Performance of different culture methods and of a commercial molecular assay for the detection of carbapenemase-producing Enterobacteriaceae in nursing homes and rehabilitation centers

Over the last several years, carbapenemase-producing Enterobacteriaceae (CPE) have been increasingly detected not only among patients in acute care hospitals, but also in long-term care facilities. In this point prevalence survey, residents from three nursing homes and patients in one rehabilitation center were screened for asymptomatic intestinal carriage of CPE by rectal swabs. The first objective was to evaluate the hypothesis of the establishment of a CPE reservoir in a geriatric/chronic care population. Secondly, we evaluated the comparative performances of different culture methods (chromID® CARBA, chromID® OXA-48, MacConkey with temocillin/meropenem, ertapenem enrichment broth) and a commercial molecular assay (Check-Direct CPE). From the 257 included residents, only one had evidence for CPE carriage. From the rectal swabs of this resident, an OXA-48-producing Klebsiella pneumoniae could be isolated and was confirmed by a molecular assay both on the strain and on the rectal swab. The specificity of the different culture methods and Check-Direct CPE was at least 97 %. Neither enrichment broth nor prolonged incubation up to 48 h increased the yield of CPE. This point prevalence survey shows a low CPE prevalence of 0.39 %. Larger scaled studies are needed in order to confirm the role of chronic care settings as secondary CPE reservoirs and to adjust the infection control and prevention recommendations.