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Antimicrobial and Antiviral Pharmacology- Part 2
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1.A patient develops profuse, watery diarrhea, fever, abdominal pain, and leukocytosis in response to antibiotic C. difficile infection in the gut i s confirmed. What i s the preferred agent for therapy of this antibiotic-associated pseudomembranous colitis (AAPMC)?
- Amphotericin B
- Cl indamycin
- Trimethoprim plus sulfamethoxazole (TMP-SMZ)
2. A patient has been taking warfarin for several months and his INR (normalized prothrombin time) has been kept within the desired therapeutic range They develop an infection and are started on antibiotic therapy. Shortly thereafter their INR ri ses to eight (very high) and they develop epistaxis and other indicators of excessive bleeding. Which antibiotic most l ikely interacted with the warfarin, increasing i ts blood levels and effects, by inhibiting warfarin’s metabolism by the hepatic P-450 system?
- Penicillin G
3. Ampicillin and amoxicillin are in the same group of penicillins (broad spectrum, or aminopenicillins). However, there i s one cl inically important Which phrase best states how amoxicillin differs from ampicillin?
- Has better oral bioavailability, particularly when taken with meals
- Is effective against penicillinase-producing organisms
- Is a broad-spectrum penicillin
- Does not cause hypersensitivity reactions
- Has great antipseudomonal activity
4. A patient’s history notes a documented severe (anaphylactoid) reaction to a What other antibiotic or class i s l ikely to cross-react and so should be avoided in this patient?
- Erythromycin Linezolid
5. A 30-year-old woman develops a severe aeruginosa infection. The physician chooses to treat i t with amikacin, not with gentamicin. Which phrase best describes how amikacin differs from gentamicin?
- Does not require monitoring of blood levels during therapy
- Exerts s ignificant bactericidal effects against anaerobes too
- Has broader spectrum against gram-negative bacilli
- Lacks ototoxic potential
- Protects against typical aminoglycoside nephrotoxicity
6. A 19-year-old being treated for leukemia develops a You give several agents that will cover bacterial, vi ral, and fungal infections. Two days later, he develops acute renal failure. Which drug was most l ikely responsible?
- Amphotericin B
- Penicillin G.
7. Penicillins, cephalosporins, and amphotericin B are quite different structurally, and the antimicrobial spectrum of amphotericin B i s decidedly different from those of the other Nonetheless, they all share a common property or action. Which statement identifies what that i s?
- Act, though various mechanisms, on cell walls or membranes of susceptible organisms
- Contraindicated in immunocompromised patients
- Interact with many drugs by inducing their hepatic metabolism
- Leukopenia (decreased white cell counts) i s a common s ide effect
- Nephrotoxicity i s common
8. Given the periodic worldwide outbreaks of “swine flu” (particularly influenza A vi rus subtype H1N1) there has been a great need for prophylactic measures in certain at-risk populations who may be Which drug i s generally recommended by the US Centers for Disease Control and Prevention for this purpose?
9. A patient with a aeruginosa infection i s receiving intravenous gentamicin. The aminoglycoside blood levels are well above the minimum inhibitory concentration (MIC), but the cl inical response i s not satisfactory. A new medication order calls for adding a penicillin, administered in a separate IV l ine to avoid a physical incompatibility. If this order i s carried out, what i s most l ikely to occur?
- The aminoglycoside will inactivate the penicillin
- The aminoglycoside will chemically neutralize and abolish the effects of the penicillin
- The patient i s l ikely to develop Clostridium difficile colitis (superinfection)
- The penicillin will act synergistically with the aminoglycoside
- The penicillin will increase the ri sk of aminoglycoside nephrotoxicity
- The ri sk of inducing resistance to both drugs increases dramatically
10. Narrow spectrum penicillins, both penicillinase-sensitive and -resistant, have relatively poor activity against gram-negative What i s the main property or characteristic that explains why these micro-organisms do not respond well to the penicillins?
- Actively transport any absorbed penicillin back to the extracellular space
- Have an outer membrane that serves as a physical barrier to the penicillins
- Lack a surface enzyme necessary to metabolically activate the penicillins
- Lack penicillin-binding proteins
- Metabolically inactivate these penicillins by mechanisms not involving β-lactamase
11. We have a patient with an intraabdominal infection, and Bacteroides fragilis i s the main organism found upon Which cephalosporin has the greatest activity against anaerobes such B. fragilis?
12. A patient with a serious infection received intensive antibiotic therapy that leads to hearing Which antibiotic most l ikely caused the ototoxicity?
- Aminoglycoside (eg, gentamicin)
- Cephalosporin, fi rst-generation
- Cephalosporin, third-generation
- Fluoroquinolone (eg, ciprofloxacin)
13. A 26-year-old woman with acquired immunodeficiency syndrome (AIDS) develops cryptococcal She refuses intravenous medication. Which antifungal agent i s the best choice for oral therapy of the meningitis?
- Amphotericin B
14. An adult patient i s being treated with a parenteral aminoglycoside for a serious Pseudomonas aeruginosa He requires immediate surgery. He i s premedicated with midazolam, followed by administration of pro-pofol for induction. A dose of succinylcholine i s often given for intubation (due to i ts rapid onset), with skeletal muscle paralysis maintained during surgery with vecuronium or another neuromuscular blocker in the same class (nondepolarizing, or competitive nicotinic receptor blocker). Other components of balanced anesthesia include nitrous oxide, i soflurane, and oxygen. What i s the most l ikely outcome of having the aminoglycoside “on board” in the perioperative setting along with all these other drugs?
- Acute hepatotoxicity from an aminoglycoside-isoflurane interaction
- Antagonism of midazolam’s amnestic and sedative effects
- Enhanced aminoglycoside toxicity to host cells
- Increased or prolonged response to neuromuscular blockers
- Reduced ri sk of catecholamine-induced cardiac arrhythmias
15. A patient with tuberculosis i s started on i soniazid (INH) as part of a multidrug The physician also starts therapy with vi tamin B6 at the same time. What i s the main reason for giving the vi tamin B6 prophylactically?
- Facilitates INH renal excretion, thereby protecting against nephrotoxicity
- Inhibits metabolism of INH, thereby increasing INH blood levels
- Is a cofactor required for activation of the INH to i ts antimycobacterial metabolite
- Potentiates the antitubercular activity of the INH
- Prevents some adverse effects of INH therapy
16. One antibiotic i s considered very effective in treatment of Rickettsia, Mycoplasma, and Chlamydia infections? It i s also used to mange some patients with acne vulgaris To which drug does this description apply?
- Penicillin G
17. You are starting therapy for an established HIV infection in a 28-year-old The drugs are ri tonavir, lopinavir, zidovudine, and didanosine. This involves, of course, using two protease inhibitors and two nucleoside reverse transcriptase inhibitors (NRTIs). What i s the main purpose of using the ri tonavir?
- Helps maintain adequate saquinavir levels by inhibiting i ts metabolism
- Induces the metabolic activation of the NRTIs, which are prodrugs
- Prevents the l ikely development of hypoglycemia
- Reduces, or hopefully eliminates, lopinavir-mediated host toxicity
- Serves as the main, most active, inhibitor of vi ral protease in this combination
18. As part of a multidrug attack on a patient’s infection with Myco bacterium tuberculosis, a physician plans to use an aminoglycoside Which drug i s most active against the tubercle bacillus and seems to be associated with the fewest problems with resistance or typical aminoglycoside-induced adverse effects?
19. Such agents as clavulanic acid, sulbactam, or tazobactam are often added to some proprietary (manufactured) penicillin combination What i s the main reason for including them, or describes their action best?
- Add antibiotic activity against Pseudomonas and many Enterobacter species
- Facilitate antibiotic penetration into the central nervous system and cerebro-spinal fluid
- Inhibit cell wall transpeptidases
- Inhibit inactivation of penicillin by β-lactamase-producing bacteria. Inhibit the normally s ignificant hepatic metabolism of the penicillin
- . Reduce the ri sk and/or severity of allergic reactions in susceptible patients
20. A patient with active tuberculosis i s being treated with i soniazid (INH) and ethambutol as part of the overall What i s the main effect expected of the ethambutol?
- Facilitated entry of the INH into the mycobacteria
- Facilitated penetration of the blood-brain barrier
- Retarded absorption after intramuscular injection
- Retarded development of organism resistance
- Slowed renal excretion of INH to help maintain effective blood levels
21. A patient has a severe infection caused by anaerobic The fi rst-year house officer writes an order for gentamicin. This approach i s doomed to fail because aminoglycosides have no activity against anaerobes. Which best explains why anaerobes will be resistant?
- Cannot metabolize the aminoglycosides, which are all prodrugs, to their bactericidal free radical forms
- Cannot oxidatively metabolize aminoglycosides to moieties that are nontoxic to host cells
- Lack molecular oxygen that i s a prerequisite for drug binding to the 50S subunit of bacterial ribosomes
- Lack the ability to transport aminoglycosides from the extracellular milieu in the absence of oxygen
- Synthesize more, and more active, resistance factors than do aerobic bacteria
22. In patients with hepatic coma or portal-systemic encephalopathy decreasing the production and absorption of ammonia from the gastrointestinal (GI) tract will be What antibiotic would be most useful in this s i tuation?
- Penicillin G
23. A 19-year-old girl who previously was healthy develops bacterial What would you consider to be the drug of choice for this s i tuation?
- Penicillin G
- Penicillin V
- Procaine penicillin
24. A patient i s being treated with an antibiotic for a vancomycin-resistant enterococcal (VRE) They consume an over-the-counter medication containing ephedrine and develop a s ignificant spike of blood pressure that leads to a pounding headache. They are transported to the hospital. As part of the work-up, blood tests indicate some bone marrow suppression. Which antibiotic i s most l ikely associated with this cl inical picture?
- Erythromycin estolate
25. You just started a rotation on the Infectious Disease consult It i s at an academic medical center that i s in a major hub ci ty for international travel, so unusual or uncommon diseases are commonly seen here. One of the patients i s receiving ethambutol. What i s the most l ikely reason for which this drug i s being given?
- Amphotericin-resistant Candida infection
- coli infection, severe, with profound fluid and electrolyte loss
- Entamoeba dispar infection (amebiasis)
- tuberculosis infection
- Plasmodium (malarial) infection