Pneumonia associada a ventilação mecânica por amostras de pseudomonas aeruginosa resistente aos carbapenêmicos: fatores de risco, prognóstico clínico e caracterização epidemiológica e molecular em uma unidade de terapia intensiva de adultos

Abstract

The prevalence of carbapenem-resistant Pseudomonas aeruginosahas increased over the past decade mainly in developing countrieshospitals. The purpose of this study was to identify epidemiological and molecular characteristics of Ventilator Associated Pneumonia (VAP)due to carbapenem-resistant vscarbapenem susceptible Pseudomonas aeruginosa isolates from one intensive care unit,Hospital de Clínicas, Universidade Federal deUberlândia, Minas Gerais from March 2011 to November 2012. The carbapenem resistant was evaluated genotypically and phenotypically, as well as an analysis of the clonal isolates (PFGE). In total sixty VAP episodes/patients were included, most resistant to carbapenems 32 (53.4%). Five (15.6%) episodes concomitantly presented P. aeruginosabacteremia, in which the origin wasthe respiratory tract. Resistant P. aeruginosaVAPs were more likely related with the severity patients than the susceptible strains(age, CPIS, Charlson and more antibiotic prescript), but when analyzed by multiple logistic regression none showed these characteristics as independentfactor associated with patients with PAVs by resistant strains. The phenotypic test was positive for13 (44.8%) samples indicating the presence of metallo-beta-lactamse, unlike what was observed with genotype, showing a low specificity, while one (3.4%) sample was positive only on the genotypic test (blaIMP). Twenty-two isolates were subjected to clonal discrimination by PFGE test showing a polyclonal profile, withpredominance of three clones (A, C, H). Our results highlight the importance of serious nosocomial infections in adult critical unit of the hospital with a predominance of P. aeruginosaasetiological agent of carbapenem resistant strains. Infections were predominantly late and in severe patients, showing a worse prognosis than those caused by susceptible samples, according to univariate statistical analysis. They also suggest that the presence of other mechanisms of resistance such as loss of porin and overexpression of the efflux pump.