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.
Section of Infectious Diseases, Department of Medicine, China Medical College Hospital, Yuh Der Road, Taichung City, Taiwan.
Wen-Liang
WL
Yu
Lii-Tzu
LT
Wu
Michael A
MA
Pfaller
Patricia L
PL
Winokur
Ronald N
RN
Jones
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