Ülkemizde Klinik Enterobacteriaceae İzolatlarında Plazmit Aracılı Kolistin Direnç Genlerini (mcr-1 ve mcr-2) Araştıran Çok Merkezli Çalışmaya Ait Sonuçlar

Abstract

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.

Molecular detection of colistin resistance genes (mcr-1, mcr-2 and mcr-3) in nasal/oropharyngeal and anal/cloacal swabs from pigs and poultry

“…We also found a high prevalence of the mcr-2 in both pigs and poultry which is surprising as this gene has only been found in a limited number of other studies 11,12,14,15,17,18,22,27 . This is likely because our PCR for mcr is more sensitive in detecting the resistance gene than the conventional methods relying on bacterial isolation as discussed above.…”

Evaluation of Plasmid Mediated Colistin Resistance in Colistin Resistant Gram-negative Bacilli

“…The mcr-1 gene, which caused plasmid-mediated colistin resistance, was first identified in 2015 in E. coli isolates, and the identification of the mcr-2 gene followed it in 2016 (10,11). The rapid spread of plasmid-mediated resistance mechanisms between species by horizontal gene transfer makes this resistance feature significant clinically and epidemiologi-cally due to the rapid increase in the frequency of colistinresistant isolates and the potential of these isolates to spread and cause epidemics (8,31).…”

“…The sensitivity of bacteria to colistin is related to the amount of phospholipid contained in the cell membrane and the level of divalent cations in the medium (5). Colistin is an antibiotic used as a last option in treating gramnegative bacteria with multi-drug and carbapenem resistance in recent years (8). Increased colistin resistance has been observed due to excessive and inappropriate use.…”

Determination of Colistin Resistance in Gram Negative Bacteria by Modified Broth Disk Elution Method

“…Ülkemizde 2018 yılında karbapenem dirençli Enterobacteriaceae'larda (CRE) yapılan bir çalışmada, referans yöntem olan SMD ile kolistin direncinin %76.19 olduğu ve MDR ve XDR suşları için düzenli bir izleme sistemine gereksinim duyulduğu bildirilmiştir (20) . Ülkemizde 2017 yılında yapılan çok merkezli bir çalışmada, mcr-1 veya mcr-2 gen bölgesi saptanmamış olmasına rağmen, ilk kez 2018 yılında mcr-1 geni taşıyan E. coli suşu izole edilmiş (7,8) ve bu tarihten itibaren kolistin direnci ülkemizde giderek artmıştır. Ülkemizdeki bu yüksek direnç oranı (20) , mcr-1 geninin yayılması ile kolistin direncinin artışını dramatik olarak göstermesi açısından anlamlıdır.…”

“…Plazmit aracılı kolistin direncine yol açan mcr-1 proteini ilk kez 2015 yılında Escherichia coli ve Klebsiella pneumoniae izolatlarında tanımlanmış ve bunu takiben 2016 yılında mcr-2 proteini tanımlanmıştır. Plazmit aracılı direnç mekanizmaları, yatay gen transferi ile hızlı bir şekilde türler arasında yayılım göstermesi ve salgın oluşturma potansiyeli taşımasından dolayı, klinik ve epidemiyolojik açılardan oldukça önemlidir (7) . Ülkemizde ilk kez 2018 yılında mcr-1 geni taşıyan E. coli suşu izole edilmiş (8) ve bu tarihten itibaren kolistin direnci ülkemizde giderek artmıştır.…”