Can Thin Layer Agar Test Play a Key Role in the Diagnosis of Tuberculosis in Low-Resource Settings?

Background: Fast, reliable, and cost-effective tests are recommended for tuberculosis diagnosis and drug susceptibility testing, especially in resource-limited settings. Objectives: This study aimed to evaluate the performance of thin-layer agar for tuberculosis diagnosis and drug susceptibility testing. Methods: Samples were collected from patients with presumptive tuberculosisandtested using thin-layer agar for tuberculosis and drug susceptibility testing in parallel with Lowenstein Jensen culture method for tuberculosis diagnosis and proportion method for drug susceptibility testing as the gold standard. Receiver operating characteristic curve analysis was performed to calculate the performance parameters. Results: Thin-layer agar method showed sensitivity and specificity values of 96.63% and 62.50%, respectively, for the isolation of Mycobacterium tuberculosis directly from specimens. Drug susceptibility results using thin-layer agar showed sensitivity values for isoniazid, rifampicin), ethambutolandstreptomycinwere94.74%, 86.84%, 94.74% and81.58%, respectively,while the specificity values were 100%, 100%, 86.27% and 100% for isoniazid, rifampicin, ethambutol and streptomycin, respectively. Results were available in a median time of 16 days for thin-layer agar and 25 days for the conventional method. Conclusions: The thin-layer agar method is a relatively rapid, simple, and cost-effective method for the diagnosis and drug susceptibility testing of M. tuberculosis. It may be a useful tool for establishing tuberculosis laboratories in resource-limited settings because it does not require expensive equipment and a high level of training. Our study may help in choosing the appropriate treatment and control of tuberculosis.