Cluster analysis and geospatial mapping of antibiotic resistant Escherichia coli O157 in southwest Nigerian communities

Abstract

Geospatial spread and antibiotic-resistant relatedness of Escherichia coli O157, which are important virulent serotypes causing severe complications leading to high intestinal morbidity and occasional mortality in several communities in southwest Nigeria, were evaluated. Biotyped Escherichia coli strains (n = 508) from subjects with diarrhea and related intestinal infections, various domestic water sources and food animal products were evaluated for antibiotic resistance relatedness, conjugative activity, virulence factor and biofilm production. Antibiotic resistance of Escherichia coli O157 encoded with stx was mapped for geospatial spread. Detected stx-encoded Escherichia coli O157 (7.56%) of human strains were significantly higher compared to water and food animal strains (p = 0.001) with high conjugative and transformative activity (OR(95%CI) = 34.65(94.5); p = 0.023). Water- Escherichia coli O157 reveal significant median resistance to ciprofloxacin, gentamycin (p < 0.05) and human diarrheagenic strains showed >60% resistance to doxycycline (MIC₅₀ 8 μg/mL and MIC₉₀ 128 μg/mL; p = 0.018), tetracycline (MIC₅₀ 4 μg/mL and MIC₉₀ 64 μg/mL), ciprofloxacin (MIC₅₀ 2 μg/mL and MIC₉₀ 128 μg/mL) and gentamycin (MIC₅₀ 4 μg/mL and MIC₉₀ 256 μg/mL). Strains from human diarrhea, UTI, colitis, cattle, fish, sheep, ground waters, streams, and rivers characterized with biofilm, hemolysin, protease productions, R-plasmid (≈14.30kbp) and MARI (0.84) were highly related. Principal component analysis (score plot) revealed a significant association between resistant human diarrheic strains with cattle and poultry strains. A high population of heterogeneous stx-encoded diarrheagenic and colitis strains was predominant in urban settings spreading with food animal and water Escherichia coli O157 strains. Human diarrheagenic Escherichia coli O157 were highly related to antibiotic resistance and virulence pattern with water and animal products strains. Strategic interventions through the implementation of One Health approach and population-target antimicrobial stewardship are needed to mitigate the increasing intestinal morbidity and reduction of mortality impact. Regular application of spatial data on clonal dissemination is important for monitoring, surveillance of antimicrobial resistance and transmission of zoonotic food-borne Escherichia coli O157 pathogens.

Keywords: Antibiotic resistance; Escherichia coli O157; Food animals; Water.

Fig 1

a. Prevalence rates of latex-positive Escherichia coli O157 strains obtained from human subjects, water sources and food animals. Fig 1b; Evaluation of shiga toxin genes (stx1, stx2, stx1/stx2), hfr-conjugants and transformants prevalent in different sources (Key: ⱡSST, Skin and Sub-cutaneous tissues; ⱡⱡOthers, including ruminant livestock; ⱡⱡⱡDomestic waters, including household water storage containers, overhead water tank).

Fig 2

Scatter plot showing phenotypic antibiotic resistance pattern of detected stx-strains with horizontal line showing the median values [H, human strains (red); FA, Food animal (purple) and W, water strains (green); cip, ciprofloxacin, gn, gentamycin; cfx, cefuroxime; ofx, ofloxacin; do, doxyclicne; cfz, ceftazidime; amx, amoxicillin; nt, nitrofurantoin].

Fig 3

Analysis of virulent factor production, encoded R-plasmid and MARI relatedness of the EC O157 strains obtained from various sources (n_A, number of antibiotic resisted; G, phylo-group).

Fig. 4

(a).Heatmap of the antibiotic-resistant profile of stx-strains from various human disease conditions, types of food animals and sources of water with commonly used antibiotics. Fig. 4 (b) Principal Component Analysis (PCA) plots showing antibiotic resistance profiles of human strains (black) with food animal (brick red) and water strains (blue) in ellipse clustering at 95% confidence interval (c) Separate related resistant profile analysis of human (black) and water strains (pink) on first and second principal component (d) PCA biplots of antibiotic resistance profiles of human (black) and food animal (blue). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 5

Spatial distribution and proportion of Escherichia coli O157 antibiotic resistance hotspots in southwest Nigeria (Red, Human strains; Green. Water strains; Blue, Animal strains).