Improving interventions to prevent the acquisition of vancomycin-resistant enterococci in hospitals

The emergence and spread of vancomycin-resistant enterococci (VRE) in hospitals has adversely impacted patient management, quality of care, and outcomes of treatment. A widely recommended strategy for minimizing the risk of transmission of VRE is contact precautions (CPs). CPs mainly involve isolation of patients in a single room, and wearing gowns and gloves before entering the room. In Australia, many hospitals use CPs for patients colonised/infected with VRE on current and each subsequent hospital admission on the basis of a “once VRE, always VRE” policy. The recommendations for CPs are based on observational studies conducted primarily during outbreaks, inductive reasoning based on theory, and expert opinion. Thus, the implementation of CPs is highly debated as its value in the endemic setting is unclear, and increasing incidents of adverse patient outcomes are being reported in association with CPs. In the context of evolving epidemiology of VRE from outbreaks to endemicity, and mounting evidence on the adverse impacts of CPs, it is imperative to better understand the predictors of the current problem, reassess the prevention strategies, test the effectiveness of safer alternatives, and guide policy according to the emerging research evidence. Overall, this thesis aims to generate further evidence to improve interventions for prevention of the spread of VRE in hospitals once VRE acquisition is endemic. In order to accomplish the aim, three major research domains were identified. The first research domain included studies to better understand the natural history and risk factors of VRE colonisation. A cross-sectional study among inpatients in a hospital where VRE is endemic showed that exposure to broad-spectrum antibiotics increases the risk of VRE colonisation, whereas proximity to colonised patients was not associated with increased risks. Similarly, in a retrospective cohort study, we found that majority of outpatients clear detectable levels of VRE over the medium term, and no patient had persisting detectable levels of VRE for more than 4 years. The predictors of long-term carriage of VRE were again found to be exposure to antibiotics, and recent inpatient stay in hospital. 9 The second research domain included studies to quantify the adverse impact of CPs on access to care and patient safety outcomes in inpatients. In these retrospective studies, we observed that patients under CPs require longer time to access computed tomography scan services, and that they are at higher risk of medication administration errors and non-pressure injuries. Finally, the third research domain included studies to explore the impact of universal daily bathing with 2% chlorhexidine gluconate (CHG) on incidence of colonisation/infection with VRE and other important hospital-acquired infections. A before-and-after study with the intervention of universal daily bathing with 2% CHG showed that the risk of VRE colonisation during the intervention period was halved compared to the standard care time period, although the result was not statistically significant. However, in the context of other published studies, a systematic review clearly showed that daily bathing with 2% CHG can significantly lower the risk of colonisation by VRE, as well as methicillin resistant Staphylococus aureus. In addition, it significantly reduces the incidence of central line associated blood-stream infections and surgical site infections. In conclusion, the studies in this thesis suggest that broad-spectrum antibiotics are factor associated with VRE colonisation, and that long-term VRE colonisation is uncommon in the absence of recent exposure to antibiotics and hospital admission. CPs are associated with delayed access to care and increases in the risk of preventable adverse outcomes. Universal interventions, such as daily bathing of all patients with CHG is effective in reducing the incidence of VRE colonisation as well as other important hospital acquired infections (HAIs). Thus, implementation of CPs should not be regarded as life-long once colonised with VRE, rather a risk-based assessment should determine the requirement for CPs in each individual patient‟s future hospital admissions. In addition, antibiotic stewardship should be a priority intervention in endemic VRE settings. Finally, horizontal interventions such as daily bathing with CHG should be favoured to control the wider problem of hospital-acquired infections including VRE in endemic situations.