Cohorting to prevent acquisition of multidrug-resistant bacteria: An interrupted time series study.

BACKGROUND: Grouping patients who acquired resistant microorganisms within a single area (cohorting) has been used to prevent cross-transmission. We aimed to assess cohorting effectiveness in the absence of an outbreak. METHODS: An interrupted time series study was performed in a general hospital considering patients admitted to wards. In the first year, patients who acquired multidrug-resistant (MDR) bacteria were isolated without physical transfer. In the second year, cohorting was implemented, and patients with mixed MDR bacteria were transferred to individual rooms in a specific isolation unit. Cultures were requested upon clinician orders, and surveillance or routine cultures were not performed. The effect of cohorting on the incidence density of MDR bacteria acquisition was assessed using segmented regression analysis. RESULTS: In the first and second years, 2.0 and 2.8 cases per 1,000 patient-days acquired MDR bacteria. The length of hospitalization and mortality rate were similar between phases. There was a linear increase of the monthly incidence densities of MDR bacteria acquisition in the first year (ß1: 0.11; 95% confidence interval [CI]: -0.02 to 0.24), though without an immediate impact of cohorting (ß2: -1.32; 95% CI: -3.81 to 1.16) or a change in the temporal trend (ß3: 0.04; 95% CI: -0.14 to 0.23) from the first to second phase. CONCLUSION: Cohorting may not reduce the incidence density of MDR bacteria acquisition in the absence of an outbreak.

Effect of ultrasonics on Enterococcus faecalis biofilm in a bovine tooth model.

INTRODUCTION: The purpose of this study was to evaluate in vitro the effect of the ultrasonic irrigation of sodium hypochlorite and EDTA in root canals of bovine teeth infected with Enterococcus faecalis. METHODS: Eighty-four bovine incisors were inoculated with E. faecalis, remaining in culture for 50 days for biofilm formation. The teeth were divided into four groups: the control group, which received no treatment; the ultrasonic + distilled water group; the conventional irrigation with sodium hypochlorite + EDTA group; and the passive ultrasonic irrigation with sodium hypochlorite + EDTA group. Microbiological tests and analysis in scanning electron microscopy (SEM) were performed. RESULTS: In microbiological testing, groups using sodium hypochlorite did not show bacterial growth. There were significant differences between the control group and the ultrasonic + distilled water group and between these groups and groups using sodium hypochlorite. In SEM analysis, at the canal wall area, there was no significant difference between the groups using sodium hypochlorite, but these were different from the others groups. The control group was significantly different from the ultrasonic + distilled water group. At the exposed tubule area, there was no significant difference between the groups. CONCLUSIONS: Passive ultrasonic irrigation can be an aid in cleaning the root canal; however, the main role in bacteria elimination is played by the irrigant.