Concordance between the zinc sulphate flotation and centrifugal sedimentation methods for the diagnosis of intestinal parasites / Concordancia entre los métodos de flotación con sulfato de zinc y sedimentación centrífuga para el diagnóstico de parásitos intestinales

Resumen Introduction: The diagnosis of intestinal parasitic infections depends on the parasite load, the specific gravity density of the parasite eggs, oocysts or cysts, and the density and viscosity of flotation or sedimentation medium where faeces are processed. Objective: To evaluate the concordance between zinc sulphate flotation and centrifugal sedimentation in the recovery of parasites in faecal samples of children. Materials and methods: Faecal samples of 330 children from day care centers were evaluated by zinc sulphate flotation and centrifugal sedimentation techniques. The frequencies of detection of parasites by each method were determined and the agreement between the diagnostic techniques was evaluated using the kappa index, with 95% confidence intervals. Results: The faecal flotation in zinc sulphate diagnosed significantly more cases of Trichuris trichiura infection when compared to centrifugal sedimentation (39/330; 11.8% vs. 13/330; 3.9%, p<0.001), with low diagnostic concordance between methods (kappa=0.264; 95% CI: 0.102-0.427). Moreover, all positive samples for Enterobius vermicularis eggs (n=5) and Strongyloides stercoralis larvae (n=3) were diagnosed only by zinc sulphate. No statistical differences were observed between methods for protozoa identification. Conclusions: The results showed that centrifugal flotation in zinc sulphate solution was significantly more likely to detect light helminths eggs such as those of T. trichiura and E. vermicularis in faeces than the centrifugal sedimentation process.

Abstract Introducción. El diagnóstico de infecciones parasitarias intestinales depende de la carga de parásitos, la densidad de la gravedad específica de los huevos, ooquistes o quistes de parásitos, y de la densidad y viscosidad de los reactivos de flotación o sedimentación usados para procesar las heces. Objetivo. Evaluar la concordancia entre el método de flotación de sulfato de zinc y la sedimentación por centrifugación en la recuperación de parásitos en muestras fecales de niños. Materiales y métodos. Se evaluaron las muestras fecales de 330 niños de guarderías mediante las técnicas de flotación con sulfato de zinc y de sedimentación por centrifugación. Se determinó la frecuencia de detección de parásitos con cada método y se evaluó la concordancia entre las técnicas de diagnóstico mediante el índice kappa, con intervalos de confianza del 95 %. Resultados. Mediante la flotación fecal con sulfato de zinc, se diagnosticó un número significativamente mayor de casos de infección por Trichuris trichiura que con la sedimentación por centrifugación (39/330; 11,8 % Vs. 13/330; 3,9 %) (p<0,001), con poco acuerdo entre los métodos (kappa=0,264; IC95% 0,102-0,427). Además, todas las muestras positivas para huevos de Enterobius vermicularis (n=5) y larvas de Strongyloides stercoralis (n=3) se diagnosticaron solamente por sulfato de zinc. No se observaron diferencias estadísticamente significativas entre los métodos para la identificación de protozoos. Conclusiones. La flotación centrífuga en una solución de sulfato de zinc presentó una probabilidad significativamente mayor de detectar los huevos livianos de helmintos como T. trichiura y E. vermicularis en heces, que el proceso de sedimentación por centrifugación.

Lack of effect of nucleotide-supplemented infant formula on the management of acute diarrhea in infants.

Nucleotides have been identified as conditionally essential nutrients. As prevention studies, conducted with nucleotide-supplemented formula, have shown statistically significant decrease in the risk of diarrhea, we tested the hypothesis that the consumption of nucleotide-supplemented formula during an acute diarrhea episode is associated with therapeutic effects in the treatment of infants with acute diarrhea and dehydration. A randomized, double-blind, controlled clinical trial was conducted in which patients were randomly assigned to 1 of 2 treatment groups. The "test" group consumed a nucleotide-supplemented infant formula and the "control" group consumed a nonsupplemented formula. Infants were accommodated in a metabolic unit where body weight, and all intakes and outputs were recorded at 24-hour intervals during hospitalization. Laboratory parameters including blood gases and electrolytes were monitored during hospitalization. Eighty-one male infants ranging in age from older than 1 month and younger than 1 year, with acute non-cholera diarrhea and dehydration were studied. Primary outcomes were stool output and duration of diarrhea and did not differ significantly between the groups, with a stool output of 304.2 (SD 254.0) vs 350.3 (SD 269.1) g/kg and a duration of diarrhea of 83.3 (SD 44.5) vs 88.8 (SD 46.6) for the test and control groups, respectively. Anemia was highly prevalent and breast-feeding practice was not frequent in both groups. The average energy intake and weight gain were similar in the 2 groups. This study demonstrated that nucleotide supplementation of infant formula during episodes of acute diarrhea has no therapeutic advantage compared to conventional infant formula.