[Molecular characterization of an outbreak of carbapenem-resistant Klebsiella pneumoniae in a tertiary care hospital in Medellín, Colombia].

INTRODUCTION: Resistance to carbapenems is considered to represent a serious threat to public health at the global level, since these antibiotics are one of the last therapeutic options for the treatment of multidrug-resistant bacteria. Molecular characterization of outbreaks due to resistant bacteria provides information that can be used in the design of infection control strategies.

OBJECTIVE: To describe the molecular characteristics of an outbreak of carbapenem-resistant Klebsiella pneumoniae that occurred in a tertiary care hospital in Medellín in 2010-2011.

MATERIALS AND METHODS: Eighty-four isolates were obtained from a collection of strains associated with the hospital outbreak, of which 32 were from patients infected at that time and 52 were carriers. Identification and susceptibility of the isolates was performed using Vitek2®. Carbapenemases were detected using a modified Hodge test and polymerase chain reaction. Genetic relationships between the isolates were evaluated using pulsed field gel electrophoresis and multiple locus sequence typing.

RESULTS: All the isolates analyzed were multidrug resistant; molecular analysis revealed that all harbored bla KPC-3 . The genetic analysis showed that 58/64 of the isolates from both infected and colonized patients were closely related (Dice similarity index >80%) and belonged to the ST258 lineage.

CONCLUSION: Using molecular typing techniques it was possible to confirm the occurrence of an outbreak caused by K. pneumoniae ST258, a carrier of bla KPC-3 with a multidrug-resistant profile which had been associated with a previous outbreak in another hospital in the city of Medellín. ST258 is a high risk clone at the global level, demonstrating the potential for dissemination of resistance in this country. Implementation of molecular tools in support of epidemiological surveillance is useful for evaluating the spread of microorganisms of public health significance.