Epidemiologia clássica e molecular de infecções por Acinetobacter baumannii MR e não MR em pacientes internados e ambiente no Hospital de Clínicas da Universidade Federal de Uberlândia

Abstract

The incidence of infections caused by multidrug-resistant A. baumannii producing carbapenemases is increasing worldwide, especially in critically ill patients. The aim of this study was to evaluate the incidence of A. baumannii in patients infected on the HC-UFU and the adult ICU of HC-UFU environment, characterizing the epidemiology, phenotypically and genotypically identifying resistance mechanisms, from August 2009 to October 2010. This study is a longitudinal prospective of the hospital epidemiology database. Additionally, we also made a case-control study, to assess risk factors associated with infection by A.baumannii; the non-MDR isolates were used as the control group. Of ICU patients with infection, in that period, was collected material environment before and after cleaning to verify surface contamination by A. baumannii. The overall hospital mortality was assessed within 30 days after diagnosis of infection with A. baumannii. Samples collected from patients and environment, held the phenotypic and genotypic identification of mechanisms of resistance and clonal relationship among samples. A total of 73 patients with 84 A. baumannii isolates were obtained between August 2009 and October 2010 in this hospital. Of all patients, the majority were males 49 (67.1 %) with mean age of 57.8 years. Among the causes of hospitalization, 49 patients (67.1 %) were clinical, followed by 17 (23.3 %) surgical. The main comorbidities observed were: nephropathy (30.1 %), malignancy (13.7%) and diabetes mellitus (10.9%). Regarding the use of invasive procedures was observed more frequently in the use of mechanical ventilation (61.6 %), central venous catheter (60.3 %), parenteral nutrition (34.2 %) and tracheostomy (34.2 %). The mean length of hospital stay among patients was 49.5. Most patients had prior use of antibiotics (58 %). In the present study, the 30-day mortality rate was 39, 7%. Of 84 A. baumannii isolates, 50 (59%) were MDR, nine (11%) were pan-resistant, and 25 (30% were non-MDR. The factors significantly associated with multidrug resistance included previous surgeries, presence of comorbidity (renal disease), use of more than two devices, parenteral nutrition, and inappropriate antimicrobial therapy. Significant predictors of 30-day mortality in the univariate analysis included pneumonia, diabetes mellitus, renal disease, use of more than two devices, and inappropriate antimicrobial therapy administered within two days of the onset of infection. The factors associated with mortality in patients with MDR A. baumannii infection in this study were: age≥ 60 years, pneumonia, diabetes mellitus, renal disease, use of more than two invasive procedures, and inappropriate antimicrobial therapy. It was possible to perform the detection of resistance genes in 72 samples (84.7%). A total of 55 samples (76%) presented a searched gene, 32 (44%) showed only the gene blaOXA-51 and 23(32%) showed the genes to blaOXA -51 and blaOXA-23. The rate of hospital mortality was 39.7 % among cases of patients with MR A. baumannii infection. The PFGE was performed on 23 random samples, with 15 clinical samples and 8 samples from the environment. Only 5 of these samples were susceptible to imipenem, 3 clinics and 2 of the environment. Thus, we observed the presence of 8 clones (A - H), and showed the temporal/spatial relationship. Although with limitations in this study, we observed a strong correlation between environmental contamination and patient. Additional studies of non-epidemic prevalence are needed to promote a better understanding of the patterns of spread of MDR A. baumannii within our hospital.