Epidemic diffusion of KPC carbapenemase-producing Klebsiella pneumoniae in Italy: results of the first countrywide survey, 15 May to 30 June 2011

Carbapenem-resistant Enterobacteriaceae (CRE) are emerging as a public health problem in various settings. In Italy, a rapid and remarkable increase of carbapenem-non-susceptible Klebsiella pneumoniae has been reported since 2010. Here we report on the results of a countrywide cross-sectional survey, carried out from 15 May to 30 June 2011 to investigate the diffusion of CRE in Italy and to characterise the most prevalent resistance mechanisms and their dissemination patterns. CRE were reported from most (23 of 25) participating laboratories, with an overall proportion of 3.5% and 0.3% among consecutive non-duplicate clinical isolates of Enterobacteriaceae from inpatients (n=7,154) and outpatients (n=6,595), respectively. K. pneumoniae was the most frequent species (proportion of carbapenem-non-susceptible isolates: 11.9%), while a minority of CRE of other species were detected. Carbapenemase production was detected in the majority (85%) of CRE. KPC-type enzymes were by far the most common (89.5% of carbapenemase producers), followed by VIM-1 (9.2%) and OXA-48 (1.3%). KPC-producing K. pneumoniae (KPC-KP) were detected in most centres and contributed majorly to the epidemic dissemination of CRE recently observed in our country. Dissemination of KPC-KP was mostly sustained by strains of clonal complex 258 (ST-258 producing KPC-2 or KPC-3, and ST-512 producing KPC-3), while a minority belonged to ST-101.