By Nawaz Yasin Islam
SHILLONG: Tuberculosis drug susceptibility testing by line probe assay will now be a reality in Meghalaya with the certification issued to the Department of Microbiology, Nazareth Hospital under the National Mycobacteriology certification system of Central TB Division under the Union Ministry of Health and Family Welfare.
Inaugurating the laboratory here on Friday, Commissioner & Secretary, Information Technology and Health, DP Wahlang lauded the initiatives taken by the hospital in this regard considering the fact that this laboratory would be the second RNTCP (Revised National Tuberculosis Control Program) certified laboratory in the North East region and the first in a catholic institute of the country. A point worth mentioning here is that the cost of the whole set up was borne by the administration alone sans external funding.
Multidrug-resistant tuberculosis (MDR-TB) has long posed a formidable challenge to TB control due to its complex diagnostic and treatment challenges. Alarming increases in MDR-TB, the emergence of extensively drug resistant TB, potential institutional transmission, and rapid mortality of MDR-TB patients with HIV co-infection, has highlighted the urgency for rapid screening methods. Line probe assays are tests for the rapid detection of mutations associated with rifampicin and isoniazid drug resistance. Line probe assays are designed to identify M. Tuberculosis complex and simultaneously detect mutations associated with drug resistance.
Drug susceptibility testing involves finding out which drugs the TB bacteria in a person are sensitive to, and therefore whether the person has got drug resistant TB.
Conventional screening procedures coupled with poor drug quality have lead to rise in drug resistance TB.
Dr Michael Mawlong, in-charge, Department of Microbiology, Nazareth Hospital, is of the firm belief that the new testing facility will go a long way in accurate diagnosis. “TB diagnosis involves a Phenotypic and Genotypic approach. The latter directly looks into the DNA of Mycobacterium tuberculosis and ascertains whether the organism is sensitive or resistant. Phenotypic diagnosis however involves the physical growing of the organism,” he said, adding that the rapid screening procedures can initiate early treatment with the reduced possibility of losing the patient and moreover, a detailed battery of anti-TB drug sensitivity tests can be further run.
Treatment of TB is via a prescribed combination of drugs, especially so for Multi Drug Resistant TB. Each drug acts as a sort of backup for the other. Therefore it is vital that a proper combination of drugs in a prescribed format, for certain duration without break be followed. Resistance occurs due to drug selection pressure.
The accuracy of such tests is also very promising as liquid culture is well known to be most sensitive. “In a wide range of studies, the sensitivity varies from 90 to 98%, with pooled data from WHO field trials saying it is 97% sensitive and 99% specific. This is more than adequate for the task at hand,” Mawlong asserted.
Regarding competent workforce handing the experimental procedures, Mawlong expressed confidence over uni-directional workflow, which according to him has been built into their working methods. “The Head of the National Referral Institute (LRS Institute of Tuberculosis & Respiratory Diseases, New Delhi) observed us and was happy. Besides we have undergone the certification process which is very stringent. We achieved a 100% concordance rate, which I think speaks for itself,” Mawlong said.
“We have Bio-safety cabinets, molecular work station (Laminar flow), Thermal cycler, refrigerated centrifuge, Hybridiser both manual and automated. In addition, each room of the facility has its own dedicated set of equipment which again is vital for accuracy and reproducibility. Our facility is small but more than adequate for the job that we have undertaken,” Mawlong said adding that necessary infrastructure required for line probe assay has been a priority in setting up of the lab.
Nazareth Hospital started this TB culture and LPA back in December 2011 of as part of their own initiative. The Central Tuberculosis Division, New Delhi came to hear about it and since only Gauhati Medical College had the facility in the North East, they were asked to get themselves accredited and to serve as the State Drug Susceptibility Testing Laboratory using LPA.