G. De Angelis

Cost‐effectiveness of universal MRSA screening on admission to surgery

Policy-makers have recommended universal screening to reduce nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infection. Risk profiling of MRSA carriers and rapid PCR tests are now available, yet cost-effectiveness data are limited. The present study assessed the cost-effectiveness of universal PCR screening on admission to surgery. A decision analysis model from the hospital perspective compared costs and the probability of any MRSA infection across three strategies: (i) PCR screening; (ii) screening for risk factors (prior hospitalization or antibiotic use) combined with pre-emptive isolation and contact precautions pending chromogenic agar results; and (iii) no screening. Clinical data were taken from studies at a Swiss teaching hospital as well as from published literature. Costs were derived from hospital accounting systems. Compared to no screening, the PCR strategy resulted in higher costs (CHF 10503 vs. 10358) but a lower infection probability (0.0041 vs. 0.0088), producing a base-case incremental cost-effectiveness ratio of CHF 30784 per MRSA infection avoided. The risk factor strategy was more costly yet less effective than PCR, although, after varying epidemiologic inputs, the costs and effects of both screening strategies were similar. Sensitivity analyses suggested that on-admission prevalence of MRSA carriage predicts cost-effectiveness, alongside the probability of cross-transmission, and the costs of MRSA infection, screening and contact precautions. Although reducing the risk of MRSA infection, universal PCR screening is not strongly cost-effective at our centre. However, local epidemiology plays a critical role. Settings with a higher prevalence of MRSA colonization may find universal screening cost-effective and, in some cases, cost-saving.

Multistate modelling to estimate the excess length of stay associated with meticillin-resistant Staphylococcus aureus colonisation and infection in surgical patients

Currently available evidence on the excess length of stay (LOS) associated with nosocomial infections is limited by methodology, including time-dependent bias. To determine the excess LOS associated with nosocomial meticillin-resistant Staphylococcus aureus (MRSA) infection and colonisation, 797 MRSA-colonised, 167 MRSA-infected and 13,640 MRSA-negative surgical patients were included in a multistate model. The occurrence of MRSA infection or colonisation was the time-dependent exposure, and discharge or death was the study endpoint. The excess LOS was extracted by computing the Aalen-Johansen estimator of the matrix of transition probabilities. Multivariate Cox regression analysis was used to assess the independent effect of MRSA on excess LOS. MRSA infection prolonged LOS by 14.5 [95% confidence interval (CI): 7.8, 21.3] days compared to uninfected patients, and by 5.9 (95% CI: 0.1, 11.7) days compared to patients only colonised by MRSA. The hazard of discharge was reduced by nosocomial MRSA infection both with respect to MRSA-free patients and MRSA carriers [adjusted hazard ratio (HR): 0.69; 95% CI: 0.59, 0.81; and HR: 0.79; 95% CI: 0.65, 0.95, respectively]. MRSA carriage alone did not decrease the hazard of discharge after adjustment for confounding (HR: 1.00; 95% CI: 0.93, 1.07). Multistate modelling is a promising statistical method to evaluate the health-economic impact of nosocomial antibiotic-resistant infections.

Burden of meticillin-resistant Staphylococcus aureus infections at a Swiss University hospital: excess length of stay and costs

BACKGROUND Meticillin-resistant Staphylococcus aureus (MRSA) infections increase hospital costs primarily by prolonging patient length of stay (LOS). AIM To estimate the health-economic burden of MRSA infections at a Swiss University hospital using different analytical approaches. METHODS Excess LOS was estimated by: (i) multistate modelling comparing MRSA-infected and MRSA-free patients with MRSA infection as time-dependent exposure; (ii) matching MRSA-infected patients with a cohort of MRSA-uninfected patients. The economic impact was assessed by: (i) comparing cost estimates between MRSA-infected and MRSA-free patients and multiplying excess LOS by bed-day cost; (ii) comparing real costs between MRSA-infected and MRSA-colonized non-infected patients. FINDINGS The crude mean LOS was 37.3, 33.0 and 8.8 days for MRSA-infected, MRSA-colonized and MRSA-free patients, respectively. Excess LOS attributable to MRSA infection was 11.5 [95% confidence interval (CI): 7.9-15] or 15.3 days according to multistate modelling and matched analysis, respectively. The likelihood of discharge after MRSA infection was significantly reduced (adjusted hazard ratio: 0.69; 95% CI: 0.59-0.81). Average bed-day costs for MRSA-infected patients were 1.49- and 1.26-fold higher than for the general population hospitalized in acute wards and MRSA-colonized patients, respectively. MRSA infection resulted in an average additional cost of about 800 Swiss francs per day. CONCLUSIONS This analysis emphasizes the financial impact of MRSA infections, demonstrates the importance of accounting for time-dependent bias and confirms that multistate modelling is a valid strategy for estimating excess LOS and costs after MRSA infection.

Optimized Use of the MALDI BioTyper System and the FilmArray BCID Panel for Direct Identification of Microbial Pathogens from Positive Blood Cultures.

ABSTRACT Despite the current reliance on blood cultures (BCs), the diagnosis of bloodstream infections (BSIs) can be sped up using new technologies performed directly on positive BC bottles. Two methods (the MALDI BioTyper system and FilmArray blood culture identification [BCID] panel) are potentially applicable. In this study, we performed a large-scale clinical evaluation (1,585 microorganisms from 1,394 BSI episodes) on the combined use of the MALDI BioTyper and FilmArray BCID panel compared to a reference (culture-based) method. As a result, the causative organisms of 97.7% (1,362/1,394) of the BSIs were correctly identified by our MALDI BioTyper and FilmArray BCID-based algorithm. Specifically, 65 (5.3%) out of 1,223 monomicrobial BCs that provided incorrect or invalid identifications with the MALDI BioTyper were accurately detected by the FilmArray BCID panel; additionally, 153 (89.5%) out of 171 polymicrobial BCs achieved complete identification with the FilmArray BCID panel. Conversely, full use of the MALDI BioTyper would have resulted in the identification of only 1 causative organism in 97/171 (56.7%) of the polymicrobial cultures. By applying our diagnostic algorithm, the median time to identification was shortened (19.5 h versus 41.7 h with the reference method; P < 0.001), and the minimized use of the FilmArray BCID panel led to a significant cost savings. Twenty-six out of 31 microorganisms that could not be identified were species/genera not designed to be detected with the FilmArray BCID panel, indicating that subculture was not dispensable for a few of our BSI episodes. In summary, the fast and effective testing of BC bottles is realistically adoptable in the clinical microbiology laboratory workflow, although the usefulness of this testing for the management of BSIs remains to be established.

Implementing strategic bundles for infection prevention and management

Healthcare-associated infections (HAI) are considered to be the most frequent adverse event in healthcare delivery. Active efforts to curb HAI have increased across Europe thanks to the growing emphasis on patient safety and quality of care. Recently, there has been dramatic success in improving the quality of patient care by focusing on the implementation of a group or “bundle” of evidenced-based preventive practices to achieve a better outcome than when implemented individually. The project entitled IMPLEMENT is designed to spread and test knowledge on how to implement strategic bundles for infection prevention and management in a diverse sample of European hospitals. The general goal of this project is to provide evidence on how to decrease the incidence of HAI and to improve antibiotic use under routine conditions.

The Control of MRSA

The control of methicillin-resistant Staphylococcus aureus (MRSA) has been largely debated and it is still a controversial issue in many hospitals worldwide. In 2008, the European Antimicrobial Resistance Surveillance System (EARSS) reported an increased incidence of MRSA bacteraemia compared to 2007 (4.8 versus 3.5 per 100,000 patient-days), despite a decreasing trend in MRSA proportion across several European countries. Control measures used to reduce the prevalence of hospital-acquired infections due to MRSA include implementation of hand hygiene, active surveillance cultures, screening at hospital admission and discharge, pre-emptive and contact isolation, cohorting, decolonisation, and antibiotic stewardship. Implementation of hand hygiene has been proven as one of the most effective strategy in the control of MRSA, while the role of screening is still controversial. Recent data showed that decolonisation with mupirocin nasal ointment and chlorhexidine soap before surgical procedures reduces the incidence of S. aureus infections, including surgical site infections. Regardless the lack of robust evidence clearly in favour of a specific control measure, at the moment, the best program to control MRSA spreading in hospital and community has to include a multifaceted approach, involving infectious diseases physicians, microbiologists, pharmacists and public health officers.