Increased sensitivity of routine laboratory detection of Strongyloides stercoralis and hookworm by agar-plate culture

The efficacy of agar-plate culture has been evaluated for the detection of Strongyloides stercoralis and hookworm, compared with direct smear, the for malin-ether sedimentation technique and the filter-paper method. Of 1085 st ool samples from the routine laboratory service at King Chulalongkorn Memor ial Hospital in Bangkok, 241 samples harboured S. stercoralis, 153 hookworm and 2 Rhabditis hominis. The recovery rate of S. stercoralis by agar-plate culture is significantly superior to the other methods (P < 0.005). The ra tios of positive results from the methods used to the total number of S. st ercoralis-positive cases were as follows: 1:1.03 by agar-plate culture, 1:1 .85 by the filter-paper method, 1:1.98 by the sedimentation technique and 1 :10.48 by direct stool smear. A similar trend of the efficacy ratio of each method was obtained for hookworm detection. The characteristic furrows lef t by hookworm larvae, and larvae and adults of S. stercoralis could be used for preliminary species identification. Daily search for furrows on agar p lates for up to 6 consecutive days resulted in an increased sensitivity for diagnosis of both S. stercoralis and hookworm infections.