Variability of specimen handling, processing, culturing, and reporting for suspected shoulder periprosthetic joint infections during revision arthroplasty

Introduction: There is no current standard by which culture specimens from revision shoulder arthroplasty should be handled, processed, cultured, and reported. Due to the relatively low numbers of cases multicenter study may provide information to form consensus recommendations. However, assimilation of multicenter data requires comparable methodologies. The objective of this study was to document and evaluate the extent of variability between surgeons and institutions. Methods: An 11-question survey was sent to 20 shoulder surgeons as part of the American Shoulder and Elbow Surgeons Periprosthetic Joint Infection Multicenter Workgroup. Questions addressed how samples are handled in the operating room by surgeons, processing of tissue samples and explants by laboratories, number of media, culture incubation durations, and culture reporting. Results: Common practices regarding specimen handling and processing were identified including prolonged culture incubation times >13 days (94% of participants). However, substantial variation in handling of tissue and explant specimens, number and type of media used, and reporting of results were identified. The majority of surgeons reported using a sterile instrument to harvest each individual tissue specimen (10/17, 59%), more so than using any available instrument (4/17, 24%) or washing and re-using the same instrument (3/17, 18%). Half of the institutions require a time limit by which samples must be processed in the laboratory (8/16, 50%). Nine institutions (9/16, 56%) report cultures in a semiquantitative manner, while 7 (44%) report cultures in a binary fashion. Five institutions reported having performed a negative control study, and the rate of positive cultures ranged between 0% and 17%. The majority of positive cultures from the negative controls contained Cutibacterium (92%). Discussion: Specimen handling, processing, culturing, and reporting varies widely between institutions. Due to the risk of false positives as demonstrated by negative control studies, surgeons should be cognizant of potential sources of contamination at the specimen handling level in the operating room and specimen processing level in the laboratory. Given the challenges in interpretation of positive cultures in revision shoulder arthroplasty, further studies are needed to determine whether assimilation of data across institutions is acceptable or whether a standard culturing methodology across institutions is necessary.