Molecular analysis of the effector mechanisms of cefoxitin resistance among bacteroides strains

J. Sóki, Silvia Marina Gonzalez, E. Urbán, E. Nagy, Juan Alfonso Ayala

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Objectives: The characterization of Bacteroides strains with regard to the cfxA gene, the MTn4555 mobilizable transposon, the role of penicillin-binding proteins (PBPs) and heterogeneous cefoxitin resistance. Methods: Eighty-four randomly selected and 11 heterogeneously or highly cefoxitin-resistant Bacteroides isolates were included. Agar dilution and Etest methods were used for the determination of cefoxitin MICs. PCR experiments and nucleotide sequencing were used to detect the cfxA gene and the molecular features of MTn4555. Cefoxitin-binding experiments to determine its affinity (IC 50) for PBPs and cefoxitinase assays were also applied. Southern blotting was used to determine the copy number of the cfxA genes. Results: Sixteen strains from the random collection proved to be positive for cfxA, and the MIC distribution for the cfxA-negative and -positive strains did not display a clear separation. The majority of the cfxA-positive strains in this collection harboured a 1.2 kb common region at the 3' end of MTn4555. This region encoded an open reading frame that exhibited homology to abortive phage infection proteins (AbiD). The cfxA genes were transferable only at low frequencies in conjugation experiments. In PBP affinity studies, the PBP-A and PBP3 species were largely insensitive to cefoxitin, whereas the other PBP species were affected at very low concentrations. Seven of the heterogeneously resistant strains were positive for cfxA and most of them had mutations in the regulatory regions of cfxA. Conclusions: Major and minor roles for Bacteroides fragilis PBPs and the CfxA cefoxitinase, respectively, were inferred. The role of the newly recognized abiD may be to control the copy number of cfxA.

Original languageEnglish
Article numberdkr339
Pages (from-to)2492-2500
Number of pages9
JournalJournal of Antimicrobial Chemotherapy
Volume66
Issue number11
DOIs
Publication statusPublished - Nov 2011

Fingerprint

Penicillin-Binding Proteins
Cefoxitin
Bacteroides
Disk Diffusion Antimicrobial Tests
Genes
Bacteroides fragilis
Gene Dosage
Nucleic Acid Regulatory Sequences
Staphylococcal Protein A
Southern Blotting
Bacteriophages
Open Reading Frames
Agar
Nucleotides
Polymerase Chain Reaction
Mutation
Infection
Proteins

Keywords

  • Cephamycinases
  • CfxA
  • MTn4555
  • Penicillin-binding protein(s)

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Cite this

Molecular analysis of the effector mechanisms of cefoxitin resistance among bacteroides strains. / Sóki, J.; Gonzalez, Silvia Marina; Urbán, E.; Nagy, E.; Ayala, Juan Alfonso.

In: Journal of Antimicrobial Chemotherapy, Vol. 66, No. 11, dkr339, 11.2011, p. 2492-2500.

Research output: Contribution to journalArticle

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