ANTIMICROBIAL RESISTANCE RATES AMONG AEROBIC GRAM-NEGATIVE BACILLI RECOVERED FROM PATIENTS IN INTENSIVE-CARE UNITS - EVALUATION OF A NATIONAL POSTMARKETING SURVEILLANCE PROGRAM

We assessed the rates of antimicrobial resistance between 1990 and 199 3 in intensive care units in the United States. A standardized microti ter minimal inhibitory concentration panel was used to test similar to 100 consecutive gram-negative aerobic isolates that were recovered pr imarily from blood, wounds, urine, and pulmonary sites in patients tre ated in each of 396 intensive care units in 45 states. Amikacin and im ipenem were the agents most active against the 33,869 nonduplicate iso lates (those recovered only once) tested, Resistance of aerobic gram-n egative bacilli to third-generation cephalosporins was found to be an emerging problem. Increases in rates of resistance to ceftazidime amon g isolates of Klebsiella pneumoniae (from 3.6% to 14.4%; P much less t han.01) and Enterobacter species (from 30.8% to 38.3 %; P = .0004) wer e noted from 1990 to 1993; rates of resistance among Pseudomonas aerug inosa isolates remained stable, Ceftazidime-resistant bacteria were fr equently resistant to aminoglycosides and ciprofloxacin. Risk factors for ceftazidime resistance included the number of beds in the hospital , the teaching status of the hospital, and specific body sites from wh ich the isolates were recovered.