Question 1

A patient is receiving the medication valacyclovir.This patient is most likely being treated for

Accepted Answer

Acyclovir and valacyclovir are effective against members of the herpesvirus family.They are most effective against HSV-1 and HSV-2.They also have activity against Epstein-Barr virus (EBV),cytomegalovirus (CMV),and varicella-zoster virus (VZV).Acyclovir and valacyclovir are clinically used for the treatment of genital infections caused by HSV and VZV.

Question 2

Caspofungin is indicated for the treatment of

Accepted Answer

All echinocandins have shown in vitro and in vivo (animal studies)activity against Candida and Aspergillus species.Caspofungin is currently indicated for the treatment of febrile neutropenia,candidemia,esophageal candidiasis,and aspergillosis in patients refractory or intolerant to amphotericin B,lipid-based amphotericin B,and itraconazole.Micafungin is indicated only for esophageal candidiasis treatment and prophylaxis after hematopoietic stem cell transplants.Anidulafungin,the most recently approved agent,is indicated for the treatment of candidemia,nonneutropenic candidiasis,and esophageal candidiasis.All echinocandins are considered ineffective against Cryptococcus species because these organisms lack (1,3)-F1F1F1S1F1F1F10-D-glucan in their cell wall.

Question 3

A 21-year-old woman presents to the emergency department after a night of alcohol consumption.Her medical complaints include flushing,thirst,palpitations,and vertigo.Her daily medication list includes albuterol,Atrovent,and Advair.She was treated in her physician's office yesterday with cefoperazone for a urinary tract infection.The medication most likely causing her current medical complaint is

Accepted Answer

Hypoprothrombinemia has been reported,especially with agents (cefotetan and cefoperazone)with a methylthiotetrazole (MTT)side chain.The MTT side chain may also induce a disulfiramlike reaction in patients who concurrently ingest alcohol (disulfiram inhibits the metabolism of alcohol).The symptoms of this uncomfortable reaction include flushing,nausea,thirst,palpitations,chest pain,vertigo,and death in some cases.

Question 4

Antivirals exert their pharmacologic activity by

Accepted Answer

Antivirals (excluding antiretrovirals)mimic nucleosides and inhibit DNA synthesis.

Question 5

Macrolides exert their pharmacologic activity by

Accepted Answer

Macrolides inhibit protein synthesis by reversibly binding to the 50S ribosomal subunit and induce the dissociation of transfer RNA from the ribosome during the elongation phase.As a result,bacterial growth is inhibited (bacteriostatic).

Question 6

Your patient's sputum culture indicated the presence of methicillin-resistant S.aureus (MRSA).Which medication is appropriate to treat this infection?

Accepted Answer

Drugs used in the treatment of tuberculosis 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.Vancomycin is a glycopeptide antibiotic with activity against gram-positive bacteria.It is not active against gram-negative bacteria.Its use in recent years has escalated as a result of the emergence of MRSA.

Question 7

While monitoring a patient on the ventilator being treated for pneumonia you notice continued fever spikes,elevated white blood cell count,and repeated positive cultures.What term is used to describe this clinical finding?

Accepted Answer

Certain laboratory parameters can be monitored to assess the efficacy of an antimicrobial regimen,but ultimately the clinical assessment of the patient is the best measure of response to therapy.Treatment failure may manifest as continued fever spikes,elevated white blood cell count (WBC),repeated positive cultures,or nonresolution of symptoms (shortness of breath,cough,sputum production).The reasons for failure can be multifactorial and require consideration of all the aforementioned factors.In addition,noncompliance with the treatment regimen can play a significant role in outpatient treatment failures.

Question 8

Macrolides exhibit activity against
1)MSSA.
2)MRSA.
3)mycoplasmas.
4)Chlamydia.
5)Legionella.

Accepted Answer

Macrolides exhibit activity against gram-positive bacteria (streptococci,methicillin-sensitive Staphylococcus aureus [MSSA]),gram-negative bacteria (Haemophilus influenzae,Moraxella catarrhalis),and atypical bacteria (mycoplasmas,rickettsiae,Legionella,Chlamydia).

Question 9

Quinolones exert their pharmacologic activity by

Accepted Answer

Quinolones exert their antibacterial effect through inhibition of DNA synthesis.They inhibit topoisomerase II (DNA gyrase)and topoisomerase IV,which are necessary for bacterial replication.Quinolones are considered bactericidal agents and exhibit concentration-dependent killing.

Question 10

_____________ is not one of the antimycobacterials used to treat tuberculosis (TB).

Accepted Answer

Drugs used in the treatment of tuberculosis 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 11

Which of the following specimens are commonly collected as the first step in identification of a pathogen?
1)Blood
2)Urine
3)Sputum
4)Pleural fluid
5)Stool

Accepted Answer

The first step toward identification of potential pathogens is the collection of specimens for culture.Specimens commonly collected include blood,urine,sputum,cerebrospinal fluid,pleural fluid,synovial fluid,peritoneal fluid,and stool.Several methods are employed to identify the pathogens rapidly,using various chemical stains,immunologic assays,and microscopic examination.

Question 12

A patient with human immunodeficiency virus (HIV)has been diagnosed with Pneumocystis carinii (jiroveci).You are asked to recommend an antibiotic that is active against Pneumocystis carinii (jiroveci).Your recommendation would be

Accepted Answer

The combination of trimethoprim and sulfamethoxazole (TMP-SMX;Bactrim)was introduced in 1968 and has since gained a place in the treatment of numerous infections.This combination is active against gram-positive (streptococci,methicillin-sensitive S.aureus [MSSA])and gram-negative (Haemophilus influenzae,Burkholderia cepacia,Stenotrophomonas maltophilia)bacteria.In addition,it is active against Pneumocystis carinii (jiroveci).

Question 13

The term that refers to the sustained suppression of bacterial growth even after the concentration of the antibiotic is no longer detectable is

Accepted Answer

If the microbial kill rate increases proportionally with drug concentration,the antimicrobial is said to have a concentration-dependent effect.If the microbial kill rate is influenced by the time of drug concentration above the minimal inhibitory concentration,the antimicrobial is defined as time dependent (or concentration independent).Another pharmacodynamic phenomenon exhibited by antimicrobials is known as the postantibiotic effect.The postantibiotic effect refers to the sustained suppression of bacterial growth even after the concentration of the antibiotic is no longer detectable.

Question 14

Cephalosporins exert their pharmacologic activity by

Accepted Answer

Cephalosporins inhibit bacterial cell wall synthesis in a manner similar to penicillins.Cephalosporins bind to the penicillin-binding proteins within the cell wall and inhibit the cross-linking of peptidoglycan;this compromises the structural integrity of the bacterial cell wall,resulting in cell lysis (bactericidal).

Question 15

The outcome of antimicrobial therapy depends on which of the following factors?

Accepted Answer

The outcome of antimicrobial therapy depends on host factors,susceptibility or resistance to the antimicrobial,and pharmacodynamics.

Question 16

The term that refers to the science of understanding the optimal effect of a drug as a function of its concentration and in vitro activity (minimal inhibitory concentration [MIC])against an organism is

Accepted Answer

Pharmacodynamics refers to the science of understanding the optimal effect of a drug as a function of its concentration and in vitro activity (MIC)against an organism.The pharmacodynamic properties of an antimicrobial are measured in vitro by using time-kill studies.

Quiz 14: Antimicrobial Agents

A patient is receiving the medication valacyclovir.This patient is most likely being treated for

Caspofungin is indicated for the treatment of

Antivirals exert their pharmacologic activity by

Macrolides exert their pharmacologic activity by

Your patient's sputum culture indicated the presence of methicillin-resistant S.aureus (MRSA) .Which medication is appropriate to treat this infection?

While monitoring a patient on the ventilator being treated for pneumonia you notice continued fever spikes,elevated white blood cell count,and repeated positive cultures.What term is used to describe this clinical finding?

Macrolides exhibit activity against 1) MSSA. 2) MRSA. 3) mycoplasmas. 4) Chlamydia. 5) Legionella.

Quinolones exert their pharmacologic activity by

_____________ is not one of the antimycobacterials used to treat tuberculosis (TB) .

Which of the following specimens are commonly collected as the first step in identification of a pathogen? 1) Blood 2) Urine 3) Sputum 4) Pleural fluid 5) Stool

A patient with human immunodeficiency virus (HIV) has been diagnosed with Pneumocystis carinii (jiroveci) .You are asked to recommend an antibiotic that is active against Pneumocystis carinii (jiroveci) .Your recommendation would be

The term that refers to the sustained suppression of bacterial growth even after the concentration of the antibiotic is no longer detectable is

Cephalosporins exert their pharmacologic activity by

The outcome of antimicrobial therapy depends on which of the following factors?

The term that refers to the science of understanding the optimal effect of a drug as a function of its concentration and in vitro activity (minimal inhibitory concentration [MIC]) against an organism is