PHAGE AMPLIFICATION TECHNOLOGY IN THE DIAGNOSIS OF PULMONARY TUBERCULOSIS: APPLICABILITY IN NIGERIA

Abstract

Though of global importance, the developing world bears the highest burden of tuberculosis (TB) worldwide and Nigeria has been rated amongst 222 countries where TB prevalence is highest worldwide. In Nigeria, diagnosis is largely by direct smear microscopy using the Ziehl-Neelson method. Studies have shown that the sensitivity of smear microscopy varies between 30 70% depending on whether direct or connected smears are examined. It is thus likely that up to half or more of TB sufferers in Nigeria are not diagnosed, automated culture and molecular methods exist but the requirement for especially dedicated, very expensive instrumentation and reagents prohibit their use in developing countries including Nigeria. The World Health Organization recognizes the need for new, affordable, rapid and highly sensitive diagnostics for use in developing countries. Phage amplification technology employs a specific mycobacteriophage which infects a live TB bacillus if represent in a sample. These replicate and lyse the cells to release progeny phage. The presence of progeny phage is detected visually as plagues on a lawn of a raid-growing, non-pathogenic Mycobacterium. Phage Amplification Technology has been evaluated and found to detect most cases missed by smear microscopy and to give results with good correlation with culture (which though highly sensitive requires 6 8 weeks incubation to give results), within 24 hours of sample preparation. It is thus faster than culture and cheaper that the new rapid automated methods, as it requires no especially dedicated instrumentation.


(Af. J. of Clinical and Experimental Microbiology: 2002 3(2): 55-63)