Increasing trend in the prevalence of plasmid-mediated AmpC β-lactamases in Enterobacteriaceae lacking chromosomal ampC gene at a Korean university hospital from 2002 to 2004

Song, Wonkeun; Kim, Jae‐Seok; Kim, Han Sung; Yong, Dongeun; Jeong, Seok Hoon; Park, Min Jeong; Lee, Kyu Man

doi:10.1016/j.diagmicrobio.2006.01.012

Cited by 62 publications

(59 citation statements)

References 18 publications

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“…%) among our Klebsiella isolates, and this figure is much higher than reports from other countries like Korea (3.1%) (24) and the United States (1.2%) (25). Additionally, our result was also less than those reported recently from Cairo (34.8%) and Korea (39.3%), respectively (26,27).…”

Section: Discussioncontrasting

confidence: 48%

Molecular determinants of ß-lactamase producing Klebsiella pneumoniae in MansouraUniversity Neonatal Intensive Care Unit

Hammad

Askar²,

Saleh³

et al. 2015

int. arab. j antimicrob. agents

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Section: Discussioncontrasting

confidence: 48%

Molecular determinants of ß-lactamase producing Klebsiella pneumoniae in MansouraUniversity Neonatal Intensive Care Unit

Hammad

Askar²,

Saleh³

et al. 2015

int. arab. j antimicrob. agents

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“…In Korea, 8.7% of pAmpC producers also produced ESBLs (8). AmpCs resist inhibition by CA, and hence, the presence of an ESBL can be masked by the expression of an AmpC.…”

mentioning

confidence: 99%

“…There are numerous reports in which Klebsiella pneumoniae and E. coli isolates have been found to produce both plasmidmediated AmpC ␤-lactamases (pAmpCs) and ESBLs (6,8). In Korea, 8.7% of pAmpC producers also produced ESBLs (8).…”

mentioning

confidence: 99%

Detection of Extended-Spectrum β-Lactamases by Using Boronic Acid as an AmpC β-Lactamase Inhibitor in Clinical Isolates of Klebsiella spp. and Escherichia coli

et al. 2007

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We evaluated highly sensitive methods using boronic acid (BA) to detect extended-spectrum ␤-lactamase (ESBL) production. A total of 182 clinical isolates of Klebsiella spp. (n ‫؍‬ 118) and Escherichia coli (n ‫؍‬ 64) were analyzed: 62 harbored only ESBLs, 80 harbored both ESBLs and plasmid-mediated AmpC ␤-lactamases (pAmpCs), and 40 harbored only pAmpCs. The CLSI confirmatory test detected all isolates that produce only ESBLs but detected 85% of isolates that produce both enzymes. When a >5-mm increase in the zone diameter of either the cefotaxime (CTX) or the ceftazidime (CAZ) disk in the presence of both clavulanic acid (CA) and BA was considered to be a positive result, the test detected all isolates that harbor ESBLs (؎ pAmpCs) but showed frequent false-positive results (50%) for isolates that produce only pAmpCs. Meanwhile, when a >3-mm increase in the zone diameter of either the CTX/BA or the CAZ/BA disk in the presence of CA was considered to be a positive result, the test also detected all isolates that harbor ESBLs (؎ pAmpCs) and showed less frequent false-positive results (5%) in isolates that produce only pAmpCs. The latter new interpretive guideline has enhanced detection of ESBLs in clinical isolates of Klebsiella spp. and Escherichia coli and allowed detection of an ESBL even when potentially masked by a pAmpC.

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“…Inducibility was screened using cefoxitin disk approximation tests with cefotaxime, ceftazidime and aztreonam disks (Song et al, 2006) because cefoxitin is a strong inducer and is stable against hydrolysis. Cephalothin hydrolysis was assayed using crude enzyme extract obtained from a sonicated suspension following a 2 h induction assay with 10 mg cefoxitin ml 21 (Sanders et al, 1986).…”

Section: Methodsmentioning

confidence: 99%

Chromosomal cephalosporinase in Enterobacter hormaechei as an ancestor of ACT-1 plasmid-mediated AmpC β-lactamase

Roh

Song

Chung

et al. 2012

Journal of Medical Microbiology

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In this study of the diversity of AmpC b-lactamase in clinical isolates of Enterobacter spp., a strain was found carrying the plasmid-mediated AmpC b-lactamase ACT-1 gene on its chromosome. The strain was identified as Enterobacter hormaechei using phylogenetic analysis of 16S rRNA and hsp60 genes. In addition, the species was confirmed by DNA-DNA hybridization. The genetic environment of the bla ACT-1 gene was characterized, including the ampR and ampG genes, using a two-step PCR. The amino acid sequences of AmpR at serine 35, arginine 86, glycine 102, aspartic acid 135 and tyrosine 264 were conserved. Measurement of the transcription level of the bla ACT-1 gene using real-time quantitative PCR showed that it increased 1.98-fold following cefoxitin induction. These results suggest that the plasmid-mediated bla ACT-1 gene originated from the chromosome of E. hormaechei.

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Increasing trend in the prevalence of plasmid-mediated AmpC β-lactamases in Enterobacteriaceae lacking chromosomal ampC gene at a Korean university hospital from 2002 to 2004

Cited by 62 publications

References 18 publications

Molecular determinants of ß-lactamase producing Klebsiella pneumoniae in MansouraUniversity Neonatal Intensive Care Unit

Molecular determinants of ß-lactamase producing Klebsiella pneumoniae in MansouraUniversity Neonatal Intensive Care Unit

Detection of Extended-Spectrum β-Lactamases by Using Boronic Acid as an AmpC β-Lactamase Inhibitor in Clinical Isolates of Klebsiella spp. and Escherichia coli

Chromosomal cephalosporinase in Enterobacter hormaechei as an ancestor of ACT-1 plasmid-mediated AmpC β-lactamase

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