The overall prevalence of Mycobacterium tuberculosis
In the present study, the overall prevalence of M. tuberculosis among presumptive TB patients was 15.3%, which is in agreement with studies conducted in Addis Ababa 15.1% (9), Hiwot Fana 15.7% (10), Felege Hiwot and Debre Tabor 14.6% (11). However, result from our study was lower than studies done in India 32.9% (12), Egyptian 19% (13), Gambo 22.4% (14) and Debre Markos 23.2% (15). The possible reasons attributable for such inconsistency were variation in subset of targeted population, setting and locations where the data was collected, and framework of study design. In contrast, it is higher than studies conducted in other parts of Ethiopia like Ataye 8.98% (16) and Tigray 7.9% (17). This lower prevalence and discrepancy in estimation with the current study might be due to dissimilarities in nature of study subjects and geographical area.
Rifampicin resistant Mycobacterium tuberculosis
In this study, the prevalence of rifampicin-resistant M. tuberculosis was 4.35%. This result is congruent with studies done in Afar 4.3% (18), Hiwot Fana 4.1% (10), and Debre Berhan 5.2% (19). However, it was higher than studies conducted in India 2.7 % (20), Nigeria 2.4% (21) and Gambo 0.3% (14). This might be due to majority of TB suspected were new cases and differences in TB control and prevention program among countries. To the contrary, there was a lower reported prevalence of rifampicin-resistant M. tuberculosis from Eastern Uttar Pradesh 26.1% (12), Debre Markos 10.3% (15) and Gondar 15.8% (22). This lower prevalence and inconsistency could be due to difference in history of taking Anti-tuberculosis drugs, possibility of HIV/AIDS acquisition and TB, TB/HIV and MDR-TB prevention and control program.
Associated factors of tuberculosis infections among TB presumptive
The prevalence of M. tuberculosis was 17% in males and 13.2% in females but no statistically significant association was observed. This study is in agreement with WHO 2020 report (23), India (12), Nigeria (21), St. Peter Tuberculosis Specialized Hospital (24), and Felege Hiwot and Debre Tabor (11). This Variation could be due to difference in community cultural expectations on attempt to get healthcare services, having habit of smoking and alcoholism, high level exposure of males to surrounding.
The results of our study showed that the assessed TB/HIV co-infection rate was 8.7%, which is comparable with studies done at Ataye 7.89% (16), Addis Ababa 6.7% (9) and WHO 2020 report (8.2%) (23).However, high rate of TB/ HIV co-infection was reported from southwest Ethiopia 35.5% (25), Felege Hiwot and Debre Tabor 41.9 % (11), and Gondar 23.8 % (22). This inconsistency could be due to difference in the high burden of HIV setting area, Lack of awareness of TB/HIV co-morbidity among communities and the extent of performed HIV testing.
The chance of getting M. tuberculosis was 6.67 fold in patients between ages 15–39 when compared to those age > 60 years, the difference being statistically significant with p value 0.038. This significance difference may be due to the extent contact of productive ages to the surrounding for different activities and movability from one location to another may be results in chance of getting tuberculosis bacilli. Our result is in agreement with similar studies in Pakistan (26), Nigeria (21) and Debre Berhan (19), and Gambella (25).
The prevalence of M. tuberculosis among previously treated patients was higher 24.1% than treatment new patients 13.4%, with statistical significant difference (P < 0.050). Our finding agrees with studies done at Nepal (27), Hiwot Fana (10) and St. Peter Tuberculosis Specialized Hospital (24). High prevalence of rifampicin resistant M. tuberculosis was also detected among patients who had a history of previously taking anti-tuberculosis drugs (15.4 %) which is comparable with studies from Eastern Uttar Pradesh (12), Nepal 13.79% (27) and Addis Ababa 27.4% (9).This might be due to lack of success from previous tuberculosis treatment history and patients with previously history of taking anti-tuberculosis drugs were more likely to harbor drug-resistant bacilli because of previous exposure of bacilli to TB agents.
In this study, high prevalence of pulmonary tuberculosis 16.7 % was detected when compared with extra-pulmonary tuberculosis which was 9.8%. This result agrees with a study done at Pakistan (26), Egyptian (13) and Hiwot Fana (10). This shows that pulmonary tuberculosis infection has inflated chance of transmission from pulmonary tuberculosis patients during coughing, sneezing and others way of bacilli transmission.
The result of this study also showed frequent utilization of congested transportation had a significant association (p < 0.05) with the prevalence of drug susceptible tuberculosis and drug resistance tuberculosis. The possible reason for such significance could be there is chance of acquiring bacilli from the index cases because of denied of opening window for different reasons and lack of ventilation during voyage. This study agrees with study done at Ataye (16).
The prevalence of detected M. tuberculosis in relation to contact history with TB patients among TB presumptive was analyzed and showed significance difference. The prevalence of M. tuberculosis was higher 26.7% in patients who had history of contact with TB patients than who had no history of contact with TB patients 12.4%, the difference being statistically significant with p value 0.02 The reasons for this high prevalence of M. tuberculosis in patients who had history of contact with TB patients might be due to the patients have poor adherence and acquiring of bacilli from TB patients. Our finding is supported by similar study from Ataye District Hospital (16) and Dubti Hospital (18).
Limitation of the study
This study was conducted in a single institution. It would have been better if we incorporated a number of health institutions for a better representation of study subjects. This study also lacks any other diagnostic tool that can be used as gold standard like culture (LJ or MGIT).