Abstract
Colistin resistant Enterobacteriaceae have emerged in humans, food producing animals and food. The aim of this study was to assess the occurrence of MCR-1 and MCR-2 producers among Enterobacteriaceae isolated from companion animals admitted to the University of Zürich veterinary clinic. A total of 347 isolates (231 from dogs, 116 from cats) were analysed. Thereof, 274 (79%) were from urine and 73 (21%) from surgical sites, abscesses and other sources. All isolates were screened by polymerase chain reaction (PCR) for the presence of the plasmid-mediated colistin resistance genes mcr-1and mcr-2. Phenotypic colistin resistance was screened for by the antibiotic broth microdilution method. None of the isolates tested positive by PCR for the mcr-1 or the mcr-2 gene. Broth microdilution tests revealed MICs of 2mg/L–64 mg/L of colistin for four isolates (two Enterobacter spp., one Klebsiella spp. and one E. coli) from dogs (one from skin exudate, one from a surgical site and two isolates from urine). This study documents the presence of non-transmissible colistin resistance in clinical isolates from dogs and cats and confirms that so far, companion animals in Switzerland do not represent a reservoir for plasmid-mediated colistin resistant Enterobacteriaceae.
Simmen, Sabrina