Prevalence of mcr-1 Gene From Hospital Isolates in Italy


The mcr-1 gene was first identified from E.coli in China during 2016. This plasmid-located gene imparts resistance to colistin, an antibiotic widely misused in China and other Asian nations to both suppress pathogens and stimulate growth.

Colistin is a last-resort drug against multi-drug resistant gram-negative bacteria and is therefore of extreme importance in hospital-acquired infections. Subsequent to the emergence of the mcr-1 gene in China, isolates of E.coli and other enterobacteriaceae carrying the gene were identified from many nations including the E.U.

The extensive study in Italy was conducted on 300 enterobacteriaceae isolated from hospital surfaces. Evaluation revealed that 8.3 percent carried the mcr-1 gene. Genera identified with the mcr-1 gene included Klebsiella, Acinetobacter, Enterobacter, Citrobacter and Pseudomonas. This suggests that the mcr-1 gene is readily transmitted among bacteria in the environment of hospitals.

Studies on E.coli have demonstrated that approximately 10 percent of animal-derived isolates in Germany carried the gene in samples obtained during the period 2010 – 2015. In contrast, only 0.1 to 2 percent of human isolates carried the mcr-1 gene. It was suggested that selective pressure exerted by antiseptics including chlorhexidine may be responsible for emerging drug resistance in gram-negative bacteria. The author stressed the need to examine both environmental as well as clinical samples in assessing resistance among gram-negative bacteria from hospital settings.

Caselli, E. et al “Spread of mcr-1 Driven Colistin Resistance on Hospital Surfaces, Italy” Emerging Infectious Diseases. 24:1752-1753 (2018)