Question 1

The most common adverse reaction to penicillin is

Accepted Answer

The most common adverse reaction to penicillins is hypersensitivity.Approximately 3% to 10% of the population is allergic to penicillin.Reactions may vary in severity from a mild rash to life-threatening anaphylaxis.Patients allergic to penicillin could potentially be allergic to all classes of F1F1F1S1F1F1F10-lactams.

Question 2

Tetracyclines are effective against which of the following?
1)Protozoa
2)Mycoplasmas
3)Rickettsiae
4)Gram-positive microorganisms
5)Gram-negative microorganisms

Accepted Answer

Tetracyclines are broad-spectrum antibiotics that exhibit activity against gram-positive and gram-negative organisms and many rickettsiae,chlamydiae,mycoplasmas,spirochetes,protozoa,and mycobacteria.The most commonly used drug in this class is doxycycline because it can be administered twice daily and is relatively inexpensive.

Question 3

What antibiotic is used to treat Pneumocystis carinii (jiroveci)infections?

Accepted Answer

The combination of trimethoprim and sulfamethoxazole (TMP-SMX;Bactrim)is active against gram-positive and gram-negative bacteria.In addition,TMP-SMX is active against P.carinii (jiroveci).

Question 4

The natural penicillins are primarily effective against
1)gram-negative bacteria.
2)gram-positive bacteria.
3)viruses.
4)anaerobes.
5)mycoplasmas.

Accepted Answer

The natural penicillins are primarily effective against gram-positive bacteria and anaerobes.They are not as effective against gram-negative bacteria or mycoplasmas,and they exhibit no effect against viral disease.

Question 5

Nosocomial transmission of tuberculosis (TB)can be prevented by

Accepted Answer

Nosocomial transmission of TB can be prevented by placing patients with suspected or confirmed TB in respiratory isolation (negative-pressure room)until they are (1)determined not to have TB,(2)discharged from the hospital,or (3)confirmed to be noninfectious.Other measures such as use of fitted respiratory masks (by health care personnel)can prevent transmission of Mycobacterium tuberculosis by aerosolization to caregivers.

Question 6

Which group of antibiotics is effective against Pseudomonas aeruginosa lung infections in cystic fibrosis patients when taken orally?

Accepted Answer

Ciprofloxacin has been shown to have the best in vitro activity of the quinolones against P.aeruginosa and other gram-negative aerobes.Ciprofloxacin,levofloxacin,and gatifloxacin have been used for the treatment of nosocomial pneumonia.The quinolones have been shown to be effective in the treatment of upper and lower respiratory tract infections,genitourinary tract infections,and skin and skin structure infections,with results comparable to results with other antiinfective agents such as cephalosporins,macrolides,and trimethoprim-sulfamethoxazole.

Question 7

The most common pathogens responsible for community-acquired pneumonia include which of the following?
1)Haemophilus influenzae
2)Chlamydia pneumoniae
3)Streptococcus pneumoniae
4)Legionella pneumophila
5)Mycoplasma pneumoniae

Accepted Answer

Research has shown that the most common pathogens responsible for community-acquired pneumonia include Streptococcus pneumoniae;Haemophilus influenzae;and atypical (intracellular)organisms such as Mycoplasma pneumoniae,Chlamydia pneumoniae,and Legionella pneumophila.Consequently,empiric therapy for community-acquired pneumonia involves antimicrobials active against this spectrum of organisms.

Question 8

The major adverse reaction to antimycobacterial agents such as isoniazid and rifampin is

Accepted Answer

An elevation in liver enzymes has been reported in patients receiving isoniazid and is reversible with discontinuation of the drug.Rare cases of serious hepatitis and death also have been reported.Hepatotoxicity usually occurs between the 4th and 8th weeks of treatment but may occur at any time.Tests used to measure hepatocellular injury should be performed and include monitoring liver transaminases such as alanine aminotransferase (ALT)and aspartate aminotransferase (AST).In addition,patients should be monitored for the development of symptoms of hepatitis such as nausea,loss of appetite,and abdominal pain.Hepatotoxicity is the major adverse reaction associated with rifamycins (of which rifampin is one).Elevations in liver transaminases are commonly reported and are usually reversible on discontinuation of the drug.Patients with preexisting liver damage are more prone to rifamycin-induced hepatotoxicity.

Question 9

Penicillins are

Accepted Answer

Penicillins are bactericidal,exhibit time-dependent killing,and can act synergistically with aminoglycosides against some bacteria.Their ability to inhibit cell wall synthesis proves deadly to bacteria,but they have no effect on viral disease.

Question 10

MRSA and VRE are examples of

Accepted Answer

Methicillin-resistant Staphylococcus aureus (MRSA)and vancomycin-resistant Enterococcus (VRE)are examples of emerging bacterial pathogens that are resistant to the action of many current antimicrobial therapies.Mechanisms of bacterial resistance include the production of enzymes that degrade or modify antibiotics,alteration of bacterial cell walls or membranes,upregulation of antimicrobial efflux pumps,and alteration of the site of antimicrobial action.

Question 11

A drug that inhibits the growth of bacteria is called

Accepted Answer

Drugs that inhibit the growth of bacteria but do not kill them are termed bacteriostatic.A bactericidal drug is one that kills bacteria.Virucidal drugs kill viruses,and fungicidal drugs kill fungi.

Question 12

A bactericidal agent

Accepted Answer

Drugs that kill bacteria are termed bactericidal.A bacteriostatic drug inhibits the growth of bacteria but does not kill them.Virucidal drugs kill viruses,and fungicidal drugs kill fungi.

Question 13

A major toxic effect of amphotericin B administration is

Accepted Answer

Parenteral administration of amphotericin B is associated with two major types of toxicity.The first is infusion related and includes flushing,fever,and chills.Pretreating patients with antipyretics and antihistamines may minimize these effects.The second major toxicity is renal impairment thought to be a result of diminished renal perfusion.Hydrating the patient with normal saline boluses before and after amphotericin B infusion has been attempted to prevent this toxicity.

Question 14

The simplest and most common method of preparing bacteria for examination and identification is

Accepted Answer

The simplest and most common preparation is the Gram stain.This stain designates bacteria into two major classes: gram-positive (stain purple)or gram-negative (stain pink).Bacteria stain differently depending on the structural components of their cell wall.These structural components also affect their susceptibility to antimicrobials.

Question 15

Ventilator-associated pneumonia (VAP)has been successfully treated with
1)cephalosporins.
2)gentamicin.
3)tobramycin.
4)quinolones.
5)penicillin.

Accepted Answer

Gentamicin and tobramycin (both aminoglycosides)have been used for nosocomial gram-negative infections such as VAP.However,they do not achieve high concentrations in bronchial secretions when administered systemically and are sometimes administered by inhalation.

Question 16

Isoniazid is indicated to treat

Accepted Answer

Treatment of TB consists of multiple antibiotic regimens for 6 to 12 months in duration.Single-agent regimens should never be used for treatment because the likelihood of developing resistance is high.Treatment failures often result from poor patient compliance and resistance to antibiotics.Drugs used in the treatment of TB can be categorized as either first-line or second-line agents depending on their efficacy and side-effect profiles.Initial therapy generally involves a combination of isoniazid,pyrazinamide,rifampin,and ethambutol.

Question 17

Aminoglycosides,such as tobramycin,have been aerosolized specifically for the treatment of

Accepted Answer

As a result of low concentrations of drug in bronchial secretions,aminoglycosides such as tobramycin (TOBI)have been administered via inhalation to control Pseudomonas aeruginosa infections in patients with cystic fibrosis.

Question 18

Aminoglycosides are used primarily for

Accepted Answer

Aminoglycosides are used for gram-negative infections,including infections caused by Pseudomonas aeruginosa.They have poor gastrointestinal absorption and require parenteral administration.Aminoglycosides include the drugs gentamicin,tobramycin,netilmicin,and amikacin.

Question 19

The treatment of choice for pulmonary infections such as aspergillosis,histoplasmosis,and coccidioidomycosis is

Accepted Answer

The polyene amphotericin B has been available for more than 50 years and remains the drug of choice for most systemic fungal infections;however,a high incidence of nephrotoxicity has been associated with this agent.

Question 20

Penicillins exert their pharmacologic activity by

Accepted Answer

Penicillins exert their pharmacologic activity by inhibiting cell wall synthesis.Penicillins bind to enzymes located within the cell wall and prevent cross-linking of the peptidoglycan structure necessary for cell wall development.

Quiz 14: Antimicrobial Agents