Altered bactericidal activity against Staphylococcus aureus in tuberculous bronchoalveolar lavage fluids

We wished to evaluate the pulmonary defence capacity against common bacterial infections in patients with pulmonary tuberculosis. Bactericidal activity against Staphylococcus aureus of bronchoalveolar lavage fluids (cell-free supernatants) of patients with active (n = 13) and inactive pulmonary tuberculosis (n = 8), and normal individuals (n = 6), were studied. The 2 and 4 h bactericidal activities were higher than the 0 h activity in lavage fluids of healthy subjects and patients with inactive pulmonary tuberculosis. Active tuberculous lavage fluids were equally competent in their bactericidal activity against S. aureus at 0 and 2 h, but a reduced S. aureus killing was seen at 4 h of incubation. Estimation of total phospholipid levels revealed no significant difference between the various lavage fluids. This reduced killing of S. aureus showed a relationship with the cellular components (lymphocytes and macrophages) of active tuberculous lavage fluids. A reduced killing was associated with no lymphocytic alveolitis, and an increased killing with lymphocytic alveolitis. This study suggests that alveolar lining material of patients with active pulmonary tuberculosis has less bactericidal activity against bacterial infections, such as S. aureus.