Changing Antibiotic Sensitivity Patterns at a University Hospital, 1992 Through 1999

Background. The emergence of antibiotic-resistant organisms is of great concern in the medical community. Antibiotic sensitivity patterns were studied at a large university hospital. Methods. From 1992 through 1999, susceptibility testing was done and results recorded for all isolates of Streptococcus pneumoniae, Enterococcus sp, Staphylococcus aureus, coagulase-negative Staphylococcus, Escherichia coli, Haemophilus influenzae, and Pseudomonas aeruginosa. Microbiologic and sensitivity data were reviewed and compiled. Results. Over the 8-year period, several common bacterial pathogens declined in susceptibility to various antimicrobial agents. Most notable were the decreased sensitivities of S pneumoniae to penicillin (96% to 63%), coagulase-negative Staphylococcus to oxacillin (50% to 38%), and P aeruginosa to aminoglycosides [(gentamicin (85% to 64%), tobramycin (96% to 83%), amikacin (92% to 74%)] and ciprofloxacin (85% to 69%). Conclusions. These decreased antibiotic sensitivities reflect increased bacterial selection pressure as a result of widespread antibiotic use. A combined approach involving infection-control specialists, infectious disease physicians, and hospital administrators is necessary to address this increasingly difficult problem.