Drug resistance and spoligotype patterns of Mycobacterium tuberculosis isolated in Nigeria

      Background: Tuberculosis (TB) has existed for millennia and ranks above HIV/AIDS as one of the top ten leading causes of death worldwide from an infectious disease. Nigeria has the world's fourth largest tuberculosis burden and drug resistance represents a public health issue. This study determines the drug susceptibility as well as the spoligotype distribution patterns of Mycobacterium tuberculosis isolated in the country.
      Methods & Materials: The sputum collected from 82 patients (48 (58.5%) Males/34 (41.5%) Females) were cultured using BACTEC MGIT960 and Lowenstein–Jensen (LJ) medium. Primary identification was carried out by immunochromatography and drug susceptibility testing (DST) by the agar proportion method. The isolates were further spoligotyped.
      Results: The DST carried out on 82 pure mycobacterial cultures showed that 32 (39%) were resistant to at least one drug. Fourteen (17.1%), 17 (20.7%), 18 (22%) and 11 (13.4%) isolates were resistant to streptomycin, isoniazid, rifampicin and ethambutol respectively. Multidrug resistance (isoniazid + rifampicin) was observed in 3/82 (3.7%) cases and resistance to the four drugs in 2/82 (2.4%) isolates. HIV positivity (20/82 (24.4%) patients) was not associated with drug resistance (p = 0.545). However, gender was associated with HIV (p = 0.011) infection but not with drug resistance (p = 0.426). All isolates from HIV positive patients were sensitive to ethambutol (p = 0.027). The distribution of 60 spoligotyped isolates included among others 39 (65%) Cameroon, 5 (8.3%) West African 1, 5(8.3%) Uganda I and 4(6.7%) Haarlem.
      Conclusion: TB remains a major health problem in Nigeria with rifampicin resistance a concern. A decreasing africanum lineage is observed and targeted education of the female most at risk of TB/HIV coinfection is advocated.