Tracking resistance: antimicrobial susceptibility of bacteria in domestic water from the Mezquital Valley, Mexico

Abstract

Graphical abstract illustrating the dynamics of wastewater that is used in the Mezquital Valley. The diagram shows the water types analyzed through bacterial determination and susceptibility tests, highlighting the presence of extended-spectrum beta-lactamase-producing E. coli. Antibiotic-resistant bacteria (ARB) in water sources constitute an important public health challenge; consequently, monitoring is necessary to mitigate their dissemination. We describe the resistance profile of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli in two zones from the Mezquital Valley, Hidalgo, where wastewater is reused for irrigation. Three sampling campaigns were conducted between 2016 and 2017 in this area. Household water and irrigation samples were processed through membrane filtration and cultured on antibiotic-supplemented media (n = 105). Presumptive E. coli colonies were isolated, after which we performed susceptibility profiles and identification using the MicroScan system. The presence of E. coli was confirmed in 96.6% of isolates, and 82.4% of them were ESBL producers. Household water from Zone A showed higher ESBL-E. coli counts compared with Zone B (p = 0.0247), likely due to its proximity to wastewater canals. Similar profiles between household water and wastewater isolates were observed (p = 0.81). Multidrug resistance (MDR) was detected in domestic and wastewater isolates. No resistance was determined for groundwater. Household water with the presence of ARB suggests wastewater contact with water supplied for human use. This case reinforces the need to meet standards and use risk assessments to mitigate negative effects of wastewater on the environment, human populations, and animals.