Estimating the Effectiveness of Isolation and Decolonization Measures in Reducing Transmission of Methicillin-resistant Staphylococcus aureus in Hospital General Wards

Abstract

Infection control for hospital pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) often takes the form of a package of interventions, including the use of patient isolation and decolonization treatment. Such interventions, though widely used, have generated controversy because of their significant resource implications and the lack of robust evidence with regard to their effectiveness at reducing transmission. The aim of this study was to estimate the effectiveness of isolation and decolonization measures in reducing MRSA transmission in hospital general wards. Prospectively collected MRSA surveillance data from 10 general wards at Guy's and St. Thomas' hospitals, London, United Kingdom, in 2006–2007 were used, comprising 14,035 patient episodes. Data were analyzed with a Markov chain Monte Carlo algorithm to model transmission dynamics. The combined effect of isolation and decolonization was estimated to reduce transmission by 64% (95% confidence interval: 37, 79). Undetected MRSA-positive patients were estimated to be the source of 75% (95% confidence interval: 67, 86) of total transmission events. Isolation measures combined with decolonization treatment were strongly associated with a reduction in MRSA transmission in hospital general wards. These findings provide support for active methods of MRSA control, but further research is needed to determine the relative importance of isolation and decolonization in preventing transmission.

Meticillin-resistant Staphylococcus aureus (MRSA) acquisition risk in an endemic neonatal intensive care unit with an active surveillance culture and decolonization programme

“…Our results are also consistent with prior mathematical modeling studies in adult patient populations. Worby et al 26 reported that the combination of isolation and decolonization reduced transmission by 64%, with the majority of observed transmission attributed to unisolated and untreated MRSA carriers. Gurieva et al 27 used a stochastic simulation model to assess the impact of decolonization and found that decolonization was highly effective even with imperfect efficacy in eliminating carriage.…”

“…This is further evidenced by the visible decline, but not elimination of MRSA acquisition in the NICU during the study period (Figure 3). This background risk of acquisition, not linked to patient-to-patient transmission, has been well-described using mathematical modeling approaches, 26 and has been shown to account for the majority of MRSA acquisition in adult settings. 28 Similarly, Price et al report that only 18.9% of S. aureus acquisitions in an adult intensive care unit could be explained by patient-to-patient transmission when whole-genome sequencing was used.…”

Point-of-care universal screening for meticillin-resistant Staphylococcus aureus : a cluster-randomized cross-over trial

“…The identification, isolation, and decontamination of patient carriers are associated with reduced MRSA transmission, although the evidence for this is limited and debated 3, 4, 5, 6, 7…”

Tracking Pseudomonas aeruginosa transmissions due to environmental contamination after discharge in ICUs using mathematical models

“…193 We used uninformative exponential priors Exp(0.001) for the transmission parameters 194 α, β, and µ. Parameters for the proposal distribution were tuned in order to ensure 195 rapid convergence. Similar to [26], we estimated the sensitivity φ and importation 196 parameter f using uninformative beta prior distributions Beta (1,1). The initial 197 bacterial load E 0 was approximated by ν µĪ withĪ being the mean prevalence in the 198 ward.…”

“…The results of our analysis build on a data-augmented MCMC algorithm [19,26]. 464 Markov chain Monte Carlo sampling is a powerful tool to estimate posterior parameter 465 distribution whenever the likelihood is analytically intractable.…”