Abstract
Background
Hospital acquired MRSA is globally endemic and is a leading cause of surgical site infection (SSI). Of great concern is the emergence of community acquired MRSA (CA MRSA) with its unique virulence characteristics. Infected hip or knee prostheses due to MRSA are associated with multiple reoperations and prolonged hospital stay. Few studies have been done to assess for risk of SSI in MRSA carriers undergoing elective orthopaedic surgery following decolonisation. However in these studies, the eradication status was not confirmed prior to proceeding for surgical intervention.
Aim
The purpose of the study was to evaluate the incidence of SSI in MRSA carriers undergoing elective hip and knee arthroplasty, who had confirmed eradication of MRSA carrier status and to compare it with incidence of SSI in non MRSA carriers.
Material and Methods
This is a retrospective analysis of 6613 patients who underwent elective hip (3347) and knee arthroplasty (3266) at our institution between January 2008 and August 2012. A cohort of patients who were preoperatively colonised with MRSA was identified. These patients were offered decolonisation protocol and successful eradication was ensured prior to surgery. The MRSA negative patients served as the control group and we looked into the incidence of SSI in both groups up to one year after surgery. Categorical variables were investigated between groups using chi-squared tests and p value of < 0.05 was taken as significant.
Results
Out of 6613 patients, MRSA colonisation was observed in 83 patients (a mean age of 76 years with a M:F ratio of 1:1.2) pre-operatively with a colonisation rate of 1.3%. A total of 79 patients had confirmed eradication of carrier status prior to surgical intervention. Of these 38 were THRs and 41 were TKRs. Total number of MRSA negative patients were 6530 with 3307 THRs and 3223 TKRs in control group. Teicoplanin was used for antibiotic prophylaxis in these patients. 5 of 79 patients had “deep SSI” within 1 year of surgery giving an infection rate of 6.32%. There were 2 MRSA infections in hip replacements with an infection rate of 5.26%. There were 2 MRSA and 1 MSSA infection in TKR resulting in an infection rate of 7.31%. These patients did not belong to the “high-risk” group for MRSA colonisation. A significant statistical difference in infection rates from MRSA negative control group was noted, which had a deep sepsis rate of 1.17% (p value − 0.03) in THRs and 0.87% in TKRs (p value − 0.0016).
Conclusions and Clinical Implication
In spite of a selective treatment program for carriers and confirmed eradication in terms of achieving a reduction in the rate of SSI, there is still a significantly increased risk of SSI in MRSA colonised patients undergoing hip and knee replacements. Also, should infection develop, MRSA is the most likely causative organism. Patients should be made aware of this higher risk of infection and the serious consequences of developing MRSA SSI.
