Institutional spread of clonally related Serratia marcescens isolates with a novel AmpC cephalosporinase (S4): a 4-year experience in Taiwan

• Published in: Diagnostic microbiology and infectious disease 2008-08, Vol.61 (4), p.460-467
• Main Authors: Yu, Wen-Liang, Ko, Wen-Chien, Cheng, Kuo-Chen, Chen, Hui-En, Lee, Ching-Chien, Chuang, Yin-Ching
• Format: Article
• Language: English
• Subjects: AmpC; Anti-Bacterial Agents - pharmacology; Bacteremia - microbiology; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Bacteriology; beta-Lactam Resistance; beta-Lactamases - biosynthesis; beta-Lactamases - genetics; beta-Lactams - pharmacology; Biological and medical sciences; Blood - microbiology; Cluster Analysis; Cross Infection - epidemiology; Cross Infection - microbiology; DNA Fingerprinting; DNA, Bacterial - genetics; Electrophoresis, Gel, Pulsed-Field; Enterobacteriaceae; Epidemiology; Fundamental and applied biological sciences. Psychology; Humans; Infectious Disease; Infectious diseases; Internal Medicine; Medical sciences; Microbiology; Miscellaneous; Molecular Epidemiology; Polymerase Chain Reaction; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Serratia Infections - epidemiology; Serratia Infections - microbiology; Serratia marcescens; Serratia marcescens - enzymology; Serratia marcescens - isolation & purification; SRT family; Taiwan - epidemiology
• ISSN: 0732-8893; 1879-0070
• DOI: 10.1016/j.diagmicrobio.2008.03.010

Abstract Resistance of Serratia marcescens , a nosocomial pathogen of Enterobacteriaceae, to the extended-spectrum β-lactams is usually mediated by an overproduced AmpC cephalosporinase. We aimed to characterize the molecular epidemiology and AmpC of S. marcescens isolates recovered from 1 medical center in southern Taiwan. AmpC-encoding genes for SRT families were investigated by polymerase chain reaction and DNA sequencing. From August 1999 through July 2003, 69 nonrepetitive bloodstream isolates were enrolled. Excluding 11 isolates, which also produced an extended-spectrum β-lactamase, 58 isolates carried an AmpC-encoding gene, including a novel S4 gene with 98% identity to SRT-1 gene ( n = 50), SRT-2 gene ( n = 3), SST-1 gene ( n = 1), and others ( n = 4). Isolates with S4 exhibited a phenotype of resistance to cefotaxime (CTX) but not ceftazidime. Genotype analysis by pulsed-field gel electrophoresis revealed that 45 (90%) of the isolates carrying S4 gene belonged to 2 major epidemic clones, including types A ( n = 28) and B ( n = 17). In conclusion, the AmpC-like S4 β-lactamase may confer CTX resistance of the S. marcescens population. Strains carrying the S4 gene with prolonged dissemination were closely related.