Abstract

NASTRO, Marcela et al. Emergence of colistin-resistant Klebsiella pneumoniae: microbiological and epidemiological characterization of the isolates producing and non-producing KPC-type carbapenemase. Rev. argent. microbiol. [online]. 2013, vol.45, n.3, pp.174-179. ISSN 0325-7541.

Sixty-four colistin-resistant Klebsiella pneumoniae isolates recovered from clinical specimens from 57 patients admitted to Hospital de Clinicas Jose de San Martin during the period 2010-2012 were studied to describe the microbiological and epidemiological characteristics and factors associated with the emergence of colistin-resistance. Fifty-four colistin-susceptible K. pneumoniae isolates from the same period were also included in the study. The genetic relatedness among the isolates was studied by a PCR assay. Fifty percent of the resistant isolates were KPC-2 producers, 45.3% were ESBL producers and 4.7% only showed resistance to aminopenicilins. All KPC-producers (resistant and susceptible to colistin) were genotipically indistinguishable except for one, whereas the presence of 7 clonal types, which were different from the ones identified in the colistin-susceptible isolates, were detected among ESBL producers. The previous use of colistin was the main factor associated with the acquisition of resistance, and in the case of non-KPC producers the stay in ICU was another significant factor observed. Colistin resistance emerged in our hospital in the year 2010, reaching 3% in nosocomial isolates and maintaining this rate in successive years, due to the selection of resistant subpopulations in the epidemic clonal type in KPC-producers and due to the dispersion of colistinresistant clonal types in non-KPC producing-isolates.

Keywords : Colistin resistance; KPC; Klebsiella pneumoniae; Epidemiological factors.

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