Resumo

Reports of nosocomial infection due to carbapenem-resistant Serratia spp. have become significantly more common. This resistance may be due to production of distinct carbapenemases, such as IMP, VIM, SME, and more recently, KPC. This enzyme, initially described in Klebsiella pneumoniae isolates, has also been detected among other organisms, such as Pseudomonas aeruginosa, Escherichia coli, Proteus spp., Acinetobacter baumanii and Serratia marcescens, emphasizing the global risk of interspecies spread of resistance genes. This work describes the first report of carbapenem-hydrolysing enzyme KPC in S. marcecens isolates in Recife, Brazil. The samples were collected between February-May/2010 from patients attended at a hospital and identified by classical bacteriological methods. Susceptibility assays were determined by disc-diffusion Müeller Hinton agar, according to CLSI (2010). Plasmid DNA was obtained by Kieser method. Carbapenemase production was investigated by modified Hodge test. Identification of the presence of bla_KPC gene was determined by specific PCR. Clonal relatedness of the isolates was evaluated by ERIC-PCR of total DNA and by PFGE of the genomic DNA digested with SpeI. Twelve clinical isolates were identified as Serratia marcescens. Results of susceptibility reveled that the isolates were resistant to imipenem (58%), ceftazidime (85%), aztreonam (92%), amikacin (92%); ciprofloxacin (42%) and sulfamethoxazole/trimetoprim (67%). Preliminary plasmid analysis showed that all the isolates shared one plasmid in common (approximately 7.8Kb). All the strains were positive for class A carbapenemase production and for presence of bla_KPC. Partial PFGE and ERIC-PCR results and the plasmid profiles suggested that the isolates belong to a unique clone, which was probably disseminated in the hospital. Further analysis will be carried out in order to characterize the plasmids and other determinants of resistance, as well.