Diarrheal bacterial pathogens and multi-resistant enterobacteria in the Choqueyapu River in La Paz, Bolivia

Abstract

Water borne diarrheal pathogens might accumulate in river water and cause contamination of drinking and irrigation water. The La Paz River basin, including the Choqueyapu River, flows through La Paz city in Bolivia where it is receiving sewage, and residues from inhabitants, hospitals, and industry. Using quantitative real-time PCR (qPCR), we determined the quantity and occurrence of diarrheagenic Escherichia coli (DEC), Salmonella enterica, Klebsiella pneumoniae, Shigella spp. and total enterobacteria in river water, downstream agricultural soil, and irrigated crops, during one year of sampling. The most abundant and frequently detected genes were gapA and eltB, indicating presence of enterobacteria and enterotoxigenic E. coli (ETEC) carrying the heat labile toxin, respectively. Pathogen levels in the samples were significantly positively associated with high water conductivity and low water temperature. In addition, a set of bacterial isolates from water, soil and crops were analyzed by PCR for presence of the genes blaCTX-M, blaKPC, blaNDM, blaVIM and blaOXA-48. Four isolates were found to be positive for blaCTX-M genes and whole genome sequencing identified them as E. coli and one Enterobacter cloacae. The E. coli isolates belonged to the emerging, globally disseminated, multi-resistant E. coli lineages ST648, ST410 and ST162. The results indicate not only a high potential risk of transmission of diarrheal diseases by the consumption of contaminated water and vegetables but also the possibility of antibiotic resistance transfer from the environment to the community.

Molecular Analyses of Fecal Bacteria and Hydrodynamic Modeling for Microbial Risk Assessment of a Drinking Water Source

“…The culture analysis indicated higher concentrations of coliforms and E. coli in samples collected in colder water. These findings are corroborated by other studies in countries with more temperate climate where higher concentrations of coliforms correlated positively with cold water and high rainfall [7] and cold water and high conductivity [64]. Bacteria measured by culture methods (coliforms, E. coli and C. perfringens) ( Figure 3) were efficiently reduced by the artificial infiltration, while ssrA DNA copies from real-time PCR analysis were detected in similar concentrations both before and after the artificial infiltration, indicating that the ssrA DNA were transported through the infiltration or that there were additional sources impacting the infiltrated water.…”

Molecular Epidemiology of Enteroaggregative Escherichia coli (EAEC) Isolates of Hospitalized Children from Bolivia Reveal High Heterogeneity and Multidrug-Resistance

“…Our findings correlate with studies in Bolivia and other developing countries where widespread use of antibiotics can be purchased over the counter and without any prescription (77). Studies in La Paz showed that diarrheagenic E. coli are 60-90% resistant to the most common antibiotics, such as ampicillin, tetracycline trimethoprim-sulfamethoxazole (7,78,79). Among healthy Bolivian children, 63% carried MDR-E. coli in their stool samples (80).…”

Sustainability Transitions in the Municipal Solid Waste Management Systems of Bolivian Cities: Evidence from La Paz and Santa Cruz de la Sierra

“…In La Paz, there is evidence of the break-through of centralized collection and disposal activities around the 1940s (Section 3.1.2), though at that time the collected waste was frequently disposed in the Choqueyapu river, which crosses the city and remains severely polluted until now [102,110]. Open dumps operated until the 1980s, considering that the first sanitary landfill in the city ("Mallasa" landfill) started operating in the 1990s (Section 3.3.2).…”