Frequência de β-lactamases dos grupos tem, shv, ctx-m e kpc produzidas por enterobactérias isoladas no estado do Rio Grande do Norte

Abstract

Bacterial resistance is a growing public health problem worldwide and dissemination of antimicrobial resistance genes comprises a recurring concern. Faced with this alarming situation, the Enterobacteriaceae family figure as one of the protagonists in our country not only by the frequency with which their representatives are isolated, but also by the evolution regarding antimicrobial resistance, mainly when directed to β-lactams by the enzymatic production of β-lactamases extended spectrum (ESBLs and carbapenemases). For the patient´s control and treatment, local data are critical, and thinking on this, it was decided to conduct an unpublished study in the state of Rio Grande do Norte, whose main object was to evaluate the occurrence of β- lactamases extended spectrum (ESBL) and the type KPC carbapenemase in Enterobacteriaceae obtained from clinical samples derived from three centers of excellence in healthcare. Two hundred enterobacteria derived from various biological sites were collected during the period between April 2012 and August 2013 and submitted to biochemical tests for species identifcation, laboratory confirmatory phenotypic analyzes (Jarilier´s disk approximation technique and modified Hodge test) and molecular identification for resistance genes blaTEM , blaSHV , blaCTX-M and blaKPC . From these enterobacteria, 73 (36.5 %) were confirmed as ESBL-producing, over half of which belonged to the species Klebsiella pneumoniae and Escherichia coli. Other less common species such as Enteroboacter cloacae, Enterobacter aerogenes, Citrobacter freundii, Providencia stuartti also expressed the same phenotype. Molecular analysis by PCR indicated that 87.5 % of 73 isolates confirmed phenotypically as ESBL harbored the blaCTX-M gene, 43 % amplified the blaSHV gene, 37.5% the blaTEM gene. As the production of carbapenemase , 7 ( 9.5% ) were positive for Modified Hodge test (MHT) , all belonging to the species Klebsiella pneumoniae , but only 5 of them confirmed the presence of blaKPC gene. Over 50 % of multiresistant enterobacteria blaESBL harbored the genes associated form. Twenty- six species of Escherichia coli (8) and Klebsiella pneumoniae (18) positive for blaCTX-M (more prevalent ) gene were analyzed for similarity using the Pulsed Field Gel Electrophoresis (PFGE ) technique and isolates with Dice coefficient greater than or equal to 80 % were considered clonal . Five PFGE profiles were found from chromosomal DNA of E.coli strains and twelve PFGE profiles were found from K.pneumoniae strains. It is expected that these results could be extended and used as a reference at a state level, preventing dispersion of this resistance and also serving as an additional national data to build a more reliable profile in respect to the epidemiology of this resistance mechanism.