Background: Osteomyelitis are infections difficult to be completely cured, and its optimal therapy had not clearly been established.
Methods: We study the bactericidal activity of polymorphonuclear leukocytes and also of serum from 13 patients with Staphylococcus aureus chronic osteomyelitis. We also studied the activity of clindamycin against intraphagocytic S. aureus. The study was done in vitro using control S. aureus strain ATCC 25923 and also microorganisms recovered from infected bone.
Results: S. aureus two hours survival rates in polymorphonuclear leukocytes were 13.5 +/- 4.4 x 10(6), 10.5 +/- 4.0 x 10(6), 11.0 +/- 4.0 x 10(6), using polymorphonuclear leukocytes from controls and patients, with control and autologous sera respectively (p greater than 0.05). We have observed a bactericidal activity defect in polymorphonuclear leukocytes from one patient and in the sera of 7 other patients. The incubation with clindamycin (10 MIC) reduces the number of cfu/ml to 2.1 +/- 0.9 x 10(6), 1.1 +/- 0.7 x 10(6) y 1.9 +/- 1.1 x 10(6), and we also detected and additional inhibition of 81.7 +/- 7%, 70.7 +/- 17% and 79.0 +/- 4% respectively.
Conclusion: The results of our study confirm that clindamycin has an intracellular action against intraphagocytic S. aureus and also showed the ability of this antimicrobial agent to cover defects in defensive mechanism of the host. Both statements give support the potential usefulness of clindamycin as therapy for bone infections due to S. aureus.