Evaluation of katG codon 315 mutations among isoniazid sensitive and resistant mycobacterium tuberculosis isolates from Thailand.

Nine isoniazid (INH)-susceptible and 11 INH-resistant Mycobacterium tuberculosis clinical isolates were analyzed for katG codon 315 mutations by polymerase chain reaction (PCR) assay using primers MYC-32 and MYC-33, followed by restriction fragment length polymorphism. After AciI digestion of PCR products, all 9 INH-susceptible isolates and 5 out of 11 (45%) INH-resistant isolates showed 0.12 kb band, which was previously reported to indicate wild type, whereas, 6 of 11 (55%) INH-resistant isolates lacked this band.

Latex agglutination test for diagnosing cryptococcosis.

Fourteen cases of systemic cryptococcosis were admitted to Siriraj Hospital during 1987 to 1989. These included 5 male and 9 female patients aged 4-65 years. The most significant manifestation was cryptococcal meningitis and systemic lupus erythematosus was the most common underlying disease. Culture test for C. neoformans was negative after 28 days of treatment and the latex agglutination test decreased to 1+ agglutination within 49 days of treatment. The latex agglutination test may also be positive in other bacterial, fungal, connective tissue and malignant diseases. A definite diagnosis must, therefore, rely on conventional methods (finding organisms in specimens, culture for the organism). The latex agglutination test is valuable for monitoring patients (decreasing titer indicates a good response). The disease recurred in 4 cases. In cases of cryptococcal meningitis, lumbar puncture should periodically be performed to obtain cerebrospinal fluid for mycological study. In addition the patients should be observed for symptoms and signs.

In vitro drug susceptibility of Mycobacterium other than tubercle bacilli.

MOTT were isolated from clinical specimens from the Division of Mycobacteriology, Department of Microbiology, Siriraj Hospital, Mahidol University, and also from natural sources, namely water and soil in the Bangkok area from January to December, 1987. The strains isolated were as follows: 30 M. fortuitum fortuitum, 5 M. fortuitum peregrinum 3 M. fortuitum 3 rd. biovariant complex, 3 M. chelonae chelonae, 7 M. chelonae abscessus. Of these, 5 strains were isolated from clinical specimens and the other 43 were from the environment. The pattern of drug susceptibility to antituberculous and antimicrobial agents revealed that they were resistant to antituberculous agents but susceptible to aminoglycosides (which contain a central ring of 2-deoxystreptamine) such as amikacin (83% of cultures), netilmicin (83%), gentamicin (77%) and kanamycin (75%). Some strains were sensitive to tetracyclines (35%), but all were resistant to penicillins and cephalosporins.

Diagnosis of systemic candidosis by immunodiffusion test with locally prepared antigen.

Locally-made C. albicans, C. tropicalis, C. krusei antigens and antisera were made and compared with reference C. albicans and C. krusei antigens and antisera from the Center for Disease Control (CDC), Atlanta, Georgia, U.S.A., and the Provincial Laboratory of Public Health, University of Alberta, Edmonton, Alberta, Canada, respectively. The local antigens and antisera showed 3 precipitin bands when reacted with locally-made and reference antisera. When tested with human sera from 171 normal persons (aged 17-24 years), 30 Candida vaginitis, 30 Candida balanitis, 30 mucocutaneous candidosis, 30 pityriasis versicolor and 10 aspergillosis patients revealed no precipitin band. When tested with cryptococcosis, 2 out of 6 sera showed a precipitin band but only at 1:1 dilution. Four candidosis sera offered by CDC showed precipitin bands at dilutions up to 1:4. Three Thai candidosis sera also showed precipitin bands at dilutions up to 1:2. Therefore, we judged the baseline titer for Thai population to be 1:2.

Mycobacterium other than tubercle bacilli in various environments in Bangkok.

This research was designed to isolate Mycobacterium other than tubercle bacilli in various environments in the Bangkok area, in 1987. The results were as follows, one hundred samples of soil yielded 1 Mycobacterium gordonae, 2 M. chelonei, 57 M. fortuitum, 1 Nocardia asteroides, one hundred samples of natural water from the Chao Phraya River and the canals of Chao Phraya River yielded 2 M. chelonei, 18 M. fortuitum, 1 N. asteroides and 1 N. brasiliensis, thirty samples of tap water yielded 3 M. gordonae. But thirty samples of water from swimming pools were negative for Mycobacterium.