All Wales surveillance of methicillin-resistant Staphylococcus aureus (MRSA): the first year's results

Staphylococcus aureus bacteraemia and endocarditis - epidemiology and outcome: a review

PURPOSE

To review the epidemiology of Staphylococcus aureus bacteraemia (SAB) and endocarditis (SAE), and discuss the short- and long-term outcome.  Materials and methods: A literature review of the epidemiology of SAB and SAE.

RESULTS

The reported incidence of SAB in Western countries is 16-41/100,000 person-years. Increasing incidence has been observed in many regions, in Iceland by 27% during 1995-2008. The increase is believed to depend on changes in population risk factors and possibly better and more frequent utilization of diagnostic procedures. S. aureus is now the leading causes of infective endocarditis (IE) in many regions of the world. It accounts for 15-40% of all IE cases, and the majority of cases in people who inject drugs (PWID). Recently, the incidence of SAE in PWID in Stockholm, Sweden, was found to be 2.5/1000 person-years, with an in-hospital mortality of 2.5% in PWID as compared to 15% in non-drug users. The 30-day mortality associated with SAB amounts to 15-25% among adults in Western countries, but is lower in children (0-9%). Mortality associated with SAE is high (generally 20-30% in-hospital mortality), and symptomatic cerebral embolizations are common (12-35%). The 1-year mortality reported after SAB and SAE is 19-62% and reflects deaths from underlying diseases and complications caused by the infection. In a subset of SAE cases, valvular heart surgery is needed (15-45%), but active intravenous drug use seems to be a reason to refrain from surgery. Despite its importance, there are insufficient data on the optimal management of SAB and SAE, especially on the required duration of antibiotic therapy.  Conclusions: The epidemiology of SAB and SAE has been changing in the past decades. They still carry a substantial morbidity and mortality. Intensified studies on treatment are warranted for improving patient outcome.

A cohort study of bacteremic pneumonia: The importance of antibiotic resistance and appropriate initial therapy?

Bacteremic pneumonia is usually associated with greater mortality. However, risk factors associated with hospital mortality in bacteremic pneumonia are inadequately described.The study was a retrospective cohort study, conducted in Barnes-Jewish Hospital (2008-2015). For purposes of this investigation, antibiotic susceptibility was determined according to ceftriaxone susceptibility, as ceftriaxone represents the antimicrobial agent most frequently recommended for hospitalized patients with community-acquired pneumonia as opposed to nosocomial pneumonia. Two multivariable analyses were planned: the first model included resistance to ceftriaxone as a variable, whereas the second model included the various antibiotic-resistant species (methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacteriaceae).In all, 1031 consecutive patients with bacteremic pneumonia (mortality 37.1%) were included. The most common pathogens associated with infection were S aureus (34.1%; methicillin resistance 54.0%), Enterobacteriaceae (28.0%), P aeruginosa (10.6%), anaerobic bacteria (7.3%), and Streptococcus pneumoniae (5.6%). Compared with ceftriaxone-susceptible pathogens (46.8%), ceftriaxone-resistant pathogens (53.2%) were significantly more likely to receive inappropriate initial antibiotic treatment (IIAT) (27.9% vs 7.1%; P < 0.001) and to die during hospitalization (41.5% vs 32.0%; P = 0.001). The first logistic regression analysis identified IIAT with the greatest odds ratio (OR) for mortality (OR 2.2, 95% confidence interval [CI] 1.5-3.2, P < 0.001). Other independent predictors of mortality included age, mechanical ventilation, immune suppression, prior hospitalization, prior antibiotic administration, septic shock, comorbid conditions, and severity of illness. In the second multivariable analysis that included the antibiotic-resistant species, IIAT was still associated with excess mortality, and P aeruginosa infection was identified as an independent predictor of mortality (OR 1.6, 95% CI 1.1-2.2, P = 0.047), whereas infection with ceftriaxone-resistant Enterobacteriaceae (OR 0.6, 95% CI 0.4-1.0, P = 0.050) was associated with lower mortality.More than one-third of our patients hospitalized with bacteremic pneumonia died. IIAT was identified as the most important risk factor for hospital mortality and the only risk factor amenable to potential intervention. Specific antibiotic-resistant pathogen species were also associated with mortality.

Population-based epidemiology and microbiology of community-onset bloodstream infections

Bloodstream infection (BSI) is a major cause of infectious disease morbidity and mortality worldwide. While a positive blood culture is mandatory for establishment of the presence of a BSI, there are a number of determinants that must be considered for establishment of this entity. Community-onset BSIs are those that occur in outpatients or are first identified <48 h after admission to hospital, and they may be subclassified further as health care associated, when they occur in patients with significant prior health care exposure, or community associated, in other cases. The most common causes of community-onset BSI include Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae. Antimicrobial-resistant organisms, including methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase/metallo-β-lactamase/carbapenemase-producing Enterobacteriaceae, have emerged as important etiologies of community-onset BSI.

Epidemiology of Methicillin-ResistantStaphylococcus aureusat a University Hospital in the Canary Islands

Objectives:

To describe the epidemiology of methicillin-resistantStaphylococcus aureus(MRSA) at a university hospital in Tenerife, Canary Islands, during a 40-month period and to evaluate the effectiveness of the application of control measures.

Design:

Laboratory-based surveillance, medical charts and microbiological records review, and characterization of strains by pulsed-field gel electrophoresis (PFGE) were used to describe the epidemiology. Infection control practices were introduced as an intervention.

Setting:

A 650-bed, tertiary-care university hospital.

Subjects:

Patients with clinical and nasal isolates of MRSA and colonized staff members.

Results:

The rate of nosocomial MRSA infections was 32.5% for 1997, 17.9% for 1998, 14.5% for 1999, and 25.6% during the first 4 months of 2000. The major sites of isolation for nosocomial MRSA infection included surgical wounds (25%) and the lower respiratory tract (24%). Intensive care units and surgical specialties had more frequent MRSA cases. Characteristics associated with nosocomial MRSA isolates included prior use of intensive antibiotic therapy, prolonged hospital stays, major underlying illness, invasive procedures, and older age. PFGE type A (subtype A1) was the strain most frequently found and the only PFGE type involved in clusters.

Conclusions:

Surveillance cultures and contact droplet precautions were followed by decreased rates for 2 years. Nevertheless, the spread of PFGE subtype Al to many different areas of the hospital and the increase in incidence during the first third of 2000 indicates either that surveillance cultures were not used widely enough or that compliance with isolation measures was suboptimal.

Staphylococcus aureus bloodstream infections in children: A population-based assessment

BACKGROUND

Although Staphylococcus aureus is a major cause of bloodstream infections, population-based data on these infections in children are limited.

OBJECTIVE

To describe the epidemiology of S aureus bacteremia in children.

METHODS

Population-based surveillance for all incident S aureus bacteremias was conducted among children (18 years of age or younger) living in the Calgary Health Region (Alberta) from 2000 to 2006.

RESULTS

During the seven-year study, 120 S aureus bloodstream infections occurred among 119 patients; 27% were nosocomial, 18% health care associated and 56% community acquired. The annual incidence was 6.5/100,000 population and 0.094/1000 live births. A total of 52% had a significant underlying condition, and this was higher for nosocomial cases. Bone and joint (40%), bacteremia without a focus (33%), and skin and soft tissue infections (15%) were the most common clinical syndromes. Infections due to methicillin-resistant S aureus were uncommon (occurring in one infection) and three patients (2.5%) died.

CONCLUSIONS

S aureus bacteremia is an important cause of morbidity in the paediatric age group. Underlying medical conditions and implanted devices are important risk factors. Methicillin-resistant S aureus and mortality rates are low.

Surgical site infection following hip fracture surgery - the role of wound surveillance

In a prospective study we assessed 440 patients, sequentially admitted to the trauma unit with hip fracture. The superficial infection rate was 7.7% and the deep infection was 1.8%. The commonest organism responsible for surgical site infection was MRSA (47.6%). 45.2% of the patients with SSI and 50 % of the patients with MRSA wound infection were admitted from institutional care or other hospital. The high prevalence of MRSA wound infection and increased mortality rate in this subgroup highlights the need for a good surveillance programme in place, to monitor trends and identify risk factors with an emphasize on minimising infection rates. Using the National Hip Fracture Database (NHFD) to make surveillance for surgical site infection a routine part of hip fracture care would be best practice in monitoring the trend and comparing care and outcomes against national benchmarks and quality standards. We recommend a close surveillance of wound in this vulnerable group.

The prevalence of methicillin resistant Staphylococus aureus in orthopaedics in a non-selective screening policy

BACKGROUND

The aim of this study was to assess the true incidence and prevalence of MRSA colonisation and infection in the elective and trauma orthopaedic population in Rotherham District General Hospital.

MATERIALS AND METHODS

This prospective study non-selectively screened 690 consecutive trauma and elective orthopaedic patients over three months in 2005.

RESULTS

Of these, 27 were positive for either colonisation or wound infection with MRSA. Of those, 13 were previously known to have been colonised with MRSA and the 14 others were unexpectedly either colonised or subsequently developed wound infections. The new cases would not have been identified using any current selective screening protocol, as they did not fall into a high-risk category. Many were young, had no co-morbidities and no contact with hospitals in the past. Our study seems to indicate that selective screening will miss a significant number of cases.

CONCLUSION

We conclude that MRSA screening for all orthopaedic patients is needed when admitted to hospital, as colonisation is no longer confined to what has been previously identified as high-risk groups. The consequences of a subsequent MRSA infection have significant implications, socially, financially and clinically.

Staphylococcus aureus bloodstream infections: risk factors, outcomes, and the influence of methicillin resistance in Calgary, Canada, 2000-2006

BACKGROUND

Reports have suggested that the epidemiological profile of invasive Staphylococcus aureus infections is changing. We sought to describe the epidemiological profile of S. aureus bacteremia and to assess whether the incidence and severity of and the antimicrobial resistance rates associated with this bacteremia are increasing.

METHODS

Population-based surveillance for S. aureus bacteremias was conducted in the Calgary Health Region (population, 1.2 million) during 2000-2006.

RESULTS

The annual incidence of S. aureus bacteremia was 19.7 cases/100,000 population. Although rates of health care-associated and nosocomial methicillin-susceptible S. aureus (MSSA) bacteremia were similar throughout the study, rates of community-acquired MSSA bacteremia gradually decreased, and rates of methicillin-resistant S. aureus (MRSA) bacteremia dramatically increased. The clonal type predominantly isolated was CMRSA-2 (i.e., Canadian [C] MRSA-2), but CMRSA-10 (USA300) strains have been increasingly isolated, especially from community-onset infections, since 2004. Dialysis dependence, organ transplantation, HIV infection, cancer, and diabetes were the most important risk factors and were comparable for MSSA and MRSA bacteremias. The overall case-fatality rate was higher among individuals with MRSA (39%) than among those with MSSA (24%; P< .0001). The annual overall population mortality rate associated with S. aureus bacteremia did not significantly change during the study.

CONCLUSIONS

Although the overall influence of S. aureus bacteremia has not significantly changed, MRSA has emerged as an important etiology in our region.

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.

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.

Trends and outcome of nosocomial and community-acquired bloodstream infections due to Staphylococcus aureus in Finland, 1995–2001

In Finland, Staphylococcus aureus bloodstream infections are caused predominantly (>99%) by methicillin-sensitive strains. In this study, laboratory-based surveillance data on Staphylococcus aureus bloodstream infections occurring in Finland from 1995 to 2001 were analyzed. Preceding hospitalizations for all persons with Staphylococcus aureus bloodstream infections were obtained from the national hospital discharge registry, and data on outcome was obtained from the national population registry. An infection was defined as nosocomial when a positive blood culture was obtained more than 2 days after hospital admission or within 2 days of admission if there was a preceding hospital discharge within 7 days. A total of 5,045 cases were identified. The annual incidence of Staphylococcus aureus bloodstream infection rose by 55%, from 11 per 100,000 population in 1995 to 17 in 2001. The increase was detected in all adult age groups, though it was most distinct in patients >74 years of age. Nosocomial infections accounted for 51% of cases, a proportion that remained unchanged. The 28-day death-to-case ratio ranged from 1% in the age group 1-14 years to 33% in patients >74 years of age. The 28-day death-to-case ratios for nosocomial and community-acquired infections were 22% and 13%, respectively, and did not change over time. The increase in incidence among elderly persons resulted in an increase in the annual rate of mortality associated with Staphylococcus aureus bloodstream infections, from 2.6 to 4.2 deaths per 100,000 population per year. Staphylococcus aureus bloodstream infections are increasing in Finland, a country with a very low prevalence of methicillin resistance. While the increase may be due in part to increased reporting, it also reflects a growing population at risk, affected by such factors as high age and/or severe comorbidity.

Infections nosocomiales à Staphylococcus aureus résistant à la méthicilline en réanimation médicale polyvalente : facteurs de risque, morbidité et impact économique

OBJECTIVE

Methicillin resistance and infections caused by methicillin-resistant Staphylococcus aureus represent a growing problem and a challenge for health-care institutions. We evaluated risk factors, morbidity and cost of infections caused by methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus.

DESIGN

We performed an un-matched case-control study in an 20-bed medical intensive care unit from 1994-2001 at Nantes teaching hospital, France. All patients with pneumonia, bacteraemia and urinary MRSA (cases) or MSSA (controls) nosocomial infections were included in the study.

RESULTS

Twenty four patients with MRSA infection were compared to 64 patients with MSSA infections. Patients with MRSA infection were older (56 vs. 45 years, P < 0.01), had longer length of stay (47 vs. 35 days, P < 0.05) and were infected later (22 vs. 10 days, P < 0.00001) than patients with MSSA infection. No difference was observed between the two groups according to the Omega index, acute simplify index and mortality. MRSA infections involved extra cost due to antimicrobial treatment (184 vs. 72 Euros, P < 0.005) and length of stay (37,278 vs. 27,755 Euros, P < 0.05).

CONCLUSION

Patient infected by MRSA seems to be different from patient infected by MSSA but without consequence on Omega index and mortality. But methicillin-resistance involves extra cost due to antimicrobial treatment and length of stay.

Toward resolving the challenges of sepsis diagnosis

Sepsis in the United States has an estimated annual healthcare cost of 16.7 billion dollars and leads to 120,000 deaths. Insufficient development in both medical diagnosis and treatment of sepsis has led to continued growth in reported cases of sepsis over the past two decades with little improvement in mortality statistics. Efforts over the last decade to improve diagnosis have unsuccessfully sought to identify a "magic bullet" proteic biomarker that provides high sensitivity and specificity for infectious inflammation. More recently, genetic methods have made tracking regulation of the genes responsible for these biomarkers possible, giving current research new direction in the search to understand how host immune response combats infection. Despite the breadth of research, inadequate treatment as a result of delayed diagnosis continues to affect approximately one fourth of septic patients. In this report we review past and present diagnostic methods for sepsis and their respective limitations, and discuss the requirements for more timely diagnosis as the next step in curtailing sepsis-related mortality. We also present a proposal toward revision of the current diagnostic paradigm to include real-time immune monitoring.

The impact of methicillin-resistant Staphylococcus aureus in a neurosurgical unit: a growing problem

OBJECT

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a growing problem worldwide. To investigate the severity of the problem, the authors surveyed the incidence of MRSA colonization and infection in the neurosurgical unit at their institution.

METHODS

Patients colonized or infected with MRSA who had been treated in the neurosurgical unit between 1993 and 1999 were retrospectively identified from laboratory records. There were 203 patients with MRSA-positive cultures, and the incidence of infection increased between 1993 (16 cases; 1.9% of admissions) and 1999 (60 cases; 6.7% of admissions). The mean duration of hospital stay was longer in patients with MRSA than in all patients treated in the unit (33.6 compared with 10.3 days, p < 0.001). Methicillin-resistant S. aureus was isolated from the nose in 89 patients, the throat in 79, the perineum in 52, surgical wounds in 16, sputum in 15, blood in 10, and from multiple sites in 69 patients. Fifty-six patients (28%) were infected with MRSA, and there were 15 deaths, of which three (20%) were likely to be due to the infection. The sources of MRSA included the neurosurgical ward in 84 patients, the intensive care unit in 28, other hospitals in 39, and the community in 17. The common strains of MRSA isolated were epidemic (E)MRSA- 16 (110 cases) and EMRSA-15 (31 cases). The microorganism was eradicated in 16 cases, not eradicated in 20, and 167 patients were discharged from the hospital before eradication was achieved. All MRSA isolates were sensitive to vancomycin and teicoplanin and there was reduced sensitivity to mupirocin.

CONCLUSIONS

Infection with MRSA is a growing problem in the neurosurgical population, and most cases are hospital-acquired and are associated with longer hospital stays. Asymptomatic colonization by this organism is far more common than infection of the surgical wound, although there is still morbidity due to MRSA sepsis. Most patients with MRSA are discharged before eradication of infection is achieved, thus increasing the risk that the infection will spread in the community. Strict adherence to the basic principles of infection control is the key to eradication of MRSA.

Two-stage evaluation and intervention program for control of methicillin-resistant Staphylococcus aureus in the hospital setting

The aim of this study was to develop a 2-stage evaluation and intervention program for control of methicillin-resistant Staphylococcus aureus (MRSA) in the hospital setting. The first stage included evaluation of MRSA prevalence throughout the entire hospital; the presence of MRSA was determined in patients or medical staff who had a high risk of carrying it (i.e. as a result of contact with surgical wounds). In the second stage, "contact isolation" (which included the use of gloves, hand washing before and after treatment of a patient and isolation of patients' personal belongings) was carried out in every patient from whom MRSA was isolated in 4 intervention departments-Surgery, Orthopaedics, General ICU and Neonatal ICU-while the same policy of attempting to isolate MRSA was maintained. Both stages lasted 7 months. A comparison between MRSA prevalence in the evaluation and intervention stages disclosed a decrease in MRSA isolates from 91 to 56 in the entire hospital (p = 0.2) and from 45 to 24 in the intervention departments (p = 0.05), respectively; while the number of patients with MRSA decreased from 87 to 55 in the entire hospital (p = 0.2) and from 45 to 18 in the intervention departments (p = 0.007). The number of patients treated with vancomycin decreased from 48 before intervention to 23 after "contact isolation" was started in the entire hospital (p = 0.02) and from 31 to 5 in the intervention departments (p = 0.001). These results provide additional evidence in favor of establishing a program to control MRSA spread.

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

A prevalence survey of methicillin-resistant Staphylococcus aureus (MRSA) in elderly patients (65 years and older) three weeks after admission to a university hospital was performed. Risk factors associated with hospital MRSA carriage were determined. The design was a cross-sectional patient-based study and all adult wards at the University Hospital Nottingham (1600 beds) were included. Three hundred and forty-two elderly individuals (65 years and older) were enrolled into the study on day 21 after admission. One hundred and twenty patients [35.08% (95% confidence intervals 29.93-40.25%)] carried S. aureus. MRSA was isolated from 54 patients. The MRSA prevalence was 158/1000 (95% CI 119-197/1000 patients). Independent risk factors for MRSA carriage in the hospital were exposure to ampicillin [adjusted odds ratio 4.1 (95% CI 1.28-13.14)] and ciprofloxacin [17.1 (95% CI 2.91-99.90)]. Forty-one MRSA isolates (75.9%) belonged to the epidemic type EMRSA 15, seven isolates to EMRSA 16 (12.9%) and six isolates were sporadic strains as determined by genetic typing. It can be expected that among this defined risk group, between 187 and 331 patients carried MRSA on discharge in the year 2000. MRSA carriage is frequent and detected in only 15% of actual carriers amongst elderly patients by routine clinical investigations three weeks after admission. The only significant risk factor identified by multivariate logistic regression was antibiotic chemotherapy. The repeated finding of a strong association between MRSA colonization and previous ciprofloxacin exposure demands attention and indicates that fluoroquinolones should be used prudently in institutions where MRSA is endemic.

The population impact of MRSA in a country: the national survey of MRSA in Wales, 1997

Continuous data collection on all new isolates of MRSA via CoSurv has taken place in Wales since January 1996. In order to audit this data collection, and to address some of the issues that it does not include, a survey of MRSA was carried out. Questionnaires were completed by infection control teams. Rates were calculated using hospital throughput denominators. Results from the one-day prevalence survey, the two-week incidence survey, and the follow-up survey carried out on new MRSA patients identified in the incidence survey, are presented. Results were found to be broadly similar to those collected via routine surveillance. MRSA was found frequently and disproportionately in the elderly, with higher rates in male than female patients. The highest incidence of total and invasive MRSA was in males aged 75 and over (total: 12.5/1000 finished consultant episodes; invasive: 2.8/1000). Although there was a large community reservoir of MRSA, most appeared to have been acquired in hospital, since most patients had a history of hospitalization, often with multiple hospital admissions. Community-based isolates from cases with no hospital history tended to have been from ulcers. Prevalence and incidence of MRSA was relatively low compared with hospital throughput (mean prevalence: 2.4/100 occupied beds; mean incidence: 3.6/1000 finished consultant episodes), there was also quite large variation between sites, even when screening samples were removed. Patients with MRSA had strikingly long stays before isolation of the organism (prevalence survey: 39 days; incidence survey: 31 days) and highest incidence occurred in elderly care wards. The outcome survey showed that approximately half of the patients were treated with some type of antimicrobial therapy for MRSA. Decontamination therapy was associated with clearance of MRSA only when controlling for sex of the patient. The majority of patients were discharged still with MRSA, mostly to their own homes. The survey emphasizes the need to continue surveillance to detect any changes, to allow guidelines based on evidence to be developed and to monitor the effectiveness of such guidelines.