Use of microbiology reports by physicians in prescribing antimicrobial agents

The purpose of this study was to examine the use of microbiologic reports by physicians in prescribing antimicrobial agents in a community hospital setting. Patients were identified by daily review of all blood, urine, and sputum cultures that grew pathogen(s) during a 7-week period. Appropriateness of antibiotic therapy was based on results of antibiotic susceptibility testing of isolated pathogen(s). The physician response to culture results was evaluated on changes made in antimicrobial therapy. Seventy-one patients with 73 cultures (infections) were identified; 70% of the infections were community acquired. The frequency of each infection during the study period was: bacteremia (N = 12), pneumonia (N = 18), definite urinary tract infection (N = 26) and probable urinary tract infection (N = 17). Initial treatment was appropriate in 49 of 73 (67%) episodes; the organism(s) isolated were resistant to initial therapy in 24 of 85 (33%) episodes. After culture results were available, 34 of 73 (47%) regimens were changed, but only 50% of the changes were considered appropriate. Overall, there was no significant difference in the proportion of all treatment regimens considered appropriate before (67%) and after (56%) culture results were known. We conclude that results of cultures and antibiotic susceptibility data had little influence on appropriateness of antibiotic prescribing in the hospital setting.