Hospital outbreak caused by Klebsiella pneumoniae producing KPC-2 beta-lactamase resistant to colistin

Abstract

We describe a hospital outbreak caused by colistin-resistant Klebsiella pneumoniae producing KPC-2 beta-lactamase in two distinct medical centres. Seven clinical isolates of K. pneumoniae exhibiting resistance to carbapenems were collected from patients with hospital-acquired infection. All isolates were phenotypically positive for carbapenemase activity but negative for metallo-beta-lactamase production. PCR analysis using specific primers for bla(KPC), bla(SHV), bla(TEM) and bla(CTX-M) demonstrated that all clinical strains of K. pneumoniae from hospital A and one isolate from hospital B were genetically related and carried bla(KPC-2) in addition to bla(SHV-12). In contrast, the remaining isolate carried bla(S)(HV-5) with bla(K)(PC-2) and yielded a different profile. These results indicate the clonal spread of KPC producers between hospitals as well as the acquisition of KPC genes by different K. pneumoniae strains. All isolates were resistant to carbapenems, beta-lactams, ciprofloxacin, aminoglycosides and colistin, but intermediately susceptible to tigecycline and susceptible to gentamicin. The infection was fatal in five cases. The emergence of colistin-resistant K. pneumoniae possessing bla(KPC)(-2) underscores the implementation of strict control measures to prevent their dissemination of these organisms in hospitals.