title: gyrA and gyrB gene mutation in ciprofloxacin-resistant Mycobacterium massiliense clinical isolates from Southern Brazil.
abstract: Fluoroquinolones (FQs) have been increasingly used for effective treatment of infections caused by rapidly growing mycobacteria, and resistance to this drug has been predominantly attributed to gyrA and gyrB mutations. Accordingly, this study investigated a total of 36 Mycobacterium massiliense clinical isolates for their susceptibility to ciprofloxacin and presence of gyrA and gyrB gene mutations. The minimal inhibitory concentration (MIC) values, determined by broth microdilution method, of 35 ciprofloxacin-resistant isolates ranged between 4 and 16 μg/mL and a single susceptible isolate was obtained. A total of 31 of 35 (88.5%) ciprofloxacin-resistant isolates presented an amino acid substitution at codon 90 (Ala-90→Val) and no isolate presented mutation at position Asp-94. Moreover, 4 of 35 (11.4%) ciprofloxacin-resistant and one susceptible isolate had no mutation in Ala-90 and Asp-94. No gyrB mutation was observed in all tested M. massiliense isolates. In conclusion, our results have shown that mutations of gyrA codon 90 are frequent and may constitute an important mechanism of resistance to FQ in M. massiliense.
authors.affiliation: Pós-graduação em Biologia Celular e Molecular, Universidade Federal do Paraná, Curitiba, Paraná, Brazil. fernandamonego@hotmail.com
authors.forename: Fernanda
authors.initials: F
authors.lastname: Monego
authors.forename: Rafael Silva
authors.initials: RS
authors.lastname: Duarte
authors.forename: Alexander Welker
authors.initials: AW
authors.lastname: Biondo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D001938:Brazil; D002939:Ciprofloxacin / Q000494:pharmacology*; D003062:Codon; D027081:DNA Gyrase / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D009161:Mycobacterium / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D009164:Mycobacterium Infections / Q000188:drug therapy / Q000382:microbiology*; D016133:Polymerase Chain Reaction
chemical_list: D000900:Anti-Bacterial Agents; D003062:Codon; D002939:Ciprofloxacin; D027081:DNA Gyrase