Burden of meticillin-resistant Staphylococcus aureus colonization and infection in London acute hospitals: retrospective on a voluntary surveillance programme.

Although meticillin-resistant Staphylococcus aureus (MRSA) is recognized as an important cause of hospital and community healthcare-associated morbidity, and colonization as a precursor to infection, few studies have attempted to assess the burden of both colonization and infection across acute healthcare providers within a defined health economy. This study describes the prevalence and incidence of MRSA colonization and infection in acute London hospital Trusts participating in a voluntary surveillance programme in 2000-2001. Hospital infection control staff completed a weekly return including details on incident and prevalent colonizations, bacteraemias and other significant infections due to MRSA. Incidence and prevalence rates were calculated for hospitals with sufficient participation across both years. Colonizations accounted for 79% of incident MRSA cases reported; 4% were bacteraemias, and 17% other significant infections. There was no change in incidence of colonization of hospital patients between 2000 and 2001. By contrast, there was an unexplained 49% increase in prevalence of colonizations over this period. For any given month, prevalent colonizations outnumbered incident colonizations at least twofold. This MRSA surveillance programme was unusual for prospective ascertainment of incident and prevalent cases of both colonization and infection within an English regional health economy. Consistent with other studies, the incidence and prevalence of colonization substantially exceeded infection. Given the small contribution of bacteraemias to the overall MRSA burden, and the surveillance, screening and control interventions of recent years, it may be appropriate to review the present reliance on bacteraemia surveillance.

Mortality in patients with meticillin-resistant Staphylococcus aureus bacteraemia, England 2004-2005.

A population-based study was undertaken to determine the short term risk of death in English patients diagnosed with meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia. All patients with an MRSA-positive blood culture taken in 2004 and 2005 in England identified through routine surveillance were matched to the national registry of deaths. The study found an overall case fatality (all-cause) within 7 days of MRSA-positive blood culture diagnosis of 20%, rising to 38% within 30 days. Risk of death was highest on the day subsequent to the blood specimen being drawn (4%). Seven-day case fatality rates in women were 16% higher than for men (odds ratio: 1.16; 95% confidence interval: 1.04-1.29), although no significant difference was discernable by day 30. Risk of death increased with rising age, with 28% (425/1513) of patients aged ≥85 years dying within 7 days and 57% (859/1513) within 30 days. A seasonal pattern in case fatality rates was evident, highest in the winter and lowest in the summer. The age-standardised mortality ratios within the first week were 180 and 225 times as high for men and women, respectively, as for the general population. This declined rapidly after 10 weeks to approximately 9 for both sexes. An estimated 5.53 deaths per 100,000 population followed MRSA bacteraemia in 2004 and 2005, although no inference on causality or attributable mortality could be made through this study. The stable, elevated risk of death observable after 10 weeks compared with that in the general population gave an indication of the background risk of death unrelated to MRSA infection.

Enhanced surveillance of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in children in the UK and Ireland.

OBJECTIVE: To determine the incidence and demographic features of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in children in the UK and Ireland and to characterise MRSA isolated from cases. DESIGN: Prospective surveillance study. SETTING: Children aged <16 years hospitalised with bacteraemia due to MRSA. METHODS: Cases were ascertained by active surveillance involving paediatricians reporting to the British Paediatric Surveillance Unit and by routine laboratory surveillance. Patient characteristics were obtained using questionnaires sent to reporting paediatricians. MRSA isolates were characterised using molecular and phenotypic techniques including antimicrobial susceptibility testing. RESULTS: 265 episodes of MRSA bacteraemia were ascertained, involving 252 children. The overall incidence rate was 1.1 per 100 000 child population per year (95% CI 0.9 to 1.2): 61% of the children were aged <1 year (a rate of 9.7 cases per 100 000 population per year (95% CI 8.2 to 11.4)) and 35% were <1 month. Clinical data were obtained from 115 cases. The clinical presentation varied, with fever present in only 16% of neonates compared with 72% of older children. A history of invasive procedure was common, with 32% having had intravascular lines and 13% having undergone surgery. 62% of patients for whom data were available were receiving high-dependency care (46% in SCBU/NICU and 16% in PICU). Of 93 MRSA isolates studied, 73% belonged to epidemic strains widely associated with nosocomial infection in the UK and Ireland. CONCLUSIONS: MRSA bacteraemia in children was relatively uncommon and was predominantly seen in very young children, often those receiving neonatal or paediatric intensive care. Bacteraemia predominantly involved well-documented epidemic strains of MRSA associated with nosocomial infection.

A methodological approach to investigating a nationwide clinical specimen contamination problem in England.

Outbreaks of pseudo-infection due to contamination of specimens have been described, often as localised incidents. From August 2006, several English hospital laboratories began to refer an unusually high number of isolates of the fungus Paecilomyces variotii from clinical specimens to the national mycology reference laboratory for microbiological testing. We describe the methods used during the outbreak investigation in order to provide infection control specialists with an overview of how such national incidents may be investigated. We surveyed the hospitals reporting the contamination problem and conducted microbiological and environmental sampling. We applied analytical epidemiology to supply chain data, comparing the supply lines of key equipment to affected and unaffected hospitals in England. The survey was useful to describe procedures and equipment in use in the hospitals reporting the problem. The microbiological aspects of the investigation helped us understand how the fungal spores were distributed in the hospital environment. In the supply chain investigation we used data that was previously only used for logistical purposes. Overall the investigation was methodologically challenging, with no existing protocol to guide the investigators. To our knowledge, this is a novel approach to the investigation of such a widespread contamination problem, affecting geographically disparate hospitals at the same time.

Epidemic of severe Streptococcus pyogenes infections in injecting drug users in the UK, 2003-2004.

During the late 1990s, increases in referrals to the national reference laboratory of Streptococcus pyogenes isolates from injecting drug users (IDUs) with severe soft tissue infection indicated an emerging problem in the UK, later confirmed during the 2003-2004 European enhanced surveillance (Strep-EURO) programme. In light of these findings, further analyses were undertaken in an attempt to understand the reasons behind this increase in referrals. Single and multivariable analyses were undertaken to compare clinical, microbiological and demographic characteristics of IDUs diagnosed with severe S. pyogenes infection during the 2003-2004 enhanced surveillance study with those of other cases arising during this same period. Temporal and spatial analyses were undertaken for IDUs to identify clustering, as a means of understanding the transmission dynamics underpinning this increase. Infections in IDUs were spread across the UK, with some concentration in northern England and London. IDUs presented with a wide range of clinical manifestations, including pneumonia, which was found to be significantly more common in IDUs (OR 3.00) than in other cases. Marked differences in type distributions were found between IDUs and other cases, in particular the concentration of emm/M83 (22% of IDUs, 2% of non-IDUs). These findings indicate that an epidemic of severe S. pyogenes infections in IDUs occurred in the UK, peaking in 2003. The explanation for this rise remains unclear.

Distribution and antimicrobial susceptibility patterns of Clostridium difficile PCR ribotypes in English hospitals, 2007-08.

A surveillance study designed to provide a representative sample of the strains of Clostridium difficile causing infections in hospitals in England was in operation from April 2007 to the end of March 2008. Six hundred and seventy-seven isolates were obtained from 186 hospitals in the nine geographical regions of England as recognised by the Health Protection Agency's Regional Microbiology Network. Typing studies revealed that PCR ribotype 027 is now the most common strain isolated from symptomatic patients, accounting for over 41.3% of isolates in English hospitals. Type 106 was the second most common strain (20.2%) and Type 001, which was once the most common strain associated with hospital outbreaks, has now been reduced to only 7.8% of the total. A mixture of 44 other PCR ribotypes accounted for the remaining 28.9% of isolates. This represents a changing distribution of strains when compared to a previous study performed two years earlier which showed roughly equal proportions of types 106, 001 and 027. Antimicrobial susceptibility testing by the E test method revealed significantly lower susceptibility to metronidazole in the more common strains when compared to the less common ribotypes, although none were classified as clinically resistant. Similarly, no resistance to vancomycin was detected. However, common PCR ribotypes were more resistant to moxifloxacin and erythromycin than the less common strains, which may indicate a selective advantage for resistance to these agents, and combined resistance to these two agents was a good indicator of a common ribotype.

Rates of surgical site infection after hip replacement as a hospital performance indicator: analysis of data from the English mandatory surveillance system.

OBJECTIVE: To describe rates of surgical site infection (SSI) after hip replacement and to use these data to provide a simple mechanism for identifying poorly performing hospitals that takes into account variations in sample size. DESIGN: Prospective surveillance study. SETTING: A total of 125 acute care hospitals in England that participated in mandatory SSI surveillance from April 1, 2004 through March 31, 2005. PATIENTS: Patients who underwent total hip replacement (THR) or hip hemiarthroplasty (HH). METHODS: A standard data set was collected for all eligible operations at participating hospitals for a minimum of 3 months annually. Defined methods were used to identify SSIs that occurred during the inpatient stay. Data were checked for quality and accuracy, and funnel plots were constructed by plotting the incidence of SSI against the number of operations. RESULTS: Data were collected on 16,765 THRs and 5,395 HHs. The cumulative SSI incidence rates were 1.26% for THR and 4.06% for HH; the incidence densities were 1.38 SSIs per 1,000 postoperative inpatient days for THR and 2.3 SSIs per 1,000 postoperative inpatient days for HH. The risk of infection associated with revision surgery was significantly higher than that associated with primary surgery (2.7% [95% confidence interval, 2.0%-3.5%] vs. 1.1% [95% confidence interval, 1.0%-1.2%]; P=.003). Rates varied considerably among hospitals. Nineteen hospitals had rates above the 90th percentile. However, the use of funnel plots to adjust for the precision of estimated SSI rates identified 7 hospitals that warranted further investigation, including 2 with crude rates below the 90th percentile. CONCLUSIONS: Funnel plots of rates of SSI after hip replacement provide a valuable method of presenting hospital performance data, clearly identifying hospitals with unusually high or low rates while adjusting for the precision of the estimated rate. This information can be used to target and support local interventions to reduce the risk of infection.

Endoscope decontamination incidents in England 2003-2004.

An Endoscope Task Force was established following the report of an endoscope decontamination failure in May 2004. The Task Force reviewed endoscope decontamination incidents in England from 2003 to 2004 and made recommendations to prevent further recurrences. Twenty-one incidents were reported from 19 National Health Service (NHS) Trusts, 18 of which matched the Task Force definition of an incident. Eight incidents involved failures to decontaminate auxiliary endoscope channels, seven incidents highlighted problems with automated endoscope reprocessors, and the remaining three involved disinfection practices not recommended by the British Society of Gastroenterology Guidelines. Following an assessment of the risk of transmission from blood-borne viruses, the Task Force recommended that look-back exercises were not indicated. The nature of the incidents suggested that there were problems associated with defining roles and responsibilities for endoscope decontamination, staff training and incompatibility between endoscopes and reprocessors. The Medicines and Healthcare Products Regulatory Agency subsequently issued recommendations to all NHS Trusts carrying out endoscopies.

Protective effect of antibiotics against serious complications of common respiratory tract infections: retrospective cohort study with the UK General Practice Research Database.

OBJECTIVE: To determine the extent to which antibiotics reduce the risk of serious complications after common respiratory tract infections. DESIGN: Retrospective cohort study. SETTING: UK primary care practices contributing to the general practice research database. DATA SOURCE: 3.36 million episodes of respiratory tract infection. MAIN OUTCOME MEASURES: Risk of serious complications in treated and untreated patients in the month after diagnosis: mastoiditis after otitis media, quinsy after sore throat, and pneumonia after upper respiratory tract infection and chest infection. Number of patients needed to treat to prevent one complication. RESULTS: Serious complications were rare after upper respiratory tract infections, sore throat, and otitis media, and the number needed to treat was over 4000. The risk of pneumonia after chest infection was high, particularly in elderly people, and was substantially reduced by antibiotic use, with a number needed to treat of 39 for those aged > or =65 and 96-119 in younger age groups. CONCLUSION: Antibiotics are not justified to reduce the risk of serious complications for upper respiratory tract infection, sore throat, or otitis media. Antibiotics substantially reduce the risk of pneumonia after chest infection, particularly in elderly people in whom the risk is highest.

The ORION statement: guidelines for transparent reporting of outbreak reports and intervention studies of nosocomial infection.

The quality of research in hospital epidemiology (infection control) must be improved to be robust enough to influence policy and practice. In order to raise the standards of research and publication, a CONSORT equivalent for these largely quasi-experimental studies has been prepared by the authors of two relevant systematic reviews, following consultation with learned societies, editors of journals and researchers. It consists of a 22 item checklist, and a summary table. The emphasis is on transparency to improve the quality of reporting and on the use of appropriate statistical techniques. The statement has been endorsed by a number of professional special interest groups and societies. Like CONSORT, ORION should be considered a 'work in progress', which requires ongoing dialogue for successful promotion and dissemination. The statement is therefore offered for further public discussion. Journals and research councils are strongly recommended to incorporate it into their submission and reviewing processes. Feedback to the authors is encouraged and the statement will be revised in 2 years.

Reducing variation in antibacterial prescribing rates for 'cough/cold' and sore throat between 1993 and 2001: regional analyses using the general practice research database.

OBJECTIVE: To use the General Practice Research Database (GPRD) to explore the regional variation in prescribing for single diagnostic episodes of 'cough/cold' and sore throat and how this changed between 1993 and 2001. METHODS: Data from the GPRD was used to conduct a longitudinal survey of morbidity and antibiotic prescribing data. RESULTS: Nationally there has been a substantial reduction in diagnosed episodes per 1000 patient years at risk for both diagnoses: from 104.6 (104.0-105.2) to 86.5 (86.0-86.9) for cough/cold (-17.3%) and from 102.8 (102.2-103.4) to 69.2 (68.8-69.6) for sore throat (-32.6%). In addition to the changes in diagnostic rate there have been reductions in diagnosis-related prescribing: from 41.8% to 34.8% of cough/cold episodes (-7.0%) and from 77.3% to 60.8% of sore throat episodes (-16.4%). These aggregated data conceal wide regional variations. For cough/cold the change in prescribing rate during the study varied from -16.0% to +5.3% and for sore throat from -28.3% to -7.3%. CONCLUSIONS: In addition to a substantial reduction in diagnosis of cough/cold and sore throat, there has been a reduction in diagnosis-related prescribing episodes in almost all regions. Although there continues to be regional variation in diagnosis-related prescribing this has reduced substantially over the 9-year study period.

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.

Gastrointestinal endoscopy decontamination failure and the risk of transmission of blood-borne viruses: a review.

The risk of blood-borne virus transmission with an inadequately decontaminated endoscope during gastrointestinal endoscopy remains unclear, although it is likely to be low. A systematic review of the literature was undertaken to determine previous episodes of blood-borne virus transmission in these circumstances. In total, 31 articles were included in this review. No articles relating to possible transmission of human immunodeficiency virus were identified. The articles included were generally case series or case reports and were written prior to the comprehensive endoscope decontamination guidelines in use today. The results suggest that hepatitis B and hepatitis C transmission are low during endoscopy with an inadequately decontaminated endoscope.

Isolation measures in the hospital management of methicillin resistant Staphylococcus aureus (MRSA): systematic review of the literature.

OBJECTIVE: To evaluate the evidence for the effectiveness of isolation measures in reducing the incidence of methicillin resistant Staphylococcus aureus (MRSA) colonisation and infection in hospital inpatients. DESIGN: Systematic review of published articles. DATA SOURCES: Medline, Embase, CINAHL, Cochrane Library, System for Information on Grey Literature in Europe (SIGLE), and citation lists (1966-2000). REVIEW METHODS: Articles reporting MRSA related outcomes and describing an isolation policy were selected. No quality restrictions were imposed on studies using isolation wards or nurse cohorting. Other studies were included if they were prospective or employed planned comparisons of retrospective data. RESULTS: 46 studies were accepted; 18 used isolation wards, nine used nurse cohorting, and 19 used other isolation policies. Most were interrupted time series, with few planned formal prospective studies. All but one reported multiple interventions. Consideration of potential confounders, measures to prevent bias, and appropriate statistical analysis were mostly lacking. No conclusions could be drawn in a third of studies. Most others provided evidence consistent with a reduction of MRSA acquisition. Six long interrupted time series provided the strongest evidence. Four of these provided evidence that intensive control measures including patient isolation were effective in controlling MRSA. In two others, isolation wards failed to prevent endemic MRSA. CONCLUSION: Major methodological weaknesses and inadequate reporting in published research mean that many plausible alternative explanations for reductions in MRSA acquisition associated with interventions cannot be excluded. No well designed studies exist that allow the role of isolation measures alone to be assessed. None the less, there is evidence that concerted efforts that include isolation can reduce MRSA even in endemic settings. Current isolation measures recommended in national guidelines should continue to be applied until further research establishes otherwise.

The community prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in older people living in their own homes: implications for treatment, screening and surveillance in the UK.

Methicillin-resistant Staphylococcus aureus (MRSA) predominantly affects those over 65 years old. There may be a substantial pool of older people with MRSA in the community. We studied the prevalence in one London general practice, screening 258 older people living in their own home. MRSA (E-MRSA 15) was found in two participants (0.78%). Past history of MRSA was the only significant risk factor. The results of this and other studies suggest that national guidelines recommending early discharge for MRSA carriers have not resulted in widespread community acquisition amongst elderly people living in their own home. Community antibiotic policies for skin and soft-tissue infection do not require amendment. Patients with previous MRSA should be isolated and screened on admission especially to high-risk units.