inhibitor combination agents.

15. Which of the following antimicrobials is MOST appropriate for the treatment of infections caused by the “atypical” bacteria? a. Clarithromycin. b. Cefazolin. c. Dicloxacillin. d. Ertapenem. 16. Which of the following antimicrobials is LEAST appropriate for the treatment of infections caused by Bacteroides fragilis and other anaerobic bacteria? a. Piperacillin/tazobactam. b. Cefotetan. c. Azithromycin. d. Metronidazole. 17. M.T. was fine and healthy 24 hours ago. However, since that time, he has developed a fever and clinical signs and symptoms of a respiratory tract infection. He has no other systemic findings. Which of the statements below would most accurately describe this infection in M.T.? a. The infection is both primary and opportunistic. b. The infection is both acute and localized. c. The infection is both latent and acute. d. The infection is both fulminant and generalized. 18. Which of the following statements regarding the acute phase of antimicrobial therapy is FALSE? a. Identification of the source of the infection is a primary consideration. b. Patient-specific factors may influence both the specific antibiotics that are selected and the types of pathogens that may be present. c. Obtaining cultures and laboratory information is important but can be delayed until after empiric antibiotics are started. d. Empiric antibiotics are typically fairly broad in spectrum of activity. 19. Which of the following statements regarding antimicrobial pharmacodynamics is FALSE? a. A pharmacodynamic goal for concentration-dependent drugs is to maximize exposure of the organism to the drug. b. A pharmacodynamic goal for time-dependent drugs is to optimize the duration of exposure of the organism to the drug. c. A pharmacodynamic goal for concentration-dependent drugs is to maximize the Cmax/MIC ratio and/or the AUC/MIC ratio.

d. A pharmacodynamic goal for time-dependent drugs is to achieve Time>MIC equal to 100% of the dosing interval.

22. Drug A and Drug B are both fluoroquinolones antibiotics. Both of these antibiotics are being considered for treatment of a serious gram-negative infection. Key pharmacokinetic parameters and MIC values for these drugs are as follows: Cmax T1/2 AUC MIC Drug A5.0 mg/L 10 hours 75 mg*hr/L 0.5 mg/L Drug B 5.0 mg/L 5 hours 60 mg*hr/L 1.0 mg/L Based on the information above, which of the following statements is TRUE? a. Drug A would be predicted to be more effective than Drug B. b. Drug B would be predicted to be more effective than Drug A. c. Drug A and Drug B would be predicted to have similar good efficacy. d. Neither Drug A nor Drug B would be predicted to be efficacious. 23. Which of the following statements regarding the dosing and pharmacodynamic properties of antimicrobials is FALSE? a. Penicillins could theoretically be dosed by continuous infusion in order to optimize the pharmacodynamic properties of the drugs. b. In patients with reduced drug clearance due to organ failure, fluoroquinolones should be given in high doses less frequently rather than in smaller doses more frequently. c. In patients with reduced drug clearance due to organ failure, imipenem should be given in high doses less frequently rather than in smaller doses at more frequently. d. In patients with reduced drug clearance due to organ failure, cephalosporins should be given in smaller doses more frequently rather than in large doses less frequently. 24. Which of the following statements concerning antimicrobial pharmacokinetics and pharmacodynamics is TRUE? a. The relatively short serum half-lives of the penicillins and most cephalosporins are not of clinical importance in the way that these drugs are dosed. b. The fluoroquinolones are generally characterized by poor penetration into tissues and fluids of the body. c. Pharmacodynamics of the fluoroquinolones can best be characterized as concentration-dependent with Time>MIC being the critical parameter. d. Extensive tissue penetration of certain drugs, e.g. the macrolides, provides a possible explanation for differences between in vitro susceptibility and clinical outcomes.

25. Which of the following statements regarding antimicrobial pharmacodynamics is FALSE? a. Pharmacodynamics is useful in helping clinicians select agents that are most likely to yield favorable clinical results. b. Pharmacodynamics is able to provide completely accurate predictions of clinical success for a given patient receiving a given drug. c. Pharmacodynamic considerations are useful in guiding the selection of the most favorable dosing strategies for a given drug and pathogen. d. Pharmacodynamics does not guarantee optimal therapy under all clinical circumstances. 26. Which of the following statements regarding general pharmacodynamic features of the fluoroquinolones is TRUE? a. High Cmax:MIC ratios (>10-12) have not been shown to be predictive of clinical or microbiological efficacy. b. AUC:MIC ratios >30 are generally correlated with good clinical and microbiological efficacy for infections caused by both gram-negative and gram- positive organisms. c. The AUC:MIC ratio is clearly more predictive of efficacy than the Cmax:MIC ratio. d. Apparent differences between pharmacodynamic predictions and actual clinical efficacy may often be explained by pharmacokinetic features such as high tissue concentrations. 27. Based on current understanding of antibiotic pharmacodynamics, which of the following antimicrobial regimens would be theoretically predicted to provide the best response during treatment of an infection with Staphylococcus aureus having an MIC of 4 mcg/ml for all agents? (Assume adequate distribution of all drugs to the site of infection.) Cmax (mg/L) T1/2 (hrs) AUC (mg·hr/L) Cefazolin 1 gram IV Q8H 180.0 1 150 Azithromycin 250 mg PO Q24H 2.0 60 175 Nafcillin 1 gram IV Q6H 20.0 1 70 a. Cefazolin. b. Azithromycin. c. Nafcillin. d. None of these agents would be predicted to be effective.

32. Which of the following statements regarding antimicrobial pharmacodynamics is FALSE? a. The clinical goal of macrolide dosing is to maximize the duration of drug exposure. b. From a pharmacodynamic standpoint, the most appropriate way to dose  -lactam antibiotics is to administer as a continuous infusion. c. The rate and extent of bacterial killing produced by the aminoglycoside antibiotics increases with increasing drug concentrations. d. From a pharmacodynamic standpoint, the most appropriate way to dose fluoroquinolones is to administer as a continuous infusion. 33. Which of the following statements is TRUE? a. Pharmacodynamics is an aid to clinicians in selecting the most favorable dosing strategies. b. Pharmacodynamic methods are able to provide accurate predictions of clinical success for any given agent in a specific patient. c. Pharmacodynamics provides easily obtainable information that allows for real-time decision making for individual patients. d. Pharmacodynamic principles do not yet provide information that allows for enhanced bacterial eradication or decreased development of resistance.

34. The graphs below depict the pharmacokinetic profiles of two drugs. Drug A is a cephalosporin; Drug B is a fluoroquinolone. Both drugs achieve Cmax concentrations of 8 mg/L. These drugs are being used to treat infections caused by organisms with MICs of 4 mg/L for both drugs. Based on the information provided, which of the following statements is TRUE? Drug A, dosed every 12 hours Drug B, dosed every 24 hours Drug Conc. MIC MIC 0 4 8 12 0 4 8 12 16 20 a. Drug A would be predicted to be more effective than Drug B. b. Drug B would be predicted to be more effective than Drug A. c. Drug A and Drug B would be predicted to have similar good efficacy. d. Neither Drug A nor Drug B would be predicted to be efficacious. 35. An E. coli has an MIC of 0.5 mg/L to gentamicin and an MIC of 0.5 to ciprofloxacin. Gentamicin is being dosed to achieve a Cmax concentration of 6 mg/L, while the ciprofloxacin achieves a Cmax of 2 mg/L with an AUC of 25 mg  hr/L. Which of the following statements is TRUE in this scenario? a. Gentamicin would be predicted to be more effective than ciprofloxacin. b. Ciprofloxacin would be predicted to be more effective than gentamicin. c. Gentamicin and ciprofloxacin would be predicted to have similar good efficacy. d. Neither gentamicin nor ciprofloxacin would be predicted to be efficacious.

39. Which of the following statements regarding resistance to the macrolide antibiotics is TRUE? a. Methylation of the ribosomal binding site potentially causes resistance to clindamycin and streptogramins as well as resistance to the macrolides. b. Decreased membrane permeability has no effect on susceptibility of either gram- positive or gram-negative organisms to the macrolides. c. Methylation of the ribosomal binding site is associated with only low-level resistance to the macrolides. d. Expression of efflux proteins in the cell membrane is a relatively rare mechanism of resistance to the macrolides but is clinically the most important. 40. Which of the following statements regarding resistance to the fluoroquinolones is FALSE? a. Mutation of the gene encoding DNA gyrase is the most important mechanism of resistance among gram-negative bacteria. b. Mutation of the gene encoding topoisomerase IV is the most common mechanism of resistance among gram-positive bacteria. c. Clinically relevant resistance to fluoroquinolones usually requires only one mutation rather than involving a “stepwise” series of mutations. d. Expression of efflux proteins has been found in many bacteria but does not usually cause clinically significant resistance. 41. Which of the following antimicrobials is MOST appropriate for the treatment of infections caused by vancomycin-sensitive Enterococcus ? a. Azithromycin. b. Ceftriaxone. c. Cefepime. d. Ampicillin. 42. Which of the following antimicrobials is LEAST appropriate for the treatment of infections caused by vancomycin-resistant Enterococcus ? a. Linezolid. b. Quinupristin/dalfopristin. c. Aztreonam. d. Chloramphenicol.

43. Which of the following statements regarding vancomycin is FALSE? a. Contrary to previous belief, the pharmacodynamic properties of vancomycin are now characterized as time-dependent rather than concentration-dependent. b. Vancomycin is rapidly bactericidal when dosed to high Cmax levels, therefore this is still the preferred dosing strategy. c. Risk of vancomycin-related nephrotoxicity and ototoxicity is not well correlated with either C max or C min drug levels. d. Risk of vancomycin-related nephrotoxicity appears to be increased in patients receiving concomitant therapy with other nephrotoxic agents. 44. Which of the following statements regarding mechanisms of resistance to the  -lactam antibiotics is FALSE? a.  -lactamase production is the most common and clinically most important mechanism of resistance to  -lactams. b. Extended-spectrum  -lactamases (ESBLs) are active against all cephalosporins and are not effectively inhibited by  -lactamase inhibitors such as tazobactam. c. Decreased membrane permeability is most common and of greatest clinical significance among gram-negative organisms. d. Alteration of penicillin binding proteins (PBPs) is a particularly common mechanism of  -lactam resistance among gram-positive organisms. 45. Which of the following statements regarding antimicrobial resistance among Staphylococcus aureus is TRUE? a. The most common mechanism of resistance is alteration of penicillin binding proteins. b. Linezolid is not effective against methicillin-resistant Staphylococcus aureus because of alterations in penicillin binding proteins. c. Penicillinases that are produced by Staphylococcus aureus cannot be inhibited by agents such as clavulanate or sulbactam. d. Fluoroquinolone resistance among Staphylococcus aureus usually involves alterations in the topoisomerase IV enzyme. 46. Based on common mechanisms of resistance among Streptococcus pneumoniae , which of the following antimicrobials would NOT be recommended for the treatment of infections caused by S. pneumoniae that are resistant to penicillin? a. Tetracycline. b. Clarithromycin. c. Levofloxacin. d. Ceftriaxone.

51. Which of the following statements is FALSE? a. Methylation of ribosomal binding sites is a less common but clinically very important mechanism of resistance to macrolide antibiotics. b. The only clinically significant resistance to vancomycin involves alteration of peptides in the bacterial cell wall that serve as vancomycin’s binding site. c. Expression of efflux proteins is a common and clinically significant mechanism of resistance to the fluoroquinolones among many gram-positive and gram- negative bacteria. d. “Stepwise” mutations and resistance are often observed among organisms with reduced susceptibility to fluoroquinolones. 52. Which of the following drugs is NOT matched with the most common mechanism of resistance to that drug among Streptococcus pneumoniae ? a. Ceftriaxone: production of extended-spectrum  -lactamase enzymes. b. Penicillin: alteration of PBPs. c. Clarithromycin: expression of efflux proteins. d. Levofloxacin: dual mutations of parC and gyrA isomerase-encoding genes. 53. Which of the following statements regarding the fluoroquinolones is FALSE? a. Fluoroquinolone-induced cardiac toxicity is uncommon in most patients, but may occur more frequently in patients with cardiac disease and in the elderly. b. Fluoroquinolones are currently FDA approved for use in children, and may be used without risk of cartilage abnormalities. c. Gastrointestinal side effects are the most common adverse effects of the fluoroquinolones but are usually mild. d. Tendon rupture is a rare but potentially serious adverse effect of the fluoroquinolones 54. Which of the following antimicrobials is LEAST appropriate for the treatment of infections caused by Bacteroides fragilis and other anaerobic bacteria? a. Piperacillin/tazobactam. b. Cefotetan. c. Amoxicillin/clavulanate. d. Levofloxacin. 55. Which of the following antimicrobials is MOST appropriate for the treatment of infections caused by the Enterobacteriaceiae ? a. Dicloxacillin. b. Ciprofloxacin. c. Nafcillin. d. Penicillin.

56. Which of the following antimicrobials is MOST appropriate for the treatment of infections caused by the “atypical” bacteria? a. Levofloxacin. b. Cefazolin. c. Dicloxacillin. d. Ertapenem.

47. c 48. b 49. c 50. d 51. c 52. a 53. b 54. d 55. b 56. a