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Introduction: Bacterial cultivation is the gold standard method for diagnosis of tuberculosis (TB). However, technique is time consuming for 28-56 days of cultivation. Therefore, several rapid tests have been developed. Real-time PCR is one of the quick TB test currently used for identifying both drug-susceptible and multidrug resistant TB (MDR-TB). However, the efficiency of real-time PCR compared to conventional method has not been elucidated.
Objective: To compare the efficiency between real-time PCR and conventional methods including cultivation in solid media and mycobacteria Growth Indicator Tube (MGIT 960) system for detection of TB and MDR-TB.
Materials and methods: One hundred and forty-seven sputum specimens collected from hospital sectors of the Office of Disease Prevention and Control 2 in Phitsanulok were decontaminated and subjected to culture in LJ medium agar slant and MGIT 960 system. Bacterial DNA was extracted and real-time PCR was performed using the AnyplexTM MTB/NTM detection kit and AnyplexTM II MDR-TB detection kit.
Results: Samples (86.2%) were positive by real-time PCR and was 39.3% higher than conventional culture. Sensitivity, specificity, positive predictive value, and negative predictive value of real-time PCR for detection of multidrug-resistant tuberculosis were 96.82%, 28.05%, 49.17%, and 92.0%, respectively, as compared to MGIT 960 system. Time required for detection of TB between MGIT 960 system and real-time PCR is 13 and 2 days. However, total cost of MGIT 960 system is cheaper than that of real-time PCR (600 Baht vs 1,500 Baht, respectively).
Conclusion: Real-time PCR is the useful diagnostic test for rapid detection of MTB and MDR-TB. Real-time PCR provides higher sensitivity and specificity than convention culture methods. This method can be used as a screening test for TB infection where rapid treatment can be achieved. However, this method has to be further on evaluated for its cost effectiveness.
Bull Chiang Mai Assoc Med Sci 2016; 49(2): 218-226. Doi: 10.14456/jams.2016.22
Personal views expressed by the contributors in their articles are not necessarily those of the Journal of Associated Medical Sciences, Faculty of Associated Medical Sciences, Chiang Mai University.
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