The rate of horizontal transmission of antibiotic resistant plasmids is increased in food preservation-stressed bacteria

Abstract number: 1734_12

McMahon M.A.S., Blair I.S., Moore J.E., McDowell D.A.

Objectives: Many modern food preservation processes involve the continuous application of one or more bacteriostatic (sub-lethal) stresses to slow or prevent bacterial growth in food within the food chain. This is very different from the approach used in traditional preservation systems, which usually apply single, brief, severe, bactericidal (lethal) treatments, with the aim of killing or permanently inactivating most of the bacteria present in the food, prior to its release into the food chain. This study investigated the possibility that sub-lethal food preservation stresses (high/low temperature, osmotic and pH stress) can alter the rate of horizontal transmission of antibiotic resistance (ABR) plasmids between E. coli strains and between E. coli and Salmonella typhimurium.

Methods: Plasmid-bearing E. coli donor cultures (NCTC 50021 – F1 plasmid R386 or NCTC 50338 – Inc I1 plasmid TP307) and E. coli recipient cultures (NCTC 35695 & NCTC 33694) and S. typhimurium (wild type st11) recipient cultures were mated under a range of sub-lethal environmental stress conditions (low temperature, high temperature, low pH and high NaCl). A transfer rate was determined for each donor/recipient/stress combination.

Results: The study found that the horizontal transmission rate of F1 plasmid R386 and Inc I1 plasmid TP307 is significantly increased (p < 0.05) when pre-stressed donor and recipient cells are mated under conditions of environmental stress (high/low temperature, osmotic and pH stress).

Conclusions: These results indicate that increased use of bacteriostatic (sub-lethal), rather than bacteriocidal (lethal) food preservation systems, may be contributing to the dissemination of ABR among important food borne pathogens.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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