Experimental estimation of the efficacy of the FLOTAC basic technique

The FLOTAC technique is a quantitative coproscopic method for the diagnosis of parasitic infection that is based on the centrifugation of a fecal sample to levitate helminth eggs with a flotation solution in a proprietary apparatus. Determination of the efficacy of the FLOTAC method and multiplication factors for calculation of the number of Toxocara, Trichuris, and Ascaris eggs in 1 g of feces on the basis of the number of detected eggs is presented. An investigation was conducted using feces samples enriched with a known number of parasite eggs: 3, 15, 50, or 100 parasite eggs of 3 nematode genera (Toxocara, Trichuris, and Ascaris) per 1 g (EPG) of feces. In addition, 80 samples of dog feces were prepared consisting of 20 repetitions for each level of contamination. The samples were analyzed using the FLOTAC basic technique. The limit of detection was calculated as the lowest level of egg content at which at least 50% of repetitions were positive. Multiplication factors for estimating the true number of parasite eggs in the samples were derived from regression coefficients that illustrated the linear relationship between the number of detected eggs and the number of eggs added to the sample. The percentages of recovered eggs for 1 chamber and for the whole apparatus ranged from 11.67 to 21.90% and from 21.33 to 40.10%, respectively, depending on dose enrichment and genus of parasite. The limit of detection calculated for the whole FLOTAC device was 3 EPG and was 15 EPG for 1 chamber for each of the 3 parasite genera. The limit of quantification calculated for whole FLOTAC was 15 EPG for each of 3 kinds of eggs. For 1 chamber, the limit of quantification was 15 EPG for Ascaris and Toxocara eggs and 50 EPG for Trichuris eggs. Multiplication factors for calculation of the number of eggs in 1 g of feces calculated for whole FLOTAC were 3 (for Toxocara and Ascaris eggs) and 4 (for Trichuris eggs). Experimentally calculated parameters of the method differ significantly from the theoretical assumptions of the authors of the FLOTAC technique and can significantly affect the reliability of the results. This does not alter the fact that the FLOTAC technique is the most effective parasitological quantitative method, which can be used to detect parasitic forms in feces. However, the results of our study emphasized the need for validation of the method before using it in the laboratory.