Mycobacterium szulgai: articular infections case report

Introduction: The bone and joint infections sustained by mycobacteria and mainly involving the synovium, tendons and bone stock, may be traumatic, especially in open fractures or iatrogenic post surgical procedures. Methods: The frustules, taken after cleaning the bone, were sent to the Microbiological Laboratory and processed for the presence of Gram-positive and Gram-negative bacterial populations, the mycobacteria Group M. tuberculosis complex and the mycobacteria belonging to the group of NTM (Non Tubercular Mycobacteria). Results: The decontaminated material was sown on liquid culture (MGIT 960 System BD Diagnostics) and on solid growth medium (Löwenstein-Jensen) and kept under observation at 37° C for 60 days. After 15 days on the solid medium there developed a mycobacterium strongly pigmented in orange. By the reverse hybridization method “GenoType® CM; Hain Diagnostika, Nehren, Germany; Arnika”, Mycobacterium szulgai was identified, an organism rarely isolated in our laboratory. On preliminary characterization it resulted scotochromogenic at 37° C and photochromogenic when cultured at 25° C. Conclusions: The isolation of M. szulgai, and the previous isolation of a M. intracellular (paper in press) from a similar material suggest that, in this type of infection, the role of mycobacteria can be clinically relevant and probably underestimated, both because the difficulty of isolating and identifying these organisms and because surgeons almost never request this type of investigation. It would therefore be appropriate to send routinely these materials to dedicated laboratories equipped to search for mycobacteria. Its identification could allow a more realistic picture on the role played by these bacterial infections in osteoarticular infections.