Exploring the Value of Paired Microbiology and Histology in Chronic Osteomyelitis and Fracture-Related Infections

Background: Microbiological culture and histology are gold standards for diagnosing chronic osteomyelitis (cOM) and fracture-related infection (FRI). This study investigated whether combining these modalities within a single tissue sample provides additional insight into disease severity. We hypothesized that high neutrophil and osteoclast numbers correlate with culture-positive microbiology and that double-positive samples may indicate more severe disease. Methods: In this prospective single-centre study, adults undergoing surgery for confirmed FRI or cOM were included. Clinical and disease classification data (FRI and BACH) were recorded. Five deep-tissue samples were collected intraoperatively and divided for paired microbiological culture and histological assessment of neutrophil infiltration, according to international diagnostic guidelines. Results: Forty-one patients were included (11 cOM, 30 FRI) of whom 68% received preoperative antibiotics. Nineteen patients (46%) were identified as culture-positive, while 32 patients (78%) were histologically positive according to international diagnostic guidelines, respectively. Among the 205 samples, 31% were culture-positive, 56% histology-positive, and 26% double-positive. Histological scores were significantly higher in culture-positive samples (p < 0.001). Treatment failure occurred in seven patients (18%), all with FRI. Paired positive samples were associated with increased odds of clinical failure and earlier revision, with odds increasing 1.68-fold for each additional paired positive sample (95% CI, 1.10-2.77). Conclusions: The paired analysis demonstrated a strong concordance between culture-positivity and suppurative inflammation within the same sample. Combining microbiology and histology may help identify patients at increased risk of revision and enhance diagnostic certainty, particularly in patients identified as culture-negative.