Tuberculosis: Newer diagnostic tests: Applications and limitations

Abstract

A public health worry as is Tuberculosis (TB) has been making more than 10 million people globally suffer from its terror and causing more than 2 million people worldwide to lose their lives every year. Mankind is putting all its efforts, since the discovery of the causative bacilli, to come up with some dramatic improvements in providing high-quality TB diagnostic services. Nevertheless, it poses a challenge and many people with TB remain use only smear microscopy for diagnosis. In an environment where transmission is becoming easier by the day the challenge becomes burdensome once disease gets associated with drug resistance, HIV, other diseases, etc. It becomes of paramount importance to address this biggest public health challenge delivering timely diagnosis using advanced technologies. Initial microscopic examination forms the backbone of TB diagnosis since 100 years along with clinical confirmations. Newer advanced diagnostic tools coming into play are genotypic assays (LPA, CBNAAT, LAMP) that are rapid molecular tests, and culture methods (liquid culture media) with standard drug susceptibility testing assays. Program ideates to correlate these rapid molecular diagnostics with turn-around time (TAT) as low as around 2 hours, with conventional standard methods. These help in reinforcing the diagnostic capacities and also provide identification of drug resistance patterns for few most important first line and second line drugs. The present day developments have brought these tests to near-patient point of care. Culture tests (liquid culture media) are gold standard technique for the analysis of TB with its increased sensitivity and highest quality over all others. An on-going search under TB diagnostics is to find an efficient, reproducible, cost effective tool with minimal infrastructure requirements. This review conveys the advances made over the past decades in the diagnosis of the disease and drug resistance.

Keywords: CBNAAT; Diagnostics; Genotypic assays; LPA; Tuberculosis.