Methicillin-resistant Staphylococcus Aureus Bacteraemias Research Articles

Vancomycin MIC as a predictor of outcome in MRSA bacteraemia in the UK context

Received 29 November 2012; returned 20 February 2013; revised 16 May 2013; accepted 18 May 2013 OBJECTIVES: Raised vancomycin MICs have been associated with poor outcomes for methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in the USA and mainland Europe. We investigated if this also applies in the UK, where EMRSA-15 (clonal complex 22) dominates. Isolates from UK patients receiving vancomycin therapy for MRSA bacteraemia in 2008-10 were collected, along with clinical details. Outcomes (i.e. patient survival or bacteraemia resolution) were reported 28 days after vancomycin therapy ended. The relationship between clinical outcome and MIC--as determined by CLSI and BSAC agar dilution methods--was assessed. Among 228 MRSA bacteraemias, 82% were caused by EMRSA-15; 65% of the patients were male and the median age was 70.5 years. MICs correlated between methods, but CLSI agar dilution testing gave a mode at 1 mg/L with only 12% of results either side, whereas the BSAC method gave a mode straddling 0.7-1 mg/L with <4% outliers. Twenty-three percent of patients died, with MRSA contributory in half; another 17% had unresolved bacteraemia at 28 days. Neither death nor unresolved bacteraemia was significantly associated with higher vancomycin MICs by either method. Rifampicin co-therapy had no quantifiable effect on outcome. The patient's age was the only significant correlate of patient outcome (P < 0.01); the underlying medical condition of the patient was important for the resolution of bacteraemia (P < 0.01), though not for overall mortality. Subtle vancomycin MIC differences did not correlate with worse outcomes for vancomycin monotherapy or for vancomycin/rifampicin co-therapy in MRSA bacteraemia. Regardless of the exact MIC-outcome relationship, detecting such small MIC differences seems unlikely to be reliable in routine laboratories.

Cross Border Comparison of MRSA Bacteraemia between The Netherlands and North Rhine-Westphalia (Germany): A Cross-Sectional Study

BackgroundWe describe the impact of methicillin-resistant Staphylococcus aureus (MRSA) in two neighbouring regions in Europe with a comparable population size, North Rhine-Westphalia (NRW) in Germany and the Netherlands.Methodology/Principal FindingsWe compared the occurrence of MRSA in blood cultures from surveillance systems. In the Netherlands in 2009, 14 of 1,510 (0.9%) Staphylococcus aureus bacteraemia episodes under surveillance were MRSA. Extrapolation using the number of clinical admissions results in a total of 29 MRSA bacteraemia episodes in the Netherlands or 1.8 episodes per 1,000,000 inhabitants. In 2010 in NRW, 1,029 MRSA bacteraemias were reported, resulting in 57.6 episodes of MRSA bacteraemia per 1,000,000 inhabitants: a 32-fold higher incidence than in the Netherlands.Conclusion/SignificanceBased on an estimated attributable mortality of 15%, the Dutch approach would save approximately 150 lives per year by the prevention of bacteraemia only.

Wearing white coats and sitting on beds: why should it matter?

A healthcare-associated infection (HCAI) is defined as any infection acquired as a consequence of a person's treatment by a healthcare provider, or which is acquired by a healthcare worker in the course of their duties.1 The Health and Social Care Act 2008 makes it clear that prevention and control of HCAI should be part of everyday practice and applied consistently by everyone.1 In 2006, about 8% of inpatients in acute hospitals in England were identified as having a HCAI.2 HCAIs obviously waste NHS resources. A patient with a methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia spends an average additional 10 days in hospital and for Clostridium difficile the additional length of stay is 21 days. Infections can cost a trust an extra £4,000–£10,000 per patient.3 Although it is not possible to prevent all infections,1 the emphasis placed on MRSA bacteraemias and C. difficile has shown it is possible to reduce numbers of these specific infections. A national target was introduced by the Department of Health (DH) in November 2004 to reduce MRSA bloodstream infection by 50% by 2008, against the baseline figure for 2003–4. Aggregate numbers for 2007–8 showed a 42% decrease, and a 61% decrease for 2008–9.4 Following the mandatory surveillance scheme introduced in January 2004, a national target was introduced in October 2007 to reduce numbers of C. difficile infection by 30% across all age groups by 2010–11, against the 2007–8 baseline. By December 2008, the numbers reported showed a 41% reduction.4 Although these two infections have been the main focus of the DH's national approach to reducing HCAI, they represent only 15% of all such infection.5 Bloodstream infections represent 7% of infections of which 19% are Staphylococcus aureus (4% are MRSA).5 The overall prevalence of HCAI in England has remained relatively constant over the past two decades, although a modest decrease in prevalence from 9% to 8.2% has been shown between the national prevalence surveys carried out in 1993–4 and 2006.5 However during this period hospital infection prevention and control teams have had to meet the challenges posed by additional new or increasingly common pathogens such as vancomycin-resistant Enterococci (VRE), extended spectrum beta lactamase (ESBL) producing coliforms, virulent C. difficile 027 strains and the newly recognised multiantibiotic resistant carbapenemase producing (NDM-1) coliforms, with increasing numbers of elderly and immunocompromised patients being treated within hospitals. Hospital medical staff in recent years have been expected to completely change the way they dress and hence how they may be perceived by patients. Compare the consultants of the 1970s, 1980s and 1990s wearing smart suits or long white coats over double cuff shirts and ties with the average hospital doctor in a short sleeved open necked shirt with no white coat. The impetus for the change was the publication of the bare-below-the-elbows (BBE) dress code.6,7 This requirement has been challenged on many fronts including not having a wristwatch8–10 and the lack of evidence that it is necessary to achieve adequate hand hygiene11,12 and the effect it has on patient perception.13 Other measures introduced for infection control reasons have also been challenged, such as not sitting on patients' beds14 and doing away with white coats.15–17 The challenges are understandable given the uncertainty about which measures introduced for infection prevention and control purposes are actually crucial and which ones have little or no effect.18 There is a concern that putting excessive time and resource into promoting hand decontamination will mean that other equally important initiatives are not fully implemented including prudent antimicrobial prescribing, ensuring optimal wound, urinary catheter and intravascular catheter care together with increased nurse:patient ratios, reduced bed occupancy and optimal cleaning. Decontaminating hands needs to be viewed as just one component of a hospital's infection prevention and control programme19 which is seen as part of the responsibility of all healthcare workers.1 The BBE campaign is just one part of the important hand decontamination initiative but there is a danger that the importance of the message about hand hygiene will be lost in the debate about specific components of the programme. There is, however, an argument that healthcare workers who roll up their sleeves, remove wrist watches and ties are taking their role in infection prevention and control seriously and offers a visible sign that the hospital is a different environment to other workplaces.

The costs and benefits of hospital MRSA screening

Methicillin-resistant Staphylococcus aureus (MRSA) infections represent a significant challenge. Rapid and accurate identification of MRSA in hospital admissions is essential for timely treatment decisions, isolation/bio-burden reduction and reducing potential cross-transmission/acquisition of these infections. Here we present the clinical benefits and cost-effectiveness of a rapid MRSA screening programme, which was implemented at Blackpool Victoria Hospital. The economic advantages of continuing the service despite a 15% cut in overall budget are also presented. In the pre-study period (2007–2008) 20 461 emergency and 21 461 elective admissions were screened and 40 cases of MRSA bacteraemia were reported. Glycopeptide unit days were 4145. During the 12-month pilot, approximately 4% of the PCR emergency screens were positive. Nine MRSA bacteraemias were reported during this period, representing a 78% reduction over the previous year. The cost of service over 12 months was £396 285. Estimated savings from the reduction in bed days and glycopeptide use ranged from 282 266 to 329 117. Hospital-acquired (post 48 hours) MRSA bacteraemias were reduced from 28 to 5. Annual glycopeptide spend was reduced by 50%, from £251 168 (2007–2008) to £124 060 (2008–2009). Rapidly available MRSA results were used to complement clinical decision making and optimize treatment. The cost-effectiveness of any screening programme is proportional to its success. The overall benefits and savings achieved in the current study more than justified the expenditure on rapid screening, and the Trust has since adopted PCR as a regular screening service for emergency admissions.

Decline of EMRSA-16 amongst methicillin-resistant Staphylococcus aureus causing bacteraemias in the UK between 2001 and 2007

Between 1998 and 2000, 95.6% of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemias in the UK were due to two epidemic strains, namely EMRSA-15 or EMRSA-16 (60.2% and 35.4%, respectively). We sought to determine the proportions of these strains before and after the general decline in MRSA bacteraemia that began around 2004. Consecutive MRSA isolates collected in 2001, 2003, 2005 and 2007 by the BSAC Bacteraemia Surveillance Programme were categorized to multilocus sequence typing (MLST) clonal complex and to SCCmec type by PCR. MICs were determined by the BSAC method. Data trends were tested for significance using a generalized linear regression model. Collectively, EMRSA-15 and EMRSA-16 consistently accounted for approximately 95% of MRSA studied between 2001 and 2007, but the proportions of EMRSA-16 declined from 21.4% in 2001 to 9% in 2007 (P < 0.05), whilst the proportion of EMRSA-15 rose commensurately, accounting for 85% of MRSA in 2007. Ciprofloxacin and erythromycin resistance were common amongst both EMRSA-15 and EMRSA-16. EMRSA-15 and EMRSA-16 remain the main MRSA strains in bacteraemia in the UK, but the proportion of EMRSA-16 declined from the late 1990 s, thus preceding the general decline in MRSA bacteraemias that began in the middle of the present decade.

Are There Better Methods of Monitoring MRSA Control than Bacteraemia Surveillance? An Observational Database Study

BackgroundDespite a substantial burden of non-bacteraemic methicillin resistant Staphylococcus aureus (MRSA) disease, most MRSA surveillance schemes are based on bacteraemias. Using bacteraemia as an outcome, trends at hospital level are difficult to discern, due to random variation. We investigated rates of nosocomial bacteraemic and non-bacteraemic MRSA infection as surveillance outcomes.Methods and FindingsWe used microbiology and patient administration system data from an Oxford hospital to estimate monthly rates of first nosocomial MRSA bacteraemia, and nosocomial MRSA isolation from blood/respiratory/sterile site specimens (“sterile sites”) or all clinical samples (screens excluded) in all patients admitted from the community for at least 2 days between April 1998 and June 2006. During this period there were 441 nosocomial MRSA bacteraemias, 1464 MRSA isolations from sterile sites, and 3450 isolations from clinical specimens (8% blood, 15% sterile site, 10% respiratory, 59% surface swabs, 8% urine) in over 2.6 million patient-days. The ratio of bacteraemias to sterile site and all clinical isolations was similar over this period (around 3 and 8-fold lower respectively), during which rates of nosocomial MRSA bacteraemia increased by 27% per year to July 2003 before decreasing by 18% per year thereafter (heterogeneity p<0.001). Trends in sterile site and all clinical isolations were similar. Notably, a change in rate of all clinical MRSA isolations in December 2002 could first be detected with conventional statistical significance by August 2003 (p = 0.03). In contrast, when monitoring MRSA bacteraemia, identification of probable changes in trend took longer, first achieving p<0.05 in July 2004.ConclusionsMRSA isolation from all sites of suspected infection, including bacteraemic and non-bacteraemic isolation, is a potential new surveillance method for MRSA control. It occurs about 8 times more frequently than bacteraemia, allowing robust statistical determination of changing rates over substantially shorter times or smaller areas than using bacteraemia as an outcome.

Significant reductions in methicillin‐resistant Staphylococcus aureus bacteraemia and clinical isolates associated with a multisite, hand hygiene culture‐change program and subsequent successful statewide roll‐out

To assess the efficacy of a multimodal, centrally coordinated, multisite hand hygiene culture-change program (HHCCP) for reducing rates of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia and disease in Victorian hospitals. A pilot HHCCP was conducted over a 24-month period (October 2004 to September 2006) in six Victorian health care institutions (4 urban, 2 rural; total beds, 2379). Subsequently, we assessed the efficacy of an identical program implemented throughout Victorian public hospitals over a 12-month period (beginning between March 2006 and July 2006). Rates of hand hygiene (HH) compliance; rates of MRSA disease (patients with bacteraemia and number of clinical isolates per 100 patient discharges [PD]). Mean HH compliance improved significantly at all pilot program sites, from 21% (95% CI, 20%-22%) at baseline to 48% (95% CI, 47%-49%) at 12 months and 47% (95% CI, 46%-48%; range, 31%-75%) at 24 months. Mean baseline rates for the number of patients with MRSA bacteraemia and the number of clinical MRSA isolates were 0.05/100 PD per month (range, 0.00-0.13) and 1.39/100 PD per month (range, 0.16-2.39), respectively. These were significantly reduced after 24 months to 0.02/100 PD per month for bacteraemia (P = 0.035 for trend; 65 fewer patients with bacteraemia) and 0.73/100 PD per month for MRSA isolates (P = 0.003; 716 fewer isolates). Similar findings were noted 12 months after the statewide roll-out, with an increase in mean HH compliance (from 20% to 53%; P < 0.001) and reductions in the rates of MRSA isolates (P = 0.043) and bacteraemias (P = 0.09). Pilot and subsequent statewide implementation of a multimodal HHCCP was effective in significantly improving HH compliance and reducing rates of MRSA infection.

Is MRSA admission bacteraemia community-acquired? A case control study

To compare characteristics of methicillin resistant Staphylococcus aureus (MRSA) and methicillin susceptible S. aureus (MSSA) bacteraemia detected on admission to a UK hospital and to determine whether these organisms are community-acquired. Consecutive cases of MRSA bacteraemia admitted to general medicine between 2003 and 2006 were identified and compared to MSSA age-matched and unmatched controls (35, 35 and 34 patients, respectively). Demographics, MRSA risk factors, previous health-care contact and clinical presentation were compared using patient notes. Multi-locus sequence typing was performed. 34/35 strains of admission MRSA bacteraemia were the health-care associated Sequence Types (ST)-22 (77%) or ST-36 (21%), whereas 20 different MSSA strains were identified. No MRSA cases fitted the CDC definition of community-acquired MRSA. Compatible with health-care associated acquisition, after matching for age MRSA cases had significantly higher levels of previous hospital exposure than MSSA controls, and more co-morbidities. Notably, 63% of MRSA cases were admitted from their own home, as opposed to secondary care facilities. Clinical presentation of MRSA and MSSA bacteraemias was similar. MRSA strains associated with health-care were responsible for almost all cases of MRSA bacteraemia on admission to hospital during the period studied. Despite this the majority of cases with MRSA admission bacteraemia were admitted from their own homes. Further research is needed into the determinants of MRSA bacteraemia among patients outside hospital.

Let MRSA-positive patients live a normal life

Methicillin-resistant Staphylococcus aureus (MRSA) infections have represented a serious burden in the USA and in Japan for years [1,2]. The incidence of MRSA is especially high in intensive care units (ICUs). MRSA is also becoming more prevalent in Europe, but with significant differences in the frequency of MRSA between single countries [3]. Patient-to-patient transmission in healthcare settings, usually via contaminated hands, clothes, or equipment of healthcare workers, has been a major factor accounting for the increase in MRSA incidence and prevalence in acute care facilities. More and more patients become MRSA-positive, often causing harmless colonization and sometimes causing infection. Special management of these patients is required in a clinical setting. Guidelines for preventing the spread of MRSA mostly recommend contact precautions and isolation of infected or colonized patients in a single room or cohort. These measures include grouping the patients geographically with designated staff. The recommended measures are very complex, time consuming and expensive. Methicillin resistance in S. aureus bacteraemia is associated with significant increases in length of hospitalization and hospital charges, at least partially as a result of the demanded additional measures [4]. A questionnaire analysis from England showed large variations in MRSA policies in ICUs [5]. As a policy, 24% of the ICUs do not isolate their MRSA patients. Also, in Germany, 34% of the ICUs do not isolate MRSA patients in a single room [6]. Fifteen percent of the English ICUs have specified wards that do not accept MRSA patients. These policies lead to a delay in ICU discharge of 63% [5]. The question which arises is the following: is the evidence for recommendations to control the spread of MRSA, especially isolation in a single room, strong enough and does it justify the additional costs, workload and loads for the patients? A before and after study in two ICUs found no tangible benefit from moving patients, in whomMRSA infection had been detected, into cohort-isolation care [7]. However, a major characteristic of this study is the excellent nursing staff of the participating ICUs, with a nurse-to-patient ratio of 3.3–4.3 per 24 h. Obviously in these circumstances, no benefit fromphysical isolation can be expected, since it will not substantially alter the number of contacts with, or proportion of, nursing staff exposed to MRSA carriers. The study shows the possible influence on results by the attendant circumstances. On the other hand, a systematic review of isolation policies found four series providing the strongest evidence that intensive control measures, including patient isolation, were effective in controlling MRSA [8]. Nevertheless, no well-designed study allows the role of isolation measures to be assessed alone. Hand washing is the most effective and economic intervention shown to reduce transmission of pathogens and nosocomial infection rates. Isolation precautions are unable to increase compliance with hand disinfection [9]. Studies have shown that 80% of staff dressing MRSA-infected wounds may carry the organism on their hands for up to 3 h. This carriage can be almost completely eradicated by immediate washing with liquid soap and water after patient contact [10,11]. In the study by Harbarth et al. [12], 1771 new cases of MRSA were reported in 9 years, including 158 MRSA bacteraemias. For the first 4 years, no control measures were in place and the total incidence of new MRSA cases and MRSA bacteraemias numbers rose rapidly. The first 2 years after the introduction of single-room isolation, together with screening and eradication, totalled to a stabilization of MRSA rates and a start in the decline of MRSA bacteraemias. The addition over the next 3 years of a hand-hygiene programme with documented improved compliance coincided with a yearly fall in MRSA bacteraemias rates, to less than one-third of the pre-intervention level. This work provided stronger evidence that an effective Correspondence and offprint requests to: Christine Geffers, Institute of Hygiene and Environmental Health, Charite – University Medicine, Heubnerweg 6, D 14059 Berlin, Germany. E-mail: christine.geffers@charite.de

Surveillance and epidemiology of MRSA bacteraemia in the UK

Surveillance of bacteraemia caused by methicillin-resistant Staphylococcus aureus (MRSA) in the UK has involved collection of data from hospital microbiology laboratories via several mechanisms, including a voluntary reporting scheme that has been operational in England and Wales since 1989 and mandatory reporting schemes that have been running independently in England, Wales, Scotland and Northern Ireland since 2001. In addition, surveillance schemes involving panels of participating sentinel laboratories that submit isolates for centralized susceptibility testing, such as the Bacteraemia Resistance Surveillance Programme run by the BSAC, have also been established. Each of these data sources have particular advantages, but they also have their individual limitations, with the result that they each give an incomplete picture if considered in isolation. However, by pooling the findings from these different but complementary surveillance programmes, a much more comprehensive and credible picture of the problem posed by MRSA is produced. These schemes have shown both a dramatic rise in the total numbers of cases of S. aureus bacteraemia reported annually and an increase in the proportion of such cases that involve MRSA (from 2% in 1990 to >40% in the early 2000s), although the most recent data indicate a slight reversal of these trends. Characterization of isolates of MRSA shows a marked temporal relationship between the rise in MRSA bacteraemias and the emergence and spread of two strains of epidemic MRSA, EMRSA-15 and EMRSA-16. Surveillance and control of MRSA infection continue to be high profile and further developments to the mandatory surveillance system in England are likely in the near future.

Cost-effectiveness of active surveillance cultures and contact/droplet precautions for control of methicillin-resistantStaphylococcus aureus

Some have reported that adopting Centers for Disease Control and Prevention guidelines requiring contact precautions for methicillin-resistant Staphylococcus aureus (MRSA) had no impact on rates of nosocomial spread or infection, and may therefore waste money. The objective of the present study was to evaluate the cost-effectiveness of active surveillance cultures and barrier precautions for controlling MRSA. Estimated costs of surveillance cultures and isolation measures used during an MRSA outbreak at this hospital were compared with the estimated attributable excess costs of methicillin resistance (i.e., the difference between MRSA and methicillin-sensitive S. aureus costs) for bacteraemias occurring during an MRSA outbreak not promptly controlled at another hospital. The study was set in the neonatal intensive care units of two tertiary care hospitals. Estimated costs of controlling the 10.5-month outbreak in this neonatal intensive care unit that resulted in 18 colonized and four infected infants ranged from $48617 to $68637. The estimated attributable excess cost of 75 MRSA bacteraemias in a second neonatal intensive care unit outbreak that resulted in 14 deaths and lasted 51 months was $1306600. Weekly active surveillance cultures and isolation of patients with MRSA halted an outbreak at this hospital, and cost 19- to 27-fold less than the attributable costs of MRSA bacteraemias in another outbreak that was not promptly controlled. The costs of infections at other body sites and the human cost of deaths from infection were not estimated but would further help to justify the cost of identifying colonized patients and implementing effective preventive measures.