Selecting an antimicrobial drug
Selecting an appropriate antimicrobial drug to treat a specific in-fection involves several important factors:
§ First, the microorganism must be isolated and identified—gen-erally through growing a culture.
§ Then its susceptibility to various drugs must be determined. Be-cause culture and sensitivity results take 48 hours, treatment usu-ally starts at assessment and then is reevaluated when test results are obtained.
§ The location of the infection must be considered. For therapy to be effective, an adequate concentration of the antimicrobial must be delivered to the infection site.
§ Lastly, the cost of the drug must be considered as well as its po-tential adverse effects and the possibility of patient allergies.
The usefulness of antimicrobial drugs is limited by pathogens that may develop resistance to a drug’s action.
§ Resistance is the ability of a microorganism to live and grow in the presence of an antimicrobial drug that’s either bacteriostatic (inhibits the growth or multiplication of bacteria) or bactericidal
§ (kills bacteria). Resistance usually results from genetic mutation of the microorganism. (See The rise of the resistance movement.)