Treated wastewater used in fresh produce irrigation in Nsukka, Southeast Nigeria is a reservoir of enterotoxigenic and multidrug-resistant Escherichia coli

Abstract

Background: Occurrences of pathogens in environmental and irrigation waters, as well as the use of inadequately treated sewage for fresh produce constitute potential public health threats worldwide. Objective: To investigate the treated wastewater used in fresh produce irrigation in Nsuskka, Southeastern Nigeria, as a reservoir enterotoxigenic and multidrug-resistant Escherichia coli. Methods: Treated wastewater (from the sewage treatment facility at Nsukka, Southeast Nigeria), soil and irrigated vegetable samples were collected and analyzed using standard procedures. Escherichia coli isolated from the samples were screened for the presence of enterotoxigenic E. coli strain encoding lt gene and profiled for antibiotic resistance using the conventional PCR and standardized agar disk diffusion assays respectively. Results: Of the total presumptive 103 isolates, PCR detected uidA gene in 87 (84 %), of which 23 (26 %) harboured the lt encoding ETEC gene. Generally, imipenem, cefuroxime and norfloxacin proved to be most effective of all the antibiotics employed. Wastewater isolates were variously susceptible to ciprofloxacin (95 %), norfloxacin (95 %), cefuroxime (93 %), chloramphenicol (93 %), trimethoprim and tetracycline (88 %), soil isolates to streptomycin (75 %) and vegetable isolates to cefuroxime (90 %), norfloxacin (86 %), ciprofloxacin (81 %) and chloramphenicol. Contrariwise, high resistances observed to other antibiotics were in the order; ampicillin (95 %), penicillin (93 %), erythromycin (90 %) and clarithromycin (83 %) among wastewater isolates, ciprofloxacin and norfloxacin (75 %) in soil isolates; penicillin, vancomycin and erythromycin (98 %), rifampicin and clarithromycin (93 %), sulphamethoxazole (83 %), ampicillin (81 %), tetracycline and imipenem (76 %), trimethoprim (72 %) and amoxicillin (71 %) among vegetable isolates, with multidrug resistance patterns ranging from three to seventeen. Conclusions: Our results reveal the treated wastewater as a reservoir of enterotoxigenic E. coli as well as multidrug resistance that may pose a health hazard for humans and animals when released to the natural environment. Hence, there is need to develop management strategies and ensure compliance in order to prevent water-borne diarrhoea caused by ETEC and reduce the menace of antibiotic resistance in the environment.

Spectrum of Diarrheagenic Escherichia coli in Drinking and Wastewater in Rafha City of Saudi Arabia

“…The prevalence of ETEC in the current study (6%) was much lower than other reported studies where it was found to be 26% [20]. Higher prevalence was also reported in some other studies [21][22][23][24][25].…”

Prevalence of multi-drug resistant bacteria associated with foods and drinks in Nigeria (2015-2020): A systematic review

“…Titilawo et al (2015), found ampicillinresistant gene to be predominant in the environment, thus transfer of the resistant gene among bacteria isolate is possible. The result for ampicillin is also supported by Adenipekun et al (2015) and Chigor et al (2020).…”

“…Industrial and household effluents dumped directly into rivers, which are primary sources of water in vegetable farms, may contribute to the MDR patterns (Titilawo et al, 2015). Chigor et al (2020) corroborated this when they reported MDR bacteria from wastewater samples. Once accumulated in the environment, bacteria species may begin to transmit antibiotics resistance genes amongst themselves posing serious public health concerns.…”

Does Irrigation with Treated and Untreated Wastewater Increase Antimicrobial Resistance in Soil and Water: A Systematic Review

“…Additionally, a study in Nigeria investigated soil irrigated with secondary-treated wastewater. While the study did not use a comparison site, 100% of E. coli isolates from wastewater-irrigated soils were resistant to ≥5 antibiotics [ 38 ].…”