Dataset Information

In Vivo Evolution of CMY-2 to CMY-33 ?-Lactamase in Escherichia coli Sequence Type 131: Characterization of an Acquired Extended-Spectrum AmpC Conferring Resistance to Cefepime.

ABSTRACT: Cefepime is frequently prescribed to treat infections caused by AmpC-producing Gram-negative bacteria. CMY-2 is the most common plasmid-mediated AmpC (pAmpC) ?-lactamase. Unfortunately, CMY variants conferring enhanced cefepime resistance have been reported. Here, we describe the evolution of CMY-2 to an extended-spectrum AmpC (ESAC) in clonally identical Escherichia coli isolates obtained from a patient. The CMY-2-producing E. coli isolate (CMY-2-Ec) was isolated from a wound. Thirty days later, one CMY-33-producing E. coli isolate (CMY-33-Ec) was detected in a bronchoalveolar lavage fluid sample. Two weeks before the isolation of CMY-33-Ec, the patient received cefepime. CMY-33-Ec and CMY-2-Ec were identical by repetitive extragenic palindromic-PCR (rep-PCR), being of hyperepidemic sequence type 131 (ST131) but showing different ?-lactam MICs (e.g., cefepime MIC, 16 and ? 0.5 ?g/ml for CMY-33-Ec and CMY-2-Ec, respectively). Identical CMY-2-Ec isolates were also found in a rectal swab. CMY-33 differs from CMY-2 by a Leu293-Ala294 deletion. Expressed in E. coli strain DH10B, both CMYs conferred resistance to ceftazidime (? 256 ?g/ml), but the cefepime MICs were higher for CMY-33 than CMY-2 (8 versus 0.25 ?g/ml, respectively). The kcat/Km or inhibitor complex inactivation (kinact)/Ki app (?M(-1) s(-1)) indicated that CMY-33 possesses an extended-spectrum ?-lactamase (ESBL)-like spectrum compared to that of CMY-2 (e.g., cefoxitin, 0.2 versus 0.4; ceftazidime, 0.2 versus not measurable; cefepime, 0.2 versus not measurable; and tazobactam, 0.0018 versus 0.0009, respectively). Using molecular modeling, we show that a widened active site (? 4-Å shift) may play a significant role in enhancing cefepime hydrolysis. This is the first in vivo demonstration of a pAmpC that under cephalosporin treatment expands its substrate spectrum, resembling an ESBL. The prevalence of CMY-2-Ec isolates is rapidly increasing worldwide; therefore, awareness that cefepime treatment may select for resistant isolates is critical.

SUBMITTER: Pires J

PROVIDER: S-EPMC4649241 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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In Vivo Evolution of CMY-2 to CMY-33 β-Lactamase in Escherichia coli Sequence Type 131: Characterization of an Acquired Extended-Spectrum AmpC Conferring Resistance to Cefepime.

Pires João J Taracila Magdalena M Bethel Christopher R CR Doi Yohei Y Kasraian Sara S Tinguely Regula R Sendi Parham P Bonomo Robert A RA Endimiani Andrea A

Antimicrobial agents and chemotherapy 20150921 12

Cefepime is frequently prescribed to treat infections caused by AmpC-producing Gram-negative bacteria. CMY-2 is the most common plasmid-mediated AmpC (pAmpC) β-lactamase. Unfortunately, CMY variants conferring enhanced cefepime resistance have been reported. Here, we describe the evolution of CMY-2 to an extended-spectrum AmpC (ESAC) in clonally identical Escherichia coli isolates obtained from a patient. The CMY-2-producing E. coli isolate (CMY-2-Ec) was isolated from a wound. Thirty days later ...[more]

PMID: 26392491

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Project description:A nationwide study on the occurrence of extended-spectrum β-lactamase (ESBL)/AmpC in nonhospitalized horses in the Netherlands was performed. Molecular characterization was done, and questionnaires were analyzed to identify factors associated with carriage. In total, 796 horse owners were approached; 281 of these submitted a fecal sample from their horse(s), resulting in 362 samples. All samples were cultured qualitatively in Luria-Bertani (LB) broth and subsequently on MacConkey agar, both supplemented with 1 mg/liter cefotaxime (LB+ and MC+). Positive samples were subsequently cultured quantitatively on MC+. Initial extended-spectrum-β-lactamase (ESBL)/AmpC screening was performed by PCR, followed by whole-genome sequencing on selected strains. Associations between ESBL/AmpC carriage and questionnaire items were analyzed using a univariate generalized estimating equation (GEE) regression analysis, followed by a multiple GEE model for relevant factors. In total, 39 of 362 samples (11%) were determined to be positive for ESBL/AmpC. blaCTX-M-1-carrying isolates were obtained from 77% of positive samples (n = 30). Other ESBL/AmpC genes observed included blaCTX-M-2, blaCTX-M-14, blaCTX-M-15, blaCTX-M-32, blaSHV-12, blaCMY-2, and blaACT-10 A high association between the presence of blaCTX-M-1 and IncHI1 plasmids was observed (46% of samples; n = 18). Based on core genome analysis (n = 48 isolates), six Escherichia coli clusters were identified, three of which represented 80% of the isolates. A negative association between ESBL/AmpC carriage and horses being in contact with other horses at a different site was observed. The presence of a dog on the premises and housing in a more densely human-populated region were positively associated.IMPORTANCE Extended-spectrum β-lactamases (ESBLs) are widespread in human and animal populations and in the environment. Many different ESBL variants exist. The dissemination of ESBLs within and between populations and the environment is also largely influenced by genetic mobile elements (e.g., plasmids) that facilitate spread of these ESBLs. In order to identify potential attributable ESBL sources for, e.g., the human population, it is important to identify the different ESBL variants, the bacteria carrying them, and the potential risk factors for ESBL carriage from other potential sources. This nationwide study focuses on ESBL carriage in the open horse population and investigated the molecular characteristics, geographical distribution throughout the Netherlands, and potential risk factors for fecal ESBL carriage in horses. These data can be used for future attribution studies in order to reduce potential transmission of ESBL-producing bacteria between sources.

Dataset Information

In Vivo Evolution of CMY-2 to CMY-33 ?-Lactamase in Escherichia coli Sequence Type 131: Characterization of an Acquired Extended-Spectrum AmpC Conferring Resistance to Cefepime.

Publications

In Vivo Evolution of CMY-2 to CMY-33 β-Lactamase in Escherichia coli Sequence Type 131: Characterization of an Acquired Extended-Spectrum AmpC Conferring Resistance to Cefepime.

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