Effect of environmental stresses on antibody-based detection of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis and Listeria monocytogenes

Abstract

Aims: To study the reaction patterns of selected antibodies to Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis and Listeria monocytogenes cells exposed to various environmental stresses. Methods and Results: Escherichia coli O157:H7, Salmonella Enteritidis and L. monocytogenes cells subjected to different environmental stress of temperatures (4 and 45°C), NaCl (5·5%), oxidative stress (15 mmol−1 H2O2), acidic pH (5·5) and ethanol (5%) for 3 h (short‐term stress) or for 5 days (long‐term stress) were analysed by ELISA and Western blotting. The ELISA results indicated that most stresses caused 12–16% reductions in reaction for anti‐E. coli O157:H7 and 20–48% reductions for anti‐Salmonella polyclonal antibodies during short‐term stress, whereas the most stresses exhibited enhanced reaction (44–100% increase) with the anti‐L. monocytogenes polyclonal antibody. During long‐term stress exposure to combined stress conditions of pH 5·5, 3·5% NaCl at 12°C or at 4°C, antibody reactions to the three pathogens were highly variable with the combined stress at 4°C showing the most reductions (8–40%). Likewise, there were about 18–59% reductions in antibody reactions with pathogens when cultured in hotdog samples with the combined stress conditions. Western blot analyses of crude cell surface antigens from both short‐ and long‐term stressed cells revealed that the changes in antibody reactions observed in ELISA were either because of repression, expression or possible denaturation of antigens on the surface of cells. Conclusions: Overall, the antibody reactions were significantly reduced in pathogens exposed to both short‐ and long‐term environmental stresses in culture medium or in meat sample because of expression, repression or denaturation of specific antigens in cells. Significance and Impact of the Study: In order to ensure the reliable detection of foodborne pathogens using antibody‐based methods, the influence of stress on antibody reactions should be thoroughly examined and understood first as the physiological activities in cells are often altered in response to a stress.

SEL, a Selective Enrichment Broth for Simultaneous Growth of Salmonella enterica , Escherichia coli O157:H7, and Listeria monocytogenes

“…This result suggests that SEL promoted increased expression of antibody-reactive antigens compared to the expression of these antigens in its counterparts. A selective-or nonselective-medium-mediated reduction in the expression of antigen or in an antigen-antibody reaction has been demonstrated previously for Salmonella, E. coli O157:H7, and L. monocytogenes (7,21,22,24). Pathogen-specific multiplex PCR assays were also successful in detecting each pathogen from the mixture without producing any nonspecific amplification (Fig.…”

“…The abilities of SEL to resuscitate stress-exposed bacterial cells and enrich samples were investigated. The two most common stress conditions, exposure to acid (pH 4.5 and 5.5) and cold (4°C) (24), were examined. Each freshly grown culture of Salmonella serovar Enteritidis, E. coli O157:H7, and L. monocytogenes was inoculated into 30 ml of TSBYE (1%, vol/vol) and then incubated at 37°C in a shaker incubator (150 rpm) to mid-log phase (see Fig.…”

“…Selective enrichment is also necessary to suppress the natural background microorganisms so as to improve detection efficiency and to avoid false results. However, the drawbacks of some of the selective enrichment broths are that the selective agents can be inhibitory or can delay the recovery and growth of healthy or stressed target pathogens (26) and may also down regulate antigen expression, thus affecting the detection of pathogens (21,24,34).…”

Immunological Methods for the Detection of Campylobacter spp. - Current Applications and Potential Use in Biosensors

“…High rates of continuous expression of the antigen is another important consideration, especially in Campylobacter cells that undergo stress during food production and processing. Detection of stressed bacteria by EIA has been shown to be reduced (Hahm & Bhunia 2006;Nyquist-Battie 2005). In this regard, the structure of the LOS, a target of many antibodies, may vary as a function of the temperature at which Campylobacter cells are grown (Semchenko et al, 2010).…”

Combined dielectrophoretic and impedance system for on‐chip controlled bacteria concentration: Application to Escherichia coli

“…Techniques like pathogenic-specific antibody coated magnetic beads [23,24] or hybridization of DNA fragments of bacteria [25], improves the analysis time, but still needs complex equipment and takes several hours to carry out. This could be improved by using IA.…”