Adherence and biofilm formation of Staphylococcus epidermidis and Mycobacterium tuberculosis on various spinal implants

Study Design. Bacterial adherence and biofilm formation in implant-associated infection may vary depending on species of microorganisms and characteristics of implant surfaces. Objectives. We evaluated the differences in adherence and biofilm formation between Staphylococcus epidermidis and Mycobacterium tuberculosis on various spinal implant surfaces. Summary of Background Data. In implant-associated infections, bacteria in biofilm are resistant to antibiotics or host defense mechanism. The removal of implants is usually necessary to eradicate infection. On the contrary, in tuberculous infection, complete debridement and antituberculous chemotherapy without removal of implant have been regarded as a safe procedure. Methods. S. epidermidis and M. tuberculosis were cultured with 4 types of metal segments, smooth or rough-surfaced stainless steel, and titanium alloy, respectively. After isolation of colonized microorganisms and biofilm with trypsin treatment and culture on plate media, colony-forming units were counted. The features of adherence and biofilm formation were observed under scanning electron microscopy. Results. Biofilm-forming S. epidermidis showed heavy adhesion and multiplication on the surface of all 4 metal segments, 16.5 times more colony-forming units than nonbiofilm-forming ones. On scanning electron microscopy, there were many aggregated microcolonies with thick biofilm in biofilm-forming S. epidermidis but much less in nonbiofilm-forming S. epidermidis. M. tuberculosis were rarely adhered to metal surfaces and showed scanty biofilm formation. Conclusions. On the contrary to S. epidermidis, adherence and biofilm formation of M. tuberculosis on implant surface are less likely, and it can provide the basis of successful instrumentation in spine tuberculosis.