Method of intraoperative tissue sampling for culture has an effect on contamination risk.

Abstract

This prospective study was designed to determine whether exposure of intraoperative tissue samples to the operating room environment affects subsequent culture results. A prospective study conducted on 125 patients undergoing primary total knee arthroplasty was conducted from August 2013 to December 2015. During surgery, three samples from the infrapatellar fat pad were obtained. The first sample was obtained using clean instruments and placed directly into a specimen cup (direct). The second sample was obtained using clean instruments, placed in the palm of an assistant, then placed in the hands of the scrub nurse, and finally transferred into a specimen cup (glove). The third sample was obtained with clean instruments, placed on a gauze pad on the back table, and transferred to a specimen cup at the time of skin closure (table). There were two (1.6%) positive cultures in the direct transfer group, none (0.0%) in the glove contact group, and eight (6.4%) in the exposed (table) group; there was a statistically significant difference between the glove contact and table samples (p=0.01). The organisms isolated were coagulase-negative Staphylococcus in five samples, Proprionibacterium acnes in two samples, Staphylococcus epidermidis in one sample, Pediococcus pentosaceus in one sample, and Corynebacterium in one sample. Contamination of tissue samples obtained for culture can occur if samples are exposed to the operating room environment. To prevent potential contamination, samples obtained for culture should be retrieved using clean instruments, transferred to a culture bottle directly, and transported to the microbiology laboratory as soon as possible. II.