Confirmation of extended-spectrum beta-lactamase-producing Serratia marcescens: preliminary report from Taiwan.
Although Serratia marcescens is a common cause of nosocomial infection in Taiwan, strains producing extended-spectrum beta-lactamases (ESBLs) are rare. We detected four clinical isolates of S. marcescens from Taiwan that exhibited resistance to cefotaxime (MICs, > 256 microg/ml) and cefepime (MICs, > or = 32 microg/ml), but were susceptible to imipenem and meropenem. Transconjugants revealed similar MIC profiles when compared to the parental strains. Isoelectric focusing revealed one major transferable beta-lactamase (pI 8.4), which was further identified as CTX-M-3 by polymerase chain reaction and gene sequencing. An AmpC-like enzyme (pI 8.8) was not transferable. All four isolates had significant MIC reductions of > or =3 log(2) dilutions for cefepime in the presence of clavulanic acid, compatible with the presence of an ESBL (CTX-M-3). Clavulanate did not significantly reduce the cefotaxime MIC for one isolate that may co-produce high-level AmpC beta-lactamase (pI 8.8). Since high-level AmpC expression has minimal effect on the activity of cefepime, isolates co-producing AmpC beta-lactamase may be recognized as additional ESBL producers by using cefepime as an ESBL screening agent.
Yu
Wen-Liang
WL
Section of Infectious Diseases, Department of Medicine, China Medical College Hospital, Yuh Der Road, Taichung City, Taiwan.
Wu
Lii-Tzu
LT
Pfaller
Michael A
MA
Winokur
Patricia L
PL
Jones
Ronald N
RN
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D012706:Serratia marcescens / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification*; D013624:Taiwan; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases