Rapid testing of patients for MRSA reduced infection rates by nearly 40%, reported the Times (19 December 2007). The newspaper accurately reported the results of a study comparing infections before and after the introduction of the test. The causal relationship between testing and the reduction in infections is uncertain.
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The Times (1) reported on 19 December 2007 that rates of infection with methicillin-resistant Staphylococcus aureus (MRSA) in patients undergoing surgery at University College Hospital, London, fell by nearly 40% following the introduction of a rapid screening test, with a 38.6% reduction in bloodstream infections and 27.9% reduction in wound infections.
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The reports were based on a study published in the British Journal of Surgery (2). In 2006, 12528 patients undergoing elective or emergency surgery were screened for MRSA using a rapid molecular technique. Of 18810 samples screened, 850 (4.5%) were positive for MRSA. Those found to be carrying the bacterium were treated with anti-bacterial nasal ointment and bodywash. Compared with the average for 2000-2005, rates of bloodstream infection with MRSA fell by 38.5% and rates of wound infection by 12.7%. Compared with 2005 alone, bloodstream infections fell by 38.6% and wound infections by 27.9%.
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The newspaper accurately reported the main findings of the research. The study appears well conducted, although this type of study cannot prove a causal connection between the introduction of the rapid screening test and the observed reduction in infection rates.
Evaluation of the evidence base for rapid molecular screening for MRSA
Where does the evidence come from?
The evidence comes from a study conducted by Mr Keshtgar and colleagues in the Departments of Surgery and Microbiology at University College Hospital (UCH), London.
What were the authors' objectives?
To establish the feasibility and cost-effectiveness of rapid molecular screening for hospital-acquired MRSA in surgical patients.
What was the nature of the evidence?
This was a study involving 18810 processed samples from 12528 patients admitted to UCH for critical care, routine or emergency surgery, and used data from patients treated in previous years as comparators. Surgical wounds were examined at 1 to 2 months after discharge.
What interventions were examined in the research?
Nasal swabs were taken and screened for the presence of MRSA using a DNA rapid MRSA screening test that provides results within hours rather than days. Patients with a positive test result were treated with mupirocin nasal ointment and chlorhexidine gluconate body and hair wash to suppress MRSA before they underwent surgery. Antibiotic prophylaxis was given in some patients.
What were the findings?
Of 18810 samples screened, 850 (4.5%) were positive for MRSA. Subsequently, 53 patients developed MRSA bloodstream infections, compared with 73 in 2005 and 573 in 2000-2005. Rates of MRSA bloodstream infection per 1000 patient days fell by 38.6% compared with 2005, and by 38.5% compared with the average for 2000-2005.
Corresponding figures for wound infections were 277 in 2006, 325 in 2005 and 2110 in 2000-2005. Rates of MRSA wound infection fell by 27.9% compared with 2005 and 12.7% compared with 2000-2005.
Compared with 2000-2005, reduction in MRSA infections was associated with cost savings of £276,220 per year; the annual cost of screening was estimated at £302,500. Compared with 2005 alone there was a cost saving of £545,426. When methicillin-susceptible Staphylococcus aureus infections were taken into account, the cost saving relative to 2000-2005 was reduced to £123,424.
What were the authors' conclusions?
Rapid MRSA screening resulted in a significant reduction in staphylococcal bloodstream infections although a causal link cannot be established with this type of study design.
How reliable are the conclusions?
This was a generally well-conducted study and the authors' cautious conclusions seem appropriate in the absence of a concurrent control group. As noted by the authors, infection rates vary between years and they took this into account by comparing 2006 with the average for 2000-2005 as well as with 2005 (a year when rates were relatively high) alone. They also stated that other aspects of practice that could have affected infection rates did not change in 2006. The conclusion focussed on the impact of screening on bloodstream infections; the reduction in surgical wound infections was considerably smaller than the reduction in bloodstream infections, though still statistically significant.
Systematic reviews
Information staff at CRD searched for systematic reviews relevant to this topic. Systematic reviews are valuable sources of evidence as they locate, appraise and synthesize all available evidence on a particular topic.
There were no related systematic reviews identified on the Cochrane Database of Systematic Reviews (CDSR), however there was one on the Database of Abstracts of Reviews of Effects (DARE)(3).
References and resources
1. MRSA test on patients cuts infections by 40 per cent. The Times, 19 December 2007, p25.
2. Keshtgar MRS, Khalili A, Coen PG, Carder C, Macrae B, Jeanes A, Folan P, Baker D, Wren M, Wilson APR. Impact of rapid molecular screening for meticillin-resistant Staphylococcus aureus in surgical wards. British Journal of Surgery, Early view. Published online 27 Nov 2007. DOI: 10.1002/bjs.6013.
3. Cooper B S, Stone S P, Kibbler C C, Cookson B D, Roberts J A, Medley G F, Duckworth G J, Lai R, Ebrahim S. Systematic review of isolation policies in the hospital management of methicillin-resistant Staphylococcus aureus: a review of the literature with epidemiological and economic modelling. Health Technology Assessment 2003;7(39):1-194. [DARE Abstract]
Consumer information
NHS Direct - MRSA
Department of Health - Healthcare associated infection
Health Protection Agency: MRSA - Information for patients in hospital
Further information about Hitting the Headlines
Further information about Hitting the Headlines, together with selected relevant links, can be found at http://www.library.nhs.uk/hth/.
