Control of Growth and Persistence of Listeria monocytogenes and β-Lactam-Resistant Escherichia coli by Thymol in Food Processing Settings

Maria Grazia Cusimano,Maria Vitale,Maria La Giglia,Francesco Pomilio,Domenico Schillaci,Vincenzo Di Marco Lo Presti,Vita Di Stefano

doi:10.3390/molecules25020383

Abstract

The main objective of this study was to evaluate the efficacy of thymol in controlling environmental contamination in food processing facilities. The effect of thymol was tested as an agent to prevent planktonic and bacterial biofilm growth of twenty-five Listeria monocytogenes isolates from a variety of foods and five Escherichia coli isolates from a farm. The E. coli isolates were positive for extended spectrum β-lactamase (ESBL) genes. All isolates and reference strains were susceptible to thymol at Minimum inhibitory concentration (MIC) values ranging from 250 to 800 μg/mL. An interesting activity of interference with biofilm formation of L. monocytogenes and E. coli was found for thymol at sub-MIC concentrations of 200, 100, 75, and 50 μg/mL. Anti-biofilm activity ranging from 59.71% to 66.90% against pre-formed 24-h-old L. monocytogenes biofilms at concentrations of 500 or 800 µg/mL, corresponding to 2× MIC, was determined against free-living forms of six isolates chosen as the best or moderate biofilm producers among the tested strains. The property of thymol to attack L. monocytogenes biofilm formation was also observed at a concentration of 100 µg/mL, corresponding to 1/4 MIC, by using a stainless-steel model to simulate the surfaces in food industries. This study gives information on the use of thymol in food processing setting.

Highlights

Each year, millions of people get infected and die from antibiotic-resistant pathogens [1].Antimicrobial resistance (AMR) is a serious concern for public health and its spread has increased over time due to the excessive use of similar antibiotic molecules in both human and animal health.Modern industrial agriculture is based on the extensive use of antimicrobials as therapeutics and prophylactics, in intensively farmed species, such as pigs and poultry [2]
The property of thymol to attack L. monocytogenes biofilm formation was observed at a concentration of 100 μg/mL, corresponding to 1/4 Minimum inhibitory concentration (MIC), by using a stainless-steel model to simulate the surfaces in food industries
AMR renders ineffective the control of diseases caused by pathogenic bacteria that are mostly common between humans and animals [3]

Summary

Introduction

Millions of people get infected and die from antibiotic-resistant pathogens [1].Antimicrobial resistance (AMR) is a serious concern for public health and its spread has increased over time due to the excessive use of similar antibiotic molecules in both human and animal health.Modern industrial agriculture is based on the extensive use of antimicrobials as therapeutics and prophylactics, in intensively farmed species, such as pigs and poultry [2]. Millions of people get infected and die from antibiotic-resistant pathogens [1]. Antimicrobial resistance (AMR) is a serious concern for public health and its spread has increased over time due to the excessive use of similar antibiotic molecules in both human and animal health. Modern industrial agriculture is based on the extensive use of antimicrobials as therapeutics and prophylactics, in intensively farmed species, such as pigs and poultry [2]. AMR renders ineffective the control of diseases caused by pathogenic bacteria that are mostly common between humans and animals [3]. It is necessary to reduce the use of antibiotics or replace them with new treatments in farms, food processing facilities, and other non-clinical settings to avoid the loss of efficacy of critically or highly important antibiotics used in clinical treatment, such as fluoroquinolones, aminoglycosides, and third- and fourth-generation cephalosporins [4].

Objectives

Methods

Results