Authors: Colin A. Neumann, Marty D. Allen, C. Daniel Benson, David A. Seligsonn, University of Louisville, Louisville, KY
Title: Open Wound Infections and Community Acquired MRSA - Is There A Correlation?
Purpose: S. aureus is the leading cause of osteomyelitis cases. There are currently two unique strains of MRSA, a hospital acquired and a community acquired. It would seem that open wounds are more likely to develop CA-MRSA than closed fractures.
Methods: The goal of this study was to determine if there is a correlation between the presence of open/closed wounds and the causative organism responsible for post-operative osteomyelitis. This was a retrospective study that looked at 100 patients at the University of Louisville Hospital and the VA Hospital of Louisville from 2006-2009. Patients in this study underwent various orthopaedic surgeries, and those that subsequently developed wound site infections after surgery had their wound sites cultured. Cultures that came back positive for MRSA, were further analyzed to determine the particular strain of MRSA. The patient information was gathered into a database from which data regarding type of injury, treatment option, whether or not hardware was implanted, anatomical location of culture site, co-morbidities, and specific type of MRSA colonization.
Results: Of the 100 patients developing a MRSA infection after undergoing orthopaedic surgeries, there were 23 females and 67 males with a mean age of 38± 15. Of the 56 patients with hardware implanted, 33 developed HA-MRSA infections and 23 developed CA-MRSA infections. Of the 44 patients that did not have hardware implanted, 31 developed HA-MRSA infections while 13 developed CA-MRSA infections. According to our data there is no relationship between the strain of MRSA and the presence of open wounds with implanted hardware as had been hypothesized. Further analysis also concluded that there is no relationship between type 2 diabetes and causative strain of MRSA (p = 0.20), nor is there a correlation between the presence of diabetic foot ulcers and a particular strain of MRSA (p = 0.10).
Discuassion and Conclusion: This study suggests that there is no real correlation between the type of orthopaedic injury/procedure and the strain of MRSA that caused osteomyelitis in our hospitals. We do feel that our study reflected the standard population of people undergoing orthopaedic surgeries with subsequent MRSA osteomyelitis. It is of interest that co-morbidities such as diabetes did not predispose our patients to infection by one particular strain of MRSA. A possibility for the outcome regarding implanted hardware and MRSA strain could be the emerging prevalence of CA-MRSA within the hospital setting, not just simply outside of hospitals as it once was. In fact, there was a larger percentage of patients that developed CA-MRSA after having hardware implanted (41%), than patients developing CA-MRSA without having implanted hardware (30%).