title: Class 1 and class 2 integrons and plasmid-mediated antibiotic resistance in coliforms isolated from ten rivers in northern Turkey.
abstract: We aimed to determine the molecular mechanisms of antibiotic resistance in coliforms isolated from ten rivers in northern region of Turkey. A total of 183 isolates were tested for antimicrobial susceptibility by disk diffusion and agar dilution methods. Resistance to ampicillin, streptomycin, trimethoprim, tetracycline, and chloramphenicol was detected in 58%, 51.9%, 24%, 28.4%, and 12.5%, respectively. Twelve (6.5%) phylogenetically distant organisms were detected to harbor self-transmissible plasmids ranging 52 to >147 kb in sizes. Resistances to ampicillin, tetracycline, trimethoprim, streptomycin, and nalidixic acid were commonly transferable traits. Transferable nalidixic acid-resistant strains harbored qnrS gene, which was the first report of plasmid-mediated quinolone resistance in bacteria of environmental origin in Turkey. Fourteen and five coliforms harbored class 1 and class 2 integrons, respectively, and some of them were located on transferable plasmids. Sequence analyses of variable regions of the class 1 and 2 integrons harbored various gene cassettes, dfrA1, dfr2d, dfrA7, dfrA16, dfrA17, aadA1, aadA5, bla(oxA-30), and sat1. A gene cassette array, dfrA16 has been demonstrated for the first time in a Citrobacter koseri isolate. Class 1 and class 2-bearing strains were clustered in different groups by BOX-PCR fingerprinting. Rivers in the northern Turkey may act as receptacle for the multi-drug resistant enterobacteria and can serve as reservoirs of the antimicrobial resistance determinants in the environment. The actual risk to public health is the transfer of resistance genes from the environmental bacteria to human pathogens.
authors.affiliation: Microbiology and Molecular Biology Research Laboratory, Department of Biology, Faculty of Arts and Sciences, Rize University, 53100 Rize, Turkey. microbsman@yahoo.com
authors.forename: Osman Birol
authors.initials: OB
authors.lastname: Ozgumus
authors.forename: Cemal
authors.initials: C
authors.lastname: Sandalli
authors.forename: Ali
authors.initials: A
authors.lastname: Sevim
authors.forename: Elif
authors.initials: E
authors.lastname: Celik-Sevim
authors.forename: Nuket
authors.initials: N
authors.lastname: Sivri
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D003227:Conjugation, Genetic; D016172:DNA Fingerprinting; D004269:DNA, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D014644:Genetic Variation; D006801:Humans; D032023:Integrons / Q000502:physiology; D009268:Nalidixic Acid / Q000494:pharmacology; D010957:Plasmids / Q000502:physiology; D011634:Public Health; D045483:Rivers; D013307:Streptomycin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D014421:Turkey; D014871:Water Microbiology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D009268:Nalidixic Acid; D000667:Ampicillin; D014295:Trimethoprim; D013752:Tetracycline; D013307:Streptomycin