HOSPITAL OUTBREAK OF KLEBSIELLA-PNEUMONIAE RESISTANT TO BROAD-SPECTRUM CEPHALOSPORINS AND BETA-LACTAM-BETA-LACTAMASE INHIBITOR COMBINATIONSBY HYPERPRODUCTION OF SHV-5 BETA-LACTAMASE

AN aminoglycoside- and ceftazidime-resistant stain of Klebsiella pneum oniae K2 producing the extended-spectrom beta-lactamase SHV-5 infected or colonized 14 pediatric patients at Guy's Hospital. The patients we re mostly neonates recovering from cardiac surgery for congenital defe cts. The organism was also isolated from a nurse and from the father o f one of the children. Four patients had septicemia, and two septicemi c neonates with postoperative renal failure died. Aminoglycoside and c ephalosporin resistance transferred to Escherichia coli in vitro on a 160-kb plasmid, and a similar resistant E. coli strain was isolated fr om the stools of one of the affected children. The epidemic organism c olonized the bowel and skin and was probably transmitted via staff han ds. Five wards were involved because of extensive patient movements. T he outbreak was controlled by patient isolation and attention to handw ashing. All of the isolates of the outbreak strain were identical by p hage typing, ribotyping, plasmid profiling, and biochemical and serolo gical testing, but they varied in their production of SHV-5. Some isol ates produced normal amounts of SHV-5 and were susceptible to beta-lac tam-beta-lactamase inhibitor combinations. Others, including the singl e isolate of multiresistant E. coli, produced up to five times as much enzyme as ''normal'' isolates. This hyperproduction resulted in incre ased resistance to several penicillins and cephalosporins and to the b eta-lactam-beta-lactamase inhibitor combinations amoxicillin-clavulani c acid, ampicillin-sulbactam, piperacillin-tazobactam, and ceftazidime -clavulanic acid. The hyperproduction of SHV-5 by K. pneumoniae and E. coli seen in this outbreak suggests that beta-lactam-beta-lactamase i nhibitor combinations may be unreliable for the treatment of organisms producing extended-spectrum beta-lactamases.