Molecular detection of multidrug resistance pattern and associated gene mutations in M. tuberculosis isolates from newly diagnosed pulmonary tuberculosis patients in Addis Ababa, Ethiopia.

INTRODUCTION: Multi-drug resistance is a major challenge in the control of tuberculosis. Despite newer modalities for diagnosis and treatment, people are still suffering from this disease. Understanding the common gene mutations conferring rifampicin and isoniazid resistance is crucial for the implementation of effective molecular tools at local and national levels. Hence, this study aimed to evaluate the molecular detection of rifampicin and isoniazid-resistant gene mutations in M.tuberculosis isolates in Addis Ababa, Ethiopia. METHOD: Health Center-based cross-sectional study was conducted between January and September 2017 in Addis Ababa, Ethiopia. The collected sputum samples were processed for mycobacterial isolation and Region of difference 9 based polymerase chain reaction for species identification. To characterize the rifampicin and isoniazid-resistant M. tuberculosis isolates, a molecular genetic assay (GenoType MTBDRplus) was used; the assay is based on DNA-STRIP technology. RESULT: Culture positivity was confirmed in 82.6% (190/230) of smear-positive newly diagnosed pulmonary tuberculosis cases enrolled in the study. From 190 isolates 93.2% were sensitive for both rifampicin and isoniazid, and 6.8% of the isolates were resistant to at least one of the tested anti-TB drugs. Gene mutations were observed in all studied multidrug resistance-associated gene loci (rpoB, katG, and inhA). Two isolates exhibited heteroresistance, a mutated, as well as wild type sequences, were detected in the respective strains. MDR-TB case was observed in 1.1% (2/190) of the cases. All the MDR-TB cases were positive for HIV and found to have a history of prior hospital admission. CONCLUSION: In our finding a relatively high prevalence of any drug resistance was observed and the overall prevalence of multidrug-resistant tuberculosis was 1.1%.The majority of drug-resistant isolates demonstrated common mutations. Heteroresistant strains were detected, signaling the existence of an M.tuberculosis population with variable responses to anti-tuberculosis drugs or of mixed infections.

Tuberculosis among Addis Ababa city bus drivers and cash collectors.

BACKGROUND: The risk of transmission of tuberculosis is high in crowded conditions. Addis Ababa has a relatively high burden of tuberculosis and its city buses are often filled with commuters. Tuberculosis is a potential occupational hazard for city bus drivers and cash collectors. OBJECTIVES: The objective of this study was to estimate the proportion of tuberculosis among city bus drivers and cash collectors. METHODS: We estimated the proportion of tuberculosis of all forms among city bus drivers and cash collectors of the Addis Ababa City Bus Organization, from January 2003 to December 2004. Study participants were screened with clinical, bacteriological and chest X-ray examination from January 2003 to December 2004. RESULTS: Sixteen cases of tuberculosis were identified among 903 study participants (466 city bus drivers and 437 cash collectors) examined, of whom 12 were already on anti-TB treatment and 4 were diagnosed during the study. The proportion of all forms of tuberculosis, smear-positive pulmonary tuberculosis and extra-pulmonary tuberculosis was 16/903 (1772/100,000), 4/903 (443/100,000) and 3/903(332/100,000), respectively. CONCLUSION AND RECOMMENDATIONS: The proportion of all forms of tuberculosis among the study population was higher than the notification case rates for Addis Ababa reported in 2003, which indicates the need for a routine screening of city bus drivers and cash collectors. Measures such as opening windows and reducing crowding in buses are recommended as a means of reducing the risk of exposure to bus drivers and cash collectors.