Two plate count methods, double layer and single layer of agar for quantification of somatic coliphages in water, were implemented using standard methodologies. Several variables were tested and provided valuable information that was not included in standard methodologies. The most important findings are described, such as the effect of using an excessively concentrated culture of E. coliand production of a log phase culture in only 4 hours of incubation, adjusting the concentration to an optical density of 0.3 at 600 nm (3.1 x 10 8 CFU / mL), or to McFarland 1 (3.0 x 108 CFU / mL). It was determined that coliphages controls must be stored at -70 °C to reduce its degradation. Quantities of reaction mixture exceeding 20 mL per Petri dish must be avoided to prevent interfere with bubbles during the counting of plate forming units (PFU). It was demonstrated that coliphages isolated from water samples can be stored for 48 hours at 4 °C without any degradation, and PFU are not observed in samples with high concentrations of coliphages, because a confluent lysis of the bacte-rial layer. There was no significant difference in the recovery of coliphages using doble layer or single layer methods, but such methods should be evaluated by means of controls, before applying them directly in the analysis of water samples.
Giardia cysts stained with hot carbolfuchsin were used as internal controls in a concentration method for surface water samples. The morphological integrity of stained cysts and the stain's stability and intensity were tested with each of the chemical reagents used in the aluminum sulfate flocculation method. No alterations in morphology or color were noted. The stained cyst preparation has a low cost, high stability, and suitability for both light and immunofluorescent microscopy, making it affordable to researchers in low-and middle-income countries.
Objetivos: (i) Determinar la prevalencia de deficiencias nutricionales y anemia en preescolares que se benefician de dos programas de ayuda nutricional (intramuros y extramuros) en los Centros de Educación y Nutrición y Centros Infantiles de Nutrición y Atención Integral (CEN-CINAI) e (ii) identificar los factores socioeconómicos asociados con deficiencias nutricionales y anemia en esta población. Métodos: Se censaron 2503 niñas y niños de 0 a 7 años de 13 centros CEN-CINAI de la Región Central Sur de Costa Rica en el período 2014-2016. La infomación sobre las características socioeconómicas de sus familias se obtuvo mediante un cuestionario estructurado. Además, se tomaron medidas antropométricas (n=2205) y muestras de sangre para hemograma (n=2203) de las niñas y los niños. Resultados: Se estimó una prevalencia de deficiencias nutricionales de 15,4% (intervalo de confianza [IC] 95%: 14,0-17,0) y una prevalencia de anemia de 7,5% (IC 95%: 6,4-8,6). Ambas condiciones fueron más frecuentes en infantes ≤5 años (23,2% para deficiencias nutricionales y 8,6% para anemia) y en beneficiarios del programa de ayuda extramuros (41,9% y 10,6%, respectivamente). Otros factores demográficos y socioeconómicos, tales como ser del sexo femenino, habitar en una vivienda no adecuada con un techo de material natural o de desecho y ser parte de una familia numerosa (>4 integrantes) también se asociaron con la presencia de deficiencias nutricionales y/o anemia. Conclusiones: Las prevalencias de deficiencias nutricionales y anemia observadas en este estudio resaltan la importancia de intervenir aquellos factores socioeconómicos modificables que influyen en estas prevalencias y mejorar la atención médica de preescolares en condición de vulnerabilidad
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