Comparative performance of Thin Layer Agar and Löwenstein–Jensen culture for diagnosis of tuberculosis

Abstract

Sputum smear microscopy for the diagnosis of tuberculosis (TB) is cheap and simple but its sensitivity is low. Culture on Löwenstein-Jensen (LJ) is more sensitive but it takes a long time to yield results. Thin-Layer Agar (TLA) culture was suggested as an equally sensitive and faster alternative. We evaluated the performance of TLA for diagnosing TB in Jogjakarta, Indonesia. People with suspected TB presenting from July 2010 to July 2011 to two chest clinics of the National TB Control Programme network of Jogjakarta were eligible for inclusion. A sputum sample was sent to the Gadjah Mada University microbiology laboratory for concentration, smearing, Ziehl-Neelsen staining and culture on LJ and TLA. Sensitivity of cultures was evaluated against a composite reference standard (any positive culture). Time to detection of Mycobacteria was recorded. Out of 1414 samples, 164 (12%) were smear positive, 99 (7%) were scanty and 1151 (81%) were negative. On TLA and LJ respectively, 168 (12%) and 149 (11%) samples were positive, 72 (5%) and 32 (2%) were contaminated (κ = 0.64; 95% CI 0.59-0.69, p <0.01). Using the reference standard, 196 (14%) TB cases were identified. The sensitivity of TLA was 0.86 (95% CI 0.80-0.90), significantly higher (p 0.03) than for LJ (0.76; 95% CI 0.69-0.81). The median time to detection in days was significantly shorter (p <0.01) for TLA (12; 95% CI 11-13) than for LJ (44; 95% CI 43-45). TLA is a rapid and sensitive method for the diagnosis of TB. Implementation studies to evaluate the cost-effectiveness and impact of its introduction into programmatic settings are urgently needed.

Reduced turn-around time for Mycobacterium tuberculosis drug susceptibility testing with a proportional agar microplate assay

“…Moreover, microplates allow the microscopic detection of bacterial colonies before they can be seen with the naked eye, further decreasing the time to results. Previous studies have shown that M. tuberculosis can be detected on M7H11 from sputum samples as early as 7 days [29][30][31]. A meta-analysis of the results obtained with thin-layer agar and microscopicobservation drug susceptibility assays, in which patients' specimens are inoculated directly on drug-free and drugcontaining medium for DST, showed that the mean turnaround times for the two assays were 11.1 days (95% CI 10.1-12.0) and 9.9 days (95% CI 4.1-15.8), respectively [32].…”

A Novel Solid Medium for Culturing Mycobacterium tuberculosis Isolates from Clinical Specimens

“…In this work, it was not possible to use microscopy to read the Lowenstein-Jensen tubes; therefore, microscopy was also not used to read the MOD9 plates, to maintain a similar method in the readings. Indeed, if we had used microscopy as for the thin-layer agar and microscopic observations of drug susceptibility protocols (14,15), this would have resulted in the rapid detection of microcolonies and thus rapid diagnosis (6).…”

Estrategias alternativas para el diagnóstico de tuberculosis: una opción para los pacientes paucibacilares

“…A pesar de los buenos resultados de estos ensayos en la detección de individuos con infección tuberculosa latente, su utilidad en el diagnóstico de pacientes con enfermedad activa es escasa [17,28,29]. Pathan y colaboradores (2001) [30] reportaron una baja frecuencia de linfocitos T CD4 + secretores de IFN-γ específicos de ESAT-6 en individuos con tuberculosis activa, en comparación con aquellos con infección tuberculosa latente.…”

“…El diagnóstico microbiológico convencional se basa en la detección del bacilo en al menos una de tres muestras de esputo recolectadas en tres días diferentes. Estas muestras se someten a tinción de ácido alcohol resistencia para evaluar al microscopio la presencia del microorganismo y se llevan a cultivo en medio Lowenstein-Jensen, lo cual es necesario para confirmar el diagnóstico [29].…”