Principles of antimicrobial therapy:

Diagnosis: Site of infection, responsible organism are deteremined.

Decide: Chemotherapy is necessary. Acute infection require chemotherapy while chronic infection may not.

Select the drug: Specificity (spectrum of activity, antimicrobial activity)

Pharmacokinetic factors (physiochemical properties of drug)

Patient related factors (allergy, renal disease)

Frequency and duration of drug administration: Inadequate dose may develop resistance, intermediate dose may not cure infection, optimize dose should be used for therapy.

Continue therapy: Some of bacterial infection require continue therapy though clinic disease recover. Ex: typhoid fever, tuberculosis and infective endocarditis require continue therapy to avoid relapse.

Test for cure:After therapy, symptoms and signs may disappear before pathogen eradicated.

Prophylactic therapy: To avoid surgical site infection.