Caracterização fenótipica e molecular de enterobactérias isoladas em um hospital público de Dourados-MS

Abstract

Infections caused by carbapenemases-producing enterobacteria are a serious public health problem, due to its high potential of spreading and multidrug resistance, leading to limitation of therapeutic options. Thus, the aim of this study was to evaluate the profile of antimicrobial susceptibility and molecular characterization of Enterobacteriaceae strains resistant to carbapenems, which were isolated from patients in a public hospital in Dourados-MS during June 2013 to November 2014. The identification of bacterial species was performed using the automated system Vitek®2 (BioMérieux). The profile of susceptibility to carbapenems (imipenem, meropenem and ertapenem) was evaluated by microdilution test with Mueller Hinton broth to determine the Minimum Inhibitory Concentration (MIC). The resistant strains were subjected to the Modified Hodge Test (MHT) for screening of carbapenemases production. The technique of Polymerase Chain Reaction (PCR) was performed to identify the presence of genes encoding carbapenemases (blaKPC-2, blaOXA-48, blaVIM-1, blaIMP-1 and blaNDM-1). It were isolated 66 strains of Enterobacteriaceae (Klebsiella pneumoniae (n = 56; 85%) and Serratia marcescens (n= 10; 15%). With the analysis of clinical data, it was possible to identify that 59% of the strains were isolated from rectal swab, and 54.5% of these patients were admitted to the Adult Intensive Care Units. Most of the strains were from male patients (64%) and aged 66-85 years (36%). In the MIC determination, 86.5% were resistant to imipenem, 80.5% to ertapenem, and 79% to meropenem. In the MHT, 8 strains of S. marcescens (80%) and 42 strains of K. pneumoniae (75%) were classified as carbapenemases producers. The PCR demonstrated that blaKPC-2 gene was present in all strains of S. marcescens and 35 strains (62.5%) of K. pneumoniae. The presence of the other genes of this study was not found. With these results it is possible identify a large number of strains of S. marcescens and K. pneumoniae producing KPC (Klebsiella pneumoniae carbapenemase) in this hospital. Therefore, the development of control measures is extremely important to hospital infection reduction.