Antimicrobial resistance amongst Klebsiella spp. collected from intensive care units in Southern and Western Europe in 1997–1998

A 1994 survey of 35 intensive care units (ICUs) in Western and Southern Europe found extended-spectrum β-lactamases (ESBLs) in 220/966 (23%) klebsiellae. A follow-up survey from May 1997 to October 1998 collected klebsiellae from 24 ICUs, including 23 that participated in 1994. Twenty-one ICUs sent 433 eligible Isolates, of which 110 (25%) had ESBLs. The prevalence of ESBLs had not changed significantly from 1994 but the proportion of ESBL-producers resistant to piperacillin/tazobactam had risen from 31% to 63% (P < 0.001), and most of this resistance was high level (MICs ≥ 128 + 4 mg/L). The proportion of Klebslella oxytoca isolates hyperproducing K1 β-lactamase rose from 8% in 1994 to 21% in 1997-1998 (P < 0.001). Most klebsiellae (99%) were very susceptible to meropenem (mode MIC 0.03 mg/L) but three had decreased susceptibility (MICs 2-4 mg/L). These could not hydrolyse carbapenems. Aminoglycoside resistance was not significantly changed in prevalence from 1994; ciprofloxacin resistance occurred in 31% of ESBL-producers in both years, but had increased among non-producers (2% in 1994 versus 7% in 1997-1998, P < 0.001).