Abstract
Antimicrobial resistance associated with colistin has emerged as a significant concern worldwide threatening the use of one of the most important antimicrobials for treating human disease.Here, we examined a collection (n = 980) of Avian Pathogenic Escherichia coli (APEC) isolated from poultry with colibacillosis from the US and internationally for the presence of mcr-1 and mcr-2, genes known to encode colistin resistance. Included in the analysis was an additional set of avian fecal E. coli (AFEC) (n = 220) isolates from healthy birds for comparative analysis. The mcr-1 gene was detected in a total of 12 isolates recovered from diseased production birds from China and Egypt. No mcr genes were detected in the healthy fecal isolates. The full mcr-1 gene from positive isolates was sequenced using specifically designed primers and were compared with sequences currently described in NCBI. mcr-1 positive isolates were also assessed for phenotypic colistin resistance and extended spectrum beta lactam phenotypes and genotypes. This study has identified mcr-1 in APEC isolates dating back to at least 2010 and suggests that animal husbandry practices could result in a potential source of resistance to the human food chain in countries where application of colistin in animal health is practiced.
Highlights
The emergence of mcr-1 and mcr-2 genes associated with colistin resistance in Enterobacteriaceae has gained international attention in light of its potential as a human health threat because of the ability of these organisms to resist one of mankind’s last drugs of resort—colistin
Perhaps the biggest concern with regards to the rapid recognition of the emergence of mcr-1 is the association between mcr and other resistance elements such as extended spectrum beta-lactam (ESBL) antimicrobial agents [1, 8, 19, 20], the carbapenemases [21, 22] and heavy metals such as copper [23] and more recently linked with New Delhi Metallo β-Lactamase (NDM) [24]
The mcr-1 gene was detected in 12 isolates from 980 isolates of Avian Pathogenic Escherichia coli (APEC) examined in this study (1.22% prevalence)
Summary
The emergence of mcr-1 and mcr-2 genes associated with colistin resistance in Enterobacteriaceae has gained international attention in light of its potential as a human health threat because of the ability of these organisms to resist one of mankind’s last drugs of resort—colistin. Reports from the USA have identified mcr-1 in human isolates of E. coli from a patient with a urinary tract infection [1] and another that was associated with a clinical case [2]; in addition isolates have been found associated with swine [3, 4]. An explosion of reports has emerged in light of the first report of the detection of mcr-1 associated resistance in isolates of E. coli from animals and humans in China [5]. Worldwide reports have identified of mcr-1 in a range of Enterobacteriaceae from human and animal hosts including Escherichia coli, Salmonella, Klebsiella and other Gram negative organisms [7,8,9,10,11,12,13,14]. Perhaps the biggest concern with regards to the rapid recognition of the emergence of mcr-1 is the association between mcr and other resistance elements such as extended spectrum beta-lactam (ESBL) antimicrobial agents [1, 8, 19, 20], the carbapenemases [21, 22] and heavy metals such as copper [23] and more recently linked with New Delhi Metallo β-Lactamase (NDM) [24]
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