Protective ability of certain lactic acid bacteria against an infection with Candida albicans in a mouse immunosuppression model by corticoid

The protective effect of Lactobacillus casei, L. acidophilus, L. delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus administered orally against an infection with Candida albicans in a corticoid immunosuppression model was studied. Balb/c mice were infected intraperitoneally with C. albicans (5 x 10(7) cells/mouse) on the third day post-corticoid inoculation. Ar 24 h after infection 1.2 X 10(9) cells/day/mouse of the bacteria under study were administered orally to the test animals for 2 days. The number of C. albicans colony forming units in liver, spleen and kidney was determined at 4-5 day intervals for 17 days. During the same period, the influence of the oral administration of the above bacteria on the immmune response of non-infected corticoid-treated mice was also studied. The phagocytic capacity of peritoneal macrophages was determined by in vitro assays, the humoral immune response by the number of plaque-forming cells and T-lymphocyte activity by she delayed hypersensitivity response for sheep red blood cell antigen. Oral administration of L. casei and L. bulgaricus in corticoid-immunosuppressed animals was demonstrated to give protection against C. albicans infection. This was due to a significant increase in the specific and non-specific immune response, which leached higher values than the non-immunosuppressed controls. L. acidophilus proved to be less effective at protection, although it reverts corticoid immunosuppression, reaching values similar to those of the normal controls. S. thermophilus was ineffective for protection, and it did not favour enhancement of the immune response, which was only slightly higher than that of the suppression controls. The authors believe that the oral administration of certain lactic acid bacteria may be extremely useful as support therapy for the control of infections produced by opportunistic microorganisms. It could affect the immunosuppression that occurs in tumour processes or other immunodeficiencies but never in autoimmune pathological events.