Perfil epidemiológico de infecção por enterococos resistentes à vancomicina em hospital universitário com alta prevalência de pacientes colonizados

Abstract

Globally the vancomycin-resistant enterococci (VRE) remains an important cause of infection related to health care. The study aimed to characterize samples of VRE isolated from patients hospitalized during the epidemic and endemic periods, determining the risk of colonized patients developing infection, its relationship with consumption antibiotics and the role of colonization pressure. Additionally, we investigated the presence of virulence determinants in samples recovered from colonization and infection. We conducted longitudinal cohort study of patients colonized and infected by Enterococcus faecium (VREfm) and E. faecalis (VREfc) resistant to vancomycin, by active search for the Microbiology Laboratory of the Clinical Hospital of the Federal University of Uberlândia, during the period of January 2010 to June 2012. The identification and antimicrobial resistance were determined by automated system Vitek®2. A record following the model of NHSN (\"National Healthcare Safety Network\") was completed for each patient, considering clinical, demographic and epidemiological factors. The risk factors were evaluated by univariate analysis and multivariate logistic regression, and Pearson and Spearman tests were used to correlate two variables, the antimicrobial DDD per 1000 patient-days and the number of VRE per 1000 patient-days. Virulence genes asa1, gelE, esp and hyl, and vanA resistance were detected by polymerase chain reaction. Among the 171 patients evaluated, VRE was the most frequent micro-organism (92%). Twenty-two patients (12.9%) developed infection by VRE on average 14 days after colonization with the prevalence of urinary tract infections (72%). Among patients infected most used urinary catheter as the most frequent device (86%). The acquisition rate of VRE was 1.92/1000 patient-days in early August 2010 and the end of January 2011 there were no cases of VREfm, when it was observed the end of the outbreak and the begin of VREfm endemicity in the hospital (0.555 VRE/1000 patient-days). There was a relationship between the temporal and spatial infected patients with evidence of cross-transmission mainly in the Intensive Care Unit for Adults. Only the use of aminoglycosides has been previously considered an independent risk factor for VRE infection (P=0.0013), however, the use of glycopeptides was correlated with the presence of that micro-organism in a hospital (r=0.717, P=0.03). Although the colonization pressure with VRE was high with variations from 0.004 to 1.32% during the 30-month study was not statistically associated with the development of VRE infection. An association was observed between samples with high-level resistance to streptomycin and penicillin and ampicillin resistance in samples VREfm, however, for samples of VREfc, the high level of resistance to gentamicin was more frequently (77%) associated only with penicillin resistance. All samples VREfm carried the vanA gene and were resistant to teicoplanin, expressing high levels of resistance to vancomycin (MIC ≥ 256 μg/ml). The esp gene was the most frequent detected in 82.4% of samples colonization and 76.5% of the clinical samples. We showed high prevalence of VREfm in a tertiary hospital, independently associated with the previous use of aminoglycosides and glycopeptides consumption.