Antibiotic prophylaxis for the prevention of methicillin-resistant Staphylococcus aureus (MRSA) related complications in surgical patients

Risk of methicillin-resistant Staphylococcus aureus (MRSA) infection after surgery is generally low, but affects up to 33% of patients after certain types of surgery. Postoperative MRSA infection can occur as surgical site infections (SSIs), chest infections, or bloodstream infections (bacteraemia). The incidence of MRSA SSIs varies from 1% to 33% depending upon the type of surgery performed and the carrier status of the individuals concerned. The optimal prophylactic antibiotic regimen for the prevention of MRSA after surgery is not known.

To compare the benefits and harms of all methods of antibiotic prophylaxis in the prevention of postoperative MRSA infection and related complications in people undergoing surgery.

In March 2013 we searched the following databases: The Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL); Database of Abstracts of Reviews of Effects (DARE) (The Cochrane Library); NHS Economic Evaluation Database (The Cochrane Library); Health Technology Assessment (HTA) Database (The Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; and EBSCO CINAHL.

We included only randomised controlled trials (RCTs) that compared one antibiotic regimen used as prophylaxis for SSIs (and other postoperative infections) with another antibiotic regimen or with no antibiotic, and that reported the methicillin resistance status of the cultured organisms. We did not limit our search for RCTs by language, publication status, publication year, or sample size.

Two review authors independently identified the trials for inclusion in the review, and extracted data. We calculated the risk ratio (RR) with 95% confidence intervals (CI) for comparing binary outcomes between the groups and planned to calculated the mean difference (MD) with 95% CI for comparing continuous outcomes. We planned to perform meta-analysis using both a fixed-effect model and a random-effects model. We performed intention-to-treat analysis whenever possible.

We included 12 RCTs, with 4704 participants, in this review. Eleven trials performed a total of 16 head-to-head comparisons of different prophylactic antibiotic regimens. Antibiotic prophylaxis was compared with no antibiotic prophylaxis in one trial. All the trials were at high risk of bias. With the exception of one trial in which all the participants were positive for nasal carriage of MRSA or had had previous MRSA infections, it does not appear that MRSA was tested or eradicated prior to surgery; nor does it appear that there was high prevalence of MRSA carrier status in the people undergoing surgery.There was no sufficient clinical similarity between the trials to perform a meta-analysis. The overall all-cause mortality in four trials that reported mortality was 14/1401 (1.0%) and there were no significant differences in mortality between the intervention and control groups in each of the individual comparisons. There were no antibiotic-related serious adverse events in any of the 561 people randomised to the seven different antibiotic regimens in four trials (three trials that reported mortality and one other trial). None of the trials reported quality of life, total length of hospital stay or the use of healthcare resources. Overall, 221/4032 (5.5%) people developed SSIs due to all organisms, and 46/4704 (1.0%) people developed SSIs due to MRSA.In the 15 comparisons that compared one antibiotic regimen with another, there were no significant differences in the proportion of people who developed SSIs. In the single trial that compared an antibiotic regimen with placebo, the proportion of people who developed SSIs was significantly lower in the group that received antibiotic prophylaxis with co-amoxiclav (or cefotaxime if allergic to penicillin) compared with placebo (all SSI: RR 0.26; 95% CI 0.11 to 0.65; MRSA SSI RR 0.05; 95% CI 0.00 to 0.83). In two trials that reported MRSA infections other than SSI, 19/478 (4.5%) people developed MRSA infections including SSI, chest infection and bacteraemia. There were no significant differences in the proportion of people who developed MRSA infections at any body site in these two comparisons.

Prophylaxis with co-amoxiclav decreases the proportion of people developing MRSA infections compared with placebo in people without malignant disease undergoing percutaneous endoscopic gastrostomy insertion, although this may be due to decreasing overall infection thereby preventing wounds from becoming secondarily infected with MRSA. There is currently no other evidence to suggest that using a combination of multiple prophylactic antibiotics or administering prophylactic antibiotics for an increased duration is of benefit to people undergoing surgery in terms of reducing MRSA infections. Well designed RCTs assessing the clinical effectiveness of different antibiotic regimens are necessary on this topic.