Microbiological safety of spinach throughout commercial supply chains in Gauteng Province, South Africa and characterization of isolated multidrug-resistant Escherichia coli

Abstract

Aim: To investigate the microbiological quality, potential foodborne pathogen presence, and to phenotypically (antimicrobial resistance [AMR] profiles) and genotypically (DNA fingerprints and diarrhoeagenic genes) characterize Escherichia coli isolated throughout spinach production systems from farm-to-sale. Methods and Results: Samples (n = 288) were collected from two commercial supply chains using either river or borehole irrigation water. E. coli was enumerated throughout the chain where river water was directly used for overhead irrigation at levels between 0.00 and 3.22 log colony forming unit (CFU) g −1 . Following enrichment, isolation and matrix-assisted laser desorption ionization time-of-flight mass spectrometry identification, E. coli was isolated from 22.57% (n = 65/288) of all samples. Salmonella spp. were isolated from 3% (n = 9/288) of river and irrigation water samples on one farm, and no Listeria monocytogenes was detected throughout the study. Of the 80 characterized E. coli isolates, one harboured the stx2 virulence gene, while 43.75% (n = 35) were multidrug resistant. Overall, 26.30% of the multidrugresistant E. coli isolates were from production scenario one that used river irrigation water, and 17.50% from the second production scenario that used borehole irrigation water. A greater percentage of resistance phenotypes were from water E. coli isolates (52.50%), than isolates from spinach (37.50%). E. coli isolates from spinach and irrigation water clustered together at high similarity values (>90%) using enterobacterial repetitive intergenic consensus-polymerase chan reaction analysis. Conclusions:This study reported the presence of multidrug-resistant environmental E. coli throughout spinach production from farm, during processing and up to retail. Furthermore, the similarity of multi-drug resistant E. coli isolates suggests transfer from irrigation water to spinach in both scenarios, reiterating that irrigation water for vegetables consumed raw, should comply with standardized microbiological safety guidelines.Significance and Impact of Study: Multidrug-resistant E. coli presence throughout spinach production emphasizes the necessity of increased surveillance of AMR in fresh produce and the production environment within a One Health paradigm to develop AMR mitigation strategies.

Genomic Evaluation of Multidrug-Resistant Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli from Irrigation Water and Fresh Produce in South Africa: A Cross-Sectional Analysis

“…87 Furthermore, the results from the current study correspond to previous South African studies showing a low prevalence of STEC O157:H7, usually associated with E. coli foodborne disease outbreaks, in fresh produce production systems. 26,[30][31][32][33]87 Although antimicrobial-resistant bacteria complicate food safety assurance, 2 building a genomic database of the virulence genes, antimicrobial resistance genes, and potential pathogenicity of environmental isolates, comparable to existing clinical data, is essential for the implementation of risk mitigation strategies. A limitation of the current study is the use of short sequencing reads, preventing complete plasmid assembly and establishing the role of the detected plasmids in gene transfer among environmental bacteria.…”

“…In South Africa, the dualistic fresh produce production system consists of highly regulated formal systems with commercial farms as well as the informal system, where predominantly small-scale farmers often have limited resources and infrastructure . However, across all fresh produce production in South Africa (both formal and informal), agricultural irrigation water sources predominantly include surface water (rivers, streams, dams, and canals) as well as borehole water. − Typically, water used for irrigation will either be directly applied to the field from the specific water source or pumped into a holding dam or water reservoir until use. , The current study aimed to evaluate the circulating antimicrobial resistance genes, virulence factors, and serotypes of 61 historically isolated multidrug-resistant ESBL-producing E. coli (2016–2019) from water and fresh produce samples in South Africa, − using WGS.…”

Bacterial communities associated with the surfaces of the fresh fruits sold around Dhaka Medical College and Hospital and their anti-microbial profiles

“…Wide spread use of antibiotics might contribute in the emergence of multidrug resistant bacteria. Moreover, application of animal manure to the agricultural field using untreated wastewater for irrigation, unhygienic handling at post-harvest stage and during transportation and processing by handlers-all contribute to the spread of drug-resistant bacteria to fresh food products (Richter et al, 2019).…”

“…are dominant. The transfer of these organisms to fresh fruits and vegetables may occur at multi-stage from production to home kitchen-during production through the use of animal manure and contaminated irrigation water, during the post-harvest stage, transport, conservation and processing by handlers (Richter et al, 2019). It certainly poses a potential public health threat since they are able to exchange resistance genes with intestinal bacteria during their colonization and passage through the intestines leading to further dissemination in the environment (van Hoek et al, 2015).…”

Identification of Three Campylobacter Lysins and Enhancement of Their Anti-Escherichia coli Efficacy Using Colicin-Based Translocation and Receptor-Binding Domain Fusion

“…The widespread emergence and dissemination of diarrheagenic Escherichia coli strains, which can be found throughout the food chain, pose serious threats to public health, especially due to the increasing multidrug resistance of the bacteria ( 1 – 3 ). In the past decade, E. coli isolates from hospitals and retail food locations in China with multidrug resistance to currently available drugs, including ampicillin, cefotaxime, ciprofloxacin, tetracycline, and florfenicol, have been reported ( 4 – 6 ).…”