Inoculation of sonicate fluid into blood culture bottles improves microbial detection in patients with orthopedic bone and soft tissue infections of the upper and lower extremities.

BACKGROUND: The usefulness of sonicate fluid culture for biological tissues in orthopedic bone and soft tissue infections have not been reported. We assessed whether inoculating the sonicate fluid of bone and soft tissue into a blood culture bottle could increase the diagnostic accuracy for biofilm-related orthopedic infections. METHODS: Twenty consecutive patients with infections (9 purulent arthritis, 4 osteomyelitis, 4 purulent tenosynovitis, 2 purulent bursitis, and 1 cellulitis) and 10 non-infected cases (6 carpal tunnel syndrome, 3 Dupuytren contracture, and 1 soft tissue tumor) between October 2018 and December 2020 were evaluated prospectively. We analyzed a total of 107 culture submissions (87 bone and tissue specimens and 20 controls); 42 intraoperative tissue specimens (32 infected samples and 10 non-infected samples) using the conventional method, 45 sonication samples (35 infected samples and 10 non-infected samples), and 20 control samples. Intraoperative infectious tissues were cultured using sonicate fluid culture in a blood culture bottle (SFC-CB). The applications of SFC-CB and the conventional culture method and the detection rate, sensitivity, and relationship between the sensitivity of the diagnostic methods and duration of administered preoperative antibiotics were assessed. RESULTS: The causative microorganism was detected only by SFC-CB in five patients (25%). The sensitivity (85% vs. 60%; P = 0.077) and detection rate (80% vs. 60%; P = 0.065) were higher for SFC-CB than for the conventional culture method. The sensitivity of SFC-CB was significantly higher than that of the conventional culture method in cases in which preoperative antibiotics were administered for more than 1 week (77% vs. 39%; P = 0.047). CONCLUSIONS: Using SFC-CB, the diagnostic accuracy for bone and soft tissue infection was significantly improved. As biofilms are readily formed in biological tissues, sonication may also be useful for diagnosis. SFC-CB was particularly useful for cases in which preoperative antibiotics were administered.