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Chapter 51: Clinical Use of Antimicrobials

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A hospitalized AIDS patient is receiving antiretroviral drugs but no antimicrobial prophylaxis. He develops sepsis with fever, suspected to be caused by a gram-negative bacillus.

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Antimicrobial treatment of this severely immune-depressed patient should not be initiated before

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(A) Antipyretic drugs have been given to reduce body temperature

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(B) Infecting organism(s) have been identified by the microbiology laboratory

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(C) Results of a Gram stain are available

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(D) Results of antibacterial susceptibility tests are available

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(E) Specimens have been taken for laboratory tests and examination

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To delay therapy until laboratory results are available is inappropriate in serious bacterial infections, but specimens for possible microbial identification must be obtained before drugs are administered. The answer is E.

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A hospitalized AIDS patient is receiving antiretroviral drugs but no antimicrobial prophylaxis. He develops sepsis with fever, suspected to be caused by a gram-negative bacillus.

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If amikacin is used in the treatment of this patient, monitoring of serum drug level may be advised because the drug

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(A) Does not penetrate into cerebrospinal fluid

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(B) Has a narrow therapeutic window

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(C) Is antagonized by beta-lactam antibiotics

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(D) Is hematotoxic

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(E) Is rapidly metabolized by the liver

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Monitoring plasma aminoglycoside levels is important because amikacin and other aminoglycosides have a low therapeutic index; toxicity may occur when plasma levels are only 3–4 times higher than minimal inhibitory concentrations. Decreases in renal function may elevate the plasma levels of aminoglycosides to toxic levels within a few hours. Aminoglycosides undergo renal elimination and they are not hematotoxic. The answer is B.

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A hospitalized AIDS patient is receiving antiretroviral drugs but no antimicrobial prophylaxis. He develops sepsis with fever, suspected to be caused by a gram-negative bacillus.

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A combination of drugs might be given to this patient to provide coverage against multiple organisms or to obtain a synergistic action. Examples of antimicrobial drug synergism established at the clinical level include the treatment of

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(A) Cryptococcal meningitis with amphotericin B and flucytosine

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(B) Coliform infections with sulfamethoxazole and trimethoprim

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(C) Enterococcal infections with rifampin and vancomycin

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(D) Pseudomonal infections with carbenicillin and gentamicin

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(E) All ...

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