Sulfatides are sulfur containing glycolipids in the cell wall of mycobacteria that prevent fusion of phagosomes of macrophages containing M. tuberculosis with lysosomes. Another cell wall constituent, LAM, is a heteropolysaccharide similar to the endotoxins of gram-negative bacteria. The mycobacteria are initially able to replicate in naive macrophages. The classic granuloma of tuberculosis is the result of this process. The disseminated disease seen in this case indicates that the bacterial strain was highly virulent or that the monkey was particularly susceptible.
Mycobacteria can spread hematogenously to many organs when granulomas rupture into blood vessels.
The granulomas may also rupture into airways, allowing the mycobacteria to be released and transmitted to other hosts in aerosols. Research is being done to develop enzyme-linked immunosorbent assays and polymerase chain reaction tests to accurately and rapidly identify and diagnosis mycobacterial infections in man and animals. In Pathologic basis of disease. Cotran RS, Kumar V, and Robbins SL eds., 5th edition, W.B. Saunders Co., 1994. The American Veterinary Medical Association and the American College of Veterinary Pathologists are co-sponsors of the Registry of Veterinary Pathology.