Diagnostic Efficacy of Light-Emitting Diode (LED) Fluorescence based Microscope, Spoligotyping and drug resistance patterns of Mycobacterium tuberculosis strains isolated from clinically suspected Tuberculous Lymphadenitis.

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Addis Abeba University


Background: Comparably efficacy of Microscopic examination for tuberculous lymphadenitis is differs from laboratory to laboratory. Emergence of drug resistant TB still a major challenge in developing countries. We therefore also investigated the drug resistant patterns and molecular epidemiology of mycobacterial isolated from tuberculous lymphadenitis patients. Methods: A cross sectional study was conducted from clinically suspected Tuberculous lymphadenitis patients. Three smears were prepared; for cytomorphology, Auramine O and ZN staining study. The left-over sample were inoculated onto Lowenstein-Jehnsen (LJ) media. The culture isolates were tested by regions of difference (RD9) to distinguish M. tuberculosis from other species of M. tuberculosis complex. Phenotypic, genotypic first-line and genotypic secondline drugs were tested for resistance pattern of isolates by using GenoType MTBDRplus and Phenotypic DST (Drug containing 7H10 Middlebrook Media), and the Spoligotyping strain dependent polymorphism test were determined. Statistical analysis was done using STATA version 11. The sensitivity, specificity, positive and negative predictive values were calculated by considering the culture results as the gold standard. Results: Among 211 FNA samples collected; 49.7% (105/211) were positive by Cytology, 32.7% (69/211) LEDFM, 23.69% (50/211) Culture and 13.7% (29/211). The efficacy of ZiehlNeelsen as compared to culture, Sensitivity were 30% [95% CI: 17.9-44.6], Specificity 91.3% [95% CI: 85.8-95.2]. For LEDFM, the Sensitivity 66% [95% CI: 51.2-78.8] and the Specificity was 77.6% [95% CI: 70.4-83.8]. The Sensitivity and Specificity of Cytology was 78% [95% CI: 64-88.5], 58.8% [95% CI: 50.7-66.5] respectively. The most predominant Spoligotyping types were NEW strains following by SIT53 and the overall drug resistance patterns among 50 cultures positive isolates were 14% (7/50); out of this 8% (4/50) isolates were mono resistance for INH, whereas 6% (3/50) isolates were resistance for both INH and Rifampicin. Conclusion: LEDFM gives a legitimate option in contrast to ZN techniques in terms of its higher sensitivity, a bit lower specificity. Three MDR-TB cases and heterogeneous strains of M. tuberculosis and the high extent of INH monoresistance from HIV patients were detected. The NEW and SIT53 (T) strains was the most prevailing strains in the study area.



M. tuberculosis, MDR-TB, TBLN, Spoligotyping