Nontuberculous mycobacterial infection attributable to Mycobacterium intracellulare serotype 10 in two rhesus monkeys

Infection with Mycobacterium intracellulare serotype 10 was diagnosed in 2 rhesus monkeys (Macaca mulatta) in a closed colony of 90 animals. The clinicopathologic presentation in 1 animal with advanced disease was characterized by a precipitous weight loss, therapeutically unresponsive diarrhea, anemia, weakness, prostration, refractory tuberculin tests (using mammalian old tuberculin and M bovis purified protein derivative tuberculin), and disseminated granulomas in the lungs, spleen, liver, kidneys, lymph nodes, salivary glands, and intestines. The lamina propria throughout the large and small intestines was infiltrated with mycobacteria-laden macrophages. Severe hypoproteinemia, hypoalbuminemia, hypoglobulinemia, mild hypocalcemia, and edema were compatible with a malabsorption-like syndrome. The 2nd animal was clinically normal, but a weak positive tuberculin reaction to M bovis purified protein derivative at 72 hours necessitated euthanasia. This animal's disease was characterized by microgranulomas in the lungs, bronchial lymph nodes, liver, and pancreas, without involvement of the gastrointestinal tract. There was no evidence of M intracellulare infection in the remaining 88 animals in the colony, as determined by mycobacterial cultures of tracheobronchial washings, additional tuberculin testing, thoracic radiography, and mycobacterial culture of the drinking water. Tuberculin testing and thoracic radiographs of personnel working with the nonhuman primates were also negative. These cases were considered to be important because both animals were infected with the same serotype and because there has been an increasing number of isolations of this organism in human infections throughout Massachusetts. Drug-sensitivity testing revealed the organism to be sensitive to cycloserine and resistant to isoniazid, rifampin, ethambutol, streptomycin, kanamycin, and pyrazinamide.