[Improvement of routine works and quality control in mycobacterial laboratory]

Many new methods have been introduced into routine laboratory works in microbiology since 1990. Molecular biology, in particular, opened a new era and promoted a technician's skill much. PCR and hybridization technique have been ordinary one in many laboratories. Since old techniques such as smear and culture are still needed, amount of routine works is increasing gradually. Thus, improving efficiency and keeping quality of routine works are becoming more and more important issues. This symposium focused on such points, and four skilled technicians around Japan presented their own tips. 1. Coexistence of M. tuberculosis and M. avium complex (MAC) in the MGIT culture system: Yasushi WATANABE (Clinical Laboratory Division, NHO Nishi-Niigata Chuo National Hospital). Sputum samples of some tuberculosis patients yielded only MAC in the MGIT culture system. Such co-infected cases presented problems to mislead proper treatment and infection control. The detection rate of MAC was significantly high, and the growth speed of MAC was significantly rapid in the MGIT culture system, compared to those of M. tuberculosis. Additionally, M. tuberculosis was not detected with even more quantity than MAC in the small amount of mixed samples. Higher sensitivity and growth speed of MAC are the important characteristics of the MGIT system. 2. Internal quality control with ordinary examination results: Akio AONO (Department of Clinical Examination, Double-Barred Cross Hospital, Japan Anti-Tuberculosis Association). Our laboratory utilizes ordinary examination results as the internal quality control for specimen pretreatment, culture, and drug susceptibility testing. The contamination rate of MGIT culture system is useful for the evaluation of the decontamination process. It was 6.3% on average in our laboratory in 2005. The number of drug resistant strains is also useful to assess the performance of drug susceptibility testing. The incidence of each anti-tuberculosis drug resistance detected monthly in 2005 is up to 5 for isoniazid (INH), 4 for rifampicin (RFP), 7 for streptomycin (SM), 1 for ethambutol (EB), and 2 for pyrazinamide (PZA), respectively. If any serious deviation from the average number is observed, action for the investigation is taken. The analysis of the ordinary examination data is useful to implement a quality control efficiently, and to improve the total laboratory performance. 3. The advanced devices for solving problems of the smears and cultivation of Mycobacteria: Motohisa TOMITA (NHO Kinki-chuo Chest Medical Center). Recently, the newly developed, standardized, commercially available kits including PCR and liquid media for confirmation and identification of mycobacteria are prevalent in Japan for the rapid diagnosis of M. tuberculosis. These tests are sensitive and accurate, but still expensive and technically demanding. The improvement of these methods, in particular, requires time-consuming process. We have optimized the culture technique, the identification method, and the drug-susceptibility testing for Mycobacteria in a time-saving manner. They should provide a basic grounding in the application of the techniques for anyone who is interested in these intriguing bacteria. 4. Ultimate quality control of specimens--teaching how to get a good sputum sample: Takeshi HIGUCHI (Kyoto University Hospital). Modern techniques including molecular biology have been applied to routine laboratory works for rapid detection, identification, and drug susceptibility testing of mycobacteria. Even in using such techniques, however, poor quality specimens yield only poor results. To get a high quality specimen, particularly sputum samples, is very important. Therefore, laboratory technicians in our hospital have directly taught each patient how to expectorate good quality sputa since 2001. The teaching of patients has improved the rate of P1 samples from 21.5% to 36.6% by Miller and Jones visual score of sputum. The teaching has also improved the rate of smear positive P1 samples from 11.4% to 28.8%. To teach each patient how to get good sputa seems useful for keeping the laboratory quality high.