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  • image Understanding the difference between normal host microbiota and typical pathogens will help to determine whether a patient is truly infected or merely colonized.

  • image Direct examination of tissue and body fluids by Gram stain provides rapid information about the causative pathogen.

  • image Isolation of the offending organism by culture or rapid diagnostic testing assists in the diagnosis of infection and allows for more definitive directed treatment.

  • image Development of molecular testing systems (or rapid diagnostic testing) has improved our ability to diagnose infection and determine the antimicrobial susceptibilities for numerous pathogens, including fastidious or slow-growing mycobacteria and viruses.

  • image In vitro antimicrobial susceptibility testing has limitations and often cannot truly mimic the conditions found at the site of an infection. This can cause discordance between in vitro susceptibility results and in vivo response to therapy.

  • image Laboratory evaluation of antimicrobial activity is an important component of the pharmacotherapeutic management of infectious diseases.

  • image When used appropriately, rapid automated susceptibility test systems appear to improve therapeutic outcomes of patients with infection, especially when they are linked with other clinical information systems.

  • image Understanding the fundamentals of antimicrobial pharmacodynamic properties will help the clinician to make drug selection and dosing decisions in situations where robust clinical data are lacking.

  • image Routine monitoring of serum concentrations is currently used for a select few antimicrobials, eg, aminoglycosides and vancomycin, in an attempt to minimize toxicity and maximize efficacy.

  • image Appropriate timing for the collection of serum samples when measuring antimicrobial serum concentrations is crucial to ensure that valid pharmacokinetic data are generated.

  • image Monitoring of aminoglycoside serum concentrations and the use of extended-interval doses can help to maximize the probability of therapeutic success and minimize the probability of aminoglycoside-related toxicity for certain infections.

  • image Vancomycin and aminoglycoside serum concentration monitoring should be routinely done to ensure adequate serum concentrations, minimize toxicity, and avoid the potential for resistance.

  • image Antimicrobial pharmacodynamics has become a crucial consideration for the selection of both empirical and pathogen-directed therapy in the current era of antimicrobial resistance.

  • image Optimization of antimicrobial pharmacodynamic parameters such as the ratio of the peak serum concentration to minimum inhibitory concentration (MIC) or the time that the antibiotic serum concentration remains above the MIC or the ratio of the area under the concentration-time curve to the MIC can improve infection treatment outcomes.


Preclass Engaged Learning Activity

The goal of this Preclass Learning Activity is to begin thinking about the appropriate interpretation of various tests used to direct antimicrobial therapy. Prior to class, please complete this chart (Fig. e122-1) by indicating in each box whether the descriptors in each column apply to the test in each row.

FIGURE e122-1

Preclass Learning Activity.


Selection of an appropriate antimicrobial regimen for a given infection requires the clinician to integrate knowledge of the infecting pathogen(s), with an understanding ...

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