Meticillin-resistant Staphylococcus Aureus Prevalence Research Articles

Cost-effectiveness of national mandatory screening of all admissions to English National Health Service hospitals for meticillin-resistant Staphylococcus aureus: a mathematical modelling study

In December, 2010, National Health Service (NHS) England introduced national mandatory screening of all admissions for meticillin-resistant Staphylococcus aureus (MRSA). We aimed to assess the effectiveness and cost-effectiveness of this policy, from a regional or national health-care decision makers' perspective, compared with alternative screening strategies. We used an individual-based dynamic transmission model parameterised with national MRSA audit data to assess the effectiveness and cost-effectiveness of admission screening of patients in English NHS hospitals compared with five alternative strategies (including no screening, checklist-activated screening, and high-risk specialty-based screening), accompanied by patient isolation and decolonisation, over a 5 year time horizon. We evaluated strategies for different NHS hospital types (acute, teaching, and specialist), MRSA prevalence, and transmission potentials using probabilistic sensitivity analyses. Compared with no screening, mean cost per quality-adjusted life-year (QALY) of screening all admissions was £89,000-148,000 (range £68,000-222,000), and this strategy was consistently more costly and less effective than alternatives for all hospital types. At a £30,000/QALY willingness-to-pay threshold and current prevalence, only the no-screening strategy was cost effective. The next best strategies were, in acute and teaching hospitals, targeting of high-risk specialty admissions (30-40% chance of cost-effectiveness; mean incremental cost-effectiveness ratios [ICERs] £45,200 [range £35,300-61,400] and £48,000/QALY [£34,600-74,800], respectively) and, in specialist hospitals, screening these patients plus risk-factor-based screening of low-risk specialties (a roughly 20% chance of cost-effectiveness; mean ICER £62,600/QALY [£48,000-89,400]). As prevalence and transmission increased, targeting of high-risk specialties became the optimum strategy at the NHS willingness-to-pay threshold (£30,000/QALY). Switching from screening all admissions to only high-risk specialty admissions resulted in a mean reduction in total costs per year (not considering uncertainty) of £2·7 million per acute hospital, £2·9 million per teaching, and £474,000 per specialist hospital for a minimum rise in infections (about one infection per year per hospital). Our results show that screening all admissions for MRSA is unlikely to be cost effective in England at the current NHS willingness-to-pay threshold, and our findings informed modified guidance to NHS England in 2014. Screening admissions to high-risk specialties is likely to represent better resource use in terms of cost per QALY gained. UK Department of Health.

Effects of national antibiotic stewardship and infection control strategies on hospital-associated and community-associated meticillin-resistant Staphylococcus aureus infections across a region of Scotland: a non-linear time-series study

Restriction of antibiotic consumption to below predefined total use thresholds might remove the selection pressure that maintains antimicrobial resistance within populations. We assessed the effect of national antibiotic stewardship and infection prevention and control programmes on prevalence density of meticillin-resistant Staphylococcus aureus (MRSA) infections across a region of Scotland. This non-linear time-series analysis and quasi-experimental study explored ecological determinants of MRSA epidemiology among 1,289,929 hospital admissions and 455,508 adults registered in primary care in northeast Scotland. Interventions included antibiotic stewardship to restrict use of so-called 4C (cephalosporins, co-amoxiclav, clindamycin, and fluoroquinolones) and macrolide antibiotics; a hand hygiene campaign; hospital environment inspections; and MRSA admission screening. Total effects were defined as the difference between scenarios with intervention (observed) and without intervention (predicted from time-series models). The primary outcomes were prevalence density of MRSA infections per 1000 occupied bed days (OBDs) in hospitals or per 10,000 inhabitants per day (IDs) in the community. During antibiotic stewardship, use of 4C and macrolide antibiotics fell by 47% (mean decrease 224 defined daily doses [DDDs] per 1000 OBDs, 95% CI 154-305, p=0·008) in hospitals and 27% (mean decrease 2·52 DDDs per 1000 IDs, 0·65-4·55, p=0·031) in the community. Hospital prevalence densities of MRSA were inversely related to intensified infection prevention and control, but positively associated with MRSA rates in neighbouring hospitals, importation pressures, bed occupancy, and use of fluoroquinolones, co-amoxiclav, and third-generation cephalosporins, or macrolide antibiotics that exceeded hospital-specific thresholds. Community prevalence density was predicted by hospital MRSA rates and above-threshold use of macrolides, fluoroquinolones, and clindamycin. MRSA prevalence density decreased during antibiotic stewardship by 54% (mean reduction 0·60 per 1000 OBDs, 0·01-1·18, p=0·049) in hospital and 37% (mean reduction 0·017 per 10,000 IDs, 0·004-0·029, p=0·012) in the community. Combined with infection prevention and control measures, MRSA prevalence density was reduced by 50% (absolute difference 0·94 cases per 1000 OBDs, 0·27-1·62, p=0·006) in hospitals and 47% (absolute difference 0·033 cases per 10,000 IDs, 0·018-0·048, p<0·0001) in the community. Alongside infection control measures, removal of key antibiotic selection pressures during a national antibiotic stewardship intervention predicted large and sustained reductions in hospital-associated and community-associated MRSA. NHS Grampian Research & Development Fund.

Current prevalence of multidrug-resistant organisms in long-term care facilities in the Rhine-Main district, Germany, 2013.

Multidrug-resistant organisms (MDRO) and in particular multidrug-resistant Gram-negative organisms (MRGN) are an increasing problem in hospital care. However, data on the current prevalence of MDRO in long-term care facilities (LTCFs) are rare. To assess carriage rates of MDRO in LTCF residents in the German Rhine-Main region, we performed a point prevalence survey in 2013. Swabs from nose, throat and perineum were analysed for meticillin-resistant Staphylococcus aureus (MRSA), perianal swabs were analysed for extended-spectrum beta-lactamase (ESBL)-producing organisms, MRGN and vancomycin-resistant enterococci (VRE). In 26 LTCFs, 690 residents were enrolled for analysis of MRSA colonisation and 455 for analysis of rectal carriage of ESBL/MRGN and VRE. Prevalences for MRSA, ESBL/MRGN and VRE were 6.5%, 17.8%, and 0.4%, respectively. MRSA carriage was significantly associated with MRSA history, the presence of urinary catheters, percutaneous endoscopic gastrostomy tubes and previous antibiotic therapy, whereas ESBL/MRGN carriage was exclusively associated with urinary catheters. In conclusion, this study revealed no increase in MRSA prevalence in LTCFs since 2007. In contrast, the rate of ESBL/MRGN carriage in German LTCFs was remarkably high. In nearly all positive residents, MDRO carriage had not been known before, indicating a lack of screening efforts and/or a lack of information on hospital discharge.

Infection control intervention on meticillin resistant Staphylococcus aureus transmission in residential care homes for the elderly.

The objectives were to evaluate the effectiveness of an infection control bundle in controlling the meticillin resistant Staphylococcus aureus (MRSA) transmission in residential care homes for the elderly (RCHEs) in Hong Kong. This was a two-arm cluster randomised controlled trial. Infection control bundles focused on hand hygiene (HH), environmental hygiene, and modified contact precautions were applied to the intervention arm. Nasal swabs from residents; staff HH compliance and effectiveness; and environmental hygiene were assessed by microbiological sampling or observation at the baseline and quarterly after the intervention. A total of 2776 residents from 36 RCHEs were recruited. The overall MRSA prevalence was 20.4% (95% confidence interval, 18.9%-21.9%). The intervention elicited an immediate effect of 2.4% absolute decrease in the prevalence and 3.7% in the intra-facility transmission, though the difference between the two arms was insignificant. Staff HH compliance increased substantially from 5.9% to 45.6% post-intervention (p < 0.001). We initiated the infection control culture into the RCHEs and gained their acceptance. However, this behavioural change takes time to emerge. Our study shows that relying on the bundle alone could not bring sustainable MRSA reduction. Administrative control for strengthening infection control infrastructure is important for continuous compliance and improvement.

Screening and isolation to control meticillin-resistant Staphylococcus aureus: sense, nonsense, and evidence

Screening and isolation to control meticillin-resistant Staphylococcus aureus: sense, nonsense, and evidence

Prevention of meticillin-resistant Staphylococcus aureus bloodstream infections in European hospitals: moving beyond policies

There is evidence that meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia can be reduced with improved infection control and antibiotic stewardship. To survey infection control and antibiotic stewardship practices within European hospitals and to identify initiatives that correlate with reduced MRSA prevalence. Online questionnaires were sent to European hospitals about their surveillance, hand hygiene, intravenous device management, admission screening, isolation, antibiotic prescribing, hospital demographics and MRSA blood culture isolates during 2010. In all, 269 replies were received from hospitals in 29 European countries. Lower MRSA prevalence showed significant association with presence of incidence surveillance, performance of root cause analysis, mandatory training requirements for hand hygiene, accountability measures for persistent non-compliance, and multi-stakeholder teamwork in antibiotic prescribing. Presence of policies on intravenous catheter insertion and management showed no variation between different MRSA prevalence groups. However, low-prevalence hospitals reported more competency assessment programmes in insertion and maintenance of peripheral and central venous catheters. Hospitals from the UK and Ireland reported the highest uptake of infection control and antibiotic stewardship practices that were significantly associated with low MRSA prevalence, whereas Southern European hospitals exhibited the lowest. In multiple regression analysis, isolation of high-risk patients, performance of root cause analysis, obligatory training for nurses in hand hygiene, and undertaking joint ward rounds including microbiologists and infectious disease physicians remained significantly associated with lower MRSA prevalence. Proactive infection control and antibiotic stewardship initiatives that instilled accountability, ownership, teamwork, and validated competence among healthcare workers were associated with improved MRSA outcomes.

Cultural determinants of infection control behaviour: understanding drivers and implementing effective change

Despite dealing with biomedical practices, infection prevention and control (IPC) is essentially a behavioural science. Human behaviour is influenced by various factors, including culture. Hofstede's model of cultural dimensions proposes that national cultures vary along consistent dimensions which can be grouped and scored as specific constructs. Studies have reported that three Hofstede constructs--power distance, uncertainty avoidance, and masculinity--show significant association with several key performance indicators relevant to IPC and antibiotic stewardship. In addition, national meticillin-resistant Staphylococcus aureus (MRSA) levels within Europe correlate well with general quality-of-care indices, including preventive strategies and patient rights. This suggests that IPC may be simply a microcosm of overall quality and safety standards within hospitals and countries. Effective improvement would therefore need to address underlying and embedded core cultural values relevant to patient safety and quality of care. Successful IPC strategies are likely to be those that are compatible with the cultural background where they are implemented. To this end, content analysis of many current IPC improvement tools identifies elements of strong compatibility with cultures that are low in uncertainty avoidance and power distance, and high in individualism and masculinity. However, this cultural combination is largely restricted to Anglo-Saxon countries, where most of the recent improvements in healthcare-associated infection (HCAI) incidence have taken place. There is a paucity of research on IPC behaviour change in different cultural backgrounds, especially countries that score high for power distance and/or uncertainty avoidance. This information is vital to inform IPC campaigns in these countries, which often show high HCAI prevalence.

Infection control strategies for preventing the transmission of meticillin-resistant Staphylococcus aureus (MRSA) in nursing homes for older people

Nursing homes for older people provide an environment likely to promote the acquisition and spread of meticillin-resistant Staphylococcus aureus (MRSA), putting residents at increased risk of colonisation and infection. It is recognised that infection prevention and control strategies are important in preventing and controlling MRSA transmission. To determine the effects of infection prevention and control strategies for preventing the transmission of MRSA in nursing homes for older people. In August 2013, for this third update, we searched the Cochrane Wounds Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), Database of Abstracts of Reviews of Effects (DARE, The Cochrane Library), Ovid MEDLINE, OVID MEDLINE (In-process and Other Non-Indexed Citations), Ovid EMBASE, EBSCO CINAHL, Web of Science and the Health Technology Assessment (HTA) website. Research in progress was sought through Current Clinical Trials, Gateway to Reseach, and HSRProj (Health Services Research Projects in Progress). All randomised and controlled clinical trials, controlled before and after studies and interrupted time series studies of infection prevention and control interventions in nursing homes for older people were eligible for inclusion. Two review authors independently reviewed the results of the searches. Another review author appraised identified papers and undertook data extraction which was checked by a second review author. For this third update only one study was identified, therefore it was not possible to undertake a meta-analysis. A cluster randomised controlled trial in 32 nursing homes evaluated the effect of an infection control education and training programme on MRSA prevalence. The primary outcome was MRSA prevalence in residents and staff, and a change in infection control audit scores which measured adherence to infection control standards. At the end of the 12 month study, there was no change in MRSA prevalence between intervention and control sites, while mean infection control audit scores were significantly higher in the intervention homes compared with control homes. There is a lack of research evaluating the effects on MRSA transmission of infection prevention and control strategies in nursing homes. Rigorous studies should be conducted in nursing homes, involving residents and staff to test interventions that have been specifically designed for this unique environment.

Comparison of strategies to reduce meticillin-resistant Staphylococcus aureus rates in surgical patients: a controlled multicentre intervention trial

ObjectiveTo compare the effect of two strategies (enhanced hand hygiene vs meticillin-resistant Staphylococcus aureus (MRSA) screening and decolonisation) alone and in combination on MRSA rates in surgical wards.DesignProspective, controlled, interventional...

A metapopulation model to assess the capacity of spread of meticillin-resistant Staphylococcus aureus ST398 in humans.

The emergence of the livestock-associated clone of meticillin-resistant Staphylococcus aureus (MRSA) ST398 is a serious public health issue throughout Europe. In The Netherlands a stringent ‘search-and-destroy’ policy has been adopted, keeping low the level of MRSA prevalence. However, reports have recently emerged of transmission events between humans showing no links to livestock, contradicting belief that MRSA ST398 is poorly transmissible in humans. The question regarding the transmissibility of MRSA ST398 in humans therefore remains of great interest. Here, we investigated the capacity of MRSA ST398 to spread into an entirely susceptible human population subject to the effect of a single MRSA-positive commercial pig farm. Using a stochastic, discrete-time metapopulation model, we explored the effect of varying both the probability of persistent carriage and that of acquiring MRSA due to contact with pigs on the transmission dynamics of MRSA ST398 in humans. In particular, we assessed the value and key determinants of the basic reproduction ratio (R 0) for MRSA ST398. Simulations showed that the presence of recurrent exposures with pigs in risky populations allows MRSA ST398 to persist in the metapopulation and transmission events to occur beyond the farming community, even when the probability of persistent carriage is low. We further showed that persistent carriage should occur in less than 10% of the time for MRSA ST398 to conserve epidemiological characteristics similar to what has been previously reported. These results indicate that implementing control policy that only targets human carriers may not be sufficient to control MRSA ST398 in the community if it remains in pigs. We argue that farm-level control measures should be implemented if an eradication programme is to be considered.

Surveillance of multi-drug resistant pathogens in two Romanian university hospitals

Health care associated infections (HC aIs) and bacterial multi-drug resistance (MDR) involve high costs and are difficult to manage in medical systems with limited resources. This study, part of the PNCDII 42121/2008 national research project, proposed the investigation of multidrug-resistant bacteria prevalence, concurrent with costs evaluation in two intensive care units (ICUs) from Timisoara university hospitals: Emergency Clinical County Hospital (ECCH) and Institute of Cardiovascular Diseases (ICD). During January-october 2010, we performed a surveillance focused on the following major exponents: meticillin-resistant Staphylococcus aureus (MRSa), extended spectrum beta-lactamase (ESBL) producing enterobacteria and carbapenem-resistant non-fermentative gram negative bacilli, with duplicates and colonisation germs exclusion. Selected germs identification and phenotyping were performed with the help of automatic VITEK 2 compact system, using VITEK 2 GP/GN identification cards and AST cards for antimicrobial sensitivity tests. We also performed Hodge tests for ESBL producing carbapenem resistant enterobacteria. at ECCH we isolated 534 bacterial strains, with a 35.44% prevalence for MRSa, 37.32% ESBL enterobacteria and 43.94% carbapenem-resistant nonfermenters. From 73 strains isolated from ICD, the MRSa prevalence was 8.00%, 23.33% ESBL enterobacteria and 11.11% carbapenem-resistant non-fermentatives. The average number of antimicrobial treatment days/ MDR infectious episode was 9.11 days in ECCH and 29.57days in ICD, with an average hospitalisation cost of

The longitudinal prevalence of MRSA in care home residents and the effectiveness of improving infection prevention knowledge and practice on colonisation using a stepped wedge study design

ObjectivesTo determine the prevalence and health outcomes of meticillin-resistant Staphylococcus aureus (MRSA) colonisation in elderly care home residents. To measure the effectiveness of improving infection prevention knowledge and practice on...

Cluster randomised controlled trial of an infection control education and training intervention programme focusing on meticillin-resistant Staphylococcus aureus in nursing homes for older people

The aim of this cluster randomised controlled trial was to test the impact of an infection control education and training programme on meticillin-resistant Staphylococcus aureus (MRSA) prevalence in nursing homes. Nursing homes were randomised to intervention (infection control education and training programme; N=16) or control (usual practice continued; N=16). Staff in intervention homes were educated and trained (0, 3 and 6 months) in the principles and implementation of good infection control practice with infection control audits conducted in all sites (0, 3, 6 and 12 months) to assess compliance with good practice. Audit scores were fed back to nursing home managers in intervention homes, together with a written report indicating where practice could be improved. Nasal swabs were taken from all consenting residents and staff at 0, 3, 6 and 12 months. The primary outcome was MRSA prevalence in residents and staff, and the secondary outcome was a change in infection control audit scores. In all, 793 residents and 338 staff were recruited at baseline. MRSA prevalence did not change during the study in residents or staff. The relative risk of a resident being colonised with MRSA in an intervention home compared with a control home at 12 months was 0.99 (95% confidence interval: 0.69, 1.42) after adjustment for clustering. Mean infection control audit scores were significantly higher in the intervention homes (82%) compared with the control homes (64%) at 12 months (P<0.0001). Consideration should be given to other approaches which may help to reduce MRSA in this setting.

Impact of active surveillance on meticillin-resistant Staphylococcus aureus transmission and hospital resource utilisation

The utility of active surveillance cultures (ASCs) for meticillin-resistant Staphylococcus aureus (MRSA) has been a controversial aspect of infection prevention. This prospective cohort study analyses the effect of ASCs for MRSA on hospital-acquired infections in a tertiary care hospital (hospital 1) and a community-based hospital (hospital 2). Both hospitals have high MRSA prevalence and are part of a large healthcare system in southeastern Michigan. Hospital-acquired infections in the intensive care unit (ICU) and in the rest of the hospital were compared before and after the implementation of ASCs in the ICUs. Patients in hospital 1 with evidence of MRSA colonisation from ASCs were placed in contact isolation during their stay in the ICU; patients from hospital 2 remained in contact isolation throughout their hospital stay. Prevalence of MRSA colonisation on admission to the ICU was 23% and 13% in hospitals 1 and 2, respectively. Average incidence of new colonisation during the study period was 1.85 per 1000 patient-days and 3.47 per 1000 patient-days in hospitals 1 and 2, respectively. A decrease in ventilator-associated pneumonia (VAP) occurred in both hospitals, whereas decrease in hospital-wide nosocomial MRSA infection was demonstrated only in hospital 2. We conclude that, in addition to standard infection prevention initiatives, ASC with contact precautions can be effective in reducing the incidence of VAP and nosocomial MRSA infection in healthcare communities with endemic MRSA.

Clinical Application of Real-Time PCR to Screening Critically Ill and Emergency-Care Surgical Patients for Methicillin-Resistant Staphylococcus aureus : a Quantitative Analytical Study

The clinical utility of real-time PCR screening assays for methicillin (methicillin)-resistant Staphylococcus aureus (MRSA) colonization is constrained by the predictive values of their results: as MRSA prevalence falls, the assay's positive predictive value (PPV) drops, and a rising proportion of positive PCR assays will not be confirmed by culture. We provide a quantitative analysis of universal PCR screening of critical care and emergency surgical patients using the BD GeneOhm MRSA PCR system, involving 3,294 assays over six months. A total of 248 PCR assays (7.7%) were positive; however, 88 failed to be confirmed by culture, giving a PPV of 65%. Multivariate analysis was performed to compare PCR-positive culture-positive (P+C+) and PCR-positive culture-negative (P+C-) assays. P+C- results were positively associated with a history of methicillin-sensitive Staphylococcus aureus infection or colonization (odds ratio [OR], 3.15; 95% confidence interval [CI], 1.32 to 7.54) and high PCR thresholds of signal intensity, indicative of a low concentration of target DNA (OR, 1.19 per cycle; 95% CI, 1.11 to 1.26). P+C- results were negatively associated with a history of MRSA infection or colonization (OR, 0.19; 95% CI, 0.09 to 0.42) and male sex (OR, 0.40; 95% CI, 0.20 to 0.81). P+C+ patients were significantly more likely to have subsequent positive MRSA culture assays and microbiological evidence of clinical MRSA infection. The risk of subsequent MRSA infection in P+C- patients was not significantly different from that in case-matched PCR-negative controls. We conclude that, given the low PPV and poor correlation between a PCR-positive assay and the clinical outcome, it would be prudent to await culture confirmation before altering infection control measures on the basis of a positive PCR result.

Cross-border comparison of the admission prevalence and clonal structure of meticillin-resistant Staphylococcus aureus

Since patient exchange between hospitals sharing a common catchment area might favour regional spread of meticillin-resistant Staphylococcus aureus (MRSA), the reliable detection of patients colonised at admission is crucial. Thus, hospitals in the Dutch-German border area EUREGIO MRSA-net aim at synchronising their local MRSA standards in order to prevent unidentified inter-hospital as well as cross-border spread. This assumes enhanced knowledge of MRSA prevalence and risk factors associated with MRSA carriage at admission. We conducted nasal MRSA screening of all inpatients admitted to 39 German hospitals (in the period 1 November to 30 November 2006) and to one Dutch hospital (in the period 1 July to 30 September 2007) in the EUREGIO MRSA-net. A total of 390 MRSA cases were detected among 25,540 patients screened. The admission prevalence was 1.6 MRSA/100 patients (6.5% of all S. aureus) in the German and 0.5 MRSA/100 patients (1.4% of all S. aureus) in the Dutch part of the border region. Overall, the predominating S. aureus protein A gene (spa) sequence types were t003, t032 and t011. One isolate (t044) carried Panton-Valentine leukocidin (PVL) encoding genes. Altogether, 79% and 67% of all MRSA patients in the German and Dutch regions respectively, were identifiable by the classical nosocomial risk factors assessed. In patients lacking all risk factors assessed, spa types t011 and t034 were predominant (P<0.001).

Cost of the meticillin-resistant Staphylococcus aureus search and destroy policy in a Dutch university hospital

Costs related to a search and destroy policy and treatment for Staphylococcus aureus bacteraemia in the University Hospital Maastricht were calculated for the period 2000 and 2004. The financial cost-benefit break-even point of the search and destroy policy was determined by modelling. On average 22,412 patients were admitted per year for an average of 8.7 days. Each year 246 patients were screened for meticillin-resistant Staphylococcus aureus (MRSA) and 74 patients were decolonised and nursed in preventive isolation. The prevalence of MRSA in the University Hospital Maastricht was 0.7%, as calculated from positive blood cultures, and mean length of stay for all patients with S. aureus bloodstream infections was 39.9 days. The annual cost of pro-active searching for MRSA in the University Hospital Maastricht was euro 1,383,200, and euro 2,736,762 for MRSA prevention and treatment of S. aureus bloodstream infections. Simulation of a variety MRSA/meticillin-susceptible S. aureus (MSSA) ratios showed that even if the MRSA prevalence reaches 8%, prevention costs are still lower than the cost of treating S. aureus infections. In conclusion, the total cost of a search and destroy policy is lower than the cost of treating S. aureus bloodstream infections in the University Hospital Maastricht. At an MRSA prevalence of <or=8% the search and destroy policy remains cost-effective. From an economic point of view, the search and destroy policy is the best alternative at maintaining an endemic MRSA level at <1%.

Temporal relationship between prevalence of meticillin-resistant Staphylococcus aureus (MRSA) in one hospital and prevalence of MRSA in the surrounding community: a time-series analysis

We studied the relationship between meticillin-resistant Staphylococcus aureus (MRSA) prevalence in the Aberdeen Royal Infirmary and in the surrounding community (Grampian region: 500 000 inhabitants). We calculated the monthly %MRSA for both hospital and community from January 1996 to February 2002. A dynamic regression model was adjusted to measure any relationship between both series. The monthly %MRSA in the community was strongly related to the monthly %MRSA observed one month before in the hospital (R(2)=90.8%). We found no relationship with antimicrobial community use, although we have previously reported a strong correlation between prior use of antibiotics and incidence of MRSA in the hospital. By using time-series analysis techniques, we demonstrated that variations in MRSA prevalence in the hospital are quickly followed by similar variations in MRSA prevalence in the surrounding community. These results suggest that the reason for the increase in MRSA prevalence in the community was a hospital MRSA outbreak. Screening at patient discharge should be evaluated as a new measure to control spread of MRSA in the community.

Nosocomial and community-acquired meticillin-resistant Staphylococcus aureus infections in hospitalized patients (Spain, 1993–2003)

A series of annual surveys on the prevalence of infections in hospitalized patients in Spain was undertaken from 1993 to 2003 to describe clinical and demographic characteristics, trends and geographical variations in the proportion of meticillin-resistant Staphylococcus aureus (MRSA). A total of 8312 S. aureus infections in patients from 296 acute care hospitals pertaining to 17 regions in Spain were observed during the study period. Overall, 23.8% of these organisms were reported as meticillin resistant. The proportion of MRSA varied widely across regions and during the study period. Patients with nosocomial infections (NIs) had a two-fold higher prevalence of MRSA (31%) than patients with community-acquired infections (CAIs) (14%; P<0.001). Nevertheless, there was an increasing trend in the prevalence of MRSA isolates, both in patients with NI (from 22% to 41%; P<0.001) and with CAI (from 7% to 28%; P<0.001) throughout the 11-year period. Geographical variations over the last three years (2001-2003) show a centripetal gradient, with the lowest MRSA prevalence in south-west Spain and the highest MRSA prevalence in the central regions. Almost five-fold differences in MRSA proportions were seen between regions (range 10.3-54.5%). Compared with bloodstream infections, infections in other sites were more likely to be caused by MRSA (adjusted odds ratios for surgical site, urinary tract, skin and respiratory infections of 1.2, 1.2, 1.5 and 2.1, respectively).