title: Characterisation of Clostridium difficile strains isolated from Groote Schuur Hospital, Cape Town, South Africa.
abstract: The C. difficile infection rate in South Africa is concerning. Many strains previously isolated from diarrhetic patients at Groote Schuur Hospital were ribotype 017. This study further characterised these strains with respect to their clonal relationships, antibiotic susceptibility, toxin production and various attributes impacting on pathogen colonisation. Multilocus variable-number tandem-repeat analysis (MLVA) was used to characterise all C. difficile isolates. Antibiotic susceptibility was determined by E-test and PCR-based analysis of the ermB, gyrA and gyrB genes. Auto-aggregation of cells was measured in broth, and biofilm formation observed in 24-well plates. Toxins were measured using the Wampole C DIFF TOX A/B II kit. Most isolates belonged to the ribotype 017 group. Identical MLVA types occurred in different wards over time, and several patients were infected with identical strains. All isolates were susceptible to vancomycin and metronidazole, but some ribotype 017 isolates showed reduced metronidazole susceptibility (≥2 mg l(-1)). Sixty-nine percent of ribotype 017 isolates were resistant to moxifloxacin, and 94 % to erythromycin, compared to 0 % and 17 % resistance, respectively, in non-ribotype 017 isolates. The ermB gene and mutations in the gyrA and/or gyrB genes were linked to erythromycin and moxifloxacin resistance, respectively. Ribotype 017 isolates auto-aggregated more strongly than other isolates and produced lower levels of the TcdB toxin than a reference strain. Certain strains produced strong biofilms. Patient-to-patient transfer and unique infection events could cause the predominance of ribotype 017 strains in the cohort. Multi-drug resistant strains are a potential reservoir for future infections.
authors.affiliation: Department of Molecular and Cell Biology, University of Cape Town, Rondebosch Cape Town, 7700, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Kullin
authors.affiliation: Department of Molecular and Cell Biology, University of Cape Town, Rondebosch Cape Town, 7700, South Africa.
authors.forename: T
authors.initials: T
authors.lastname: Brock
authors.affiliation: Department of Medicine, Division of Gastroenterology, University of Cape Town, Cape Town, South Africa.
authors.forename: N
authors.initials: N
authors.lastname: Rajabally
authors.affiliation: School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AR, USA.
authors.forename: F
authors.initials: F
authors.lastname: Anwar
authors.affiliation: School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AR, USA.
authors.forename: G
authors.initials: G
authors.lastname: Vedantam
authors.affiliation: Department of Molecular and Cell Biology, University of Cape Town, Rondebosch Cape Town, 7700, South Africa.
authors.forename: S
authors.initials: S
authors.lastname: Reid
authors.affiliation: Department of Molecular and Cell Biology, University of Cape Town, Rondebosch Cape Town, 7700, South Africa. valerie.abratt@uct.ac.za.
authors.forename: V
authors.identifier: http://orcid.org/0000-0003-4631-3355
authors.initials: V
authors.lastname: Abratt
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion; D001427:Bacterial Toxins / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development; D016360:Clostridioides difficile / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D003015:Clostridium Infections / Q000382:microbiology*; D027081:DNA Gyrase / Q000235:genetics; D003967:Diarrhea / Q000382:microbiology*; D052978:Disk Diffusion Antimicrobial Tests; D005838:Genotype; D006761:Hospitals; D006801:Humans; D010865:Pilot Projects; D016133:Polymerase Chain Reaction; D021521:Ribotyping; D013019:South Africa
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D027081:DNA Gyrase