Sustained activity and spectrum of selected extended-spectrum beta-lactams (carbapenems and cefepime) against Enterobacter spp. and ESBL-producing Klebsiella spp.: report from the SENTRY antimicrobial surveillance program (USA, 1997-2000).
Enterobacter spp. and Klebsiella spp. are important clinical pathogens that frequently exhibit resistance to third-generation cephalosporins. In Enterobacter spp. strains, resistance is usually due to derepression of the Amp C locus, whereas plasmid-encoded extended-spectrum beta-lactamases (ESBLs) are primarily responsible for resistance in Klebsiella spp. Here we report the results from the SENTRY Antimicrobial Surveillance Program concerning the rates and trends of resistance to extended-spectrum beta-lactams and other antimicrobial agents in Enterobacter spp. and Klebsiella spp. isolated between 1997 and 2000 in participating hospitals in the United States. Among Enterobacter spp., resistance (MIC>or=32 mg/l) to aztreonam, ceftazidime and ceftriaxone ranged from 12.3 to 21.2% over the 4 years, whereas resistance in Klebsiella (MIC>or=2 mg/l) ranged from 5.9 to 6.8%. There was no trend toward increased resistance to these beta-lactam agents over the monitored period. Carbapenems (imipenem, meropenem) and cefepime had excellent activity against both ceftazidime-susceptible and -resistant Enterobacter spp. and Klebsiella spp. (>99% susceptible), although the minimum inhibitory concentration values of cefepime were higher in ceftazidime-resistant isolates compared with ceftazidime-susceptible isolates. Co-resistance to other antimicrobial agents was common in both tested genus groups.
Jones
Ronald N
RN
The JONES Group/JMI Laboratories, 345 Beaver Kreek Centre, Suite A, North Liberty, IA 52317, USA. ronald-jones@jmilabs.com
Biedenbach
Douglas J
DJ
Gales
Ana C
AC
D015780:Carbapenems / Q000494:pharmacology*; D000077723:Cefepime; D002511:Cephalosporins / Q000494:pharmacology*; D004754:Enterobacter / Q000187:drug effects*; D007709:Klebsiella / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000096:biosynthesis*
D015780:Carbapenems; D002511:Cephalosporins; D000077723:Cefepime; D001618:beta-Lactamases