Sex differences and HIV status of tuberculosis in adults at a rural hospital in southern Ethiopia: an 18-year retrospective cross-sectional study

Risk factors of multidrug resistant tuberculosis among patients with tuberculosis at selected multidrug resistance treatment initiative centres in southern Ethiopia: a case-control study

OBJECTIVE

To identify the risk factors for multidrug resistant tuberculosis (MDR-TB) among patients with TB at selected MDR-TB treatment initiative centres, southern Ethiopia, 2021.

DESIGN

An unmatched case-control study was employed.

SETTING

Multidrug resistance treatment initiative centres in southern Ethiopia (Nigist Elen Mohamed Memorial Comprehensive Specialized Hospital and Butajira General Hospital).

PARTICIPANTS

A total sample size of 392 (79 cases and 313 controls) were selected by the systematic sampling technique. Cases were all patients with TB with culture proven or line probe assay confirmed Mycobacterium tuberculosis resistant to at least both isoniazid and rifampicin and registered on second-line TB treatment. Controls were all patients with bacteriological (molecular) proven drug-susceptible TB strains and whose recent smear results were turned to negative and registered as cured. Both bivariate and multivariable logistic regression analysis was used to identify risk factors of MDR-TB infections.

MAIN OUTCOME MEASURE

Identifying the risk factors for MDR-TB.

RESULTS

A total of 392 participants (79 cases and 313 controls) were interviewed. Multivariable analysis showed that direct contact with known patients with TB (AOR =4.35; 95% CI: 1.45 to 9.81), history of previous TB treatment (AOR=2.51; 95% CI: 1.50 to 8.24), history of cigarette smoking (AOR=3.24; 95% CI :2.17 to 6.91) and living in rural area (AOR=4.71; 95% CI :3.13 to 9.58) were identified risk factors for MDR-TB infections.

CONCLUSIONS

The study findings revealed that direct contact with known patients with TB, previous history of TB treatment, history of cigarette smoking and rural residence were potential risk factors for the occurrence of MDR-TB. In order to reduce the burden of drug resistance, strategies of controlling MDR-TB in the study area should emphasise on enhancing public health education and reducing treatment interruptions of patients with TB and drug-resistant TB.

Sex and Gender Differences in Tuberculosis Pathogenesis and Treatment Outcomes

Tuberculosis remains a daunting public health concern in many countries of the world. A consistent observation in the global epidemiology of tuberculosis is an excess of cases of active pulmonary tuberculosis among males compared with females. Data from both humans and animals also suggest that males are more susceptible than females to develop active pulmonary disease. Similarly, male sex has been associated with poor treatment outcomes. Despite this growing body of evidence, little is known about the mechanisms driving sex bias in tuberculosis disease. Two dominant hypotheses have been proposed to explain the predominance of active pulmonary tuberculosis among males. The first is based on the contribution of biological factors, such as sex hormones and genetic factors, on host immunity during tuberculosis. The second is focused on non-biological factors such as smoking, professional exposure, and health-seeking behaviors, known to be influenced by gender. In this chapter, we review the literature regarding these two prevailing hypotheses by presenting human but also experimental animal studies. In addition, we presented studies aiming at examining the impact of sex and gender on other clinical forms of tuberculosis such as latent tuberculosis infection and extrapulmonary tuberculosis, which both appear to have their own specificities in relation to sex. We also highlighted potential intersections between sex and gender in the context of tuberculosis and shared future directions that could guide in elucidating mechanisms of sex-based differences in tuberculosis pathogenesis and treatment outcomes.

Sex Differences in Active Pulmonary Tuberculosis Outcomes in Mali, West Africa

Men and women often respond differently to infectious diseases and their treatments. Tuberculosis (TB) is a life-threatening communicable disease that affects more men than women globally. Whether male sex is an independent risk factor for unfavorable TB outcomes, however, has not been rigorously investigated in an African context, where individuals are likely exposed to different microbial and environmental factors. We analyzed data collected from a cohort study in Mali by focusing on newly diagnosed active pulmonary TB individuals who were treatment naive. We gathered baseline demographic, clinical, and microbiologic characteristics before treatment initiation and also at three time points during treatment. More males than females were affected with TB, as evidenced by a male-to-female ratio of 2.4:1. In addition, at baseline, males had a significantly higher bacterial count and shorter time to culture positivity as compared with females. Male sex was associated with lower smear negativity rate after 2 months of treatment also known as the intensive phase of treatment, but not at later time points. There was no relationship between patients' sex and mortality from any cause during treatment. This study suggests that sex-based differences in TB outcomes exist, with sex-specific effects on disease outcomes being more pronounced before treatment initiation and during the intensive phase of treatment rather than at later phases of treatment.

Genetic and hormonal mechanisms underlying sex-specific immune responses in tuberculosis

Tuberculosis (TB), the world's deadliest bacterial infection, afflicts more human males than females, with a male/female (M/F) ratio of 1.7. Sex disparities in TB prevalence, pathophysiology, and clinical manifestations are widely reported, but the underlying biological mechanisms remain largely undefined. This review assesses epidemiological data on sex disparity in TB, as well as possible underlying hormonal and genetic mechanisms that might differentially modulate innate and adaptive immune responses in males and females, leading to sex differences in disease susceptibility. We consider whether this sex disparity can be extended to the efficacy of vaccines and discuss novel animal models which may offer mechanistic insights. A better understanding of the biological factors underpinning sex-related immune responses in TB may enable sex-specific personalized therapies for TB.

[Limitations of the Xpert-MTB/RIF® assay in the initial diagnosis of tuberculosis in the context of a rural hospital in Ethiopia]

OBJECTIVE

To evaluate the implementation of Xpert-MTB/RIF®, as an early diagnosis technique, in a rural area of Ethiopia.

METHODS

Data were retrospectively collected from those patients over 13 years of age who were requested to take the Xpert MTB/RIF® test in a rural hospital located 45 km from the reference laboratory, during the first 3 years of its implementation (2015, April -2018, April).

RESULTS

A total of 306 patients older than 13 years were evaluated, in 85 (27.8%) there was an error in the processing of the test and the result was not obtained. Of the 221 samples with results, the median time between obtaining the sample and receiving the result was 21 days and 42 of them were positive (19%, 95% CI: 14.2-24.9%). The sample with the highest diagnostic yield was adenopathy (88.8%; [8/9]; p<0.001).

CONCLUSIONS

There are more bacteriological diagnoses with Xpert-MTB/RIF®, but with a delay in obtaining the result and its main objective, which is early diagnosis, is not achieved.