Classic criteria for pathogenicity of MOTTs are major criteria with (1) repeated isolation (> than 4 episodes) of colonies in large numbers (>100) with clinical symptoms or (2) positive cultures with histopathologic changes. Minor criteria are (1) repeated discharge or large numbers of organisms, (2) positive cultures of secretions with clinical symptoms, (3) positive cultures of tissue, and (4) stronger reaction of skin testing with atypical mycobacterial antigen compared with regular tuberculin. This was modified in 1988 to clinical evidence of disease and either (1) isolation of the organism in large numbers (colony counts of 100 on 4 occasions), or (2) isolation from a sterile source, or (3) culture from a biopsy specimen. According to these criteria, we would have missed the 12 patients with possible disease. None of our patients had isolation of the organism in colony counts of 100 on 4 occasions, and only 2 had isolation from sterile sources.
More sensitive criteria were developed at Johns Hopkins University for the evaluation of “atypical” mycobacterial disease in HIV-positive patients. Pulmonary disease was defined as a triad of respiratory symptoms for at least 2 weeks, infiltrations on CXR, and 2 positive cultures from respiratory sites. With these criteria, the number of patients with disease would increase to 4 (patients 1, 2, 4, and 11). Possible pulmonary disease was defined as a triad of clinical symptoms, abnormalities on CXR, and one positive culture of sputum. With these criteria, 13 of the 15 patients with respiratory secretions positive for M gordonae would have possible disease (including patients 5, 7, 9, 13, 14, 16, 17, 19, and 21). Is it worthwhile to do such an extensive workup, including multiple biopsies, in every HIV-positive patient with M gordonae in respiratory secretions?