[Objectives] To elucidate the characteristics of the index and secondary patients in clusters containing multiple TB patients who were examined epidemiologically.
[Subjects and Methods] The subjects of this retrospective study were 3, 783 TB patients registered in Aichi between 1989 and 2003. All recorded files were reviewed to identify multiple TB patients in the same transmission group. When multiple patients with a registration interval of less than 10 years were found in the same transmission group, the first patient was considered as the index case, and the other patients were regarded as secondary cases.
[Results] A total of 106 index patients and 132 secondary patients were found. The index patients occupied 2. 8 % of the total 3, 783 registered patients, or 0. 9 per 100, 000 population. Secondary patients occupied 3. 5% and 1. 2 per 100, 000. Of the 106 clusters, 77. 4% consisted of two patients, 15. 1 % three patients, and 7. 5% four or more patients. Smear-positive patients were found in 66. 0% of the index patients, 27. 3% of the secondary patients, and 30. 3% of the 3, 783 overall patients, and the differences were highly significant between the index and secondary patients, as well as between the index and overall registered patients (p< 0. 001). The proportion of the index patients to all registered patients was 6. 1% for smear-positive patients, 1. 8% for culture-positive patients, and 1. 1% for bacilli-negative patients. The differences were highly significant between smear-positive and culture-positive patients, as well as between smear-positive and bacillinegative patients (p < 0. 001).
[Conclusion] The fi ndings of this retrospective study suggest that 2. 8 % of the total registered patients, 6. 1% of smearpositive patients, and 0. 9 per 100, 000 population was the index patients.

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[Objective] To evaluate the performance of the BACTEC MGIT 960 system for drug susceptibility testing (MGIT AST) of Mycobacterium tuberculosis to isoniazid, rifampin, streptomycin and ethambutol.
[Design] Fifty external quality assessment strains of M. tuberculosis provided by the Coordinating Centers of WHO/ IUATLD were tested by BACTEC MGIT 960 system, and the results were compared with the referee results of the WHO/IUATLD Supranational Reference Laboratory Network (SRLN).
[Results and conclusion] Overall concordance rates of the results obtained by MGIT AST and the referee results of the SRLN were 97. 3% for four first-line drugs. Agreement ra tes were particularly high for isoniazid, rifampin, and streptomycin (agreement rate of over 97%), but somewhat lower for ethambutol, which relates to a lower sensitivity of MG IT AST. Turnaround times from inoculation to drug susceptibility results ranged from 6 to 13 days for the MGIT AST system with a median time of 7 days; this contrasted with three weeks for the proportion method using Middlebrook 7H10 agar, indicating that MGIT AST system has the potential to consistently meet with the turnaround time guidelines suggested by the Centers for Disease Control and Prevention of the United States. These results demonstrate that the fully automated BACTEC MGIT 960 AST system is useful for the rapid diagnosis of drug resistant tuberculosis.

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A 68 year-old man who had worked as a stone mason for more than 50 years with a heavy smoking history consulted our clinic with symptoms of cough, low grade fever, weightloss, malaise and a single expectoration of hemo-sputum. He had been diagnosed as silicosis by the mas s survey 5 years ago based on nodular shadows with egg-shell calcification in hilar lymphnodes on his chest radiography, and has received chest radiographic examination once a year. As the author was not so familiar with the radiographic features of silicotuberculosis, it was difficult to interprete illdefined contour of silicotic nodules accompanied by patchy opacities formation in right midlung field and silicotic conglomeration accompanied by an ischemic cavity in the left basal segments. A definitive diagnosis could not be established until 10 months later when a second attack of exacerbation of silicotuberculosis occurred showing multiple thin walled fresh tuberculous cavities on the chest radiography with positive smear and culture. Among multiple tuberculous cavities, there was a cirrhotic-walled cavity caused by endogenous reactivation of a quiescent tuberculous lesion on the right apex. This lesion was considered to be the source of dissemination of this case. Finally, it took about two and a half years before establishing the diagnosis in this case because of a series of doctors delays. He was treated successfully with antituberculous drugs for one and a half years including one year rifampicin medication.
The clinico-pathological fin dings of silicotic conglomeration in the left basal segments were discussed based on the findings of transbronchial biopsy from occluded B¹⁰ and chest radiographic findings, and it was revealed that silicotic conglomeration might consist of inflammatory granulation combined with granulomatous tubercle, but not a fibrous lesion.

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[Objectives] To discuss the optimal TB control system in health care facilities for the elderly where the periodic TB screening is currently not obligatory.
[Methods] A study was condu cted in three health care facilities for the elderly in Tokyo during the period from 2002 to 2004, and 212 admitted elderly persons were enrolled in this study. Medical charts were analyzed to identify informations about mental and physical conditions and TB risk factors. Questionnaire-based interviews were conducted in 58 residents who had no dementia or no serious conditions. TB mass screening was carried out with a mobile vehicle equipped with computed radiography, financially supported by the Tokyo Metropolitan Government. Since this mobile vehicle is equipped with a special wheelchair for chest X-ray examination, most elderly persons were able to receive chest X-ray examination. Medical chart review and interview were conducted at around the time of TB mass screening. The screening results of 183 elderly residents who received X-ray examination were reviewed.
[Results] Of the 212 persons admitted to the facilities, 73. 1 % were women. The mean ages of men and women were 80. 7 and 84. 2 years, respectively. Mental disorders were observed in 42. 9% and dysfunction of extremities in 54. 7%. At the time of admission, chest X-ray records were submitted by the attending doctors in 73. 1% of the residents, but this proportion differed among facilities. From these records, old TB was found in 12. 3%; however this proportion was 20. 8% according to the TB mass screening results. A history of TB was more prevalent in the group interviewed than in the non-interview group (24. 1 % vs. 6. 5%; p < 0. 001). Two facilities had conducted TB screening for three consecutive years and comparative reading of chest X-ray films could be done in 35. 8%. The remaining facility conducted TB screening for the first time, and comparative reading was not possible. The proportion of cases requiring further investigations was higher in the facility where TB screening was conducted for the first time (2. 8% vs. 13. 0%; p =0. 008). No active TB patient was detected in this study.
[Conclusion] From the viewpoint of risk management for tuberculosis, it is important to establish a system of early case finding for the aged persons admitted to health care facilities for the elderly. Therefore, the information on risk factors should be collected properly at the time of admission, and careful attention should be paid to the residents with risk factors, for the possible development to active disease. X-ray records submitted by the attending doctors or by screening would provide useful informations for early diagnosis, when abnormal shadows are found on chest X-ray films.

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