[Experimental study on prevention of diabetes complicated with tuberculosis by Mycobacterium vaccae].

Objective: To study if Mycobacterium vaccae has any effect in prevention of rats with diabetes from tuberculosis.

Methods: Wistar rats with diabetes which were produced by injection of streptozotocin one week before were divided into four groups. Mycobacterium vaccae was injected into Wistar rats with diabetes and one month later H(37)R(v) was injected intravenously. The rats were sacrificed six weeks later to observe pathomorphologic changes in lung tissues. Indexes for evaluation included quantitative culture of Mycobacterium tuberculosis of lung tissue, tubercular lesion, count of Mycobacterium tuberculosis in alveolar macrophages and histopathological changes.

Results: Pathological change index of tubercular lesion, quantitative culture of Mycobacterium tuberculosis in lung tissue, count of Mycobacterium tuberculosis in alveolar macrophages were 2.5 +/- 0.7, (4.1 +/- 0.6) x 10(4) cfu, 2.6 +/- 0.9 respectively in group injected with Mycobacterium vaccae, while 3.3 +/- 0.5, (9.9 +/- 1.0) x 10(4) cfu, 7.2 +/- 0.7 respectively in the control group. Statistically significant differences were found between the two groups (P < 0.05, < 0.01, < 0.01 respectively). The histopathological changes of lung tissue in group of diabetes complicated with tuberculosis revealed that the lesions were predominant with necrosis, while in group injected with Mycobacterium vaccae, the lesions showed proliferation mainly. This indicated that Mycobacterium vaccae could decrease the damage to the lung tissue of the rat with diabetes by tubercle bacilli.

Conclusion: Mycobacterium vaccae might play a role in prevention of rat with diabetes from tuberculosis.