Modificación de una técnica de muestreo para mejorar la recuperación de Vibrio cholerae en aguas superficiales y residuales

Abstract

To improve retrieval of Vibrio choleraefrom fresh and sewage water, a new design of the Moore swab, increasing its sampling area several-fold, was tested. The new swab was exposed to concentrations of 7 . 5 ~013 , 1. 5x104,3 . 0 5O14 and 7.5x104 colony forming units (CFU) of Vibrio cholerae 01 and no 01 in trials involving fresh as well as sewage water, using two models: dynamic, water in constant movement, and static, being still water. 20-liter glass containers were used to run the assays in samples being taken at 12,24,36 and 48 hours. Brain-heart infusion (BHI) and thiosulfate-citratebile- sucrose (TCBS) were used as growing media. The new swab retrieved 99.4% (1741175), of V. cholerae from fresh water and 100% (1881188) from sewage waterwhen grown on BHI, in both models. OnTCBS, V. cholerae was positive in 60% (1051174) of the samples for fresh water and 92.6% (174/188), for sewage water. Overall, retrieval on BHI was 99.7% (3621363), and 76.3% (2791363) onTCBS.The best sampling time was established at 24 hours.