Dependence of serum procalcitonin level on microflora in the infection site in chronic osteomyelitis

Introduction The study of procalcitonin (PCT) levels simultaneously with blood cultures for sterility is an important addition to the diagnostic algorithm for chronic osteomyelitis detection. Purpose of work is to study the relationship of serum PCT with the microflora isolated from blood, wounds and fistulas in patients with chronic osteomyelitis. Materials and methods A retrospective analysis of wound microflora, blood cultures for sterility, and procalcitonin test results was performed. Results Gram-positive microorganisms prevailed in the microbial tests from wounds, fistulas and blood in patients with PCT less than 0.5 ng/ml and from 0.5 to 2.0 ng/ml. In patients with PCT levels from 2.0– 10.0 and above10 ng/ml, both gram-positive and gram-negative bacteria were isolated. Among positive blood cultures, S. epidermidis strains were the most frequently isolated, followed by S. aureus, K. pneumoniae, S. agalactae, and S. hominis isolates. PCT in the blood of seven patients was higher than 10 ng/ml; and six patients had it from 2.0–10.0 ng/ml. Two subjects had a low PCT level, but an infectious agent was detected in their blood. Discussion In patients with PCT lower than 0.5 ng/ml, gram-positive microorganisms are most often found in the microflora of wounds and fistulas. The proportion of patients with PCT values ≥ 2 ng/ml and gram‑negative bacteria in the focus was higher compared to patients with gram-positive microflora. Nevertheless, the detected high correlation relationship between the microbiocenosis of patients' wounds and procalcitonin values confirms the leading role of gram-positive bacteria in the development of osteomyelitis. Conclusion In positive blood cultures, the serum PCT level was usually higher than 2.0 ng/ml. The presence of gram-negative bacteria in the blood, as well as in the wound, was accompanied by PCT values higher than 10 ng/ml.