Characterization of Mycobacterium tuberculosis isolated from cancer patients with suspected tuberculosis infection in Egypt: identification, prevalence, risk factors and resistance pattern

Clin Microbiol Infect 2012; 18: E438E445 Abstract Data are sparse on Mycobacterium tuberculosis infection among patients with cancer in Egypt. We sought to detect the presence of tuberculosis (TB) disease among patients with malignant conditions and suspected TB and to study the main risk factors. Also, we compared different diagnostic procedures and detected the antimicrobial susceptibility of M.similar to tuberculosis isolates against rifampin and isoniazid. One hundred patients were included in this study, all of them had malignant conditions and were suspected by the clinicians of having TB. Identification of M.similar to tuberculosis in different specimens was performed by smear microscopy, followed by LowensteinJensen medium and Mycobacterium growth indicator tube (MGIT) cultures and artus (R) real-time PCR. In addition, an indirect MGIT anti-TB susceptibility test was carried out against rifampin and isoniazid. A total of 76% of studied cases were found to be TB positive. The frequencies of TB-positive cases in the bronchogenic, haematological and solid tumour malignancy groups were 21%, 25% and 30%, respectively. Significant differences between pulmonary and extrapulmonary TB in different malignancy groups were recorded. Real-time PCR showed the highest overall diagnostic efficiency. Multidrug-resistance of M.similar to tuberculosis to both rifampin and isoniazid was detected in 28.6% of examined isolates. Infection in cancer patients with TB was significantly more often recorded among elderly patients and those suffering from poverty. Pulmonary TB is more common than extrapulmonary TB in patients with malignancy. Real-time PCR is the most accurate and rapid method for TB diagnosis. MGIT-rifampin resistance may be used as a reliable marker for detection of multidrug-resistant TB. Diagnosis and instituting treatment course for active or latent TB infection are crucial before starting anticancer therapy.