[Outbreak of multidrug-resistant Mycobacterium tuberculosis infection in the middle and advanced age]

We experienced a small outbreak of multidrug-resistant Mycobacterium tuberculosis infection (MDR-TB) among persons of in the middle and advanced age. The index case was 48-year-old man, and had complained productive cough since January 1996. He visited a doctor due to his symptom, and chest X-ray revealed cavitary lesion and sputum smear was positive for tubercle bacilli. He could not continue his admission because of his absence without leave and drinking, he was discharged on Day 54. The drug resistance was observed for INH (0.1 microgram/ml), RFP, and SM. Later, case 2, 52-year-old male, and case 3, 43-year-old-male, who were companions in mah-jongg with the index case, were diagnosed as pulmonary tuberculosis. The analysis of restriction fragment length polymorphism (RFLP) was done on 3 strains, and all showed the same pattern. Among other companions in mah-jongg with the index case, case 4, 28-year-old male, was treated as MDR-TB, and the drug resistance pattern was the same to that of the index case, but the details were unknown. Case 5, 65-year-old male, was diagnosed as drug sensitive pulmonary tuberculosis, thus he might incidentally suffer from pulmonary tuberculosis at the same time. Case 6, 46-year-old male, who had been treated for alcoholic liver cirrhosis, was introduced to our hospital as his sputum smear was positive, and the drug resistance pattern was observed similar to that of the index case. All the companions in mah-jongg suffered from MDR-TB except case 5. The RFLP analysis showed that the index case, case 2, and case 3 were caused by the same strain of M. tuberculosis. The drug resistance pattern of, case 4 and case 6 was the same to that of the index case. Based on these findings, it is highly suspected that this small outbreak was originated from the index case.