Supervivencia de Escherichia coli y Salmonella Typhimurium en agua recreativa de río

Abstract

In Mexico, the use of rivers as recreational centers drives the regional economy, however, most of these do not comply with the safety and quality of the water, therefore the microbiological risk derived from poor hygiene practices and discharges of industrial and urban waste increases every day, leaving public health exposed due to the deficiency in the monitoring of pathogens associated with infectious outbreaks. Escherichia coli (E. coli) and Salmonella Typhimurium (S. Typhimurium) have a high prevalence in rivers of Sinaloa, they are considered indicators of contamination and are of the main causes of gastrointestinal infections worldwide, due to their ability to survive in numerous natural environments. Therefore, in this research, the survival of both bacteria in recreational water from the Fuerte River, San José de Ahome, Sinaloa, Mexico, was evaluated. To determine bacterial survival, water samples from two river locations were used, before and after the 2019 Easter holiday period. The concentration of total dissolved solids was determined for each sample, and these were inoculated with E. coli and S. Typhimurium independently, at a concentration of 6 Log10 CFU mL-1, simulating river conditions in the laboratory. For this, both bacteria were evaluated every 48 h using the plate extension technique. The results obtained showed that both bacteria prior to the Easter period survived 12 days, with 6.2X101 CFU mL-1 and 4.5 X101 CFU mL-1 of E. coli at sampling points 1 and 2, respectively and, 4.66X101 CFU mL-1 and 5.4 X101 CFU mL-1 of S. Typhimurium at sampling points 1 and 2, respectively; likewise, after the holiday period they survived 1.2X102 CFU mL-1 until day 16 and 4 CFU mL-1 until day 20 of E. coli at sampling points 1 and 2, respectively, also 1.65 X102 CFU mL-1 until day 16 and 22 CFU mL-1 until day 22 of S. Typhimurium, at sampling points 1 and 2, respectively. By comparison of means with the Tukey test showed that, there are significant differences between the survival of E. coli and S. Typhimurium in the sampling dates, which could be attributed to the capacity to use nutrients, derived from the organic waste generated by human influx.