Methicillin-resistant Staphylococcus Aureus Control Measures Research Articles

The dynamic fomite transmission of Methicillin-resistant Staphylococcus aureus in hospitals and the possible improved intervention methods

Hospital-acquired Methicillin-resistant Staphylococcus aureus (MRSA) is a significant health concern worldwide. Surface cleaning and antimicrobial surfaces could be potentially important MRSA control measures in concert with hand hygiene, and more explorations are required on how to implement them efficiently. We developed a Markov chain model to simulate the dynamic transmission of MRSA among fomites in a general medical ward, and acquired the temporal and spatial patterns of MRSA distributions. In addition, we conducted network analyses to better understand the contact relationship between patients’ hands and environmental surfaces. Furthermore, we investigated the effectiveness of applying different levels of the two interventions to seven types of surfaces, and utilized the MRSA distribution patterns and network analyses to account for the findings. Frequent surface cleaning and antimicrobial surfaces had larger impacts on MRSA exposures when applied to surfaces around the index and the adjacent patients and to public surfaces in the ward than when applied to surfaces around other susceptible patients in the ward. This study provides evidence for the effectiveness of the two intervention methods in reducing MRSA exposure, and contributes to the development of appropriate control measures for MRSA in hospitals.

Reduction in the rate of methicillin-resistant Staphylococcus aureus acquisition in surgical wards by rapid screening for colonization: a prospective, cross-over study

AbstractIdentification of patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) and subsequent isolation and decolonization is pivotal to the control of cross infection in hospitals. The aim of this study was to establish if early identification of colonized patients using rapid methods alone reduces transmission. A prospective, cluster, two-period cross-over design was used. Seven surgical wards at a large hospital were allocated to two groups, and for the first 8 months four wards used rapid MRSA screening and three wards used a standard culture method. The groups were reversed for the second 8 months. Regardless of the method of detection, all patients were screened for nasal carriage on admission and then every 4 days. MRSA control measures remained constant. Results were analysed using a log linear Poisson regression model. A total of 12 682/13 952 patient ward episodes (PWE) were included in the study. Admission screening identified 453 (3.6%) MRSA-positive patient ward episodes, with a further 268 (2.2%) acquiring MRSA. After adjusting for other variables, rapid screening was shown to statistically reduce MRSA acquisition, with patients being 1.49 times (p 0.007) more likely to acquire MRSA in wards where they were screened using the culture method. Screening of surgical patients using rapid testing resulted in a statistically significant reduction in MRSA acquisition. This result was achieved in a routine surgical service with high bed occupancy and low availability of isolation rooms, making it applicable to the majority of health-care systems worldwide.

Methicillin-resistantStaphylococcus aureus(MRSA) in food production animals

Until recently, reports on methicillin-resistant Staphylococcus aureus (MRSA) in food production animals were mainly limited to occasional detections in dairy cattle mastitis. However, since 2005 a MRSA clone, CC398, has been reported colonizing pigs, veal calves and broiler chickens and infecting dairy cows. Many aspects of its prevalence in pigs remain unclear. In other livestock, colonizing capacity and reservoir status still require elucidation. MRSA CC398 has also been detected in meat, but, as for other MRSA, the risk this poses is somewhat unclear. Currently, the most worrying aspect of MRSA CC398 appears to be its capacity to spread to humans. This might complicate MRSA control measures in human healthcare, urging research into risk factors and transmission routes. Although infections with MRSA CC398 are much less reported than carriage, more investigation into its pathogenic potential is required. Moreover, the origin and evolution of this clone remain unknown.

Effect of delayed infection control measures on a hospital outbreak of methicillin-resistant Staphylococcus aureus

All patients positive for methicillin-resistant Staphylococcus aureus (MRSA) at the University Hospitals of Geneva, Switzerland, between 1989 and 1997 (N = 1771) were included in a cohort study to evaluate the consequences of delayed containment of a hospital-wide outbreak occurring during a 4-year absence of MRSA control measures. The effects of efforts to control both the MRSA reservoir and the number of bacteraemic patients were assessed. Intensive infection control measures were initiated in 1993 and included patient screening, on-site surveillance, contact isolation, a computerized alert system, and hospital-wide promotion of hand hygiene. An increase in the rate of new MRSA-infected or -colonized patients was observed between 1989 and 1994 (from 0.05 to 0.60 cases per 100 admissions), which subsequently decreased to 0.24 cases in 1997 (P<0.001). However, the proportion of laboratory-documented methicillin-resistant isolates among all S. aureus showed little variation in the years from 1993 onwards (range, 19–24%), reflecting the result of an increase in the number of screening cultures. The annual number of patients with MRSA bacteraemia strongly correlated with the hospital-wide prevalence of MRSA patients (R2= 0.60;P = 0.01) and the rate of new MRSA patients (R2= 0.97;P<0.001). Consequently, the attack rate of nosocomial MRSA bacteraemia served as an excellent marker for the MRSA patient reservoir. In conclusion, despite delayed implementation, infection control measures had a substantial impact on both the reservoir of MRSA patients and the attack rate of MRSA bacteraemia.

Methicillin-Resistant Staphylococcus aureus Epidemiology and Control in Belgian Hospitals, 1991 to 1995

Objectives: To describe the Belgian methicillin-resis-tant Staphylococcus aureus (MRSA) surveillance network, the evolution of methods used in Belgian hospitals for MRSA detection and control, and MRSA incidence from 1994 to1995.Design, Setting, and Participants: Questionnaire surveys; infection control physicians from acute-care hospitals in Belgium.Intervention: Publication of national guidelines for MRSA control in 1993.Results: The participation rate in surveys ranged from 42% to 57% of hospitals. In 1995, 88% of participants detected MRSA strains by disk diffusion tests, with little improvement in standardization since 1991. More centers employed the oxacillin agar screen method (27%), automated systems (29%), or a combination of methods (29%) than in 1991 (P&lt;.005). Between 1991 and 1995, the proportion of hospitals reporting MRSA control measures increased from 68% to 95% (P&lt;.01). Practices that were used increasingly included patient placement in private room (from 50% to 93%, P&lt;.01) and hand decontamination with antiseptic (from 43% to 87%, P&lt;.01). The proportion of centers that reported screening MRSA carriers and treating them topically increased two- and threefold, respectively (P&lt;.05). Surveillance data from 1994 to 1995 showed that MRSA represented a mean of 21.3% of S aureus clinical isolates (range, 1.6% to 62.4%). The median incidence of nosocomial MRSA acquisition was 2.8 per 1,000 admissions, with a wide range (0 to 13.7 per 1,000 admissions) across hospitals of all sizes. The median incidence decreased over the first three semesters of surveillance in hospitals with continuous participation.Conclusion: MRSA detection and control measures have improved in Belgian hospitals after publication of national guidelines. However, MRSA incidence rates show the persistence of nosocomial transmission, with large variations between centers. The national MRSA surveillance network should indicate whether control efforts eventually will curb the problem.

Methicillin-ResistantStaphylococcus aureusEpidemiology and Control in Belgian Hospitals, 1991 to 1995

AbstractObjectives:To describe the Belgian methicillin-resis-tantStaphylococcus aureus(MRSA) surveillance network, the evolution of methods used in Belgian hospitals for MRSA detection and control, and MRSA incidence from 1994 to1995.Design, Setting, and Participants:Questionnaire surveys; infection control physicians from acute-care hospitals in Belgium.Intervention:Publication of national guidelines for MRSA control in 1993.Results:The participation rate in surveys ranged from 42% to 57% of hospitals. In 1995, 88% of participants detected MRSA strains by disk diffusion tests, with little improvement in standardization since 1991. More centers employed the oxacillin agar screen method (27%), automated systems (29%), or a combination of methods (29%) than in 1991 (P&lt;.005). Between 1991 and 1995, the proportion of hospitals reporting MRSA control measures increased from 68% to 95% (P&lt;.01). Practices that were used increasingly included patient placement in private room (from 50% to 93%,P&lt;.01) and hand decontamination with antiseptic (from 43% to 87%,P&lt;.01). The proportion of centers that reported screening MRSA carriers and treating them topically increased two- and threefold, respectively (P&lt;.05). Surveillance data from 1994 to 1995 showed that MRSA represented a mean of 21.3% ofS aureusclinical isolates (range, 1.6% to 62.4%). The median incidence of nosocomial MRSA acquisition was 2.8 per 1,000 admissions, with a wide range (0 to 13.7 per 1,000 admissions) across hospitals of all sizes. The median incidence decreased over the first three semesters of surveillance in hospitals with continuous participation.Conclusion:MRSA detection and control measures have improved in Belgian hospitals after publication of national guidelines. However, MRSA incidence rates show the persistence of nosocomial transmission, with large variations between centers. The national MRSA surveillance network should indicate whether control efforts eventually will curb the problem.

Methicillin-resistant Staphylococcus aureus epidemiology and control in Belgian hospitals, 1991 to 1995. Groupement pour le Dépistage, l'Etude et la Prévention des Infections Hospitalières.

To describe the Belgian methicillin-resistant Staphylococcus aureus (MRSA) surveillance network, the evolution of methods used in Belgian hospitals for MRSA detection and control, and MRSA incidence from 1994 to 1995. Questionnaire surveys; infection control physicians from acute-care hospitals in Belgium. Publication of national guidelines for MRSA control in 1993. The participation rate in surveys ranged from 42% to 57% of hospitals. In 1995, 88% of participants detected MRSA strains by disk diffusion tests, with little improvement in standardization since 1991. More centers employed the oxacillin agar screen method (27%), automated systems (29%), or a combination of methods (29%) than in 1991 (P < .005). Between 1991 and 1995, the proportion of hospitals reporting MRSA control measures increased from 68% to 95% (P < .01). Practices that were used increasingly included patient placement in private room (from 50% to 93%, P < .01) and hand decontamination with antiseptic (from 43% to 87%, P < .01). The proportion of centers that reported screening MRSA carriers and treating them topically increased two- and threefold, respectively (P < .05). Surveillance data from 1994 to 1995 showed that MRSA represented a mean of 21.3% of S aureus clinical isolates (range, 1.6% to 62.4%). The median incidence of nosocomial MRSA acquisition was 2.8 per 1,000 admissions, with a wide range (0 to 13.7 per 1,000 admissions) across hospitals of all sizes. The median incidence decreased over the first three semesters of surveillance in hospitals with continuous participation. MRSA detection and control measures have improved in Belgian hospitals after publication of national guidelines. However, MRSA incidence rates show the persistence of nosocomial transmission, with large variations between centers. The national MRSA surveillance network should indicate whether control efforts eventually will curb the problem.

Control of methicillin-resistant Staphylococcus aureus bacteraemia in high-risk areas.

In a 3,000-bed tertiary care hospital, 88 cases of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia were identified from 22,383 blood cultures (0.39%) submitted to the microbiology laboratory over a one-year period. Two high-risk areas were identified: the paediatric oncology unit, in which 12 cases of MRSA bacteraemia were identified from 924 blood cultures (1.3%), and the intensive care unit (ICU), in which 14 cases of MRSA bacteraemia were identified from 1,391 blood cultures (1.0%). In a one-year targeted intervention programme in which staff and patients were screened for MRSA carriage, patient carriers isolated, and mupirocin and chlorhexidine treatment administered, the number of MRSA bacteraemia cases decreased in these areas to 0 and 4, respectively (p = 0.000123 and 0.016), while the incidence of MRSA bacteraemia in non-targeted areas increased from 62 of 20,068 blood cultures (0.3%) to 82 of 18,784 blood cultures (0.44%) (p = 0.047). In the year post intervention the incidence of MRSA bacteraemia increased to 3 of 815 cultures (0.37%) in the paediatric oncology unit, 10 of 1,934 cultures (0.5%) in the ICU, and 112 of 18,977 cultures (0.59%) in the rest of the hospital (p = 0.00004 versus preintervention period). This study demonstrates the efficacy of targeted MRSA control measures in a hospital in which MRSA is endemic.

A descriptive survey of uncontrolled methicillin-resistant Staphylococcus aureus in a twin site general hospital.

Over a five year period beginning in 1981, during which control measures were applied intermittently, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) isolates increased steadily within a twin site general hospital. A retrospective chart review of 154 patients identified in 1984-1985 showed that the MRSA 'definitely' contributed to three deaths (2%) and 'probably' contributed to a further 15 (10%). The prolonged median duration of hospital admission (22 days) before first isolation of MRSA, together with the clustering of cases in time on certain wards, suggested that most, if not all, affected patients acquired the MRSA in hospital. As the virulence of MRSA in our outbreak appeared the same as that reported from teaching hospitals, MRSA control measures need to be comprehensively applied in general hospitals.