[Risk Assessment in the Therapy for Osteomyelitis using Immunological Parameters]

The treatment of osteomyelitis is based on the surgical eradication of the septic focus and the additional administration of antibiotics (local and/or systemic). In some cases the course of the therapy may be prolonged without any obvious reason in terms of the quality of the surgical treatment, virulence and type of bacteria or the co-morbidities.

Can these patients at risk be detected by immunological assessments? Will these immunological features lead to a more individualised therapeutic strategy?

20 patients suffering from chronic osteomyelitis of the lower extremity were included in our study. Group 1: 15 patients showed a prolonged course of the disease and/or an abnormal high rate of surgery. These courses could not be correlated with the bacterial spectrum or the co-morbidities. Group 2: 5 patients showed a clinical course as expected.

Blood samples of all patients were analysed by immunological methods: lymphocytes were analysed by using 8 colour flow cytometry. CD4/8 ratio and double negative T cells were calculated. T cell response to recall antigens was determined by elispot testing.

In group 1 double negative T cell and cytotoxic T cell counts were significantly lower in comparison to group 2. This was not the case for T cells and T helper cells. In ROC analysis, area under the curve (AUC) analysis revealed best discrimination by double negative T cells (0.88). At a cut-off of 60 double negative T cells/µL, discrimination of septic complications revealed 100 % specificity and 87 % sensitivity. In elispot testing, reactivity to tetanus toxoid established best results (AUC 0.76).

The analysis of the above data shows that the detection of higk-risk patients during the therapy for osteomyelitis based on immunological features seems to be possible. Further studies are needed to verify the data collected from our pilot study.