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ANTIBIOTIC RESISTANCE

""The rationale use of antibacterial drugs should be based on two principles. First, the specific identify of the infecting organism must be determined. Second, a test must be devised which will provide an accurate estimate that the antibiotic will be effective in vivo."
            -Petersdorf and Plorde, 1963
●90 60 RULE:
Infection caused by a susceptible isolates respond to appropriate antimicrobial approximately 90% of time, whereas infections caused by resistant isolates actually respond to inappropriate antimicrobial about 60% of the time.
This variability is observed probably because, the in vitro antibiotic sensitivity test do not take into account Pharmacokinetic/ Pharmacodynamic (PK/PD) properties. Also the microbial load at the site of infection is different than that in testing.
●ANTIBIOGRAM:
Periodic summary of antimicrobial sensitivity of local bacterial isolates,  submitted to the hospital's clinical microbiological laboratory, used to assess local sensitivity and pattern. It is utilized as an aid in selecting empirical antimicrobial therapy,  and in monitoring resistance trends over time, within an institution.
Therefore collective antibiotic sensitivity testing result,  compiled as an antibiogram, allows hospital to use local sensitivity data to guide empirical therapy, before culture and sensitivity results. This enables the clinician to start early, appropriate therapy, ensuring improved patient outcome.
Optimizing the doses according to dynamic PK/PD properties of individual antibiotics, during the course of illness, is another requisite for success of the therapy.

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