Trends in antibiotic utilization and bacterial resistance. Report of the National Nosocomial Resistance Surveillance Group.

The increasing use of "third-generation" cephalosporins has been associated with a rising prevalence of resistant bacteria possessing type-I beta-lactamases. At Millard Fillmore Hospital (Buffalo, New York), we observed an unusually high occurrence of multiply resistant Enterobacter cloacae infections, especially in the intensive care unit. Susceptibilities were found to have declined substantially from 1988 to 1990, most notably for ceftazidime and mezlocillin, which decreased from 83% to 54% and from 85% to 64%, respectively. During the same period, there was a substantial increase in the use of ceftazidime and a decline in the use of the broad-spectrum penicillins. The latter drugs had been used in combination with an aminoglycoside as the primary empiric antibiotic therapy for nosocomial infections. This change in antibiotic-prescribing patterns was coincident with the decline in E. cloacae susceptibility, and therefore the emergence of multiply resistant E. cloacae was probably a direct consequence of the increased prescribing of ceftazidime. The experience at out institution led to the formation of the National Nosocomial Resistance Surveillance Group (NNRSG) to determine whether this antibiotic use-mediated resistance was a nationwide phenomenon. Clinical pharmacists and medical microbiologists were recruited and asked to complete a survey of hospital demographics, antibiotic purchases (between the beginning of 1988 and the third quarter of 1990), and bacterial susceptibilities of six representative organisms to 12 commonly used antibiotics (primarily broad-spectrum penicillins and cephalosporins). Evaluable data were obtained from 18 hospitals varying widely in bed capacity, antibiotic use, and geographic location.(ABSTRACT TRUNCATED AT 250 WORDS)