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Antimicrobial resistance in large clostridial toxin-negative, binary toxin-positive Clostridium difficile ribotypes.
Anaerobe. 2018 Dec; 54:55-60.A

Abstract

Antimicrobial resistance (AMR) is commonly found in Clostridium difficile strains and plays a major role in strain evolution. We have previously reported the isolation of large clostridial toxin-negative, binary toxin-producing (A-B-CDT+) C. difficile strains from colonised (and in some instances diarrhoeic) food animals, as well as from patients with diarrhoea. To further characterise these strains, we investigated the phenotypic and genotypic AMR profiles of a diverse collection of A-B-CDT+C. difficile strains. The in vitro activities of 10 antimicrobial agents were determined for 148 A-B-CDT+C. difficile strains using an agar dilution methodology. Whole-genome sequencing and in silico genotyping was performed on 53 isolates to identify AMR genes. All strains were susceptible to vancomycin, metronidazole and fidaxomicin, antimicrobials currently considered first-line treatments for C. difficile infection (CDI). Differences in antimicrobial phenotypes between PCR ribotypes (RTs) were observed but were minimal. Phenotypic resistance was observed in 13 isolates to tetracycline (TetR, MIC = 16 mg/L), moxifloxacin (MxfR, MIC = 16 mg/L), erythromycin (EryR, MIC ≥128 mg/L) and clindamycin (CliR, MIC = 8 mg/L). The MxfR strain (RT033) possessed mutations in gyrA/B, while the TetR (RT033) strain contained a tetM gene carried on the conjugative transposon Tn6190. All EryR and CliR strains (RT033, QX521) were negative for the erythromycin ribosomal methylase gene ermB, suggesting a possible alternative mechanism of resistance. This work describes the presence of multiple AMR genes in A-B-CDT+C. difficile strains and provides the first comprehensive analysis of the AMR repertoire in these lineages isolated from human, animal, food and environmental sources.

Authors+Show Affiliations

School of Biomedical Sciences, The University of Western Australia, Western Australia, Australia; PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Western Australia, Australia.School of Veterinary and Life Sciences, Murdoch University, Western Australia, Australia.School of Biomedical Sciences, The University of Western Australia, Western Australia, Australia.Communicable Disease Control Directorate, Department of Health, Western Australia, Australia.School of Biomedical Sciences, The University of Western Australia, Western Australia, Australia; PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Western Australia, Australia; School of Veterinary and Life Sciences, Murdoch University, Western Australia, Australia; School of Medical and Health Sciences, Edith Cowan University, Western Australia, Australia. Electronic address: thomas.riley@uwa.edu.au.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30053486

Citation

Androga, Grace O., et al. "Antimicrobial Resistance in Large Clostridial Toxin-negative, Binary Toxin-positive Clostridium Difficile Ribotypes." Anaerobe, vol. 54, 2018, pp. 55-60.
Androga GO, Knight DR, Lim SC, et al. Antimicrobial resistance in large clostridial toxin-negative, binary toxin-positive Clostridium difficile ribotypes. Anaerobe. 2018;54:55-60.
Androga, G. O., Knight, D. R., Lim, S. C., Foster, N. F., & Riley, T. V. (2018). Antimicrobial resistance in large clostridial toxin-negative, binary toxin-positive Clostridium difficile ribotypes. Anaerobe, 54, 55-60. https://doi.org/10.1016/j.anaerobe.2018.07.007
Androga GO, et al. Antimicrobial Resistance in Large Clostridial Toxin-negative, Binary Toxin-positive Clostridium Difficile Ribotypes. Anaerobe. 2018;54:55-60. PubMed PMID: 30053486.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Antimicrobial resistance in large clostridial toxin-negative, binary toxin-positive Clostridium difficile ribotypes. AU - Androga,Grace O, AU - Knight,Daniel R, AU - Lim,Su-Chen, AU - Foster,Niki F, AU - Riley,Thomas V, Y1 - 2018/07/25/ PY - 2018/05/12/received PY - 2018/07/13/revised PY - 2018/07/20/accepted PY - 2018/7/28/pubmed PY - 2019/3/23/medline PY - 2018/7/28/entrez KW - A(−)B(-)CDT(+) KW - Antimicrobial resistance KW - Binary toxin KW - C. difficile KW - Ribotype SP - 55 EP - 60 JF - Anaerobe JO - Anaerobe VL - 54 N2 - Antimicrobial resistance (AMR) is commonly found in Clostridium difficile strains and plays a major role in strain evolution. We have previously reported the isolation of large clostridial toxin-negative, binary toxin-producing (A-B-CDT+) C. difficile strains from colonised (and in some instances diarrhoeic) food animals, as well as from patients with diarrhoea. To further characterise these strains, we investigated the phenotypic and genotypic AMR profiles of a diverse collection of A-B-CDT+C. difficile strains. The in vitro activities of 10 antimicrobial agents were determined for 148 A-B-CDT+C. difficile strains using an agar dilution methodology. Whole-genome sequencing and in silico genotyping was performed on 53 isolates to identify AMR genes. All strains were susceptible to vancomycin, metronidazole and fidaxomicin, antimicrobials currently considered first-line treatments for C. difficile infection (CDI). Differences in antimicrobial phenotypes between PCR ribotypes (RTs) were observed but were minimal. Phenotypic resistance was observed in 13 isolates to tetracycline (TetR, MIC = 16 mg/L), moxifloxacin (MxfR, MIC = 16 mg/L), erythromycin (EryR, MIC ≥128 mg/L) and clindamycin (CliR, MIC = 8 mg/L). The MxfR strain (RT033) possessed mutations in gyrA/B, while the TetR (RT033) strain contained a tetM gene carried on the conjugative transposon Tn6190. All EryR and CliR strains (RT033, QX521) were negative for the erythromycin ribosomal methylase gene ermB, suggesting a possible alternative mechanism of resistance. This work describes the presence of multiple AMR genes in A-B-CDT+C. difficile strains and provides the first comprehensive analysis of the AMR repertoire in these lineages isolated from human, animal, food and environmental sources. SN - 1095-8274 UR - https://www.unboundmedicine.com/medline/citation/30053486/Antimicrobial_resistance_in_large_clostridial_toxin_negative_binary_toxin_positive_Clostridium_difficile_ribotypes_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1075-9964(18)30127-6 DB - PRIME DP - Unbound Medicine ER -