Outbreak of KPC-2-producing Klebsiella pneumoniae in a university hospital, Ribeiro Preto City, Brazil

Abstract number: P1686

Andrade L.N., Clímaco E.C., Ferreira J.C., Martinez R., Darini A.L.C.

Objectives: The main objective of this study was to investigate the resistance mechanism of carbapenem-resistant K. pneumoniae outbreak in a university hospital in the Ribeirão Preto city – Brazil.

Methods: 43 carbapenem-resistant K. pneumoniae were isolated from non-repeated patients in the Intensive Care Unit of "Hospital das Clínicas de Ribeirão Preto (HCRP)", from April of 2007 to June of 2008. Identification and antimicrobial susceptibility profile of the isolates were evaluated with Vitek^®1 System. Genetic profiles of carbapenem-resistant K. pneumoniae were determined by Pulsed Field Gel Electrophoresis (PFGE). Minimum inhibitory concentration (MIC) of imipenem, meropenem and ertapenem were determined using ETest. Modified Hodge test was performed to detect carbapenemase production. PCR and sequencing were used to investigate several carbapenemases encoding genes (blaKPC, blaGES, blaSPM, blaIMP, blaVIM) and their genetic environment. Conjugation experiment was utilised to investigate carabepenem resistance transfer.

Results: The isolates demonstrated susceptibility only to polymyxin B and tigecycline. PFGE revealed the spread of a unique clonal type. Imipenem, meropenem and ertapenem MICs values were, respectively, 8 mg/L, 8 mg/L and 32 mg/L. Modified Hodge test was positive, indicating carbapenemase production. PCR amplification and sequencing identified blaKPC-2 gene, flanked by insertion sequence ISKpn7 and ISKpn6. This genetic environment suggests that blaKPC-2 gene may be mobilised by transposon Tn4401, as published previously. Conjugation experiment demonstrated that blaKPC-2 gene and carabapenem-resistant phenotype was transferred to recipient strain.

Conclusion: An outbreak of KPC-2-producing K. pneumoniae took place in the HCRP. The spread of blaKPC genes was related with a unique clonal type of K. pneumoniae, however, this gene was associated with mobile elements and can be transferred to other bacterial species. The KPC-producing K. pneumoniae can be considered as the "select of select" of multiresistant bacteria and it can become pandrug-resistant in little time.