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Antibiotics are among the most widely used classes of drugs worldwide1,2,3,4,5. Antibiotic overuse is common and leads to the emergence of antimicrobial resistant pathogens. Infections with resistant microbes are difficult to treat, requiring alternative drug regimen that can be costly and toxic. This makes selecting appropriate antimicrobial agent(s) to treat infective disease an important and challenging task. The table below provides a systematic approach for selection of antimicrobial drug therapy.

Table 1Systemic Approach for Selection of Antimicrobials2,3

In the event that a delay in antibiotic treatment of an infectious disease can result in serious morbidity or mortality, an antimicrobial therapy should be initiated. The initial selection of antimicrobial therapy often occurs prior to documentation and identification of the offending organism(s), which is known as empiric treatment. When culture and susceptibilities are available, empiric antimicrobial should be streamlined to narrower spectrum treatment in order to limit side effects and toxicities associated with broad-spectrum antibiotics. The empirical antibiotic treatment should be selected based on patient's history and physical examination (patient exposures/risk factors), and Gram stains results or other rapidly performed test results from the infected site (infection location). This information, along with knowledge of the most likely offending organism(s) and an institution's susceptibility patterns, should provide an appropriate selection of antimicrobial regimens.

There are three factors that may affect decision making in infectious disease approach, (1) the patient (host), (2) the anti-infective agent (drug), and (3) the disease-causing microbe (pathogen) (see table 2 below).

Table 2Three Factors for Decision Making in Infectious Disease Approach4,5

Host, drug, and pathogen factors must be taken into account when selecting an appropriate antibiotic regimen. For instance, patients with reduced renal and hepatic function ...

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