The Nottingham Staphylococcus aureus population study: prevalence of MRSA among the elderly in a university hospital

Environmental organisms from different hospital wards

T hree clinical wards in the same hospital, High Dependency (HDU), Care of the Elderly (CE) and Acute Psychiatry (AP), were screened for environmental organisms. The screening programme ran for four weeks and targeted comparable sites from all three units. Floor areas were similar, as were staffing levels, cleaning schedules, infection control policies and patient numbers.

Organisms such as coagulase-negative staphylococci, Bacillus spp., coliforms, oxidase-positive Gram-negative bacilli, Clostridium difficile, enterococci, various fungi and Staphylococcus aureus were isolated. Staphylococci and Gram-negative bacilli were tested against clinically appropriate antibiotics. There was little variation in diversity or density of organisms from any of the wards, except for significant differences in antibiotic susceptibilities of the organisms (P<0.0001 HDU v AP, P=0.0057 CE v AP and P=0.0365 HDU v CE).

From HDU, 49% (of 43) isolates were resistant to four or more antibiotics and from CE, 37% (of 54) isolates were resistant to four or more. From AP, just 2% (of 52) were resistant to four or more antibiotics. 9% HDU organisms were fully susceptible, as compared with 20% of those from CE and 27% from AP.

Antibiotic data (in Defined Daily Doses (g)/100 bed-days) showed that HDU consumed over 12 times more antibiotics than CE, which in turn consumed twice as much as AP; these were mostly intravenous broad-spectrum agents for HDU, as opposed to oral preparations for the other two wards (Chi-square for each ward for linear trends by level of antibiotic intake were all P<0.0001).

It was concluded that the only significant difference between environmental bacteria from wards of varying specialities in this hospital is their resistance to antibiotics. Heavy use of antibiotics in a hospital unit, as demonstrated by antibiotic consumption data, may be associated with increased antibiotic resistance in environmental organisms originating from that unit.

Prior antibacterial drug exposure in dogs with meticillin-resistant Staphylococcus pseudintermedius (MRSP) pyoderma

BACKGROUND

The emergence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) has become a significant animal health problem. Recent studies have indicated that previous antibacterial drug exposure is a factor in acquisition of meticillin-resistant strains of staphylococci.

HYPOTHESIS/OBJECTIVES

The purpose of this study was to identify factors associated with prior antimicrobial drug use and MRSP pyoderma in dogs presented to a veterinary teaching hospital.

ANIMALS

Dogs diagnosed with pyoderma associated with MRSP (n = 53) or meticillin-sensitive S. pseudintermedius (MSSP; n = 45).

METHODS

The medical records of dogs diagnosed with pyoderma associated with isolation of S. pseudintermedius between January 2006 and November 2012 were reviewed. All cases with a complete twelve month to 3 yr drug history prior to the diagnosis were included.

RESULTS

Fifty two of 53 (98%) MRSP cases and 42 of 45 (93%) MSSP cases had received at least one course of antibacterial drug prior to diagnosis. The total number of antibacterial drug prescriptions provided to pet owners and the variety of antibacterial drug classes represented were higher for cases with MRSP than for cases with MSSP (P < 0.0001 and P = 0.009, respectively). More cases with MRSP (98%) received beta-lactam drugs than those with MSSP (82%; P = 0.007) and the proportion of MRSP cases that had received concurrent immunomodulatory therapy was higher (62% versus 42%; P = 0.048).

CONCLUSIONS AND CLINICAL IMPORTANCE

These results suggest that the total number of antibacterial drug prescriptions, exposure to multiple drug classes (beta-lactams in particular) and concurrent immunomodulatory therapy may be associated with increased risk for acquisition of MRSP.

Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases)

BACKGROUND

Superficial bacterial folliculitis (SBF) is usually caused by Staphylococcus pseudintermedius and routinely treated with systemic antimicrobial agents. Infection is a consequence of reduced immunity associated with alterations of the skin barrier and underlying diseases that may be difficult to diagnose and resolve; thus, SBF is frequently recurrent and repeated treatment is necessary. The emergence of multiresistant bacteria, particularly meticillin-resistant S. pseudintermedius (MRSP), has focused attention on the need for optimal management of SBF.

OBJECTIVES

Provision of an internationally available resource guiding practitioners in the diagnosis, treatment and prevention of SBF.

DEVELOPMENT OF THE GUIDELINES

The guidelines were developed by the Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases, with consultation and advice from diplomates of the American and European Colleges of Veterinary Dermatology. They describe optimal methods for the diagnosis and management of SBF, including isolation of the causative organism, antimicrobial susceptibility testing, selection of antimicrobial drugs, therapeutic protocols and advice on infection control. Guidance is given for topical and systemic modalities, including approaches suitable for MRSP. Systemic drugs are classified in three tiers. Tier one drugs are used when diagnosis is clear cut and risk factors for antimicrobial drug resistance are not present. Otherwise, tier two drugs are used and antimicrobial susceptibility tests are mandatory. Tier three includes drugs reserved for highly resistant infections; their use is strongly discouraged and, when necessary, they should be used in consultation with specialists.

CONCLUSIONS AND CLINICAL IMPORTANCE

Optimal management of SBF will improve antimicrobial use and reduce selection of MRSP and other multidrug-resistant bacteria affecting animal and human health.

The prevalence and significance of methicillin-resistant Staphylococcus aureus colonization at admission in the general ICU Setting: a meta-analysis of published studies

OBJECTIVE

To estimate the prevalence and significance of nasal methicillin-resistant Staphylococcus aureus colonization in the ICU and its predictive value for development of methicillin-resistant S. aureus infection.

DATA SOURCES

MEDLINE and EMBASE and reference lists of all eligible articles.

STUDY SELECTION

Studies providing raw data on nasal methicillin-resistant S. aureus colonization at ICU admission, published up to February 2013. Analyses were restricted in the general ICU setting. Medical, surgical, and interdisciplinary ICUs were eligible. ICU studies referring solely on highly specialized ICUs populations and reports on methicillin-resistant S. aureus outbreaks were excluded.

DATA EXTRACTION

Two authors independently assessed study eligibility and extrapolated data in a blinded fashion. The two outcomes of interest were the prevalence estimate of methicillin-resistant S. aureus nasal colonization at admission in the ICU and the sensitivity/specificity of colonization in predicting methicillin-resistant S. aureus-associated infections.

DATA SYNTHESIS

Meta-analysis, using a random-effect model, and meta-regression were performed. Pooled data extracted from 63,740 evaluable ICU patients provided an estimated prevalence of methicillin-resistant S. aureus nasal colonization at admission of 7.0% (95% CI, 5.8-8.3). Prevalence was higher for North American studies (8.9%; 95% CI, 7.1-10.7) and for patients screened using polymerase chain reaction (14.0%; 95% CI, 9.6-19). A significant per year increase in methicillin-resistant S. aureus colonization was also noted. In 17,738 evaluable patients, methicillin-resistant S. aureus infections (4.1%; 95% CI, 2.0-6.8) developed in 589 patients. The relative risk for colonized patients was 8.33 (95% CI, 3.61-19.20). Methicillin-resistant S. aureus nasal carriage had a high specificity (0.96; 95% CI, 0.90-0.98) but low sensitivity (0.32; 95% CI, 0.20-0.48) to predict methicillin-resistant S. aureus-associated infections, with corresponding positive and negative predictive values at 0.25 (95% CI, 0.11-0.39) and 0.97 (95% CI, 0.83-1.00), respectively.

CONCLUSIONS

Among ICU patients, 5.8-8.3% of patients are colonized by methicillin-resistant S. aureus at admission, with a significant upward trend. Methicillin-resistant S. aureus colonization is associated with a more than eight-fold increase in the risk of associated infections during ICU stay, and methicillin-resistant S. aureus infection develops in one fourth of patients who are colonized with methicillin-resistant S. aureus at admission to the ICU.

Targeted versus universal screening and decolonization to reduce healthcare-associated meticillin-resistant Staphylococcus aureus infection

BACKGROUND

The benefits of universal meticillin-resistant Staphylococcus aureus (MRSA) admission screening, compared with screening targeted patient groups and the additional impact of discharge screening, are uncertain.

AIMS

To quantify the impact of MRSA screening plus decolonization treatment on MRSA infection rates. To compare universal with targeted screening policies, and to evaluate the additional impact of screening and decolonization on discharge.

METHODS

A stochastic, individual-based model of MRSA transmission was developed that included patient movements between general medical and intensive care unit (ICU) wards, and between the hospital and community, informed by 18 months of individual patient data from a 900-bed tertiary care hospital. We simulated the impact of universal and targeted [for ICU, acute care of the elderly (ACE) or readmitted patients] MRSA screening and decolonization policies, both on admission and discharge.

FINDINGS

Universal admission screening plus decolonization resulted in 77% (95% confidence interval: 76-78) reduction in MRSA infections over 10 years. Screening only ACE specialty or ICU patients yielded 62% (61-63) and 66% (65-67) reductions, respectively. Targeted policies reduced the number of screens by up to 95% and courses of decolonization by 96%. In addition to screening on admission, screening on discharge had little impact, with a maximum 7% additional reduction in infection.

CONCLUSIONS

Compared with universal screening, targeted screening substantially reduced the amount of screening and decolonization required to achieve only 12% lower reduction in infection. Targeted screening and decolonization could lower the risk of resistance emerging as well as offer a more efficient use of resources.

A genomic portrait of the emergence, evolution, and global spread of a methicillin-resistant Staphylococcus aureus pandemic

The widespread use of antibiotics in association with high-density clinical care has driven the emergence of drug-resistant bacteria that are adapted to thrive in hospitalized patients. Of particular concern are globally disseminated methicillin-resistant Staphylococcus aureus (MRSA) clones that cause outbreaks and epidemics associated with health care. The most rapidly spreading and tenacious health-care-associated clone in Europe currently is EMRSA-15, which was first detected in the UK in the early 1990s and subsequently spread throughout Europe and beyond. Using phylogenomic methods to analyze the genome sequences for 193 S. aureus isolates, we were able to show that the current pandemic population of EMRSA-15 descends from a health-care-associated MRSA epidemic that spread throughout England in the 1980s, which had itself previously emerged from a primarily community-associated methicillin-sensitive population. The emergence of fluoroquinolone resistance in this EMRSA-15 subclone in the English Midlands during the mid-1980s appears to have played a key role in triggering pandemic spread, and occurred shortly after the first clinical trials of this drug. Genome-based coalescence analysis estimated that the population of this subclone over the last 20 yr has grown four times faster than its progenitor. Using comparative genomic analysis we identified the molecular genetic basis of 99.8% of the antimicrobial resistance phenotypes of the isolates, highlighting the potential of pathogen genome sequencing as a diagnostic tool. We document the genetic changes associated with adaptation to the hospital environment and with increasing drug resistance over time, and how MRSA evolution likely has been influenced by country-specific drug use regimens.

Length of exposure to the hospital environment is more important than antibiotic exposure in healthcare associated infections by methicillin-resistant Staphylococcus aureus: a comparative study

OBJECTIVES

Both total antimicrobial use and specific antimicrobials have been implicated as risk factors for healthcare-associated methicillin-resistant Staphylococcus aureus (HCA-MRSA) infection. The aims of this study were: (I) to explore predictors of a new HCA-MRSA infection in comparison with a new healthcare-associated methicillin-sensitive Staphylococcus aureus (HCA-MSSA); (II) to thoroughly assess the role of recent antibiotic use qualitatively and quantitatively.

METHODS

The time-period for our study was from October 1997 through September 2001. Through applying strict criteria, we identified two groups of inpatients, one with a new HCA-MRSA infection and one with a new HCA-MSSA infection. We recorded demographic, clinical and antibiotic use-related data up to 30 days before the positive culture date.

RESULTS

We identified 127 and 70 patients for each group, respectively. Two logistic regression models were carried out to assess the role of antimicrobial use (qualitatively and quantitatively). In model I, duration of hospital stay, presence of chronic wounds, aminoglycoside and fluoroquinolone use retained statistical significance. In model II, duration of hospital stay and history of intubation during the last month stood out as the only significant predictors of a subsequent HCA-MRSA infection. No significant differences in outcome were noted.

CONCLUSIONS

The length of exposure to the hospital environment may be the best predictor of a new HCA-MRSA infection. Use of aminoglycosides and fluoroquinolones may also stand independently along with presence of chronic ulcers and surgical procedures. No independent association between quantitative antibiotic use and subsequent HCA-MRSA infection was documented.

Methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in residents of Veterans Affairs long-term care facilities: role of antimicrobial exposure and MRSA acquisition

OBJECTIVE

To identify risk factors associated with methicillin-resistant Staphylococcus aureus (MRSA) acquisition in long-term care facility (LTCF) residents.

DESIGN

Multicenter, prospective cohort followed over 6 months.

SETTING

Three Veterans Affairs (VA) LTCFs.

PARTICIPANTS

All current and new residents except those with short stay (<2 weeks).

METHODS

MRSA carriage was assessed by serial nares cultures and classified into 3 groups: persistent (all cultures positive), intermittent (at least 1 but not all cultures positive), and noncarrier (no cultures positive). MRSA acquisition was defined by an initial negative culture followed by more than 2 positive cultures with no subsequent negative cultures. Epidemiologic data were collected to identify risk factors, and MRSA isolates were typed by pulsed-field gel electrophoresis (PFGE).

RESULTS

Among 412 residents at 3 LTCFs, overall MRSA prevalence was 58%, with similar distributions of carriage at all 3 facilities: 20% persistent, 39% intermittent, 41% noncarriers. Of 254 residents with an initial negative swab, 25 (10%) acquired MRSA over the 6 months; rates were similar at all 3 LTCFs, with no clusters evident. Multivariable analysis demonstrated that receipt of systemic antimicrobials during the study was the only significant risk factor for MRSA acquisition (odds ratio, 7.8 [95% confidence interval, 2.1-28.6]; P = .002). MRSA strains from acquisitions were related by PFGE to those from a roommate in 9/25 (36%) cases; 6 of these 9 roommate sources were persistent carriers.

CONCLUSIONS

MRSA colonization prevalence was high at 3 separate VA LTCFs. MRSA acquisition was strongly associated with antimicrobial exposure. Roommate sources were often persistent carriers, but transmission from roommates accounted for only approximately one-third of MRSA acquisitions.

Predictors of agr dysfunction in methicillin-resistant Staphylococcus aureus (MRSA) isolates among patients with MRSA bloodstream infections

Despite emerging evidence that dysfunction in the accessory gene regulator (agr) locus is associated with deleterious outcomes among patients treated with vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) infections, factors predictive of agr dysfunction have not been evaluated. This study describes the epidemiology of agr dysfunction, identifies predictors of agr dysfunction in MRSA isolates among those with MRSA bloodstream infections, and describes the relationship between agr dysfunction and other microbiologic phenotypes. A cross-sectional study of patients with MRSA bloodstream infections at two institutions in upstate New York was performed. Clinical data on demographics, comorbidities, disease severity, hospitalization history, and antibiotic history were collected. Microbiologic phenotypes, including agr dysfunction, MIC values by broth microdilution (BMD) and Etest, and vancomycin heteroresistance (hVISA) were tested. Multivariable analyses were performed to identify factors predictive of agr dysfunction. Among 200 patients with an MRSA bloodstream infection, the proportion of strains with agr dysfunction was 31.5%. The distribution of MICs determined by both BMD and Etest were equivalent across agr groups, and there was no association between agr dysfunction and the presence of hVISA. Severity of illness, comorbidities, and hospitalization history were comparable between agr groups. In the multivariate analysis, prior antibiotic exposure was the only factor of variables studied found to be predictive of agr dysfunction. This relationship was predominantly driven by prior beta-lactam and fluoroquinolone administration in the bivariate analysis. Identifying these institution-specific risk factors can be used to develop a process to assess the risk of agr dysfunction and guide empirical antibiotic therapy decisions.

[Generalized or targeted screening for carriage of MRSA on admission to a geriatric hospital]

OBJECTIVES

To confirm previously risk factors for MRSA carriage in our geriatric patient population and to suggest a simplified risk score with a combination of these risk factors, to test the Novel Score and to check if a targeted MRSA screening on admission is possible to reduce the screening workload and cost.

DESIGN

a prospective in-hospital cohort study.

SUBJECTS

1125 geriatric patients were screened for MRSA carriage within 24 hours after admission to a geriatric hospital.

METHODS

Risk factors, based on recently published risk scores (Preop Score and Ger Score) were determined.

RESULTS

Prevalence of MRSA carriage was 8.44%. In a multivariate analysis age > or = 87 year (OR 1,864; 95% CI 1,145-3,035), presence of a long-term catheter (OR 2,813; 95% CI 1,562-5,065) and prior carriage of MRSA (OR 13,25; 95% CI 8,007-21,926) remained predictors of MRSA carriage. The Novel Score (cut-off > or = 1) had a sensitivity of 73.7%, a specificity of 64%, PPV 15.9%, NPV 96.3% and AUC of 0.688. The Novel Score allows reduction of the screening load by 57.2%, but misses 26% of positive cases. 16% of MRSA carriers develop an infection that needs to be treated with vancomycin.

CONCLUSION

With targeted MRSA screening on admission based on a risk score a substantial reduction of workload and costs is possible compared to generalized screening for MRSA. Because MRSA carriers can be missed with a risk score, the epidemiological context and the risk of transmission and infection with MRSA must be taken in to account when introducing a targeted screening.

Effect of systemic antibiotics and topical chlorhexidine on meticillin-resistant Staphylococcus aureus carriage in intensive care unit patients

Antibiotics and antiseptics have the potential to influence carriage and transmission of meticillin-resistant Staphylococcus aureus (MRSA), although effects are likely to be complex, particularly in a setting where multiple agents are used. Here admission and weekly MRSA screens and daily antibiotic and antiseptic prescribing data from 544 MRSA carriers on an intensive care unit (ICU) are used to determine the effect of these agents on short-term within-host MRSA carriage dynamics. Longitudinal data were analysed using Markov models allowing patients to move between two states: MRSA positive (detectable MRSA carriage) and MRSA negative (no detectable carriage). The effect of concurrent systemic antibiotic and topical chlorhexidine (CHX) on movement between these states was assessed. CHX targeted to MRSA screen carriage sites increased transition from culture positive to negative and there was also weaker evidence that it decreased subsequent transition from negative back to positive. In contrast, there was only weak and inconsistent evidence that any antibiotic influenced transition in either direction. For example, whereas univariate analysis found quinolones to be strongly associated with both increased risk of losing and then reacquiring MRSA carriage over time intervals of one day, no effect was seen with weekly models. Similar studies are required to determine the generalisability of these findings.

MRSA prevalence in European healthcare settings: a review

BACKGROUND

During the past two decades, methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly common as a source of nosocomial infections. Most studies of MRSA surveillance were performed during outbreaks, so that results are not applicable to settings in which MRSA is endemic. This paper gives an overview of MRSA prevalence in hospitals and other healthcare institutions in non-outbreak situations in Western Europe.

METHODS

A keyword search was conducted in the Medline database (2000 through June 2010). Titles and abstracts were screened to identify studies on MRSA prevalence in patients in non-outbreak situations in European healthcare facilities. Each study was assessed using seven quality criteria (outcome definition, time unit, target population, participants, observer bias, screening procedure, swabbing sites) and categorized as 'good', 'fair', or 'poor'.

RESULTS

31 observational studies were included in the review. Four of the studies were of good quality. Surveillance screening of MRSA was performed in long-term care (11 studies) and acute care (20 studies). Prevalence rates varied over a wide range, from less than 1% to greater than 20%. Prevalence in the acute care and long-term care settings was comparable. The prevalence of MRSA was expressed in various ways - the percentage of MRSA among patients (range between 1% and 24%), the percentage of MRSA among S. aureus isolates (range between 5% and 54%), and as the prevalence density (range between 0.4 and 4 MRSA cases per 1,000 patient days). The screening policy differed with respect to time points (on admission or during hospital stay), selection criteria (all admissions or patients at high risk for MRSA) and anatomical sampling sites.

CONCLUSIONS

This review underlines the methodological differences between studies of MRSA surveillance. For comparisons between different healthcare settings, surveillance methods and outcome calculations should be standardized.

Modelling the costs and effects of selective and universal hospital admission screening for methicillin-resistant Staphylococcus aureus

Background

Screening at hospital admission for carriage of methicillin-resistant Staphylococcus aureus (MRSA) has been proposed as a strategy to reduce nosocomial infections. The objective of this study was to determine the long-term costs and health benefits of selective and universal screening for MRSA at hospital admission, using both PCR-based and chromogenic media-based tests in various settings.

Methodology/Principal Findings

A simulation model of MRSA transmission was used to determine costs and effects over 15 years from a US healthcare perspective. We compared admission screening together with isolation of identified carriers against a baseline policy without screening or isolation. Strategies included selective screening of high risk patients or universal admission screening, with PCR-based or chromogenic media-based tests, in medium (5%) or high nosocomial prevalence (15%) settings. The costs of screening and isolation per averted MRSA infection were lowest using selective chromogenic-based screening in high and medium prevalence settings, at $4,100 and $10,300, respectively. Replacing the chromogenic-based test with a PCR-based test costs $13,000 and $36,200 per additional infection averted, and subsequent extension to universal screening with PCR would cost $131,000 and $232,700 per additional infection averted, in high and medium prevalence settings respectively. Assuming $17,645 benefit per infection averted, the most cost-saving strategies in high and medium prevalence settings were selective screening with PCR and selective screening with chromogenic, respectively.

Conclusions/Significance

Admission screening costs $4,100–$21,200 per infection averted, depending on strategy and setting. Including financial benefits from averted infections, screening could well be cost saving.

Prevalence of antimicrobial-resistant bacteria isolated from older versus younger hospitalized adults: results of a two-centre study

OBJECTIVES

To compare the proportion of antimicrobial-resistant strains among bacterial isolates from younger and older hospital patients and to quantify changes in the proportion of antimicrobial-resistant strains in both groups over time.

PATIENTS AND METHODS

A retrospective analysis of microbiology data from two centres in Maryland and Chicago was performed. Adult hospital inpatients with positive clinical cultures for specific antimicrobial-resistant bacterial pathogens between 1999 and 2005 (55 427 isolates) were included. The proportions of isolates not susceptible to specific antimicrobial agents were compared between patients > or =65 and <65 years. Additional analyses examined temporal trends in the frequency of resistance and the frequency of resistance among the oldest patients (> or =80 years), in bacteria isolated from blood cultures and in bacteria obtained from intensive care unit patients.

RESULTS

Heterogeneity was observed in the frequency of resistance among different bacteria between older and younger patients, between the two centres and over the study period. Staphylococcus aureus isolates were more likely to be resistant to methicillin when obtained from older patients at Chicago (50.9% versus 40.9%; P < 0.001). In contrast, younger patients yielded a greater proportion of enterococci resistant to vancomycin at Maryland (19.4% versus 16.5%; P = 0.009). Results were variable when resistance to fluoroquinolones, cephalosporins and imipenem were compared for Pseudomonas aeruginosa, Escherichia coli and Klebsiella spp.

CONCLUSIONS

Overall, advanced patient age was not uniformly associated with a greater likelihood of antimicrobial resistance among all bacterial pathogens. Moreover, the frequency of resistance in older and younger patients varied considerably at the two sites over the study period. Variability in the frequency of resistance precludes simplistic conclusions regarding the relationship between age and resistance.

Mixture model to assess the extent of cross-transmission of multidrug-resistant pathogens in hospitals

OBJECTIVE

Creation of a mixture model based on Poisson processes for assessment of the extent of cross-transmission of multidrug-resistant pathogens in the hospital.

METHODS

We propose a 2-component mixture of Poisson processes to describe the time series of detected cases of colonization. The first component describes the admission process of patients with colonization, and the second describes the cross-transmission. The data set used to illustrate the method consists of the routinely collected records for methicillin-resistant Staphylococcus aureus (MRSA), imipenem-resistant Pseudomonas aeruginosa, and multidrug-resistant Acinetobacter baumannii over a period of 3 years in a German tertiary care hospital.

RESULTS

For MRSA and multidrug-resistant A. baumannii, cross-transmission was estimated to be responsible for more than 80% of cases; for imipenem-resistant P. aeruginosa, cross-transmission was estimated to be responsible for 59% of cases. For new cases observed within a window of less than 28 days for MRSA and multidrug-resistant A. baumannii or 40 days for imipenem-resistant P. aeruginosa, there was a 50% or greater probability that the cause was cross-transmission.

CONCLUSIONS

The proposed method offers a solution to assessing of the extent of cross-transmission, which can be of clinical use. The method can be applied using freely available software (the package FlexMix in R) and it requires relatively little data.

Current antimicrobial usage for the management of neutropenic fever in Korea: a nationwide survey

A nationwide questionnaire-based survey was performed to evaluate the current clinical practices for the management of neutropenic fever in hematology units and hematopoietic stem cell transplantation (HSCT) centers throughout Korea. A 86.9% response rate was obtained from a total of 46 doctors and practical policies of the 33 sites were analysed. Approximately 42.4% and 84.8% of the sites responded that they used oral fluoroquinolone as prophylaxis for neutropenic patients receiving chemotherapy and HSCT, respectively. Additionally, 42.4% of the sites responded that they used antifungal prophylaxis in the chemotherapy groups whereas 90.9% of the sites responded that they used antifungal prophylaxis in HSCT recipients. Approximately half of the responding sites prescribed combination regimen with 3rd or 4th cephalosporin plus aminoglycoside as a first-line therapy. Most of the sites considered persistent fever for 2-4 days or aggravated clinical symptoms for 1-2 days as failure of the first-line regimen, and they changed antibiotics to second-line regimens that varied widely among the sites. Twenty-seven sites (84.4%) responded that they considered adding an antifungal agent when fever persisted for 5-7 days despite antibacterial therapy. Amphotericin B deoxycholate was preferred as a first-line antifungal, which was probably due to the limitations of the national health insurance system. The role of oral antibiotics in the management of neutropenic fever still accounted for a small portion. To the best of our knowledge, this survey is the first report to examine the practical policies currently in place for the management of neutropenic fever in Korea and the results of this survey may help to establish a Korean guideline in the future.

Screening for methicillin-resistant Staphylococcus aureus (MRSA) carriage on admission to a geriatric hospital

Our objective is to identify risk factors for carriage of MRSA on admission to a geriatric hospital where MRSA is endemic. A prospective screening for MRSA carriage was conducted by swabbing anterior nares and anal skin for 6 weeks. One hundred and thirty-eight patients aged over 65 were enrolled after obtaining their informed consent. Swabs of anterior nares and anal skin of patients were submitted for culture for MRSA. The demographic, administrative, and clinical data for each participant were recorded, and their association with MRSA carriage was determined by stepwise regression analysis. MRSA was recovered from 11 patients (11/138 patients, 8.0%), and from anal skin in 8 of them. Without screening of anal skin, 5 out of 11 carriers had been missed. Multivariate analysis revealed that hypoalbuminemia (adjusted risk ratio, RR=6.39, 95% confidence interval, CI=1.08-37.84) and bedridden status (RR=8.26, CI=1.04-65.31) were independent risk factors. Screening of elderly patients for gastrointestinal colonization on admission had implications for early detection of the reservoir of MRSA. Systematic selective screening for MRSA carriage targeting high-risk patients with hypoalbuminemia or bedridden status would be useful for infection control of this resistant organism.

Methicillin-resistant Staphylococcus aureus Control at the National University Hospital, Singapore: A Historical Perspective

Singapore has a sophisticated healthcare system and is an important referral centre for Asia. Like much of the world, methicillin-resistant Staphylococcus aureus (MRSA) is now endemic across its health system. MRSA infection has been associated with considerable attributable mortality, morbidity plus personal and public cost. Nosocomial infections are potentially preventable and need to be considered an unacceptable complication rather than a tolerable byproduct of healthcare. Failure to introduce long-term sustainable infection control initiatives is not an option for responsible clinical leaders and managers. Control of MRSA transmission in Singapore is achievable but we need to accept the challenge and acknowledge that it will take perhaps a decade. It requires implementation of many varied infection control measures to be rolled out sequentially and across all health services. Our ambition, in Singapore, should be for hospitals to achieve an inpatient prevalence of <1% MRSA colonised patients. Identified transmission of MRSA should be regarded as a serious breech. Successful control will require extraordinary collaboration, support, resources, accountability and consistency of effort. Currently, efforts are evolving significantly and today, we have a good opportunity to embark on this difficult journey. Implementing infection control initiatives successfully over the next few years will save lives in the future. Key words: Colonisation, Infection, Infection control

Methicillin-resistant Staphylococcus aureus Control in Singapore – Moving Forward

Singapore has a sophisticated healthcare system and is an important referral centre for Asia. Like much of the world, methicillin-resistant Staphylococcus aureus (MRSA) is now endemic across its health system. MRSA infection has been associated with considerable attributable mortality, morbidity plus personal and public cost. Nosocomial infections are potentially preventable and need to be considered an unacceptable complication rather than a tolerable byproduct of healthcare. Failure to introduce long-term sustainable infection control initiatives is not an option for responsible clinical leaders and managers. Control of MRSA transmission in Singapore is achievable but we need to accept the challenge and acknowledge that it will take perhaps a decade. It requires implementation of many varied infection control measures to be rolled out sequentially and across all health services. Our ambition, in Singapore, should be for hospitals to achieve an inpatient prevalence of <1% MRSA colonised patients. Identified transmission of MRSA should be regarded as a serious breech. Successful control will require extraordinary collaboration, support, resources, accountability and consistency of effort. Currently, efforts are evolving significantly and today, we have a good opportunity to embark on this difficult journey. Implementing infection control initiatives successfully over the next few years will save lives in the future. Key words: Colonisation, Infection, Infection control

Financial implications of plans to combat methicillin-resistant Staphylococcus aureus (MRSA) in an orthopaedic department

INTRODUCTION

The aim of this study was to calculate retrospectively the cost of MRSA infections in the elective and trauma orthopaedic population in Rotherham District General Hospital in a 3-month period during 2005.

PATIENTS AND METHODS

A total of 686 patients were admitted to the orthopaedic wards and the surgical wounds 10 patients became infected with MRSA.

RESULTS

The cost of these infections when extrapolated over 12 months was pound384,000 excluding staff costs.

CONCLUSIONS

The key in the fight against MRSA in the hospital setting is multifactorial and requires a combination of measures. Our solution is: cohort nursing; non-selective screening of all admissions to the orthopaedic wards; use of a polymerase chain reaction as a diagnostic tool; ring-fencing of beds; and separate wound dressing rooms for each ward. The total cost is projected to be pound301,000.

Prevalence of methicillin-resistant Staphylococcus aureus colonization among older residents of care homes in the United Kingdom

OBJECTIVE

To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among older residents of care homes in Leeds, United Kingdom, and to identify resident and care home risk factors for carriage.

DESIGN

We conducted a cross-sectional prevalence survey of 715 residents from 39 care homes. All participants were tested for nasal colonization with S. aureus, including MRSA. A short questionnaire was completed about each participant and each care home. A multivariable model was used to determine which risk factors were independently associated with MRSA colonization.

SETTING

Care homes for older residents in Leeds, United Kingdom.

PARTICIPANTS

All residents in participating homes who were able to give informed consent.

RESULTS

A total of 159 of 715 residents tested positive for MRSA, for a prevalence of 22% (95% confidence interval, 18%-27%) The resultant multivariate model showed that residence in a home with a low ratio of nurses to beds, residence in a care home in a deprived area, male sex, presence of an invasive device, and a hospitalization duration of more than 10 days during the previous 2 years were independently associated with MRSA colonization.

CONCLUSIONS

This study found a large reservoir of MRSA within the care home population. Control strategies need to be coordinated between care homes and hospitals. Increasing the ratio of nurses to beds, reducing the duration of hospitalization, and improving the management of invasive devices could help reduce the prevalence of MRSA colonization. Further research is required to ascertain the potential health benefits of reducing the rate of MRSA colonization among care home residents.

Clinical impact of MRSA in a stem cell transplant unit: analysis before, during and after an MRSA outbreak

Meticillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen, with an increased incidence in the UK since 1993, causing serious morbidity and mortality in immunosuppressed patients. We analysed the frequency and outcome of MRSA infection in a single-centre transplant population over a 5-year period. The total number of patients infected was 41/776 (5%). The frequency in autologous, sibling and unrelated donor transplants was 3, 6 and 9%, respectively. Prior to 2004, the incidence was <4%/year; however, an outbreak in the day unit resulted in 22 patients becoming newly infected. Over 90% of infections were clinically relevant, half (49%) being bacteraemia. Three patterns were seen: known MRSA positive at any time before transplant (n=15), MRSA first detected during the neutropenia phase (n=5) and MRSA only post discharge (n=21). MRSA was implicated in a number of deaths, at all time points, in those infected. An intensive eradication policy resulted in new infections dropping to <2%. In conclusion, MRSA is likely to remain endemic in our unit, but robust early screening protocols and aggressive eradication strategies have effectively limited the spread of and morbidity due to this pathogen.

A survey of the management of neutropenic fever in oncology units in the UK

A nationwide questionnaire-based survey was performed to define the different practices in managing febrile neutropenia in oncology units and the use of antimicrobial chemotherapy prophylaxis. A 69.7% response rate was obtained from a total of 165 units. Fifty percent of the responding oncologists used combination therapy with piperacillin/tazobactam plus gentamicin as a first-line treatment in febrile neutropenia. When response to initial empirical therapy does not occur after 24-48h, 51.3% of oncology units add a glycopeptide (vancomycin or teicoplanin) and 39.2% change to a carbapenem and a glycopeptide. The role of oral antibiotics in managing febrile neutropenia is still low. Approximately 30% of studied units might consider using an oral antibiotic in this setting. When response to initial empirical therapy does not occur after 3-7 days, 46.1% of oncologists preferred liposomal amphotericin to conventional amphotericin (28.7%) in treating persistent febrile neutropenia. The antimicrobial chemotherapy treatment of febrile neutropenia in oncology patients and the use of antimicrobial prophylaxis varies significantly across the UK. This survey is the first to examine the prescribing practices of UK oncology units in this area and could help in the formulation of practice guidelines.

Antibiotic prescribing for chronic skin wounds in primary care

The aim of this study was to describe and quantify systemic antibiotic prescribing for patients with chronic skin wounds presenting at the primary care, nonspecialist setting. Data for 1 year were extracted from a general practice morbidity database comprising approximately 185,000 patients attending family medical practitioners in Wales. Patients with chronic wounds (PCW) were identified using Read Codes and compared with nonwound patients who were randomly selected after matching for age-band, sex, and general practice. PCW received a significantly greater number of antibiotic courses than nonwound patients (p<0.001). This increased level of prescribing was evident for flucloxacillin, co-amoxiclav, cefaclor, cefalexin, erythromycin, trimethoprim, metronidazole, and ciprofloxacin (p<0.01 for all). While PCW also had a significantly higher prevalence of diabetes (16.5% compared with 6.6%, p<0.001), and attended at general practice significantly more frequently than nonwound patients (median (interquartile range) of 25 (17-40) visits per year compared with 12 (4-20), p<0.001), importantly, exclusion of diabetic patients and analysis of the proportion of visits on which patients received antibiotics did not affect the significance of the difference in antibiotic consumption. These data show a strong association between occurrence of chronic wounds and prescribing of antibiotics in primary health care, and wide variation in the type and duration of antibiotic therapy for chronic wounds. Further work is now indicated to rationalize this prescribing and determine the role that this exposure to antibiotics plays in the prevalence of antibiotic resistance in this at-risk elderly population.

Managing methicillin-resistant staphylococci: a paradigm for preventing nosocomial transmission of resistant organisms

Multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are endemic in healthcare settings in the United States and many other countries of the world. Nosocomial transmission of MRSA serves as a source of hospital outbreaks, and recent reports of vancomycin-resistant S aureus strains in the United States emphasize the need for better control of MRSA and other resistant bacteria within healthcare settings. Colonization with S aureus or MRSA is relatively common in both healthy and hospitalized individuals, most often involves the anterior nares, and is frequently asymptomatic. Colonization increases risk of infection. Patient-to-patient transmission of MRSA within healthcare settings primarily occurs via carriage on the hands of healthcare workers. The Society for Healthcare Epidemiology of America (SHEA) has developed guidelines for the prevention of transmission of MRSA and vancomycin-resistant enterococci within healthcare settings, and chief among the recommendations is an emphasis on adherence to hand hygiene guidelines. Other measures that may prevent the nosocomial transmission of MRSA include improved antibiotic stewardship, staff cohorting, maintenance of appropriate staffing ratios, reductions in length of hospital stays, contact isolation, active microbiologic surveillance, and better staff education. Currently, the efficacy of many of these individual infection control interventions remain in doubt. Many studies reporting improvement in infection control outcomes (eg, reduced transmission, decreasing prevalence) involve simultaneous institution of several of these measures, making it impossible to tease out the effects of any of the individual components. Nonetheless, the best approach in the current environment probably involves hand hygiene plus a careful assessment of an institution's particular circumstances, applying more aggressive procedures such as patient isolation, staff cohorting, and active surveillance cultures, as indicated.

Managing methicillin-resistant staphylococci: a paradigm for preventing nosocomial transmission of resistant organisms

Multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), are endemic in healthcare settings in the United States and many other countries of the world. Nosocomial transmission of MRSA serves as a source of hospital outbreaks, and recent reports of vancomycin-resistant S aureus strains in the United States emphasize the need for better control of MRSA and other resistant bacteria within healthcare settings. Colonization with S aureus or MRSA is relatively common in both healthy and hospitalized individuals, most often involves the anterior nares, and is frequently asymptomatic. Colonization increases risk of infection. Patient-to-patient transmission of MRSA within healthcare settings primarily occurs via carriage on the hands of healthcare workers. The Society for Healthcare Epidemiology of America (SHEA) has developed guidelines for the prevention of transmission of MRSA and vancomycin-resistant enterococci within healthcare settings, and chief among the recommendations is an emphasis on adherence to hand hygiene guidelines. Other measures that may prevent the nosocomial transmission of MRSA include improved antibiotic stewardship, staff cohorting, maintenance of appropriate staffing ratios, reductions in length of hospital stays, contact isolation, active microbiologic surveillance, and better staff education. Currently, the efficacy of many of these individual infection control interventions remain in doubt. Many studies reporting improvement in infection control outcomes (e.g., reduced transmission, decreasing prevalence) involve simultaneous institution of several of these measures, making it impossible to tease out the effects of any of the individual components. Nonetheless, the best approach in the current environment probably involves hand hygiene plus a careful assessment of an institution's particular circumstances, applying more aggressive procedures such as patient isolation, staff cohorting, and active surveillance cultures, as indicated.

Non-multiresistant methicillin-resistant Staphylococcus aureus bacteraemia in Sydney, Australia: emergence of EMRSA-15, Oceania, Queensland and Western Australian MRSA strains

AIMS

To describe clinical features and molecular epidemiology of non-multiresistant methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia.

METHODS

Patients with non-multiresistant MRSA isolated from blood at South Western Area Pathology Service from 1 January 1999 to 31 December 2001 were enrolled. Pulsed field gel electrophoresis, phage typing, and (selected instances) multilocus sequence and staphylococcal cassette chromosome typing was performed. PCR was used to detect Panton-Valentine leukocidin (PVL), toxic shock syndrome toxin-1 (TSST-1), and enterotoxin genes.

RESULTS

Sixteen patients were detected: eight with UK EMRSA-15 (ST22-MRSA-IV), three with Oceania (South-West Pacific/Western Samoan phage pattern) (ST30-MRSA-IV), two with WA MRSA-5 (ST8-MRSA-IV), and one each with WA MRSA-1 (ST1-MRSA-IV), Queensland strain (ST93-MRSA-IV), and WA MRSA-15 (ST59-MRSA-IV). Prior hospital admissions occurred with six of the eight patients with UK EMRSA-15, none of the three with Oceania, and three of the five with other strains. Thirteen of 16 patients had underlying disease. Three of the three patients with Oceania strain bacteraemia were Polynesians; 11 of 13 of the others were Caucasians. PVL genes were detected in four of 16 isolates (all Oceania and Queensland strains). entC was detected in two EMRSA-15 strains; entA in one Oceania, two WA MRSA-5 and the WA MRSA-1 strain, with entA and entB in the WA MRSA-15 strain. tst was not detected.

CONCLUSIONS

Multiple epidemic strains cause non-multiresistant MRSA bacteraemia. Most patients had risk factors. Oceania and Queensland strains possess the PVL gene.

Guidelines for the control and prevention of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Meticillin-resistant Staphylococcus aureus (MRSA) remains endemic in many UK hospitals. Specific guidelines for control and prevention are justified because MRSA causes serious illness and results in significant additional healthcare costs. Guidelines were drafted by a multi-disciplinary group and these have been finalised following extensive consultation. The recommendations have been graded according to the strength of evidence. Surveillance of MRSA should be undertaken in a systematic way and should be fed back routinely to healthcare staff. The inappropriate or unnecessary use of antibiotics should be avoided, and this will also reduce the likelihood of the emergence and spread of strains with reduced susceptibility to glycopeptides, i.e. vancomycin-intermediate S. aureus/glycopeptide-intermediate S. aureus (VISA/GISA) and vancomycin-resistant S. aureus (VRSA). Screening for MRSA carriage in selected patients and clinical areas should be performed according to locally agreed criteria based upon assessment of the risks and consequences of transmission and infection. Nasal and skin decolonization should be considered in certain categories of patients. The general principles of infection control should be adopted for patients with MRSA, including patient isolation and the appropriate cleaning and decontamination of clinical areas. Inadequate staffing, especially amongst nurses, contributes to the increased prevalence of MRSA. Laboratories should notify the relevant national authorities if VISA/GISA or VRSA isolates are identified.

Can pre-operative skin marking transfer methicillin-resistant Staphylococcus aureus between patients?

National guidelines state that in patients undergoing operations the site of the procedure should be marked. In clinical practice the same marker is used repeatedly. We are not aware of any investigation regarding the theoretical risk of transferring organisms such as methicillin-resistant Staphyloccocus aureus (MRSA) between patients by a skin marker.

In an experimental setting, Penflex and Viomedex skin markers were tested 30 times each after contaminating them with a standard inoculum of MRSA. The survival of the organism on the tip of the markers was assessed by culture on MRSA-indicator nutrient agar plates at 0, 5, 15 and 60 minutes, 24 and 48 hours and at 1, 2, and 3 weeks after contamination.

There was a significant difference between the markers, with the Penflex showing no survival of MRSA after 15 minutes whereas the Viomedex product continued to produce MRSA cultures for up to three weeks.

Controlling methicillin-resistant Staphylococcus aureus: quantifying the effects of interventions and rapid diagnostic testing

Control of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) has been unsuccessful in most countries. Yet, some countries have maintained low endemic levels by implementing nationwide MRSA-specific infection control measures, such as "search & destroy" (S&D). These strategies, however, are not based on well designed studies, and their use in countries with high levels of endemicity is controversial. We present a stochastic three-hospital model and an analytical one-hospital model to quantify the effectiveness of different infection control measures and to predict the effects of rapid diagnostic testing (RDT) on isolation needs. Isolation of MRSA carriers identified by clinical cultures is insufficient to control MRSA. However, combined with proactive search (of high-risk patients on admission and/or contacts of index patients), it will maintain prevalence levels <1%. Concerted implementation of S&D in countries with high nosocomial endemicity reduces nosocomial prevalence to <1% within 6 years. Stepwise implementation of control measures can reduce isolation capacities needed. RDT can reduce isolation needs by >90% in low-endemic settings and by 20% in high-endemic settings. Surveillance of colonization and improved hand hygiene can markedly increase control efficacy. These findings strongly suggest that: (i) causality exists between S&D and low MRSA prevalence; (ii) isolating MRSA carriers identified by clinical cultures as a single measure is insufficient for control; (iii) a combined approach of isolation and screening confers efficacy; and (iv) MRSA-prevalence levels can be reduced to <1% in high-endemic settings by S&D or a stepwise approach to interventions. RDT can markedly enhance feasibility.

The point prevalence and associated factors of nasal methicillin-resistant Staphylococcus aureus colonisation in eight geriatric hospitals in Korea

The prevalence and associated factors of nasal methicillin-resistant Staphylococcus aureus (MRSA) colonisation were investigated among patients in geriatric hospitals in Korea. S. aureus was isolated from 317 (50.2%) of 632 patients. The nasal MRSA colonisation prevalence was 36.1%. In bivariate analysis, stay in an intensive care unit, decreased functional status, recent use of antibiotics, use of urinary catheters and the existence of skin breaks were associated with nasal MRSA colonisation (p < 0.05). Of these factors, only decreased functional status and recent use of systemic antibiotics were associated independently with nasal MRSA colonisation following logistic regression analysis.

Cross-transmission of nosocomial pathogens in an adult intensive care unit: incidence and risk factors

The incidence and determinants of cross-transmission in an adult intensive care unit (ICU) were examined under normal conditions. Four hundred and thirty patients were followed for 3947 patient-days. Cross-transmitted pathogens were identified by genetic typing. A cross-transmission episode was defined as when two or more patients had indistinguishable isolates and had been treated in the ICU during intervals up to seven days apart. The direction of cross-transmission was confirmed if the incriminated pathogen was isolated from the donor before admission of the recipient; otherwise, both patients could potentially be a donor or a recipient. These patients were excluded from the risk factor analysis. Recipients of pathogens were compared with those who were not involved in cross-transmission. Out of 22 056 examined specimens, 275 isolates were typed and 40 episodes of cross-transmission were detected. The overall incidence of cross-transmission was 10.7 [95% confidence intervals (CI) 7.6-14.5] per 1000 patient-days. In multivariate analysis, those who were nursed in an understaffed environment [odds ratio (OR) = 3.3, 95% CI 1.4-7.8], had a nasogastric tube (OR = 2.9, 95% CI 1.1-7.8) and were ventilated (OR = 2.5, 95% CI 1.1-6.0) for all of their stay, compared with none or part of their stay, showed an increase in the risk of cross-transmission. Repeated bronchoscopy (OR = 5.1, 95% CI 1.04-25) compared with no bronchoscopy and immunosuppresion (OR = 3.9, 95% CI 1.2-12.5) also increased the risk. This study showed that cross-transmission of nosocomial pathogens in the ICU is associated with understaffing, immunosuppression and factors that result in multiple staff/patient contacts, thus emphasizing the importance of hand hygiene.

Guidelines for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the UK

These evidence-based guidelines have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA) infection. The guidelines were further informed by antibiotic susceptibility data on MRSA from the UK. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection. There are several antibiotics currently available that are suitable for use in the management of this problem and potentially useful new agents are continuing to emerge.

Evaluation of an intervention designed to decrease the rate of nosocomial methicillin-resistant Staphylococcus aureus infection by encouraging decreased fluoroquinolone use

OBJECTIVE

Society for Health Care Epidemiology guidelines recommend decreasing the use of fluoroquinolone antibiotics in institutions where methicillin-resistant Staphylococcus aureus (MRSA) is endemic. We evaluated whether an intervention to limit fluoroquinolone use was associated with a lower rate of nosocomial MRSA infection and summarized changes in antibiotic use, changes in other variables potentially correlated with a lower rate of MRSA infection, and rates of nosocomial infections due to other pathogens.

DESIGN

Single-center quasi-experimental design. A time series of nosocomial MRSA infections was measured at monthly intervals from July 2001 through June of 2004; there were 80 MRSA infections recorded. Segmented regression analysis (ie, quasi-Poisson generalized linear models) was used to evaluate variables possibly associated with the nosocomial MRSA infection rate.

SETTING

An 87-bed Veterans Affairs teaching hospital with an extended-care facility.

INTERVENTION

A physician-directed computer-generated intervention designed to limit the use of fluoroquinolone antibiotics was initiated, and institutional changes in antibiotic use and nosocomial MRSA infection rates were tracked.

RESULTS

After the intervention, fluoroquinolone use decreased by approximately 34%, and levofloxacin use decreased by approximately 50%. Decreased fluoroquinolone use was offset by increased cephalosporin, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole use. The nosocomial MRSA infection rate decreased from 1.37 to 0.63 episodes per 1,000 patient-days after the study intervention (P=.02). Coagulase-negative Staphylococcus and Enterococcus infection rates also decreased. However, the rate of infection with gram-negative organisms increased. The rate of MRSA infection was positively correlated with levofloxacin use (P=.01) and azithromycin use (P=.08), whereas it was negatively correlated with summer season (P=.05). In a subsequent model, the rate of MRSA infection was negatively correlated with the study intervention (P=.04).

CONCLUSION

Reduction in the institutional use of fluoroquinolones may be associated with a lower nosocomial MRSA infection rate.

Methicillin-resistant Staphylococcus aureus in elderly care facilities

Among multidrug-resistant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) is of immediate concern, given its potential for pathogenicity and widespread presence in geriatric hospitals. Epidemiological surveys indicate that rates of MRSA cross-transmission are increasing in elderly care facilities. MRSA carriage is far more frequent than MRSA-positive clinical specimens in this setting, and the consequences of these epidemics in terms of morbidity, remain limited within these facilities. However, given that patients are continually transferred between long-term and acute-care facilities, it is reasonable to consider these units together with all other care units and to measure the effect of MRSA on a regional healthcare network, rather than on the scale of a given ward or hospital. With regard to the worldwide increase in morbidity associated with MRSA, the emergence of a community-based disease linked to these strains and the emergence of glycopeptide-resistant strains, the application of a voluntary strategy including screening, isolation and eventually, topical decolonization in elderly care facilities, appears to be an urgent matter of priority, even if this strategy will be expensive.

A survey of the antibiotic treatment of febrile neutropenia in haematology units in the United Kingdom

We performed a nationwide survey to define the different practices in managing febrile neutropenia in haematology units. A questionnaire was sent out to a named haematologist in each of 220 haematology units in the UK. Questions were asked regarding antibiotics of choice in managing febrile neutropenia and the use of antibiotic prophylaxis. Responses were received from 167 (76%) haematology units. Combination therapy with piperacillin-tazobactam and gentamicin is used first-line in febrile neutropenia by 72% of units. Piperacillin-tazobactam monotherapy is used first-line by 5% of units. When response to initial empirical therapy does not occur after 24-48 h, 32% of haematology units add a glycopeptide (vancomycin or teicoplanin) and 31% change to a carbapenem and a glycopeptide. Seventy-one percent of units use oral fluoroquinolone prophylaxis for all neutropenic patients. The antibiotic treatment of febrile neutropenia in haematology patients, and the use of antibiotic prophylaxis, vary significantly across the UK. This survey is the first to examine the prescribing of UK haematology units in this area, and could help in the formulation of practice guidelines.

Clinical and epidemiologic features of methicillin-resistant Staphylococcus aureus in elderly hospitalized patients

We describe characteristics of elderly patients with MRSA identified in 37 Canadian hospitals between 1995 and 2002. Of these inpatients, 6,613 (66%) were older than 65 years. They were more likely than younger patients to have been colonized without infection and to have had MRSA isolated from urine or the perineum. The epidemiology and clinical features of these patients is distinct from that of younger patients.

MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003

OBJECTIVE

To describe the incidence and determinants of methicillin resistant and methicillin sensitive Staphylococcus aureus (MRSA and MSSA) bacteraemia in patients presenting to acute hospitals.

DESIGN

Anonymised record linkage study with information from hospital information systems and microbiology databases.

SETTING

One teaching hospital and one district general hospital in Oxfordshire.

PARTICIPANTS

All patients admitted to a teaching hospital 1 April 1997 to 31 March 2003 and to a district general hospital 1 April 1999 to 31 March 2003.

MAIN OUTCOME MEASURES

Detection of MRSA and MSSA from blood cultures taken during the first two days of admission to hospital.

RESULTS

In the teaching hospital, there were 479 patients with MSSA and 116 with MRSA bacteraemia admitted from the community. Among this group, which comprised 24% of all hospital MRSA cases, 31% (36 cases) of patients had been admitted to renal, oncology, or haematology services for intensive day case therapy. The 69% remaining were most commonly patients admitted as medical or surgical emergencies. At least 91% had been in hospital previously; the median time since discharge was 46 days. About half of cases were in patients in whom MRSA had not been isolated before. Similar epidemiology was observed in the district general hospital.

CONCLUSION

Diagnostic algorithms and policies on use of antibiotics need to reflect the fact that a quarter of hospital MRSA cases occur in patients who have previously been in hospital and are subsequently readmitted.

Impact of restricting fluoroquinolone prescription on bacterial resistance in an intensive care unit

The purpose of this study was to assess the effect of reducing prescription of fluoroquinolones in an intensive care unit (ICU) upon bacterial resistance, particularly as regards Pseudomonas aeruginosa. For six months between January 2001 and June 2001, administration of fluoroquinolones was kept to a minimum. A bacteriological screening of patients was performed to assess the incidence of fluoroquinolone-resistant bacteria. There was a 75.8% restriction in prescriptions of fluoroquinolones. There was no significant change in bacterial ecology between the periods preceding (12 months) and following (12 months) restriction. There was a significant recovery of sensitivity of P. aeruginosa to ciprofloxacin (P<or=0.01), with a decrease in resistant strains from 71.3% in the pre-restriction period to 52.4% in the post-restriction period. Regarding clinical data, no significant differences were noted between the pre-restriction and the post-restriction periods, except for the number of cases of ventilator-associated pneumonia with P. aeruginosa resistant to ciprofloxacin. This study demonstrated the possibility of introducing rotation of antibiotics in an ICU.

Carriage of resistant microorganisms in repatriates from foreign hospitals to The Netherlands

In a prospective survey conducted between May 1998 and September 2001, the prevalence of carriage of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and gentamicin-resistant Gram-negative bacilli (GGNB) was determined in 1167 patients repatriated from foreign hospitals to The Netherlands. Swab specimens, demographic data and clinical data were obtained during transfer of the patients from the foreign hospitals. The total prevalence of carriage of resistant microorganisms was 18.2%. MRSA was carried by 2.7% of all patients, and by 4.7% of the patients repatriated to a Dutch hospital. Antimicrobial treatment (adjusted odds ratio (OR) 3.4; 95% confidence interval (CI) 1.2-9.7), length of stay in a foreign hospital of > 14 days (adjusted OR 5.4; 95% CI 2.3-12) and artificial ventilation (adjusted OR 8.5; 95% CI 1.8-41) were risk factors for carriage of MRSA. VRE and GGNB were isolated from 2.7% and 14.1% of the patients, respectively. Transfer from Asia, and southern, southeastern and eastern Europe, were risk factors for carriage of GGNB. These carriage rates were high compared to those found in patients in Dutch hospitals, where the rates are < 1% for MRSA, 2% for VRE, and 4.5% for GGNB. The highest risk of acquisition of GGNB was associated with the country from where the patient was repatriated, rather than with the antimicrobial treatment received by the individual patient in the foreign hospital.

Methicillin-resistant Staphylococcus aureus: impact on dermatology practice

Methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) emerged in the 1960s and is now commonly seen in hospitals, clinics and, since the mid-1990s, the community. Risk factors for the acquisition of MRSA include chronic dermatoses, underlying medical illnesses, attending healthcare facilities, use of prescription antibacterials, surgery, intravenous lines, hospitalization in an intensive care unit, and proximity to patients colonized with MRSA. Recent community-associated strains often occur in patients without these risk factors. Staphylococci are readily spread from person to person and readily contaminate the environment. Infection control measures thus involve identifying the infected patients, separating them from other non-infected patients, cleaning of the environment and, most important of all, scrupulous attention to hand hygiene. Alcoholic antiseptic hand rubs offer an alternative to antiseptic hand washes and increase compliance. Treatment of MRSA skin infections is challenging. Topical agents such as mupirocin or fusidic acid can be used, but the organisms often become resistant. Systemic therapy involves non-beta-lactams. Parenteral treatment is generally with glycopeptides such as vancomycin; oral therapy is more complex. Monotherapy with quinolones, rifampin (rifampicin), and fusidic acid often results in the development of resistance and so, if any of these agents are chosen it should be in combination. There are no data on combination therapy, although rifampin-containing combinations are often chosen. Fourth-generation quinolones and linezolid are expensive but promising alternatives.

Use of perioperative mupirocin to prevent methicillin-resistant Staphylococcus aureus (MRSA) orthopaedic surgical site infections

We have examined whether topical perioperative prophylaxis can reduce the incidence of methicillin-resistant Staphylococcus aureus (MRSA) surgical site infections (SSIs). Using a controlled before and after approach on patients from four orthopaedic wards, undergoing orthopaedic surgery involving insertion of metal prostheses and/or fixation, received perioperative prophylaxis with nasal mupirocin for five days, and a shower or bath with 2% (v/v) triclosan before surgery (PPNMT). After introduction of PPNMT there was a marked decrease in incidence of MRSA SSIs (per 1000 operations) from 23 in the six months beforehand (period A) to 3.3 (P<0.001) and 4 (P<0.001) in subsequent consecutive six-month periods (B and C, respectively). Of 11 MRSA SSI cases that occurred during periods B and C, only one had actually received PPNMT, and 10 occurred after acute, as opposed to elective, surgery (P<0.001). Point prevalence nasal MRSA carriage decreased from 38% before PPNMT to 23% immediately after, and 20%, 7%, 10% and 8% (P<0.001) at six-monthly intervals post-intervention. Conversely, the prevalence of nasal MRSA carriage in a control elderly medicine ward did not change significantly. Vancomycin usage, in terms of defined daily doses, declined by 23%. Low-level mupirocin resistance was found in 2.3% of S. aureus isolates from orthopaedic patients before PPNMT, and in 3.9%, 6.1%, 10% and 0% in subsequent six month periods. No S. aureus isolates with high-level mupirocin resistance were found. PPNMT can reduce the incidence of MRSA SSls after orthopaedic surgery, probably by reducing nasal MRSA carriage in the endemic setting, without selecting for mupirocin resistance.

Eradication of methicillin-resistant Staphylococcus aureus from pressure sores using warming therapy

BACKGROUND

Nosocomial infection is a major cause of surgical morbidity and mortality. Methicillin-resistant Staphylococcus aureus (MRSA) has become a prominent organism in colonization and infection in surgical patients. Pressure sores are a major reservoir of MRSA.

MATERIALS AND METHODS

In this study, 33 patients with full-thickness pressure sores were randomized to receive standard care or radiant heat therapy using a Warm Up device (Augustine Medical, Eden Prairie, MN). Weekly microbial sampling was used for assessment of bacterial presence. None of the patients received antibiotics prior to or during the eight weeks of study.

RESULTS

More than 50 species of bacteria were present in the pressure sores with a median of four organisms per sample. Methicillin-resistant S. aureus was found in 14 of the patients' pressure sores. In the warming group (n = 8), MRSA was eradicated in six patients within 2 weeks of warming, whereas in the control group none had eradication (Fisher's exact test, p = 0.01). Eradication was defined as three consecutive weekly swabs without bacterial growth.

CONCLUSION

The warming of pressure sores is being assessed as an adjunct to healing, but there is some promise that colonization by MRSA may be eradicated, thereby reducing a potential reservoir of organisms. The risk to surgical patients when patients are harboring MRSA may be minimized by warming therapy.

SHEA guideline for preventing nosocomial transmission of multidrug-resistant strains of Staphylococcus aureus and enterococcus

BACKGROUND

Infection control programs were created three decades ago to control antibiotic-resistant healthcare-associated infections, but there has been little evidence of control in most facilities. After long, steady increases of MRSA and VRE infections in NNIS System hospitals, the Society for Healthcare Epidemiology of America (SHEA) Board of Directors made reducing antibiotic-resistant infections a strategic SHEA goal in January 2000. After 2 more years without improvement, a SHEA task force was appointed to draft this evidence-based guideline on preventing nosocomial transmission of such pathogens, focusing on the two considered most out of control: MRSA and VRE.

METHODS

Medline searches were conducted spanning 1966 to 2002. Pertinent abstracts of unpublished studies providing sufficient data were included.

RESULTS

Frequent antibiotic therapy in healthcare settings provides a selective advantage for resistant flora, but patients with MRSA or VRE usually acquire it via spread. The CDC has long-recommended contact precautions for patients colonized or infected with such pathogens. Most facilities have required this as policy, but have not actively identified colonized patients with surveillance cultures, leaving most colonized patients undetected and unisolated. Many studies have shown control of endemic and/or epidemic MRSA and VRE infections using surveillance cultures and contact precautions, demonstrating consistency of evidence, high strength of association, reversibility, a dose gradient, and specificity for control with this approach. Adjunctive control measures are also discussed.

CONCLUSION

Active surveillance cultures are essential to identify the reservoir for spread of MRSA and VRE infections and make control possible using the CDC's long-recommended contact precautions.