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- Class 1 and Class 2 Integrons and Plasmid-Mediated Antibiotic Resistance in Coliforms Isolated from Ten Rivers in Northern Turkey
- Osman Birol Ozgumus , Cemal Sandalli , Ali Sevim , Elif Celik-Sevim , Nuket Sivri
- J. Microbiol. 2009;47(1):19-27. Published online February 20, 2009
- DOI: https://doi.org/10.1007/s12275-008-0206-z
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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, blaOXA-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.
- Reflection on Kinetic Models to the Chlorine Disinfection for Drinking Water Production
- Yoon-jin Lee , Sang-ho Nam
- J. Microbiol. 2002;40(2):119-124.
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Abstract
- Experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform used as a general indicator organism based on the chlorine residuals as a disinfectant. The water samples were taken from the outlet of a settling basin in a conventional surface water treatment system that is provided with the raw water drawn from the mid-stream of the Han River. The inactivation of total coliform was experimentally analyzed for the dose of disinfectant, contact time, filtration and mixing intensity. The curves obtained from a series of batch processes were shaped with a general tailing-off and biphasic mode of inactivation, i.e. a sharp loss of bacterial viability within 15 min followed by an extended phase. In order to observe the effect of carry-over suspended solids on chlorine consumption and disinfection efficiency, the water samples were filtered, prior to inoculation with coliforms, with membranes of both 2.5 um and 11.0 um pore size, and with a sand filter of 1.0 mm in effective size and of 1.4 in uniformity coefficient. As far as the disinfection efficiency is concerned, there were no significant differences. The parameters estimated by the models of Chick-Watson, Hom and Selleck from our experimental data obtained within 120 min are: log(N/N_0 )=-0.16CT with n=1, log(N/N_0 )=-0.71C^0.87 T with n=/1 for the Chick-Watson model, log (N/N_0 )=-1.87C^0.47 T^ 0.36 for the Hom model, log (N/N_0 )=-2.13log (1+CT/0.11) for the Selleck model. It is notable that among the models reviewed with regard to the experimental data obtained, the Selleck model appeared to most closely resemble the total coliform survival curve.
- Determination of Enteric Bacteria at Microbiologically Risky Points by Multiplex Polymerase Chain Reaction
- Mahir Gulec , Bilal Bakir , Recai Ogur , Omer Faruk Tekbas
- J. Microbiol. 2002;40(4):327-330.
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Abstract
- The purpose of this research was to test multiplex polymerase chain reaction in investigating the microbiological quality of the risky surfaces in social living places of a military base where over 15 thousand people live together. In 22 samples of 99, there were no bacteria. Only four of the samples contained Shigella, and one of them contained Salmonella, but 77 of the samples contained thermotolerant coliform organisms. There was no statistically significant difference among the microbiological quality of different sites and different equipment surfaces (p>0.05).
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