Emergence of Colistin Resistance in Carbapenems Resistant Enterobacteriaceae strains

Abstract

The multidrug resistant organisms are major problem of public health worldwide.

Enterobacteriaceae   is one of the family that is increasing in drug resistance especially to carbapenems, a broad spectrum and high potency antibiotic. Colistin has been used as the last resort for the treatment of carbapenems resistant strains. In the recent years, there are many reports of colistin resistance by gene transfer via the mechanism of plasmid mediated colistin resistance gene,  mcr-1.  This research aimed to study the emergence of colistin resistance and the resistance gene profile in carbapenem resistant Enterobacteriaceae (CRE). During August to December 2019, 80 isolates of CRE (68  Klebsiella  pneumoniae,  8 Escherichia  coli  and 4

Enterobacter cloacae) which were isolated from the clinical microbiology unit, Maharat Nakhon Ratchasima Hospital were studied. The bacteria were identified by using a Vitek 2 compact instrument. Antimicrobial susceptibility testing was performed by disk diffusion method. The minimal inhibitory concentration (MIC) of colistin was done by microbroth dilution method via

Sensititre machine. Six resistance genes (blaNDM,  blaOXA48-like,  blaIMP,  blaKPC,  blaVIM  and mcr-1) were detected by multiplex PCR. The results showed that colistin-resistance  rate was 18.8% (15/80)  whereas the  mcr-1  gene was not found. The detecting resistance gene profile of 15

colistin resistant isolates were blaNDM  9 isolates, blaOXA48-like  5 isolates and one isolate without any resistance gene was detected. Although the mcr-1  gene was not found, it showed that the colistin resistance mechanism does not depend only on this gene and it is still necessary for

further study to avoid the emergence of more colistin resistant in CRE isolates.