title: Impact of Ciprofloxacin and Clindamycin Administration on Gram-Negative Bacteria Isolated from Healthy Volunteers and Characterization of the Resistance Genes They Harbor.
abstract: The aim of this study was to assess the impact of ciprofloxacin, clindamycin, and placebo administration on culturable Gram-negative isolates and the antibiotic resistance genes they harbor. Saliva and fecal samples were collected from healthy human volunteers before and at intervals, up to 1 year after antibiotic administration. Samples were plated on selective and nonselective media to monitor changes in different colony types or bacterial species. Following ciprofloxacin administration, there was a decrease of Escherichia coli in feces and after clindamycin administration a decrease of Bacteroides in feces and Leptotrichia in saliva, which all returned to pretreatment levels within 1 to 4 months. Ciprofloxacin administration also resulted in an increase in ciprofloxacin-resistant Veillonella in saliva, which persisted for 12 months. Additionally, 949 aerobic and anaerobic isolates purified from ciprofloxacin- and clindamycin-containing plates were screened for the presence of resistance genes. Resistance gene carriage was widespread in isolates from all three treatment groups, and no association was observed between genes and antibiotic administration. Although the anaerobic component of the microbiota was not a major reservoir of aerobe-associated antimicrobial resistance (AMR) genes, we detected the sulfonamide resistance gene sul2 in anaerobic isolates. The longitudinal nature of the study allowed identification of distinct Escherichia coli clones harboring multiple resistance genes, including one carrying an extended-spectrum β-lactamase blaCTX-M group 9 gene, which persisted in the gut for up to 4 months. This study provided insight into the effects of antibiotic administration on healthy microbiota and the diversity of resistance genes harbored therein.
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Roderick M
authors.initials: RM
authors.lastname: Card
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Muriel
authors.initials: M
authors.lastname: Mafura
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Theresa
authors.initials: T
authors.lastname: Hunt
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom.
authors.forename: Miranda
authors.initials: M
authors.lastname: Kirchner
authors.affiliation: Institute for Laboratory and Transfusion Medicine at the Heart and Diabetes Centre, University Hospital of the Ruhr University, Bochum, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Weile
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Mamun-Ur
authors.initials: MU
authors.lastname: Rashid
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Andrej
authors.initials: A
authors.lastname: Weintraub
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Carl Erik
authors.initials: CE
authors.lastname: Nord
authors.affiliation: Department of Bacteriology, Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom muna.anjum@apha.gsi.gov.uk.
authors.forename: Muna F
authors.initials: MF
authors.lastname: Anjum
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D002939:Ciprofloxacin / Q000008:administration & dosage*; D002981:Clindamycin / Q000008:administration & dosage*; D024881:Drug Resistance, Bacterial / Q000187:drug effects* / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D064368:Healthy Volunteers; D006801:Humans; D064307:Microbiota / Q000187:drug effects; D012463:Saliva / Q000382:microbiology; D001618:beta-Lactamases / Q000008:administration & dosage
chemical_list: D000900:Anti-Bacterial Agents; D002981:Clindamycin; D002939:Ciprofloxacin; D001618:beta-Lactamases