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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Residue Chemistry and Predictive Microbiology Research » Research » Publications at this Location » Publication #391548

Research Project: Development and Validation of Predictive Models and Pathogen Modeling Programs; and Data Acquisition for International Microbial Databases

Location: Residue Chemistry and Predictive Microbiology Research

Title: Antibiotic resistance influences growth rates and cross-tolerance to lactic acid in E. coli O157: H7 H1730

item OGUADINMA, IKECHUKWU - University Of Georgia
item MISHRA, ABHINAV - University Of Georgia
item Juneja, Vijay
item DEVKUMAR, GOVINDARAJ - University Of Georgia

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: The prevalence of antibiotic resistance in Shiga toxigenic Escherichia coli continues to be a concern for the food industry. A common intervention strategy to prevent the presence of microbial contaminants on beef is the use of lactic acid sprays on carcasses. We evaluated the tolerance of ampicillin and streptomycin resistant variants of E. coli O157:H7 H1730 to lactic acid. The results suggested that E. coli O157:H7 strains with antibiotic resistance profiles might be more tolerant to lactic acid and this resistance is lactic acid concentration dependent. These findings will help understand the risks of antibiotic associated lactic acid cross-tolerance in E. coli O157:H7.

Technical Abstract: Escherichia coli O157:H7 contamination has been implicated in numerous food-borne outbreaks. Contamination occurs despite the use of antimicrobial interventions such as lactic acid. Also, resistance to antibiotics such as ampicillin and streptomycin has been frequently reported among isolates of E. coli O157:H7. The influence of antibiotic resistance on growth rates and cross-tolerance of E. coli O157:H7 H1730 to lactic acid was evaluated in this study. Antibiotic resistant strain variants of E. coli O157:H7 H1730 were generated by conferring resistance to either ampicillin (amp C) or streptomycin (strep C) or both ampicillin and streptomycin (amp C strep C) through incremental exposure to the antibiotics. Ampicillin resistance was also conferred using a plasmid to generate strains amp P and amp P strep C. The MIC of lactic acid on all the strains evaluated was 0.375% v/v. The lag phase duration of all strains except E. coli O157:H7 amp P strep C increased with increasing concentration of lactic acid. Strains amp P strep C, and amp C were most tolerant to 2.5% lactic acid with declines in cell population of 2.86 and 2.56 log CFU/ml respectively (p<0.05). Strain amp P strep C was the most tolerant when evaluated by the Live/dead viability assay. Tolerance to lactic acid was significantly influenced by both antibiotic resistance profile of the strain and lactic acid concentration. The results from this study indicate that E. coli O157:H7 strains with certain antibiotic resistance profiles might be more tolerant to lactic acid.