Over the last decade one bacterium has fuelled more scare stories than any other. Methicillin Resistant Staphylococcus Aureus or MRSA has become shorthand for all that is supposedly wrong with the level of patient care in modern hospitals. Indeed the bacterium has become so prevalent in our lives that since April 2009 the Department of Health has required that all patients undergoing elective admissions to hospital in England should be screened for MRSA. Yet is this screening programme justified? The answer according to this well-presented paper1 is yes, particularly in the case of low-risk patients undergoing total joint replacement surgery.
Over the course of a three year period the authors examined the effects of screening on a population of 5933 patients who were undergoing elective orthopaedic surgery. They found in a retrospective study that, despite effective eradication therapy, six of 90 previously positive patients had SSI (Surgical Site Infections) following joint replacement within one year from the operation and that of these infections four were deep infections caused by MRSA.
By presenting these findings the authors help to illuminate the often heated debate on the usefulness or not of MRSA screening in elective surgery. In 2009 Millar questioned the value of MRSA screening in low risk patients considering the effect that isolation can have on patients and arguing that ethical principles, including a lack of transparency in information to patients and a lack of fairness of screening on low risk patients, were breeched. He additionally claimed that other courses of managing this problem were more cost effective and that actions to extend screening to low risk patients are not in proportion to the risk to or from these patients.2 Millar’s important paper queried the role of routine MRSA screening and raised vital questions regarding the position of patients’ rights in the screening process.
The paper by Murphy et al1 which acknowledges Millar’s2 concerns and also examines other vital issues on the actual process of MRSA screening. Is the screening process itself effective and indeed are the patients admitted soon enough after the screening has taken place? Does the clearance programme work? Are the antibiotics that are given appropriate? Where do the patients who have MRSA when undergoing elective orthopaedic surgery come from?
Regarding the first point, the authors found that after effectively screening patients for MRSA they were admitted several months later for their operation and that some of these patients went on to develop a superficial or deep infection. In other words the timing of surgery after screening is crucial in order not to let recolonisation occur and therefore months spent waiting between screening and surgery is inappropriate.
The authors concluded that rapid admission to hospital after a negative screen is recommended in order to minimise the risk of recolonisation and that if a clearance programme is necessary patients should then be admitted shortly after this has taken place. It is evident therefore that the timing for surgery following screening should be in days not months.
The use of PCR (polymerised chain reaction) in identifying MRSA quickly could increase the turn round time for identification of patients with MRSA and thus speed up their passage through hospital. It is, however, worth noting that Herdman et al3 doubted its value and concluded that it was currently more prudent to await the culture confirmation before altering infection control measures on the basis of a positive PCR result. Furthermore, as non-PCR methods get faster and there are more centralised laboratories the use of PCR is arguably only of benefit to high risk patients.
The article also raises points concerning the effect that changing the antibiotic prophylaxis regime would have on the outcomes of infection following surgery. Cefuroxime is an appropriate and widely used antibiotic as prophylaxis against infection following total joint replacement and has been given for a number of years.4 Should this prophylaxis regime be continued? The authors wisely argue that the random use of the effective antibiotics against MRSA namely Vancomycin and Teicoplanin could well lead to the development of MRSA resistance if they are used widely especially as long term prophylaxis. Resistance would clearly have a disastrous effect on treating established infections and it would make a great deal of sense, as the authors suggest, to ensure that these powerful antibiotics should only be used as a prophylaxis for those patients who are identified as having MRSA on screening and not used routinely, reinforcing the value of the screening process in identifying those patients who are at risk.
The findings in the paper that patients who developed MRSA infections were from the community and not institutions is itself important and is different from those patients who following trauma sustain, for example, a fracture of the neck of the femur.5 Certainly those patients undergoing hip joint surgery seem particularly prone to MRSA, which raises the question as to whether certain patients are more prone to developing MRSA then others or that the hip joint area is for example more likely to be contaminated with MRSA then the knee joint. Therefore there is even more justification for screening all patients undergoing elective hip joint surgery in particular in order to identify this important group of patients. The clearance programme used by the authors of this paper appears to be effective and indeed these techniques are currently widely practised in hospitals in the UK, however the question does still need to be raised as to how good the screening methods really are.
The disturbing questions raised by Millar regarding patient confidentiality and the flaws within the screening system have not been fully answered. The paper does, however, show that it is possible to identify patients who are carriers and who do need eradication treatment and that those patients do then need selected antibiotic therapy to be prescribed at the time of surgery in order to prevent MRSA infections especially following total hip replacement.
Thus, for the moment at least, screening for MRSA in low risk patients undergoing elective orthopaedic surgery is justified on the basis of identifying patients who are at risk of MRSA especially when undergoing total hip joint replacement surgery.
Ultimately, however, the question that this valuable paper has really posed is whether now it is time for a large multicentre UK trial, in order to find out if low risk patients undergoing elective surgery really do need to be screened for MRSA, whether a second course of eradication is necessary if these patients are found to be positive for MRSA, if early admission for surgery is beneficial after negative screening and, finally, whether changing the antibiotics is of any value.
1. Murphy E, Spencer SJ, Young D, Jones B, Blyth MJG. MRSA colonisation and subsequent risk of infection despite effective eradication in orthopaedic elective surgery. J Bone Joint Surg [Br] 2011;93-B:548-51.
2. Millar M. Should we screen low risk patients for methicillin resistant Staphylococcus Aureus? BMJ 2009;339:b4035
3. Herdman MT, Wyncoll D, Halligan E, Cliff PR, French G, Edgeworth JD. Clinical Application of Real-Time PCR to screening Critically Ill and Emergency –Care Surgical Patients for Methicillin-Resistant Staphylococcus Aureus. A Quantitative Analytical Study J Clin Microbiol 2009 47 4102 -4108.
4. Hughes SPF, Want S, Darrell JH, Dash CH, Kennedy M. Prophylactic Cefuroxime in total joint replacement. Int Orthop 1982;6:155-61.
5. Tai CC, Nirvani AA, Homes A, Hughes SPF. Methiciliin-resitant Staphylococcus aureus in orthopaedic surgery Int Orthop 2004;28:32-35.
Emeritus Professor Orthopaedic Surgery
Imperial College London.