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      Prevalence of Plasmid-Mediated Quinolone Resistance Genes among Extended-Spectrum β -Lactamase-Producing Klebsiella pneumoniae Human Isolates in Iran

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          Abstract

          The purpose of this study was to determine the prevalence and molecular characterization of plasmid-mediated quinolone resistance (PMQR) genes ( qnrA, qnrB, qnrS, aac(6′)-Ib-cr, and qepA) among ESBL-producing Klebsiella pneumoniae isolates in Kashan, Iran. A total of 185 K. pneumoniae isolates were tested for quinolone resistance and ESBL-producing using the disk diffusion method and double disk synergy (DDST) confirmatory test. ESBL-producing strains were further evaluated for the bla CTX-M genes. The PCR method was used to show presence of plasmid-mediated quinolone resistance genes and the purified PCR products were sequenced. Eighty-seven ESBL-producing strains were identified by DDST confirmatory test and majority (70, 80.5%) of which carried bla CTX-M genes including CTX-M-1 (60%), CTX-M-2 (42.9%), and CTX-M-9 (34.3%). Seventy-seven ESBL-producing K. pneumoniae isolates harbored PMQR genes, which mostly consisted of aac(6′)-Ib-cr (70.1%) and qnrB (46.0%), followed by qnrS (5.7%). Among the 77 PMQR-positive isolates, 27 (35.1%) and 1 (1.3%) carried 2 and 3 different PMQR genes, respectively. However, qnrA and qepA were not found in any isolate. Our results highlight high ESBL occurrence with CTX-M type and high frequency of plasmid-mediated quinolone resistance genes among ESBL-producing K. pneumoniae isolates in Kashan.

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          The worldwide emergence of plasmid-mediated quinolone resistance.

          Fluoroquinolone resistance is emerging in gram-negative pathogens worldwide. The traditional understanding that quinolone resistance is acquired only through mutation and transmitted only vertically does not entirely account for the relative ease with which resistance develops in exquisitely susceptible organisms, or for the very strong association between resistance to quinolones and to other agents. The recent discovery of plasmid-mediated horizontally transferable genes encoding quinolone resistance might shed light on these phenomena. The Qnr proteins, capable of protecting DNA gyrase from quinolones, have homologues in water-dwelling bacteria, and seem to have been in circulation for some time, having achieved global distribution in a variety of plasmid environments and bacterial genera. AAC(6')-Ib-cr, a variant aminoglycoside acetyltransferase capable of modifying ciprofloxacin and reducing its activity, seems to have emerged more recently, but might be even more prevalent than the Qnr proteins. Both mechanisms provide low-level quinolone resistance that facilitates the emergence of higher-level resistance in the presence of quinolones at therapeutic levels. Much remains to be understood about these genes, but their insidious promotion of substantial resistance, their horizontal spread, and their co-selection with other resistance elements indicate that a more cautious approach to quinolone use and a reconsideration of clinical breakpoints are needed.
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            Community terminal restriction fragment length polymorphisms reveal insights into the diversity and dynamics of leaf endophytic bacteria

            Background Plant endophytic bacteria play an important role benefiting plant growth or being pathogenic to plants or organisms that consume those plants. Multiple species of bacteria have been found co-inhabiting plants, both cultivated and wild, with viruses and fungi. For these reasons, a general understanding of plant endophytic microbial communities and their diversity is necessary. A key issue is how the distributions of these bacteria vary with location, with plant species, with individual plants and with plant growing season. Results Five common plant species were collected monthly for four months in the summer of 2010, with replicates from four different sampling sites in the Tallgrass Prairie Preserve in Osage County, Oklahoma, USA. Metagenomic DNA was extracted from ground, washed plant leaf samples, and fragments of the bacterial 16S rDNA genes were amplified for analysis of terminal restriction fragment length polymorphism (T-RFLP). We performed mono-digestion T-RFLP with restriction endonuclease DdeI, to reveal the structures of leaf endophytic bacterial communities, to identify the differences between plant-associated bacterial communities in different plant species or environments, and to explore factors affecting the bacterial distribution. We tested the impacts of three major factors on the leaf endophytic bacterial communities, including host plant species, sampling dates and sampling locations. Conclusions Results indicated that all of the three factors were significantly related (α = 0.05) to the distribution of leaf endophytic bacteria, with host species being the most important, followed by sampling dates and sampling locations.
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              Prevalence and molecular epidemiology of CTX-M extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae in Russian hospitals.

              A total of 904 consecutive nosocomial isolates of Escherichia coli and Klebsiella pneumoniae collected from 28 Russian hospitals were screened for production of extended-spectrum beta-lactamases (ESBLs). The ESBL phenotype was detected in 78 (15.8%) E. coli and 248 (60.8%) K. pneumoniae isolates. One hundred fifteen isolates carried the genes for CTX-M-type beta-lactamases, which, as shown by PCR-restriction fragment length polymorphism analysis, were distributed into the two genetic groups of CTX-M-1 (93%)- and CTX-M-2 (7%)-related enzymes. Isolates producing the enzymes of the first group were found in 20 hospitals from geographically distant regions of the country and were characterized by considerable diversity of genetic types, as was demonstrated by enterobacterial repetitive consensus PCR typing. Within this group the CTX-M-3 and the CTX-M-15 beta-lactamases were identified. In contrast, the enzymes of the CTX-M-2 group (namely, CTX-M-5) were detected only in eight clonally related E. coli isolates from a single hospital. Notably, the levels of resistance to ceftazidime were remarkably variable among the CTX-M producers. This study provides further evidence of the global dissemination of CTX-M type ESBLs and emphasizes the need for their epidemiological monitoring.
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                Author and article information

                Journal
                J Pathog
                J Pathog
                JPATH
                Journal of Pathogens
                Hindawi Publishing Corporation
                2090-3057
                2090-3065
                2015
                4 November 2015
                : 2015
                : 434391
                Affiliations
                1Department of Microbiology and Immunology, School of Medicine, Kashan University of Medical Sciences, P.O. Box 8715988141, Kashan, Iran
                2Department of Parasitology and Mycology, School of Medicine, Alborz University of Medical Sciences, P.O. Box 3149779453, Karaj, Iran
                Author notes
                *Farzaneh Firoozeh: ffiroozeh@ 123456ut.ac.ir

                Academic Editor: Alexander Rodriguez-Palacios

                Article
                10.1155/2015/434391
                4649097
                d188a49d-473b-42e8-9fa4-02913bd426fb
                Copyright © 2015 Ehsaneh Shams et al.

                This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 29 May 2015
                : 6 September 2015
                Categories
                Research Article

                Infectious disease & Microbiology
                Infectious disease & Microbiology

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