873. Use of Sonication for Diagnosis of Orthopedic Hardware Infection
Session: Poster Abstract Session: Bone, Joint, and Soft Tissue Infection
Friday, October 19, 2012
Room: SDCC Poster Hall F-H
Posters
  • IDSA poster 8x4ver2.pdf (802.5 kB)
  • Background:

    Management of failed orthopedic implants depends on whether infection is present. Sonication of hardware disrupts the bacterial biofilm attached to prosthesis surface and is more sensitive than peri-prosthetic culture of tissue in the setting of prosthetic joint infection.

    Methods:

    A retrospective cohort of adult patients between 06/2009- 06/2011 at KUMC was evaluated to compare results of sonication compared to bacterial culture of tissue from orthopedic hardware. Patients were included if tissue was cultured at the same time as hardware sonicate fluid cultures (plates, screws, nails and K-wires). Sonicate fluid was incubated on blood, McConkey and chocolate agar, broth media and inoculated into aerobic and anaerobic blood culture bottles. The agreement between sonicate culture methods and cultures of tissue was assessed using kappa statistic.  

    Results:

    48 patients with a median age of 55 years were analyzed. 30 patients (63%) were male, 8 (16.7%) were diabetic and 12 (25%) were on antibiotics 14 days prior to culture. Sonication fluid was positive in 23/48 (47.9%) patients and 9/48 (18.75%) of the patients had coagulase negative Staphylococcus. The yield from sonication was highest from blood culture bottle inoculation (46 %) followed by agar (33 %) and broth culture (13 %). Positive culture from tissue was noted in 20 patients (41.6 %). Sonication identified infection in 6 (13%) additional patients compared to culture of tissue.  Culture of tissue identified a pathogen in 3 (6%) additional patients compared to sonication. Sonication fluid culture inoculated into blood culture bottles agreed with culture of tissue 79% of the time (k= 0.58); agar plating had 83.3% agreement with culture of tissue (k= 0.68) and broth culture had 72% agreement with culture of tissue (k= 0.355). Sonication by any method had 77% agreement with culture of tissue (k= 0.62). 

    Conclusion:

    Sonication method significantly increased yield of bacteria compared to the culture of tissue.  However occasionally, culture of tissue detects organisms not detected by sonication. Blood culture inoculation increases the yield of sonication cultures compared to direct plating or broth culture. Sonication is a promising method for the diagnosis of infected orthopedic implant infections, but the methodology requires optimization.

    Samina Khumri, MD, University of Kansas Medical Center, Kansas City, KS, Lisa Clough, MD, Infectious Diseases, University of Kansas Medical Center, Kansas City, KS, Rebecca Horvat, PhD, Pathology and Laboratory Medicine, University of Kansas, Kansas City, KS and Wissam El Atrouni, MD, Infectious Diseases, Kansas University Medical Center, Kansas City, KS

    Disclosures:

    S. Khumri, None

    L. Clough, None

    R. Horvat, None

    W. El Atrouni, None

    Findings in the abstracts are embargoed until 12:01 a.m. PST, Oct. 17th with the exception of research findings presented at the IDWeek press conferences.