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Abstract

Background: There has been a surge in the number of extrapulmonary tuberculosis cases in the recent years. Isolation of M. tuberculosis from clinical samples by culture is the "gold standard" for a definitive diagnosis of EPTB. Isolation by Mycobacterial culture is difficult especially due of the paucibacillary nature of extrapulmonary TB. Aim: To compare automated and conventional mycobacterial culture in terms of positivity, time taken for detection, contamination rates and overall cost benefit. Setting and Design: This study on extra-pulmonary tuberculosis was conducted in the department of Microbiology, Medical College, Kozhikode for a period of one year. Materials and Methods: All the specimens received during the one year period were included in the study. History, clinical examination findings and results of relevant investigations were obtained and recorded in a proforma. All specimens were processed by modified Petroff's method and subjected to smear microscopy. The processed specimens were cultured by both MB/Bact and Lowenstein-Jenson medium(LJ medium). Results: Out of the 118 specimens included in the study. Isolation was obtained in 14 sample from MB/Bact culture and in 4 samples by LJ culture Isolation rate by automated method was 11.86% whereas by conventional method it was only 3.38%. Average detection time was 14.7 days by automated method and 34 days by conventional LJ medium culture. The contamination rate by automated method was 5.08% and by conventional method it was 17.79%. On comparing with MB/Bact, the specificity of LJ medium is 92.1% while the sensitivity is only 28.57%. MDR TB was detected in 28.85% patients. Conclusion: Automated mycobacterial culturing system is rapid and less labor-intensive which may be considered as a valuable alternative to the conventional culture especially in cases of smear negative extrapulmonary tuberculosis.