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Rapid detection and quantification of plasmid-mediated colistin resistance genes (mcr-1 to mcr-5) by real-time PCR in
R Tolosi1, I Apostolakos1, A Laconi1
1Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro, Italy.
Aim:
The aim of the study was to validate a rapid method to detect and quantify colistin resistance genes (mcr-1 to mcr-5) by real-time polymerase chain reaction (RT-PCR) in diverse matrices.
Methods And Results:
The detection limit of two newly designed SYBR Green real-time PCR assays for mcr-4 and mcr-5 and of previously published protocols for mcr-1 to mcr-3 was assessed using serial dilutions of reference strains. The assays could detect all five mcr genes with the lower limit of 102 copy numbers. Escherichia coli isolates (n = 1062) and environmental samples (n = 93) were tested for the presence of mcr genes. The assays enabled the detection of colistin resistance genes both in bacterial isolates and in complex environmental samples.
Conclusions:
This method represents a set of sensitive, rapid and effective assays for the screening of colistin resistance directly from the environment.
Significance And Impact Of The Study:
Colistin is an antimicrobial commonly used in animals and has recently emerged as a last-resort treatment in humans. Plasmid-mediated mcr genes confer resistance to colistin and represent a major threat for public health since they can be easily disseminated through horizontal gene transfer. The rapid and sensitive detection of mcr genes is of utmost necessity.
