692. Patient characteristics and organisms involved in surgical site infections post-total knee arthroplasty: The Incidence of Methicillin Resistant Staphylococcus Aureus and Evaluation of the appropriate use of peri-operative antibiotic prophylaxis
Session: Poster Abstract Session: Skin, Soft Tissue and Joint Infections
Friday, October 21, 2011
Room: Poster Hall B1
  • IDSA-Lydia Tang Oct 2011.pdf (198.2 kB)
  • Background:Current guidelines state that patients undergoing knee replacement should receive a prophylactic antibiotic 1 hour prior to the surgical incision and be discontinued within 24 hours. The goal for antibiotic prophylaxis is to prevent surgical site infections without antibiotic overuse. Emerging drug-resistant bacteria and changing patterns of infection may pose challenges to this “one-size fits all” approach. This retrospective study aimed to determine the incidence of SSI post-total knee arthroplasty (TKA) in a large medical center, identify potential risk factors for infection, and describe the the microbiology of the isolated organisms

    Methods:Retrospective chart review of surgical site infections, including culture negative infections, occurring among the post-TKA performed at Orlando Health from January 2004 through December 2009. Only skeletally mature patients and primary arthroplasties were included. All intraoperative, knee, blood and urine cultures were examined. Descriptive statistics with p-value significance set at 0.05 were utilized.

    Results:2187 TKA were performed. Forty-eight cases of surgical site infections were reported (2.2%), with 34 cultured. 24 cases required surgical intervention. Mean age was 63 years (43-92). 42% were male. Mean BMI was 32 (21-51). Operative time ranged from 0:55h to 3:14h (mean 1:56h). Mean length of stay was 5.1 days (2-12), and mean time to culture was 92.7 days (2-839). Mean time of preop antibiotic administration was 0:46h (0:03-4:49). 52 isolates were obtained: 37 (71.2%) gram-positives, 10 (19.6%) gram-negatives, and 5 (9.8%) fungi. 9 of the 48 cases had MRSA (18.8%). 40 cases received cefazolin, 6 vancomycin, 2 both cefazolin and vancomycin, 1 clindamycin and 1 no antibiotic. The incidence of MRSA post cefazolin versus vancomycin was not statistically significant. Positive cultures post 1g of cefazolin compared to 2g was significantly greater (p<0.001). Of the 52 isolates, 16 (34.8%) were sensitive to, and 30 (65.2%) resistant to the preoperative antibiotic utilized.

    Conclusion:Though Gram positive organisms including MRSA predominate, Gram negatives were also common. In this retrospective sample, higher than standard doses of preop cefazolin appeared protective.

    Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

    Lydia Tang, MD1, Mary T. Busowski, MD2, Linda Papa, MD3, Mai Vo, M.D.1, Amanda Paul, MD3, Paula Harriot, RN CCRC3, Margaret Parr, RN BSN CIC4, C. Andrew DeRyke, Pharm.D.2,5, Stanley Kupiszewski, MD3 and Mark R. Wallace, MD2, (1)Internal Medicine, Orlando Health, Orlando, FL, (2)Infectious Diseases, Orlando Health, Orlando, FL, (3)Orlando Health, Orlando, FL, (4)Infection prevention, orlando health, Orlando, FL, (5)Pharmacy, Orlando Health, Orlando, FL


    L. Tang, None

    M. T. Busowski, None

    L. Papa, None

    M. Vo, None

    A. Paul, None

    P. Harriot, None

    M. Parr, None

    C. A. DeRyke, None

    S. Kupiszewski, None

    M. R. Wallace, None

    Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.