title: Extended-Spectrum β-lactam Resistance in the Enteric Flora of Patients at a Tertiary Care Medical Centre.
abstract: The dissemination of Enterobacteriaceae expressing resistance to extended-spectrum cephalosporins, which are therapeutically used in both human and veterinary medicine, is of critical concern. The normal commensal flora of food animals may serve as an important reservoir for the zoonotic food-borne transmission of Enterobacteriaceae harbouring β-lactam resistance. We hypothesized that the predominant AmpC and ESBL genes reported in US livestock and fresh retail meat products, blaCMY-2and blaCTX-M, would also be predominant in human enteric flora. We recovered enteric flora from a convenience sample of patients included in a large tertiary medical centre's Clostridium difficile surveillance programme to screen for and estimate the frequency of carriage of AmpC and ESBL resistance genes. In- and outpatient diarrhoeic submissions (n = 692) received for C. difficile testing at the medical centre's clinical diagnostic laboratory from July to December, 2013, were included. Aliquoted to a transport swab, each submission was inoculated to MacConkey broth with cefotaxime, incubated at 37°C and then inoculated to MacConkey agars supplemented with cefoxitin and cefepime to select for the AmpC and ESBL phenotypes, with blaCMYand blaCTX-Mgenotypes confirmed by PCR and sequencing. From the 692 diarrhoeic submissions, our selective culture yielded 184 isolates (26.6%) with reduced susceptibility to cefotaxime. Of these, 46 (6.7%) samples harboured commensal isolates carrying the AmpC blaCMY. Another 21 (3.0%) samples produced isolates harbouring the ESBL blaCTX-M: 19 carrying CTX-M-15 and 2 with CTX-M-27. Our results indicate that β-lactam resistance genes likely acquired through zoonotic food-borne transmission are present in the enteric flora of this hospital-associated population at lower levels than reported in livestock and fresh food products.
authors.affiliation: The Ohio State University College of Nursing, Columbus, OH, USA.
authors.forename: T F
authors.initials: TF
authors.lastname: Landers
authors.affiliation: Department of Veterinary Preventive Medicine, The Ohio State University College of Veterinary Medicine, Columbus, OH, USA.
authors.forename: D F
authors.initials: DF
authors.lastname: Mollenkopf
authors.affiliation: Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Faubel
authors.affiliation: The Ohio State University College of Nursing, Columbus, OH, USA.
authors.forename: A
authors.initials: A
authors.lastname: Dent
authors.affiliation: Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
authors.forename: P
authors.initials: P
authors.lastname: Pancholi
authors.affiliation: Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, OH, USA.
authors.forename: J B
authors.initials: JB
authors.lastname: Daniels
authors.affiliation: Department of Veterinary Preventive Medicine, The Ohio State University College of Veterinary Medicine, Columbus, OH, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Wittum
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects*; D006801:Humans; D007422:Intestines / Q000382:microbiology*; D062606:Tertiary Care Centers; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams
keywords: Extended-spectrum β-lactamase; food-borne; healthcare; livestock