Risk of Illness with Salmonella Spp. and Antibiotic-Resistant Salmonella sp. due to Consumption of Lettuce Irrigated with Water from La Ramada Irrigation District.

Abstract

Despite heavy contamination of the Bogotá River with domestic and industrial waste, it remains vital for various purposes, including agricultural use at La Ramada Irrigation District. There are important concerns regarding pathogen concentrations in irrigation water at La Ramada, including the presence of antibiotic-resistant Salmonella spp. This study aimed to estimate the risk of Salmonella-related illness from consuming lettuce irrigated with Bogotá River water at La Ramada. We collected lettuce samples from 4 different sites, all irrigated with water from La Ramada. The methodology involved a process to detach Salmonella spp. from lettuce leaves, quantification through plate counts on SS agar, and establishment of antibiotic-resistant bacteria concentrations through growth on media supplemented with ampicillin or ciprofloxacin. The results showed concentrations of Salmonella spp. of 10^3.59,10^2.66, and 10^4.56 CFU/g lettuce at sites 1, 2, and 3, respectively, and ampicillin-resistant Salmonella spp. of 10^1.93, 10^1.31, and 10^2.07 CFU/g lettuce at sites 1, 2, and 3, respectively. No colonies were obtained from lettuce samples collected from site 4. Notably, we detected no isolates resistant to ciprofloxacin at any of the sites. Salmonella spp. concentrations varied greatly among sampling sites. Salmonella spp. concentrations were used to predict the daily probability of illness, with a probability of 0.59 (0.33 to 0.78, CI 95%) for Salmonella spp. and 0.3 (0.03 to 0.53, CI 95%) for ampicillin-resistant Salmonella spp.