Epidemiology of drug-resistant tuberculosis in Bahrain, five years review

Introduction: Tuberculosis (TB) remains a major cause of morbidity and mortality worldwide, drug resistance is one of the major contributors to that. No existing published data about the burden of Multi-Drug Resistant (MDR) TB in the kingdom of Bahrain, the aim of our study is to estimate the prevalence of MDR TB in the kingdom and to defi ne its resistance profi le. Materials and methods: Retrospective observational study of patients with clinical diagnosis of TB between January 2014 and December 2018, cases with positive MTB culture were included for further analysis based on the results of phenotypic drug susceptibility testing to fi rst line antituberculous. Result of molecular testing (MTB PCR & rifampicin resistant gene) were also retrieved and included in the analysis. Results: During the study period, the incidence of TB in Bahrain have dropped from 17 per 100,000 population in 2014 to 11 per 100,000 population in 2018. A total of 946 patients were reported to the public health with clinical diagnosis of TB, out of which; Five hundred and eighty eight (59%) had confi rmed positive culture of Mycobacterium Tuberculosis (MTB). MDR TB was identifi ed among 15 out of the 588 positive isolates (3%). Majority of MDR (12cases ,80%) were Non Bahraini and 10 cases, (67%) were males, pulmonary involvement encountered among 11 cases (73%). Discussion: Our rate of MDR is comparable to other reported data among neighboring Arabian Gulf countries who illustrated an average of 4% MDR-TB prevalence. Similar prevalence rate was estimated among European countries (3.8%). Among other drug resistance pattern, isoniazid monoresistnt was the most predominant resistant pattern among our population, it account for 9% among all tested isolates, this in agreement with most other previous studies among different population. Conclusion: Incidence of MTB in Bahrain is dropping, our MDR TB rate is comparable to other reported data from developed countries. Research Article Epidemiology of drugresistant tuberculosis in Bahrain, fi ve years review Safaa AlKhawaja* Infectious Diseases Consultant, Salmaniya Medical Center, Ministry of Health, PO.Box 12, Kingdom of Bahrain, Bahrain Received: 20 January, 2020 Accepted: 31 January, 2020 Published: 03 February, 2020 *Corresponding author: Safaa AlKhawaja, Infectious Diseases Consultant, Salmaniya Medical Center, Ministry of Health, PO.Box 12, Kingdom of Bahrain, Bahrain, Tel: +97339733356; E-mail:


Introduction
Tuberculosis (TB) remains a major public health concern worldwide with attributable morbidity and mortality despite all enormous efforts [1,2], drug resistance is one of the major contributors to that.
The World Health Organization (WHO) declared multi-drug resistant TB (MDR-TB), defi ned as Mycobacterium tuberculosis resistant to isoniazid and rifampicin, as a public health crisis in 2013. Furthermore, the risk is aggravated with the emergence of extensively drug-resistant TB (XDR-TB), defi ned as resistant to isoniazid, rifampicin, one fl uoroquinolone and one second-line injectable drug [3,4]. MDR-TB treatment requires the use of toxic and expensive medications for 20months or more [2], in addition to its fi nancial burden, it is usually associated with a poor outcome and this have been documented in many published data that treatment success rates for drug-sensitive TB is signifi cantly higher than that of MDR-TB with lower attributable mortality [5].
Obtaining precise fi gures about the global burden of MDR-TB is challenging, as drug susceptibility testing for MTB is not performed in many resource-limited settings on routine basis, in addition to the underreporting [6]. According to the available published data in WHO 2018 Global Tuberculosis Report, the No existing published data about the burden of MDR TB in the kingdom of Bahrain, the aim of our study is to estimate the prevalence of MDR TB in the kingdom and to defi ne its resistance profi le.

Epidemiology of MDR TB & resistance to fi rst line antituberculous drugs
During the study period, the incidence of MTB in Bahrain have dropped from 17 per 100,000 population in 2014 to11 per 100,000 population In 2018. A total of 946 patients were reported to the public health with clinical diagnosis of TB; out of which; Five hundred and eighty eight (59%) had confi rmed positive culture of MTB Table 1. is considered as one of the low endemicty countries for TB with majority of TB patients (85%) are Non Bahraini [7].
Results of our study revealed MDR rate of 3% among all TB cases , which is comparable to other reported data among neighboring Arabian Gulf countries as published by Areeshi, et al., [8], who illustrated an average of 4% MDR-TB prevalence among 4 Arabian Gulf countries , with highest prevalence among UAE population (9.2%), followed by Kuwait (5.9%) and then Saudi Arabia (4.3%), whereas lowest prevalence rate was observed in Oman (1%).
Similar prevalence rate was estimated among European countries [9], as 3.8% among all TB cases, stratifi ed into 15% among retreatment & 2.4% among new cases , while USA reported overall lower MDR prevalence rate of 1.2 % [10].
Among other drug resistance pattern, isoniazid monoresistnt was the most predominant resistant pattern among our population, it account for 9% among all tested isolates, this in agreement with most other previous studies among different population such as USA data [11], which showed comparable rate of INH monoresistant (9.3 %) and other published studies in different geographical region including neighboring Arabian Gulf countries [11][12][13].
Rifampicin Resistance (RR) detection by molecular testing using Gene X-pert among our isolates was accurate predictor for MDR, 17 isolates were early identifi ed by Gene X-pert as RR & the same isolates were confi rmed later as rifampicin resistant by phenotypic drug susceptibility testing, out of these 17 isolates; two turn to be isoniazid sensitive, so were classifi ed as rifampicin monresistant while the remaining 15 (88%) were all confi rmed as MDR by further phenotypic sensitivity testing (resistant to isoniazid and rifampicin).
Accordingly, in agreement with other previously published data [14], rapid testing for RR by molecular method is of great importance for early recognition of MDR for timely initiation of appropriate antituberculous therapy.
This study has some limitations, primarily related to its

Conclusion
Incidence of MTB in Bahrain is dropping, our MDR TB rate is comparable to other reported data from developed countries & neighboring Arabian gulf countries.