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Open Access Highly Accessed Research article

Tuberculosis in Sudan: a study of Mycobacterium tuberculosis strain genotype and susceptibility to anti-tuberculosis drugs

Ghada S Sharaf Eldin12, Imad Fadl-Elmula1, Mohammed S Ali1, Ahmed B Ali1, Abdel Latif GA Salih3, Kim Mallard4, Christian Bottomley5 and Ruth McNerney4*

Author Affiliations

1 Al Neelain University, Khartoum, P. O. Box 12702, 11121 Khartoum, Sudan

2 Tuberculosis Reference Laboratory, TB Reference Laboratory, Ministry of Health, P. O. Box 941, 1331 Khartoum North, Sudan

3 Khartoum Teaching Hospital, P.O. Box 102, Hospital Street, 11111 Khartoum, Sudan

4 Department of Pathogen Molecular Biology, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK

5 Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK

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BMC Infectious Diseases 2011, 11:219  doi:10.1186/1471-2334-11-219

Published: 16 August 2011

Abstract

Background

Sudan is a large country with a diverse population and history of civil conflict. Poverty levels are high with a gross national income per capita of less than two thousand dollars. The country has a high burden of tuberculosis (TB) with an estimated 50,000 incident cases during 2009, when the estimated prevalence was 209 cases per 100,000 of the population. Few studies have been undertaken on TB in Sudan and the prevalence of drug resistant disease is not known.

Methods

In this study Mycobacterium tuberculosis isolates from 235 patients attending three treatment centers in Sudan were screened for susceptibility to isoniazid, rifampicin, ethambutol and streptomycin by the proportion method on Lowenstein Jensen media. 232 isolates were also genotyped by spoligotyping. Demographic details of patients were recorded using a structured questionnaire. Statistical analyses were conducted to examine the associations between drug resistance with risk ratios computed for a set of risk factors (gender, age, case status - new or relapse, geographic origin of the patient, spoligotype, number of people per room, marital status and type of housing).

Results

Multi drug-resistant tuberculosis (MDR-TB), being resistance to at least rifampicin and isoniazid, was found in 5% (95% CI: 2,8) of new cases and 24% (95% CI: 14,34) of previously treated patients. Drug resistance was associated with previous treatment with risk ratios of 3.51 (95% CI: 2.69-4.60; p < 0.001) for resistance to any drug and 5.23 (95% CI: 2.30-11.90; p < 0.001) for MDR-TB. Resistance was also associated with the geographic region of origin of the patient, being most frequently observed in patients from the Northern region and least in the Eastern region with risk ratios of 7.43 (95%CI:3.42,16.18; p: < 0.001) and 14.09 (95%CI:1.80,110.53; p:0.026) for resistance to any drug and MDR-TB. The major genotype observed was of the Central Asia spoligotype family (CAS1_Delhi), representing 49% of the 232 isolates examined.

Conclusions

We conclude that emergence of drug resistant tuberculosis has the potential to be a serious public health problem in Sudan and that strengthened tuberculosis control and improved monitoring of therapy is needed. Further surveillance is required to fully ascertain the extent of the problem.