HONG KONG, Dec. 5 (Xinhua) -- Bacteria carrying the colistin resistance gene mcr-1 were found commonly existing in human and various types of food and environmental samples collected from Hong Kong and the Chinese mainland, according to a report released on Tuesday.
The mcr-1 gene is a new plasmid-encoded colistin resistance mechanism discovered in 2015. Colistin has been a last-resort antibiotic used to treat severe infections caused by carbapenem resistant Enterobacteriaceae (CRE) strains. The prevalence of mcr-1 in ecosystem challenges the role of colistin as the last resort antibiotic to treat infections caused by CRE, according to the Hong Kong Polytechnic University (PolyU).
Determining the origin of mcr-1 is important in assessing the degree of mcr-1 contamination, which can potentially impact the clinical use of colistin.
Chen Sheng, a professor from the Department of Applied Biology and Chemical Technology of PolyU, has recently developed a sensitive and specific method for isolation of mcr-1-bearing bacteria from various sources and investigation of the prevalence of mcr-1 in various sample types.
Using this approach, Chen and his team found that mcr-1 was present in organisms recovered from human, a wide range of food and environment samples.
The nature of distribution of mcr-1-bearing organisms in the test samples suggests that this resistance gene most likely originates from E. coli in the gastrointestinal (GI) tract of animals due to the prolonged usage of colistin in livestock as growth promoters.
Colistin has been effective in treatment of infections caused by CRE. However, since mcr-1-bearing, colistin resistant Enterobacteriaceae strains are extremely common in the ecosystem, the chance by which CRE strains acquire this highly prevalent mobile colistin resistance gene is much higher than we originally thought.
An increasing prevalence of CRE strains which are also colistin resistant would lead to an increased rate of untreatable infections, especially among immune-compromised patients.
Chen's findings highlight a need to develop effective inhibitors of MCR-1 or intervention measures that disrupt the transmission of mcr-1-bearing plasmids in order to preserve the value of colistin as a last-line antibiotic to treat life-threatening bacterial infections.
The study was published in Enrosurveillance, a journal published by the European Center for Disease Prevention and Control.
