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    Investigation of the Frequency and Distribution of Beta-Lactamase Genes in the Clinical Isolates of Acinetobacter baumannii Collected From Different Regions of Turkey: A Multicenter Study
    (Ankara Microbiology Soc, 2016) Beris, Fatih Saban; Budak, Emine Esra; Gulek, Duygu; Uzun, Aytul; Cizmeci, Zeynep; Mengeloglu, Firat Zafer; Direkel, Sahin
    The diversity and distribution of TEM, SHV and CTX-M type of extended-spectrum beta-lactamases (ESBLs) are important for the treatment and control of infections. Determination of ESBL genes in clinical isolates by polymerase chain reaction (PCR) and DNA sequencing can obtain useful data for their molecular epidemiology and risk. The aim of this study was to investigate the frequency of beta-lactamase genes in Acinetobacter baumannii strains isolated from different regions of Turkey. A total of 519 A. baumannii strains collected from hospitals located at 12 different provinces of Turkey (Bolu (n=67), Tokat (n=47), Trabzon (n=25), Ordu (n=27), Diyarbakir (n=47), Nigde (n=31), Kayseri (n=36), Ankara (n=41), Kirikkale (n=26), Kahramanmaras (n=25), Mersin (n=40), Istanbul (n=107)] between 2011-2012 period were included in the study. Identification of the isolates were performed by both conventional methods and automated systems, VITEK2 Compact (BioMerieux, France) and API 32GN (BioMerieux, France). Disc diffusion method was used for the detection of antibiotic susceptibilities of the isolates and the results were evaluated according to CLSI (Clinical and Laboratory Standards Institute) criteria. Tigecycline and colistin sensitivities of the isolates were evaluated according to BSAC (British Society for Antimicrobial Chemotherapy) criteria. The presence of beta-lactamase genes, namely bla(oxa-51), bla(TEM), bla(SHV), bla(CTX-M1), bla(CTX-M2), bla(GES) and bla(VIM) were detected by PCR. In our study, the resistance rates against colistin, tigecycline, ampicillin-sulbactam, amoxicillin-clavulanic acid, cefoperazone/sulbactam, tobramycin, ceftriaxone, piperacillin-tazobactam, gentamicin, ampicillin, tetracycline, cefepime, piperacillin, amikacin, trimethoprim-sulfamethoxazole, meropenem, levofloxacin, ciprofloxacin, imipenem and ceftazidime were detected as; 0.6%, 2.7%, 11.9%, 15.2%, 21%, 22.9%, 23.9%, 48.6%, 59.5%, 61.8%, 66.3%, 67.8%, 69.2%, 71.1%, 77.5%, 78.6%, 81.1%, 82.9%, 87.5% and 89.4%, respectively. All of the isolates (100%) were OXA-51 positive, while 443 (85.4%) out of 519 strains harbored other beta-lactamase genes searched in the study. When the distribution of the genes were evaluated, bla(TEM-1) was found as the predominant one with a frequency rate of 55.7% (n=289/519), followed by bla(CTX-M2) (63/519, 12.1%), bla(CTX-M1) (42/519, 8.1%), bla(SHV) (40/519, 7.7%), bla(GES) (8/519, 1.5%) and bla(VIM) (1/519, 0.2%). Cooccurence of ESBL genes was detected in 16.3% (72/443) of the strains, being mostly TEM+CTX-M2 (20/72, 27.8%), TEM+SHV (11/72, 15.3%) and TEM+CTX-M1 (10/72, 13.9%). In addition, it was noted that the distribution of ESBL genes between isolates showed differences according to the provinces. Accordingly, none of the strains isolated from four provinces (Bolu, Nigde, Mersin, Kahramanmaras) and from three provinces (Bolu, Kahramanmaras, Diyarbakir) harbored bla(CTX-M1/M2) and bla(SHV) genes, respectively. The bla(TEM) gene was detected in isolates collected from all of the provinces, with a highest frequency in Nigde (28/31, 90.3%) and lowest in Trabzon (1/25, 4%). The presence of GES-11 type ESBLs was found only in the isolates sent from Nigde province (8/31; 25.8%). Screening of metallo-beta-lactamase VIM gene also yielded a single positive result amongst only Nigde isolates (1/31; 3.2%), and this gene was identified as VIM-5 type by DNA sequencing. This study which is the first comprehensive national research to characterize ESBLs in A. baumannii isolates by molecular methods, showed that the most prevalent ESBL type is TEM (289/519, 55.7%) amongst A. baumannii strains isolated from different regions of our country. The data of our study is parallel to the results of previous studies carried out from Turkey.
  • [ X ]
    Öğe
    Results of a Multicenter Study Investigating Plasmid Mediated Colistin Resistance Genes (mcr-1 and mcr-2) in Clinical Enterobacteriaceae Isolates from Turkey
    (Ankara Microbiology Soc, 2017) Sari, Ayse Nur; Suzuk, Serap; Karatuna, Onur; Ogunc, Dilara; Karakoc, Ayse Esra; Cizmeci, Zeynep; Aliskan, Hikmet Eda
    Colistin is a polymyxin antibiotic which is considered as one of the last line agents against infections due to multidrug resistant or carbapenem resistant gram-negative pathogens. Colistin resistance is associated with chromosomal alterations which can usually cause mutations in genes coding specific two component regulator systems. The first plasmid-mediated colistin resistance gene, mcr-1 was described in Escherichia coli and Klebsiella pneumoniae isolates in December 2015 and followed by another plasmid-mediated colistin resistance gene mcr-2 in 2016. The rapid and interspecies dissemination of plasmid-mediated resistance mechanisms through horizontal gene transfer, have made these genes considerably threatening. After the first reports, although mcr-1/mcr-2 producing Enterobacteriaceae isolates have been reported from many countries, there have been no reports from Turkey. Thus, the aim of this study was to investigate the presence of mcr-1/mcr-2 in clinical Enterobacteriaceae isolates from different parts of our country. A total of 329 Enterobacteriaceae isolates from 22 laboratories were collected which were isolated between March, 2015 and February, 2016. mcr-1/mcr-2 were investigated by polymerase chain reaction during February-March, 2016. Two hundred and seventeen of Klebsiella pneumoniae (66%), 75 of Salmonella spp. (22.8%), 31 of Esherichia coli (9.4%), 3 of Enterobacter cloacae (0.9%), 2 of Klebsiella oxytoca (0.6%) and 1 of Enterobacter aerogenes (0.3%) isolates were included to the study. Agarose gel electrophoresis results of PCR studies have shown expected band sizes for positive control isolates as 309 bp for mcr-1 and 567 bp for mcr-2. However, the presence of mcr-1/mcr-2 genes was not detected among the tested study isolates of Enterobacteriaceae. Although mcr-1/mcr-2 were not detected in our study isolates, it is highly important to understand the mechanism of resistance dissemination and determine the resistant isolates by considering that colistin is a last-line antibiotic against infections of multidrug or carbapenem resistant gram-negative bacteria. Thus, it is suggested that these mechanisms should be followed-up in both clinical and non-clinical (e.g. isolates from food animals, raw meats and environment) isolates of special populations.