Investigation of colistin resistance gene mcr in gut bacteria from patients with acute diarrheal

Abstract

Objective: To investigate the presence of colistin resistance gene mcr in gut bacteria from patients with acute diarrhea. Methods: Fresh stool samples were collected from 150 outpatients with acute diarrhea in the intestinal clinic of Henan Provincial People's Hospital, and were directly detected for the presence of mcr by PCR after enrichment in the broth.The mcr-producing bacteria were further isolated and identified by MALDI-TOF MS (Bruker Biotyper). Antimicrobial susceptibility of these isolates was conducted by micro-broth dilution method.The presence of other antimicrobial genes were investigated by PCR and sequencing. Results: Among the 150 cases of acute diarrhea, 4 patients(2.7%) were positive for mcr-1 gene, and only 1(0.7%) contained both mcr-1 and mcr-3.Four isolates of Escherichia coli and one isolate of Aeromonas veronii were obtained from the mcr positive cases.The presence of mcr-1 gene was found in all of the E. coli isolates, and the mcr-3 gene was identified in A. veronii. Conclusions: Our study demonstrated the relatively low prevalence of colistin resistant gene in the faeces of acute diarrhea outpatients, and mcr-1 is the dominant colistin resistant gene.The presence of mcr-3 gene was also found in the clinical sample, and it indicats the coexistence of mcr-1 and mcr-3 in the intestinal tract of diarrhea patient.We should pay attention to the potential transmission of these resistance genes and further investigations are urgently needed.