title: Identification of new bacteria harboring qnrS and aac(6')-Ib/cr and mutations possibly involved in fluoroquinolone resistance in raw sewage and activated sludge samples from a full-scale WWTP.
abstract: Wastewater treatment plants (WWTPs) harbor bacteria and antimicrobial resistance genes, favoring gene exchange events and resistance dissemination. Here, a culture-based and metagenomic survey of qnrA, qnrB, qnrS, and aac(6')-Ib genes from raw sewage (RS) and activated sludge (AS) of a full-scale municipal WWTP was performed. A total of 96 bacterial isolates were recovered from nalidixic acid-enrichment cultures. Bacteria harboring the aac(6')-Ib gene predominated in RS, whereas qnrS-positive isolates were specific to AS. Novel qnrS- and aac(6')-Ib-cr positive species were identified: Morganella morganii, Providencia rettgeri, and Pseudomonas guangdongensis (qnrS), and Alcaligenes faecalis and P. rettgeri (aac(6')-Ib-cr). Analysis of qnrS and aac(6')-Ib sequences from isolates and clone libraries suggested that the diversity of qnrS is wider than that of aac(6')-Ib. A large number of amino acid mutations were observed in the QnrS and AAC(6')-Ib proteins at previously undetected positions, whose structural implications are not clear. An accumulation of mutations at the C72, Q73, L74, A75 and M76 positions of QnrS, and D181 of AAC(6')-Ib might be important for resistance. These findings add significant information on bacteria harboring qnrS and aac(6')-Ib genes, and the presence of novel mutations that may eventually emerge in clinical isolates.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Campus Dona Lindu, Universidade Federal de São João del Rei, Divinópolis, Minas Gerais, Brazil.
authors.forename: Magna C
authors.initials: MC
authors.lastname: Paiva
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Mariana P
authors.initials: MP
authors.lastname: Reis
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Costa
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Marcela F
authors.initials: MF
authors.lastname: Dias
authors.affiliation: Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Lucas
authors.initials: L
authors.lastname: Bleicher
authors.affiliation: Centro de Pesquisas René Rachou - FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Larissa L S
authors.initials: LLS
authors.lastname: Scholte
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Regina M D
authors.initials: RMD
authors.lastname: Nardi
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. Electronic address: amaral@ufmg.br.
authors.forename: Andréa M A
authors.initials: AMA
authors.lastname: Nascimento
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000302:isolation & purification*; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010957:Plasmids / Q000187:drug effects; D015363:Quinolones; D012722:Sewage
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D015363:Quinolones; D012722:Sewage
keywords: Activated sludge; Bacteria; Quinolone; Raw sewage; aac(6′)Ib; aac(6′)Ib-cr; qnrS