[Results of a multicenter study investigating plasmid mediated colistin resistance genes (mcr-1 and mcr-2) in clinical Enterobacteriaceae isolates from Turkey]. / Ülkemizde klinik Enterobacteriaceae izolatlarinda plazmit aracili kolistin direnç genlerini (mcr-1 ve mcr-2) arastiran çok merkezli çalismaya ait sonuçlar.

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.

[Investigation of plasmid mediated AmpC beta-lactamases among Escherichia coli and Klebsiella pneumoniae isolated from blood cultures]. / Escherichia coli ve Klebsiella pneumoniae Kan Kültürü Izolatlarinda Plazmid Aracili AmpC Beta-Laktamaz Varliginin Arastirilmasi

The aim of this study was to investigate the prevalence and types of plasmid-mediated AmpC (pAmpC) beta-lactamase enzymes in Escherichia coli and Klebsiella pneumoniae strains isolated from blood cultures of hospitalized patients in Dokuz Eylul University Hospital between 2007 and 2012. A total of 261 isolates which consisted of 184 E.coli (70.5%) and 77 K.pneumoniae (29.5%) were included in the study. All isolates were resistant to cefotaxime and/or ceftazidime but susceptible to imipenem. Cefoxitin resistance was investigated as an indicator of AmpC type enzymes. A total of 57 (21.8%) isolates which were cefoxitin-resistant (32 E.coli, 25 K.pneumoniae), were screened for pampC genes by a multiplex polymerase chain reaction (PCR) assay. Additionally, 10 of each cefoxitin susceptible isolates per year were chosen randomly and screened by the same PCR assay to detect the presence of ACC enzymes, which can not hydrolyze cefoxitin. Positive PCR results were confirmed by sequence analysis. Plasmid analysis and macrorestriction analysis were performed for pampC-positive isolates. The presence of pAmpC enzymes has been shown in 9.4% (3/32) of cefoxitin-resistant E.coli, and 8% (2/25) of cefoxitin-resistant K.pneumoniae strains. It was noted that there were no strains producing this enzyme isolated in 2007 and 2008, however the prevalence of pAmpC was detected as 1.6% in 2009 (one ACT-1 producing K.pneumoniae), increasing to 4.8% in 2011 (one ACT-1 producing K.pneumoniae) and 6.4% in 2012 (three CMY-2 producing E.coli). These enzymes were found to be carried on 81 kb size plasmids in K.pneumoniae isolates and on a 9 kb size plasmid in E.coli isolates. Macrorestriction analysis indicated that two of the three CMY-2 producing E.coli had the same PFGE (Pulsed-field gel electrophoresis) pattern. If these two strains are considered as identical, it can be concluded that the prevalence of pAmpC was low in the strains isolated between 2007-2012 (4/261; 1.5%) in our institution. On the other hand, the increasing prevalence of pAmpC in 2011 and 2012 should be considered as a warning for the implementation of infection control measures and monitorization of the prevalence in order to prevent the dissemination of pAmpC. As far as the current literature is concerned, this is the first study that demonstrated the presence of the ACT-1 enzyme in K.pneumoniae isolates in Turkey.

The first report on the outbreak of OXA-24/40-like carbapenemase-producing Acinetobacter baumannii in Turkey.

Carbapenem resistance due to OXA-type carbapenemases seriously limits therapeutic options in nosocomial infections caused by Acinetobacter baumannii. Previous studies have shown the presence of OXA-51, OXA-58, and OXA-23 carbapenemases but not OXA-24/40 in A. baumannii in Turkey. In this study, we investigated carbapenem-hydrolyzing class D ß-lactamases (CHDLs) in A. baumannii and the molecular epidemiology of CHDL producers at the Dokuz Eylul Hospital, Izmir Turkey, and detected blaOXA-24/40 in a clinical isolate from a patient in the medical intensive care unit (ICU). The specific enzyme type was OXA-72. Additional studies revealed 22 more isolates from 20 patients and that the OXA-72-producing strain caused an outbreak in the medical ICU from September 2012 to March 2013, which still continues. To our knowledge, this is the first report of OXA-24/40 carbapenemases in A. baumannii in Turkey. Emergency infection control should be implemented following the arrival of a new OXA at a hospital where A. baumannii is highly endemic.