Abstract
Light-emitting-diode microscopy(LED) has recently been endorsed by the WHO. However, it is unclear if LED is as accurate and cost-effective as Ziehl-Neelsen(ZN) or mercury-vapour-fluorescence-microscopy(MVFM) in TB-HIV co-infected persons.
Direct and concentrated sputum smears from TB suspects were evaluated using combinations of LED, ZN-microscopy and MVFM. Median reading time per slide was recorded and a cost analysis performed. Mycobacterial culture served as the reference standard.
647 sputum samples were obtained from 354 patients[88(29.8%) HIV-infected and 161(26%) culture-positive for M.tb]. Although overall sensitivity of LED compared to ZN-microscopy or MVFM was similar, sensitivity of all three modalities was lower in HIV-infected patients. In the HIV-infected group the sensitivity of LED was higher than ZN using unconcentrated samples(46 vs. 39%;p=0.25), and better than MVFM using concentrated samples(56 vs. 44;p=0.5). A similar trend was seen in the CD4 count <200cells·mm−3 subgroup. Median(IQR) reading time was quicker with LED compared to ZN-microscopy[1.8(1.7–1.9) vs. 2.5(2.2.–2.7) minutes,p=<0.001]. Average cost per slide read was cheaper for LED-microscopy(U$1.63) compared to ZN-microscopy(U$2.10).
Among HIV-TB co-infected patients LED-microscopy was cheaper and performed as well as ZN-microscopy or MVFM independent of the staining(ZN or Auramine-O) or processing method used.
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