The prevalence of plasmid-mediated AmpC β-lactamases among clinical isolates of Escherichia coli and Klebsiella pneumoniae from five children’s hospitals in China

Ding, Hui; Yang, Yonghong; Lu, Quan; Wang, Y; Chen, Y; Deng, Li; Wang, A; Deng, Qiulian; Zhang, H; Wang, C; Liu, L; Xu, Xiping; Wang, L; Shen, Xuzhuang

doi:10.1007/s10096-008-0532-4

Cited by 57 publications

(37 citation statements)

References 27 publications

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“…These strains were amplified with full-length primer encoding a fragment of 1,140 bp, and the PCR products obtained were purified, sequenced and identified as being the DHA-1 type. The positive rate of pAmpC β-lactamase-producing Klebsiella pneumoniae in the samples from Xuzhou tertiary hospitals was 10.8%, which was consistent with the report by Ding et al (29), but higher than the rate reported by Alvarez et al (30). Although CMY is the most common type of AmpC β-lactamase in the world, the DHA-1 and ACT types predominate in China (31).…”

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confidence: 87%

Detection and genotype analysis of AmpC β-lactamase in Klebsiella pneumoniae from tertiary hospitals

Liu

2016

Experimental and Therapeutic Medicine

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Abstract. The aim of the present study was to investigate the phenotype and genotype of plasmid-mediated AmpC (pAmpC) β-lactamase in Klebsiella pneumoniae and its antibiotic resistance. A total of 130 non-repetitive clinical isolates of Klebsiella pneumoniae, obtained from tertiary hospitals, were phenotypically screened for pAmpC β-lactamase production with the cefoxitin disk diffusion test. β-lactamase genes in the screened isolates were detected using multiplex polymerase chain reaction (PCR); carbapenemase genes in pAmpC β-lactamase-producing isolates that were resistant to imipenem were detected using PCR. Out of the 130 isolates of Klebsiella pneumoniae, 62 strains (47.7%) were resistant to cefoxitin, including 14 strains (10.8%) positive for pAmpC β-lactamase (DHA type), among which 12 strains (85.7%) were susceptible to imipenem, and 2 strains, which were carrying Klebsiella pneumoniae carbapenemase (KPC)-2 gene, were resistant to imipenem. The pAmpC β-lactamase-producing Klebsiella pneumoniae isolates from the tertiary hospitals were mainly of DHA-1 genotype, and the majority were susceptible to carbapenems; drug-resistant strains were associated with KPC-2 expression. IntroductionAmpC β-lactamase, which is a type of cephalosporinase (1), is known to be responsible for antimicrobial resistance in gram-negative bacilli (2). The knowledge of potential risk factors for that resistance may help to limit its impact by enabling the implementation of effective control measures and judicious antimicrobial therapy (3). AmpC β-lactamases are either plasmid-or chromosomal-mediated (4). With regard to plasmid-mediated AmpC (pAmpC), no single phenotypic method is satisfactory for its detection; the combined application of phenotypic tests is necessary for the screening and confirmation of the presence of pAmpC-mediated resistance (5). Chromosomal-mediated AmpC hyperproducing Escherichia coli (E. coli) continues to be mostly susceptible to third-generation cephalosporins (6). Polymerase chain reaction (PCR) remains the gold standard for the detection of AmpC β-lactamases (7). As β-lactam antibiotics are widely used, the production of AmpC β-lactamases by bacteria results in considerable antibiotic resistance (8).Resistance to broad-spectrum β-lactams mediated by extended spectrum broad-spectrum β-lactamases (ESBLs) and AmpC β-lactamase enzymes is an increasing problem worldwide (9). In Portugal, 104/124 (83.9%) of Enterobacteriaceae isolates that were resistant to third generation cephalosporins were also resistant to fourth generation cephalosporins (10). In comparison with ESBL-producing gram-negative bacilli, AmpC β-lactamase-producing strains show more extensive antibiotic resistance; 29% of Acinetobacter strains, for example, were found to produce both ESBL and AmpC enzymes (11). To be more specific, the majority of Acinetobacter baumannii isolates were producers of carbapenemase and metallo-β-lactamase (12). In a study of isolates collected between 2002 and 2008, DHA-1 was the most prevalent acquired AmpC (94%)...

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confidence: 87%

Detection and genotype analysis of AmpC β-lactamase in Klebsiella pneumoniae from tertiary hospitals

Liu

2016

Experimental and Therapeutic Medicine

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“…In addition, chromosomal Ambler class C AmpC genes have been mobilized and are now being disseminated on plasmids, reminiscent of the early dissemination and evolution of ESBLs (11). Increasingly, reports document the detection of plasmid-mediated AmpC resistance (pAmpC) in E. coli (4,6,12). Data from the SENTRY antimicrobial surveillance program for North America show that 19/65 ESBL screen-positive E. coli isolates harbored pAmpC (5).…”

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confidence: 99%

Unreliable Extended-Spectrum β-Lactamase Detection in the Presence of Plasmid-Mediated AmpC in Escherichia coli Clinical Isolates

Robberts¹,

Kohner²,

Patel

2009

J Clin Microbiol

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The emergence of extended-spectrum ␤-lactamase (ESBL) and plasmid-mediated AmpC (pAmpC) enzymes in Escherichia coli raises concern regarding accurate laboratory detection and interpretation of susceptibility testing results. Twenty-six cefpodoxime ESBL screen-positive, cefoxitin-resistant E. coli clinical isolates were subjected to clavulanate ESBL confirmatory testing employing disk augmentation, Etest, and the BD Phoenix NMC/ID-132 panel. Phenotypic pAmpC production was assessed by boronic acid disk augmentation. ESBL and pAmpC genes were detected by gene amplification and sequencing. ESBL genes (SHV and/or CTX-M-type genes) were detected in only 7/26 ESBL screen-positive isolates. Of 23 aminophenylboronic acid screen-positive isolates, pAmpC genes were detected in 20 (CMY-2 or FOX-5 genes). High incidences of false-positive ESBL confirmatory results were observed for both clavulanate disk augmentation (9/19) and BD Phoenix (5/19). All were associated with the presence of pAmpC genes with or without TEM-1. Etest performed poorly, as the majority of interpretations were nondeterminable. In addition, false-negative ESBL confirmatory results were observed in isolates possessing concomitant ESBL and pAmpC genes for Etest (four of five), BD Phoenix (three of five), and disk augmentation (one of five). The results indicate poor performance of currently employed ESBL confirmatory methods in the setting of concomitant pAmpC. Some isolates with pAmpC and ESBL genes fell within the susceptible category to extended-spectrum cephalosporins, raising concern over currently employed breakpoints.Ambler class A extended-spectrum ␤-lactamase (ESBL) genes in Escherichia coli are well documented. Possible ESBL production has been reported to occur in up to 9% of European E. coli isolates (15). In addition, chromosomal Ambler class C AmpC genes have been mobilized and are now being disseminated on plasmids, reminiscent of the early dissemination and evolution of ESBLs (11). Increasingly, reports document the detection of plasmid-mediated AmpC resistance (pAmpC) in E. coli (4,6,12). Data from the SENTRY antimicrobial surveillance program for North America show that 19/65 ESBL screen-positive E. coli isolates harbored pAmpC (5).The ESBL hydrolytic spectrum includes the oxyimino-cephalosporins and monobactams but not 7-␣-methoxy-cephalosporins (cephamycins) and is inhibited by clavulanate, sulbactam, and tazobactam. The broader spectrum of the AmpC enzymes includes the cephamycins, and AmpC enzymes are not inhibited by clavulanate, sulbactam, or tazobactam. The Clinical and Laboratory Standards Institute (CLSI) recommends that antimicrobial susceptibility testing include screening for ESBL production in E. coli, employing cefpodoxime, ceftazidime, aztreonam, cefotaxime, or ceftriaxone, followed by phenotypic confirmation with clavulanate (3).ESBL screening results are reviewed to select for those organisms that need phenotypic ESBL confirmation, as recommended by CLSI, and results are issued with the aim of preventing inappropriate u...

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“…In addition, chromosomal Ambler class C AmpC genes have been mobilized and are now being disseminated on plasmids, reminiscent of the early dissemination and evolution of ESBLs (21). Increasingly, reports document the detection of plasmid-mediated AmpC ␤-lactamase (pAmpC) resistance in the Enterobacteriaceae (7,9,22). Data from the SENTRY Antimicrobial Surveillance Program for North America show that 19 of 65 ESBL screen-positive E. coli isolates harbored pAmpC (8).…”

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confidence: 99%

Cephalosporin MIC Distribution of Extended-Spectrum-β-Lactamase- and pAmpC-Producing Escherichia coli and Klebsiella Species

Kohner¹,

Robberts²,

Cockerill³

et al. 2009

J Clin Microbiol

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The acquisition of ␤-lactamases in members of the Enterobacteriaceae family poses a challenge to antimicrobial susceptibility testing in the clinical laboratory. We correlated the distribution of the MICs for Klebsiella spp. and Escherichia coli with the presence of extended-spectrum ␤-lactamase (ESBL) and plasmid-mediated AmpC ␤-lactamase (pAmpC) genes. A total of 264 isolates were subjected to cefazolin, ceftriaxone, cefotaxime, ceftazidime, cefepime, and aztreonam agar dilution MIC determination; ESBL screening and confirmatory testing by the methods of the Clinical and Laboratory Standards Institute (CLSI); and for isolates for which the MICs of extended-spectrum cephalosporins were >1 g/ml or the MICs of cefpodoxime were >4 g/ml, PCR amplification and sequencing of the ESBL and pAmpC genes. PCR was positive for 73/81 isolates (45 isolates with an ESBL gene alone, 24 isolates with a pAmpC gene alone, with 4 isolates with both genes). Compared to PCR, confirmatory testing by the CLSI method yielded a sensitivity and a specificity of 98.0 and 96.3%, respectively; there were six false-positive results and one false-negative result. No distinction in the MIC distribution was apparent between isolates with the ESBL gene and isolates with the pAmpC gene. A substantial percentage of the isolates with PCR-confirmed ESBL and/or pAmpC genes fell within the current CLSI susceptible category. For a ceftazidime, ceftriaxone, or cefotaxime MIC of >2 g/ml, a dichotomy existed between isolates with and without ESBL and pAmpC genes in most cases. This suggests that the presence of the ESBL and the pAmpC enzymes may yield similar MICs of extended-spectrum cephalosporins, many of which fall within the current nonresistant categories. Lowering of the current CLSI breakpoints for cephalosporins appears to be warranted.

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The prevalence of plasmid-mediated AmpC β-lactamases among clinical isolates of Escherichia coli and Klebsiella pneumoniae from five children’s hospitals in China

Cited by 57 publications

References 27 publications

Detection and genotype analysis of AmpC β-lactamase in Klebsiella pneumoniae from tertiary hospitals

Detection and genotype analysis of AmpC β-lactamase in Klebsiella pneumoniae from tertiary hospitals

Unreliable Extended-Spectrum β-Lactamase Detection in the Presence of Plasmid-Mediated AmpC in Escherichia coli Clinical Isolates

Cephalosporin MIC Distribution of Extended-Spectrum-β-Lactamase- and pAmpC-Producing Escherichia coli and Klebsiella Species

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