Audit Article

MRSA in patients presenting with femoral fractures

B.F. Levy, J.W. Rosson, A. Blake
Department of Orthopaedics and Trauma, Royal Surrey County Hospital, Egerton Road, Guildford, Surrey, GU2 7XX, UK

Correspondence to: B.F. Levy, Department of Orthopaedics and Trauma, Royal Surrey County Hospital, Egerton Road, Guildford, Surrey, GU2 7XX, UK
Email: brucelevy22@hotmail.com

Aim Method Results

Discussion References

Keywords: MRSA, fractured femur, deep wound infection
Surg J R Coll Surg Edinb Irel., 2 June 2004, 171-172

Aim: To assess MRSA carrier status in patients from different residences presenting with femoral fractures and to assess the incidence of MRSA deep wound infections post-operatively with regard to MRSA status on presentation. Method: One hundred and five patients were screened for MRSA on arrival over a 20-week period. They were then followed up post-operatively to determine the number of patients developing MRSA deep wound infection. Results: One out of three patients came from an institution (nursing, residential home or hospital). Nearly one in four of these patients were MRSA carriers, compared with a carrier rate of less than 1 in 20 in patients admitted from home. Of the 11 cases presenting as MRSA carriers, two developed a MRSA deep wound infection, compared with 2 out of the 94 patients not colonised with MRSA (X² p<0.01)

AIM
This study was prompted by a clinical impression that patients from nursing homes are more likely to develop methicillin resistant staphylococcus aureus (MRSA) deep wound infections, following operative treatment of femoral fractures, than patients living independently in their own homes.

The aim of the study was to determine in patients over the age of 55 years presenting with fractured femurs, the MRSA carrier status of patients with reference to their places of residence, the time to surgery from admission and the number of patients developing MRSA deep wound infections.

METHOD
All patients over 55 years of age who presented with a femoral fracture over a 20 week period, were studied. On arrival to the Accident and Emergency Department, an audit form was completed documenting their details and date of arrival. The patients were screened for the presence of MRSA in the groin and the nose using a wet swab. The date of surgery was noted and all patients were followed-up postoperatively to monitor for the development of MRSA deep (peri-prosthetic) wound infections. Patients were followed-up until their wounds had healed completely or until a MRSA deep wound infection occurred. (A deep wound infection was defined as a periprosthetic infection).

RESULTS
During the 20-week period, 105 patients fulfilled the above criteria. Thirty five patients were admitted from an institution (nursing home, residential home or another hospital). Three of the 70 patients admitted from home were carriers of MRSA on admission, compared with 8 out of 35 patients admitted from an institution. One in 4 patients from nursing homes and 1 in 5 patients from residential homes were MRSA carriers on admission, as compared with less than 1 in 20 of the patients presenting from their own home. The mean age of patients presenting already colonised with MRSA was 84 years (range 76-91 years) and the mean age of those presenting without MRSA was 82 years (range 58-102 years).

Figure 1 shows the cumulative number of patients operated upon. Seventy eight per cent of patients had been operated on within two days of admission.

Of the 105 admissions, 11 were colonised with MRSA on admission. Table 1 shows that of the 11 patients carrying MRSA on arrival, two (18%) developed MRSA deep wound infections, compared with 2 (2%) of the 94 patients who were MRSA free on admission. This difference was found to be statistically significant with a X² test (p<0.01). Of those who developed a deep wound MRSA infection, the mean age was 88 years (range 80-94 years).

DISCUSSION
With over 55,000 patients a year in the UK presenting with fractures of the neck of the femur, and the current prevalence of MRSA, the issue of prophylactic antibiotics is very pertinent.^1,2

The importance of this topic is emphasised by the incidence reported by Khan et al. (2002) in their study from Nottingham, UK, where their incidence of MRSA was 6%.3 This is slightly lower than overall incidence in our study which was 10%. Patients from nursing homes, male and age over 70 are risk factors which have been clearly documented in the literature.4

The use of prophylactic antibiotics in surgical orthopaedic procedures is well known to be beneficial. Tengve and Kjellander (1978) showed that by using cephalexin and cephalothin, the infection rate post-operatively was reduced from 16.9% to 1.8%.^5,6 Albers et al. (1994) showed that antibiotic prophylaxis in closed fractures was cost-effective if the risk of deep infection was decreased by as little as 0.25%.

Figure 1: Graph showing that 78% of patients were operated on by day two

The prophylactic antibiotic used needs to cover all relevant pathogenic organisms. Three doses of cephazolin were used in our hospital at the time of this study. The use of cephazolin selects out sensitive organisms, leaving MRSA to colonise the wound. The issue of MRSA colonising a wound is important due to its prevalence in these patients. In our study every third patient presenting with a fractured femur was from an institution, and within this sub-group, one in four patients were colonised with MRSA.

Furthermore, one in five of the patients carrying MRSA on presentation developed a deep wound MRSA infection, compared with only 1 in 50 of the patients not colonised with MRSA. This difference is substantially more that the 0.25% decrease, as suggested by Albers et al. (1994), in ensuring antibiotic prophylaxis was cost-effective.⁷

Prophylactic antibiotics, therefore, need to be targeted against MRSA in patients who are at high risk of being carriers, in an attempt to narrow this wide discrepancy in infection rates. Screening patients on presentation is not appropriate to determine MRSA carriers, as it takes two days to obtain a result by which time most patients have had their surgery.

The results of this study suggest that patients presenting from an institution should benefit from antibiotic prophylaxis targeted against MRSA. Additionally, patients who have a prolonged hospital stay prior to surgery should be considered for MRSA targeted prophylaxis.

We would also suggest that patients admitted from institutions should be placed in isolation while their MRSA status is determined. This may not be possible due to bed limitations in which case we would suggest placing all these patients together in one bay of the ward rather than spreading them out randomly throughout the ward.

REFERENCES
1. Department Of Heath. Hospital Episode Statistics, England: financial year 1990-1991; Vol 1. London: HMSO; 1994.
2. Audit Commission, United They Stand; November 1995.
3. Khan OA, Weston VC, Scammell BE. Methicillin-resistant Staphylococcus aureus incidence and outcome in patients with neck of femur fractures. J Hosp Infect 2002; 51:185-8.
4. Samad A, Banerjee D, Carbarns N, Ghosh S. Prevalence of methicillinresistant Staphylococcus aureus colonization in surgical patients, on admission to a Welsh hospital. J Hosp Infect 2002; 51:43-6.
5. Gillespie WJ, Walenkamp G. Antibiotic prophylaxis for surgery for proximal femoral and other closed long bone fractures. Cochrane Database of Systemic Reviews. 2000; 2:CD000244; 10796333.
6. Tengve B, Kjellander J. Antibiotic prophylaxis in operations on trochanteric femoral fractures. Journal of Bone & Joint Surgery. 1978; 60: 97-99.
7. Albers BA, Patka P, Haarman HJ, Kostense PJ. Cost effectiveness of preventive antibiotic administration for lowering risk of infection by 0.25%. Unfallchirurg 1994; 97:625-28.

Copyright: 17 March 2004