Sequence type 101 (ST101) as the predominant carbapenemnon-susceptible Klebsiella pneumoniae clone in an acute generalhospital in Italy

Klebsiella pneumoniae is one of the most common multidrugresistant (MDR) Gram-negative organisms worldwide, responsible for high morbidity and mortality both in hospitals and alternative healthcare settings. Recently, increasing use of carbapenems has promoted the emergence and dissemination of carbapenemnon- susceptible MDR K. pneumoniae strains. In Italy, both metallo--lactamases belonging to the VIM type and, more recently, carbapenemases of the K. pneumoniae carbapenemase (KPC) type have been detected in these strains. Here we provide an update regarding CNSKP spread in the area of Prato, Tuscany, Italy, by describing its unique epidemiological behaviour from 2009 to 2011. All of the CNSKP strains isolated between January 2009 and December 2011 in the General Hospital of Prato (Prato, Italy) were studied. CNSKP accounted for 0.3% and 3.0%, respectively, of all isolates of K. pneumoniae identified in the same hospital in the years 2009 and 2010–2011. Twentyfive isolates with imipenem minimum inhibitory concentrations (MICs) ≥4.0 mg/L were identified from as many patients. These findings indicate that, unlike previously reported by other authors from different regions of Italy, K. pneumoniae producing KPC-2 and belonging to ST101 have been established in the area of Prato, Tuscany, Italy. Moreover, based on MLST, PFGE and resistance gene pattern analysis, we can hypothesise that a combination of selection of multiple clones and clonal expansion of some of them is supporting the circulation of CNSKP in the area under study. This study also confirms the previously reported involvement of multiple clones of K. pneumoniae in the spread of carbapenem resistance in Tuscany, Italy . It is also noteworthy that ST101 is an emerging clone that has been previously identified within outbreak and sporadic K. pneumoniae strains carrying OXA-48 and CTX-M- 15 in some Mediterranean countries such as Spain and Tunisia.