Infect Chemother.  2010 Oct;42(5):280-284. 10.3947/ic.2010.42.5.280.

Prevalence of Extended-spectrum beta-lactamase among Enterobacteriacae Blood Isolates with Inducible AmpC beta-lactamase

• Cheong HS
• Ko KS
• Kang CI
• Chung DR
• Peck KR
• Song JH

• KMID: 1806889
• DOI: http://doi.org/10.3947/ic.2010.42.5.280

Abstract

BACKGROUND
Among the inducible AmpC beta-lactamase-producing members of the family Enterobacteriaceae such as Enterobacter spp., Citrobacter spp., Serratia spp., and Morganella morganii (ECSM), the prevalence of ESBL-producing isolates are increasing. However, there have been only a limited number of studies that have investigated the prevalence for ESBL-production in blood isolates of these organisms.
MATERIALS AND METHODS
We performed a prospective observational study to evaluate the prevalence for ESBL production among ECSM blood isolates. All consecutive blood isolates in the Samsung Medical Center were included from Oct 2006 to Mar 2008. Antimicrobial susceptibility test was performed by broth microdilution method. ESBLs were confirmed by double-disk synergy test and ESBL phenotypes were determined by PCR.
RESULTS
The 124 isolates (94 Enterobacter spp., 18 Citrobacter spp., 8 Serratia spp. and 4 Morganella spp.) were investigated. Among 124 ESCM isolates, 30 isolates (24.2%) showed ESBL-producing activity. Derepressed or partially derepressed AmpC mutants and derepressed AmpC mutants with ESBL production accounted for 36.3% (45/124) and 16.9% (21/124), respectively. Of ESBL producers, the most prevalent ESBL was SHV-12 (5/24, 20.8%).
CONCLUSIONS
The prevalence of ESBL-producing isolates is high in Enterobacter spp., Serratia marcescens and Citrobacter spp. clinical isolates. It suggested that routine screening test for ESBLs among Enterobacteriacae blood isolates with inducible AmpC beta-lactamase should be needed.

Keyword

Enterobacter spp.; Extended-spectrum beta-lactamase; AmpC beta-lactamase

MeSH Terms

Bacterial Proteins
beta-Lactamases
Citrobacter
Enterobacter
Enterobacteriaceae
Humans
Mass Screening
Morganella
Morganella morganii
Phenotype
Polymerase Chain Reaction
Prevalence
Prospective Studies
Serratia
Serratia marcescens
Bacterial Proteins
beta-Lactamases

Figure

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  Figure 1 Difference of cefepime MICs between derepressed AmpC β-lactamase producing isolates and derepressed AmpC β-lactamase with ESBL producing isolates. FEP, cefepime.

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