Mycobacterial cultures not necessary for most periprosthetic joint infections
Routinely ordering mycobacterial cultures for patients with periprosthetic joint infections is not cost-effective and testing is not necessary in most cases, according to a study.
“I was working on another project looking at outcomes in patients with prosthetic joint infections and was struck by how often mycobacterial cultures were being ordered. As a result, we decided to look at the utility of these cultures,” Marjorie Golden, MD, associate professor of clinical medicine and site chief of infectious diseases at the Yale New Haven Hospital St. Raphael Campus, told Healio. “We found that the cultures are routinely being ordered, even when a bacterial pathogen had already been identified.”
For their retrospective study, Golden and colleagues reviewed operating room (OR) cultures for 97 patients admitted to Yale-New Haven Hospital between Sept. 1, 2017, and Dec. 31, 2019, who met the criteria for first hip or knee periprosthetic joint infection (PJI), and then calculated the costs.
Among 256 surgical procedures performed during the study period, “intraoperative specimens were always sent for bacterial culture and routinely for mycobacterial culture,” the researchers wrote.” More than one OR specimen was submitted for mycobacterial culture for most (93.4%) of the 97 patients, with a total of 556 mycobacterial cultures being sent throughout the study period.
According to the study, among 29 patients undergoing revision arthroplasty following hardware removal and culture-directed antibiotics, 21 (72.4%) still had mycobacterial cultures sent at time of reimplantation even through the causative organisms had already been identified. Additionally, 16 of 22 patients who underwent revision arthroplasty for failure of the prosthesis had mycobacterial cultures sent, even though concern was rare.
The researchers found that over the course of the study, mycobacterial cultures cost $8,740.32 and took 462 hours of technologists’ time. They hypothesized that by discontinuing routine mycobacterial cultures, there would be a cost savings of $18,730 over 5 years and a substantial 990 hours of savings in technologist time without sacrificing quality of care.
Based on these findings, Golden said mycobacterial cultures “should be ordered only in certain situations, such as epidemiologic risk for TB” — a hot tub exposure or gardening, for example — “immunocompromised patients, patients with exposure to [nontuberculosis mycobacteria] and those with culture-negative PJI.”