Coexistence of mycobacterial infections - Mycobacterium tuberculosis and Mycobacterium leprae - in Sri Lanka: a case series.

Background: Leprosy is one of the oldest mycobacterial infections and tuberculosis is the most common mycobacterial infection with a higher degree of infectivity than leprosy. Although both diseases are prevalent in clusters in developing countries, simultaneous occurrence of them in an individual is a rare entity, even in an endemic setting.

Case Presentation: We describe six cases of tuberculosis and leprosy coinfection: a 57-year-old Sinhalese woman, a 47-year-old Tamil woman, a 72-year-old Tamil man, a 59-year-old Sinhalese man, a 54-year-old Sinhalese man, and a 50-year-old Sinhalese man. In this case series, five patients had lepromatous leprosy and the majority of patients were men. Three patients were detected to have tuberculosis at the outset of treatment of leprosy, while two developed tuberculosis later and one had extrapulmonary tuberculosis 5 years before the diagnosis of leprosy. The latter developed pulmonary tuberculosis as a reactivation while on treatment for leprosy. A majority of our patients with pulmonary tuberculosis had positive Mantoux test, high erythrocyte sedimentation rate, radiological evidence, and acid-fast bacilli in sputum. Human immunodeficiency virus and diabetes were detected in one patient. One patient had rifampicin-resistant tuberculosis, while she was on monthly rifampicin therapy for leprosy.

Conclusion: An immunocompromised status, such as human immunodeficiency virus infection, diabetes, and immunosuppressive drugs, are risk factors for tuberculosis infection. The use of steroids in the treatment of leprosy may increase the susceptibility to develop tuberculosis. Development of rifampicin resistance secondary to monthly rifampicin in leprosy is a major concern in treating patients coinfected with tuberculosis. Despite the paucity of reports of coinfection, it is advisable to screen for tuberculosis in patients with leprosy, especially if there are respiratory or constitutional symptoms, high erythrocyte sedimentation rate, and abnormal chest X-ray. The fact is that positive Mantoux and QuantiFERON Gold tests and presence of acid-fast bacilli in sputum are misleading, chest X-ray evidence of active tuberculosis and positive tuberculosis cultures are important diagnostic clues for active tuberculosis infection in a patient with leprosy. This is important to avoid monthly rifampicin in patients with suspected coinfections, which may lead to development of drug resistance to tuberculosis treatment. Whether prolonged steroid therapy in leprosy is a risk factor for development of tuberculosis is still controversial.