Korean J Clin Microbiol.  2005 Apr;8(1):57-65.

Emergence of CTX-M-9 Extended-Spectrum beta-Lactamase-Producing Enterobacter cloacae Isolates

• Hong YR
• Yu H
• Bae IK
• Kwon SB
• Jeong SH
• Kim HJ
• Kim YH
• Lee SH

Abstract

BACKGROUND
The aim of this study is to assess the prevalence and to investigate the molecular epidemiology of Ambler class A extended-spectrum beta-lactamase (ESBL)-producing Enterobacter cloacae isolates in a university hospital in Busan, Korea.
METHODS
Non-duplicated clinical isolates of E.cloacae from patients admitted in Kosin University Gospel Hospital were collected during the period from January through September, 2003. ESBL-production was examined by the double-disk synergy test (DDST) and the transferability of cefotaxime-resistance by conjugation. MICs of beta-lactam antibiotics were determined by the agar dilution method and Ambler class A ESBL genes were searched by PCR amplification. Enterobacterial repetitive intergenic consensus (ERIC) PCR was performed to investigate epidemiological relationships among bla CTX-M-9 gene-carrying E.cloacae isolates.
RESULTS
Antimicrobial resistance rates of E.cloacae isolates (n=148) to ceftazidime, cefotaxime, and aztreonam were 50.0%, 29.6%, and 48.0%, respectively. Among 50 E.cloacae isolates intermediate or resistant to more than one expanded-spectrum beta-lactam agent, 41 (27.7%) showed positive results in DDST; of these 41 isolates, 1 was found to carry bla TEM-52 gene, 16 carried bla SHV-12 gene, 4 bla CTX-M-9 gene, and 19 both bla SHV-12 and bla CTX-M-9 genes. The 23 E.cloacae isolates carrying bla CTX-M-9 gene showed 9 different profiles by ERIC PCR.
CONCLUSION
ESBL-producing E.cloacae was not uncommon in a university hospital in Busan, Korea. The commonest types of ESBLs produced by E.cloacae isolates were SHV-12 and CTX-M-9. CTX-M-9 ESBL-producing E.cloacae isolates showed diverse ERIC-PCR profiles, indicating that they were not originated from a common source.

Keyword

Enterobacter cloacae; SHV-12; CTX-M-9; Enterobacterial repetitive intergenic con-sensus; Polymerase chain reaction

MeSH Terms

Agar
Anti-Bacterial Agents
Aztreonam
beta-Lactamases
Busan
Cefotaxime
Ceftazidime
Consensus
Enterobacter cloacae*
Enterobacter*
Humans
Korea
Molecular Epidemiology
Polymerase Chain Reaction
Prevalence
Agar
Anti-Bacterial Agents
Aztreonam
Cefotaxime
Ceftazidime
beta-Lactamases