No evidence so far for the dissemination of carbapenemase-producing Enterobactericeae in the community in Switzerland

BACKGROUND: Carbapenemase-producing Enterobacteriaceae represent an increasing threat to public health and to the treatment of serious nosocomial infections. The aim of this study was to screen for the presence of carbapenemase-producing Enterobacteriaceae in human carriers in community settings in Switzerland, a country representative of central Europe. FINDINGS: Three hundred and fourteen stool samples of healthy staff members of a meat-processing company and 291 fecal swabs from primary care patients were recovered in Switzerland between April 2012 and July 2012 and were tested for carbapenemase-producing Enterobacteriaceae isolates by selecting for growth on a carbapenem-containing selective medium. Six resulting isolates (5 Escherichia coli and 1 Citrobacter youngae) were subjected to antimicrobial susceptibility tests and PCR analysis by screening for the carbapenemase genes bla(OXA-48), bla(VIM), bla(NDM-1), and bla(KPC) as well as for the extended-spectrum ß-lactamase genes bla(TEM,)bla(SHV), bla(CTX-M) and bla(CMY-2). No carbapenemase genes were detected. Resistance to ß-lactam antibiotics was due to carriage of the extended-spectrum ß-lactamase CTX-M-15 in 4 isolates, to CTX-M-14 in one further isolate and to the plasmidic AmpC-ß-lactamase CMY-2 in one isolate. CONCLUSIONS: These results show that carbapenemase-producing Enterobacteriaceae are as yet not present in the community. Continuous surveillance is necessary to anticipate future trends in the prevalence and dissemination of carbapenem resistant isolates in the population.