Mycobacterium simiae. Clinical features and follow-up of twenty-four patients.

The charts of twenty-four patients from whom Mycobacterium simiae was isolated from the sputum were reviewed and the patients seen in follow-up examination when possible. They were divided into 3 groups: 2 patients were felt to have had definite infection with M. simiae, 3 were felt to have had probable infection, and 19 showed no evidence of infection during follow-up for as long as 6 yr. All patients in the study had underlying pulmonary abnormalities. The results of PPD skin tests were negative in patients without evidence of tuberculosis. The patients without evidence of M. simiae infection were found to have had negative initial Acid Fast Bacillus smears, fewer sputum cultures positive for M. simiae, and lighter yields from cultures of M. simiae compared with those in the patients with M. simiae infection. We conclude that M. simiae is a nontuberculous mycobacterium capable of causing progressive granulomatous lung infection, but that it may also be identified as a causal isolate from the sputum of susceptible persons. Antituberculosis chemotherapy should not be employed in this latter group.

Comparison of coccidioidin and spherulin in complement fixation tests for coccidioidomycosis.

Coccidioidin, an extract from the saprophytic mycelial form of Coccidioides immitis, has been a very useful antigen preparation in serological tests for coccidioidomycosis. Its sensitivity has been very good for detecting most types of clinical disease, but tests with coccidioidin have been negative for 40% or more of patients with chronic pulmonary disease, the clinical entity which must be differentiated from other cavitary, nodular, or fibrotic pulmonary disease, e.g., tuberculosis and cancer. The specificity of coccidioidin has also been good although it results in positive tests for an average of 16% among patients with noncoccidioidal mycoses. Recently spherulin, an extract from the parasitic endosporulating spherule form of C. immitis, was reported to be more sensitive than coccidioidin in concurrent complement fixation tests with sera from selected cases. We have compared coccidioidin and spherulin in concurrent complement fixation tests with 614 sera submitted routinely for coccidioidal serology and with 159 selected sera from patients with noncoccidioidal mycoses. Among the former, spherulin was positive with 25% and coccidioidin with 23%, and correlation of titer scores was highly significant. Statistical analysis revealed no significant differences with respect to frequency of positive specimens, titer scores, or diagnosis for current coccidioidomycosis. The results with sera from noncoccidioidal mycoses revealed marked differences. Coccidioidin was positive with 20%, and spherulin was positive with 48%. The titer scores with spherulin were consistently and significantly higher, and there was no correlation for results with the two antigens. Thus, coccidioidin and spherulin were equally sensitive, but spherulin was considerably less specific.

Mycobacterium simiae infection in the United States. A case report and discussion of the organism.

The clinical and bacteriologic features of a case of mycobacteriosis in which Mycobacterium simiae was thought to be the causative agent are presented. The unique features of this organism, includeing its positive niacin reaction and photochromogenicity, which may lead to confusion with other mycobacterial species, are duscussed.

Comparison of methods for tuberculosis bacteriology.

To improve efficiency of isolation of tubercle bacilli from clinical specimens, the following recommendations are presented. (i) Employ multiple specimens consisting of a combination of morning sputums for the early detection of positives, along with 24-hr sputum pools for the greatest total yield of positives. (ii) When timing is rigorously controlled, Zephiran-trisodium phosphate and sodium hydroxide-acetylcysteine are comparable, but if timing cannot rigidly be controlled, employ the Zephiran-trisodium phosphate digestion procedure to allow the greatest freedom in exposure time with the lowest kill rate to tubercle bacilli. (iii) Employ both an agar medium incubated in 5% CO(2), for the early detection of positives as well as positives in the presence of contaminants, and an egg medium, preferably with CO(2), to increase the yield of positives.