Tuberculosis (TB) is a chronic infectious disease caused by a group of acid fast bacteria called the Mycobacterium tuberculosis complex (MTC)(1). It has been decades since the tubercle bacilli was identified and described, and with a consensus agreement on the treatment guidelines(2). Despite the tremendous progress made in diagnosis and management of patients including introduction of rapid diagnostic techniques such as GeneXpert MTB/RIF system(3), tuberculosis is still among the 10 highest causes of death, in the developing world and it is the leading cause of death from an infectious disease(3). The persistent high rate in morbidity and mortality from tuberculosis is in part due to a higher incidence of drug-resistance Mycobacterium tuberculosis resulting in more expensive and difficult treatment options(2). In addition, some factors such as poverty, civil unrest or wars in some countries, internally displaced persons (IDP) camps and recently the SARS-CoV-2 pandemic have all resulted into poor life quality. In addition, poor housing systems, overcrowding, malnutrition and inability to access appropriate health care are also contributing to an increase in disease burden and poorer outcomes(3).
There were an estimated 10 million new cases of TB in 2019 and the Africa continent accounted for 25% of these cases(2), some eight countries accounted for two thirds of the total cases globally: India (26%), Indonesia (8.5%), China (8.4%), the Philippines (6.0%), Pakistan (5.7%), Nigeria (4.4%), Bangladesh (3.6%) and South Africa (3.6%)(2).
Rifampicin resistance (RR-TB) is resistance to rifampicin (one of the first line drugs used in treatment of tuberculosis) detected using either phenotypic or genotypic methods, with or without resistance to the other anti-TB drugs(4). It includes any resistance to rifampicin whether monoresistance, multidrug resistance, polydrug resistance or extensive drug resistance(4). Rifampicin resistance is accepted as a surrogate marker of multidrug-resistant tuberculosis and it often reveals presence of greater than 90% of isoniazid resistance(5).
Multidrug-resistant TB (MDR-TB) is defined as resistance to isoniazid and rifampicin(4). In the past few decades, there was a record of low prevalence of drug-resistant TB in Sub-Saharan Africa(6). However, recent studies have shown an increase in cases of drug-resistant TB on the continent. Some studies have reported a high prevalence of MDR-TB in patients from Nigeria ranging from 4% to 76.4% (7) (8)(9) (10), these studies were done at different times and at different regions in different categories of patients. However, the highest prevalence from these reports were in patients who were previously treated for tuberculosis.
Worldwide in 2019, close to half a million people developed rifampicin-resistant TB (RR-TB), and 78% of these cases were multidrug-resistant TB (2). It was also found worldwide that a large number of the patients with MDR-TB were previously treated tuberculosis patient. The World Health Organization (WHO ) reported that globally in 2019, 3.3% of new TB cases and 17.7% of previously treated cases were MDR/RR-TB cases(2). Transmission of Drug-resistant TB is both from person to person and emergence in a previously treated tuberculosis patient(2) and this poses a great challenge in the global fight against tuberculosis.
Despite the success made so far in the control of TB, Nigeria remains one of the 30 high burden TB countries in the world(2). One of the factors negatively affecting the fight against TB is the on-going transmission of Drug-resistant TB(2). It is imperative to carry out surveys to determine the prevalence of resistance to all commonly used drugs in the management of tuberculosis on regular basis, this will aid development of policies in management of patients with tuberculosis.
This study aimed to determine retrospectively the prevalence of rifampicin resistance (RR-TB) and its associated factors in patients who attended the tuberculosis clinic and treatment center at Bowen University Teaching Hospital (BUTH), Ogbomoso between January 2015 and December 2019.