Enterobacterial repetitive intergenic consensus polymerase chain reaction typing of isolates of Enterobacter cloacae from an outbreak of infection ina neonatal intensive care unit

Background: Enterobacter cloacae has become a common cause of nosocomial in fections. This study was designed to investigate the pattern of spread of E cloacae during an outbreak in a neonatal intensive care unit. Methods: Enterobacterial repetitive intergenic consensus polymerase chain r eaction was used to examine 111 E cloacae isolates from 17 patients, includ ing 81 from surveillance cultures, 23 from endotracheal tubes, 3 from eyes, and 1 each from blood, urine, skin, and throat. Antibiotic susceptibility profiles were also obtained. Results: Infection with E cloacae resulted from endogenous bacteria and fro m horizontal transmission. One group of 61 isolates, a third of which were obtained from clinical specimens, was uniformly susceptible to imipenem and ciprofloxacin only. A second group of 50 isolates, only 18% of which were obtained from clinical specimens, was susceptible to all antibiotics tested except for aminopenicillins and first-generation cephalosporins. Conclusion: These data indicate that (1) patient-to-patient spread is an im portant cause of E cloacae infection in the neonatal intensive care unit an d (2) highly antibiotic-resistant E cloacae may emerge during an outbreak.