INT J TUBERC LUNG DIS e-publication ahead of print 7 May 2012 © 2012 The Union; 1–6 http://dx.doi.org/10.5588/ijtld.11.0547 Microscopic observation drug susceptibility assay in the diagnosis of multidrug-resistant tuberculosis O. Rasslan,* S. F. Hafez,* M. Hashem, † O. I. Ahmed,* M. A. S. Faramawy, ‡ W. S. Khater,* D. A. Saleh, § M. I. Mohamed, ¶ M. A. M. Khalifa, # F. A. Shoukry, # E. H. El-Moghazy** * Department of Microbiology and Immunology, Ain Sham University, Faculty of Medicine, Cairo, Egypt; † Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, USA; ‡ Department of Medicine, Chest Division, Ain Sham University Faculty of Medicine, Cairo, § Department of Community Medicine, Faculty of Medicine, Cairo University, Cairo, ¶ Central Public Health Laboratory, Ministry of Health, Cairo, # Al-Abbasseya Chest Hospital, Ministry of Health, Cairo, ** Chest Diseases Department & National Tuberculosis Program, Ministry of Health, Cairo, Egypt Correspondence to: Mohamed Hashem, Department of Epidemiology and Public Health, University of Maryland School of Medicine, 660 West Redwood Street, HH101, Baltimore, MD 21201, USA. Tel: (+1) 410 706 2228. Fax: (+1) 410 706 8013. e-mail: mhashem@epi.umaryland.edu Article submitted 10 August 2011. Final version accepted 26 January 2012. BACKGROUND: Early detection of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) is of primary importance for both patient management and infection control. Optimal methods for identifying MDR-TB in a timely and affordable manner in resource-limited set- tings are not yet available. OBJECTIVES: To evaluate the performance of a low- technology but rapid drug susceptibility testing method, the microscopic observation drug susceptibility assay (MODS), in the concurrent detection of M. tuberculosis and its susceptibility to isoniazid (INH) and rifampin (RMP) directly from sputum specimens. METHODS: A total of 115 smear-positive TB patients admitted to Abbasia Chest Hospital, Cairo, Egypt, were simultaneously tested using MODS and the BACTEC™ MGIT™ 960 mycobacterial detection system for the detection of M. tuberculosis and the identification of MDR-TB samples. RESULTS: MODS detected 112 (97.4%) samples and BACTEC MGIT detected 115 (100%). Of the 115 iso- lates tested for susceptibility to INH, RMP and MDR- TB, complete agreement between MODS and MGIT re- sults was found among respectively 92.9%, 95.5% and 97.3% of samples. The sensitivity, specificity, and posi- tive and negative predictive values of MODS in the de- tection of MDR-TB were respectively 95.3%, 98.6%, 97.6% and 97.1%. MODS results were obtained in a median of 8 days (range 5–21). CONCLUSION: MODS is an optimal alternative method for timely and affordable identification of MDR-TB in resource-limited settings. KEY WORDS: Mycobacterium tuberculosis; MDR-TB; MODS; BACTEC MGIT 960; Egypt TUBERCULOSIS (TB) is considered the most impor- tant resurgent infectious disease worldwide. About one third of the world’s population is infected with Mycobacterium tuberculosis. In 2008, there were an estimated 8.9–9.9 million incident cases of TB and an estimated 1.3 million deaths. Globally, TB incidence is rising at a rate of 1.1% per year. 1 Egypt has an in- termediate level of incidence and mortality (respec- tively 24 and 3 per 100 000 population). Approxi- mately 19 000 new TB cases occur in Egypt annually, of which two thirds occur among the socially and eco- nomically productive age groups of 15–54 years. The case detection rate in 2004 was around 57%, far be- low the World Health Organization (WHO) target of 70% for a successful TB programme. 2,3 Among all TB cases worldwide, 3.6% are esti- mated to have multidrug-resistant TB (MDR-TB). 4 Inappropriate prescribing practices, non-adherence to treatment and the upsurge of human immuno- deiciency virus (HIV) infection are factors contribut- ing to recent outbreaks and the continued spread of MDR-TB. 5,6 The estimated prevalence of MDR-TB in Egypt is respectively 2.2% and 38.2% among new and previously treated cases. 7 Although much progress has been made in improv- ing TB cure rates, diagnosis and case detection remain major obstacles to TB control. 8 Conventional drug susceptibility testing (DST) methods for M. tuberculo- sis take approximately 6 weeks to yield results, which leads to loss of time and delayed initiation of proper treatment, resulting in the transmission of drug- resistant disease in the community. 9 SUMMARY