Screening for fecal carriage of MCR-producingEnterobacteriaceaein healthy humans and primary care patients.
BACKGROUND
The extent of the occurrence of the plasmid-encoded colistin resistance genesmcr-1andmcr-2among humans is currently sparsely studied in Western Europe.


OBJECTIVE
To determine the occurrence of MCR-producingEnterobacteriaceaein fecal samples of healthy humans with high occupational exposure to food and primary care patients in Switzerland.


METHODS
Stool samples from 1091 healthy individuals and fecal swabs from 53 primary care patients were screened for polymyxin-resistantEnterobacteriaceaeusing LB agar containing 4 mg/L colistin. Minimal inhibitory concentrations (MICs) of colistin were determined for non-intrinsic colistin-resistant isolates. Isolates were screened by PCR for the presence ofmcr-1andmcr-2genes.


RESULTS
The fecal carriage rate of colistin resistant (MIC value >2 mg/l)Enterobacteriaceaewas 1.5% for healthy people and 3.8% for primary care patients. Isolates includedHafnia alvei(n= 9),Escherichia coli(n= 3),Enterobacter cloacae(n= 4),Klebsiella pneumoniae(n= 1) andRaoultella ornithinolytica(n= 1). None of the isolates harbored themcr-1ormcr-2genes.


CONCLUSIONS
There is no evidence for the presence of MCR-producers in the fecal flora of healthy people or primary care patients. Therefore, the risk of transfer ofmcrgenes from animals, food or the environment to humans is likely to be low in Switzerland.
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
Katrin
K
Zurfluh
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
Roger
R
Stephan
Division of Infectious Diseases and Hospital Epidemiology, University of Basel, 4031 Basel, Switzerland.
Andreas
A
Widmer
Emerging Antibiotic Resistance, Medical and Molecular Microbiology Unit, Department of Medicine, University of Fribourg, 1700 Fribourg, Switzerland.
Laurent
L
Poirel
Emerging Antibiotic Resistance, Medical and Molecular Microbiology Unit, Department of Medicine, University of Fribourg, 1700 Fribourg, Switzerland.
Patrice
P
Nordmann
Practice for General Medicine, Birchstrasse 2, 8472 Seuzach, Switzerland.
Hans-Jakob
HJ
Nüesch
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
Herbert
H
Hächler
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
Magdalena
0000-0002-3242-9739
M
Nüesch-Inderbinen
Colistin; Fecal carriage; MCR; Population