Investigating the Virulence Potential of E. coli Isolates Obtained from Cocoa Beans, Using Whole Genome Sequence Analyses
Authors: Nwanosike Hephzibah , Chung Taejung , Condello Megan A. , Xiaoli Lingzi , Lamendella Regina , Dudley Edward G , Kovac Jasna 
Published: June 2021

Foodborne illness is of major concern in the United States. The CDC estimates that 48 million people get sick due to foodborne pathogens and 128,000 people are hospitalized every year. Thus, as a preventive measure, the Food Drug and Administration enacted a new law – Food Safety Modernization Act that aims to improve safety of foods, including microbiological safety. In food systems, a common indirect way to test for microbiological safety of food is by using coliforms as indicator organisms. Presence of coliforms suggests that the food has been produced in unhygienic conditions that increase chances of introducing foodborne pathogens. Escherichia coli is one of such commonly used indicator microorganisms. In this research, we whole genome sequenced four E. coli isolates obtained from cocoa beans imported from Bolivia that had > 1,100 MPN/g of E. coli. We analyzed the sequences to characterize their pathogenic potential and antimicrobial resistance. Based on whole genome sequences, we identified these isolates' MLST sequence types, serotypes, virulence genes and antimicrobial resistance genes using tools available on Center for Genomic Epidemiology server, and BTyper. The STs identified for the four analyzed isolates, ST 2074, ST 118 and ST 8369 had been previously found in food and clinical samples. We identified four virulence genes in three isolates and two in one isolate. Some of these virulence genes had been associated with enteropathogenic E. coli (lpfA) extraintestinal E. coli (iss), and enteroaggregative E. coli (air, eilA). Furthermore, we identified antimicrobial resistance genes: ampH, ampC1, ampC2 and penicillin binding protein‐encoding gene. We also tested isolates for antibiotic resistance using disk diffusion, which showed that all four isolates were sensitive to ampicillin, ciprofloxacin, cephalothin and tetracycline, but were resistant to vancomycin, according to CLSI M100 (2018) guideline. The findings of this study indicate that the beans may contain pathogenic microorganisms since the E. coli STs and virulence genes identified have been associated with pathogenic strains in the past.

Support or Funding Information

H. N. was supported by the USDA‐funded Research and Extension Experiences for Undergraduates (REEU) project “Bugs in my Food: Research and Professional Development in Food Safety for Undergraduates from Non‐Land Grant Institutions” (USDA‐NIFA 2017‐67032‐26022). J. K. and E. G. D. were supported by the USDA National Institute of Food and Agriculture Hatch Appropriations under projects #PEN04646 and #PEN04522 and accessions #1015787 and #0233376, respectively. L. X. and sequencing was supported by the U.S. Food and Drug Administration grant number 1U18FD006222‐01 to E. G. D. for support of the GenomeTrakr in Pennsylvania.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.