Molecular typing of Mycobacterium tuberculosis isolated from adult patients with tubercular spondylitis

Abstract

Tuberculosis (TB) is endemic in Taiwan and usually affects the lung, spinal TB accounting for 1-3% of all TB infections. The manifestations of spinal TB are different from those of pulmonary TB. The purpose of this study was to define the epidemiological molecular types of mycobacterial strains causing spinal TB. We retrospectively reviewed the medical charts of adult patients diagnosed with spinal TB from January 1998 to December 2007. Patients with positive culture results and/or pathological findings characteristic of TB were enrolled in this study. Spoligotyping was performed to type the Mycobacterium tuberculosis isolates. A total of 38 patients with spinal TB were identified. Their mean age was 68 years, and their median duration of symptoms was 60 days (range 3-720 days). The lumbar and thoracic spine accounted for 76% of the sites involved. Thirteen specimens (from seven male and six female patients) were available for typing. Spoligotyping of these 13 specimens revealed three Beijing (23%) and 10 non-Beijing types (77%). The non-Beijing types included two EAI2 Manilla (15%), two H3 (15%), two unclassified (15%), and one each of BOVIS1, U, T2, and orphan type. No significant predominant strain was found in this study, and no drug-resistant Beijing strains were identified. TB spondylitis was found to occur in older patients. Spoligotyping results showed that most of the TB spondylitis cases were caused by non-Beijing type Mycobacterium tuberculosis.