Detection of Mycobacterium tuberculosis Antigen in Cough Samples in Northern Ethiopia

Abstract

1. Abstract Tuberculosis is a highly infectious disease that is spread from person to person by infected aerosols emitted by patients with respiratory forms of the disease. We describe a novel device, the TB “Breathalyser” (Rapid Biosensor Systems Ltd) that collects human cough samples and utilizes immuno- sensor and bio-optical technology to detect M. tuberculosis (MTB) Antigen (Ag85B) in them, and demonstrate its use under field conditions during a pilot study in Ethiopia. The TB Breathalyser was field tested on outpatients of three governmental Hospitals in the Tigray region, Ethiopia using a cross sectional study design. Of 427 patients tested, 192 were diagnosed as TB positive from Sputum and/or X-ray. Rapid Biosensor test results were recorded and assessed using two different thresholds for pos/neg diagnosis. Of the 192 TB positive patients 149 (at the -40 threshold) and 130 (at the -60 threshold) gave positive Breathalyser results. A further 120 (at the -40 threshold) and 106 (at the -60 threshold) were Breathalyser positive/sputum negative/X-ray negative and most were clinically positive, at an early stage of infection. The Breathalyser had sensitivities ~97-99% and specificities ~97% for early stage and actively infectious later stage patients. The Breathalyser detected 65-75% of well-established/relapsed patients. The detection of significant numbers of early stage and infectious TB patients, clearly has huge implications regarding the potential for improving the rate of detection of TB in High Burden countries where rates ~30% mostly late stage patients, are currently typical. 2. Keywords: <span style=font-size:10.0pt;mso-bidi-font-family: times= new= roman=> <span style=font-size:10.0pt;mso-bidi-font-family: times= new= roman=> AFB; Breathalyser Test; Mycobacterium tuberculosis