EVIDENCE OF INTERHOSPITAL TRANSMISSION OF EXTENDED-SPECTRUM BETA-LACTAM-RESISTANT KLEBSIELLA-PNEUMONIAE IN THE UNITED-STATES, 1986 TO 1993

BACKGROUND: In addition to single-hospital outbreaks, interhospital tr ansmission of extended-spectrum beta-lactam-resistant (ESBLR) Klebsiel la pneumoniae has been suspected in some reports. However, these studi es lacked sufficient epidemiological information to confirm such an oc currence. METHODS: We reviewed the surveillance data reported to the N ational Nosocomial Infections Surveillance (NNIS) System during 1986 t o 1993 for K pneumoniae isolates and their susceptibility to either ce ftazidime, cefotaxime, ceftriaxone, or aztreonam. Pulsed-field gel ele ctrophoresis (PFGE) was used to study available ESBLR K pneumoniae iso lates. RESULTS: Among 8,319 K pneumoniae isolates associated with noso comial infections, 727 (8.7%) were resistant or had intermediate-level resistance to at least one of these antibiotics. One hospital (hospit al A) accounted for 321 isolates (44.2%) of ESBLR K pneumoniae. During 1986 to 1993, the percentage of K pneumoniae isolates that were ESBLR increased from 9 to 57.7% in hospital A, from 0 to 35.6% in NNIS hosp itals 0 to 20 miles from hospital A (area B), and from 1.6 to 7.3% in NNIS hospitals more than 20 miles from hospital A, including hospitals located throughout the United States. Analysis of PFGE restriction pr ofiles showed a genetic relationship between a cluster of isolates fro m hospital A and some isolates from one hospital in area B, and consec utive admission in these two hospitals was confirmed for two patients from whom isolates were available. CONCLUSIONS: These data provide evi dence of interhospital transmission of ESBLR K pneumoniae in one regio n of the United States and stress the interrelationship between hospit als when trying to control antimicrobial resistance (Infect Control Ho sp Epidemiol 1997;18:492-498).