Outpatient antimicrobial susceptibility: comparison with inpatient susceptibility patterns

Because specific outpatient epidemiologic data on the susceptibility of organisms are not readily available to guide empiric antibiotic therapy in the ambulatory setting, we reviewed all positive culture reports of clinical specimens (n = 935) isolated exclusively from outpatients of the Eastern Carolina Family Practice Center over a 1-year period. Eighty percent were from urine cultures, 12 percent from wound cultures, and 5 percent from sputum cultures. An antibiogram was developed that showed a pattern of bacterial resistance similar to that reported elsewhere. More than 80 percent of urinary tract infections were caused by Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. More than 50 percent of skin and soft tissue infections were caused by Staphylococcus aureus and other Staphylococcus species. Susceptibilities of these organisms were compared with those reported by the local hospital, and antimicrobial resistance patterns were similar, which suggests that the choice of empiric antibiotic therapy can follow susceptibility patterns derived from either inpatient or outpatient laboratories in areas with similar resistance patterns. Further research into the epidemiology and susceptibility of organisms isolated from outpatients is needed. Whether the susceptibility of inpatient and outpatient antimicrobial resistance found in this investigation can be extrapolated to other geographic areas remains to be determined.