Abstract
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.
Highlights
The increasing resistance to carbapenems among Enterobacteriaceae has become a public health problem of major concern [1,2]
In Italy, sporadic cases or outbreaks caused by Carbapenem-resistant Enterobacteriaceae (CRE) of various species and with different resistance mechanisms have been reported since the early 2000s [11,12,13,14,15,16,17,18,19,20,21,22,23,24], but only since 2010 an abrupt and notable increase in the proportion of carbapenem-non-susceptible K. pneumoniae has ben reported by the EARS-NET surveillance system
In this work we report the results of a countrywide cross-sectional survey promoted by the Italian Society of Clinical Microbiologists (AMCLI) and carried out in mid-2011, to investigate the diffusion of CRE in Italy and to characterise the most prevalent resistance mechanisms and their dissemination patterns
Summary
The increasing resistance to carbapenems among Enterobacteriaceae has become a public health problem of major concern [1,2]. At least two mechanisms can be responsible for acquired carbapenem resistance in Enterobacteriaceae: (i) reduced outer membrane permeability by porin loss in combination with the production of an extendedspectrum beta-lactamase (ESBL) or of AmpC-type betalactamase; and (ii) production of beta-lactamases capable of hydrolysing carbapenems (carbapenemases) [2]. While the former mechanism is a result of mutation and has a low overall propensity to disseminate, acquired carbapenemases are encoded by transferable genes that can disseminate among different strains and different species, and carbapenemase production is the leading carbapenem resistance mechanism in Enterobacteriaceae [2,6,7]. In Italy, sporadic cases or outbreaks caused by CRE of various species and with different resistance mechanisms have been reported since the early 2000s [11,12,13,14,15,16,17,18,19,20,21,22,23,24], but only since 2010 an abrupt and notable increase in the proportion of carbapenem-non-susceptible K. pneumoniae has ben reported by the EARS-NET surveillance system
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