Document Detail

Comparative analysis of acid resistance in Listeria monocytogenes and Salmonella enterica strains before and after exposure to poultry decontaminants. Role of the glutamate decarboxylase (GAD) system.
MedLine Citation:
PMID:  19835779     Owner:  NLM     Status:  MEDLINE    
Data on the ability of chemical poultry decontaminants to induce an acid stress response in pathogenic bacteria are lacking. This study was undertaken in order to compare the survival rates in acid broths of Listeria monocytogenes and Salmonella enterica strains, both exposed to and not exposed to decontaminants. The contribution of the glutamate decarboxylase (GAD) acid resistance system to the survival of bacteria in acid media was also examined. Four strains (L. monocytogenes serovar 1/2, L. monocytogenes serovar 4b, S. enterica serotype Typhymurium and S. enterica serotype Enteritidis) were tested before (control) and after exposure to trisodium phosphate, acidified sodium chlorite, citric acid, chlorine dioxide and peroxyacids (strains were repeatedly passed through media containing increasing concentrations of a compound). Stationary-phase cells (10(8) cfu/ml) were inoculated into tryptic soy broth (TSB) acidified with citric acid (pH 2.7 and 5.0) with or without glutamate (10 mM) added, and incubated at 37 degrees C for 15 min. Survival percentages (calculated from viable colonies) varied from 2.47 +/- 0.67% to 91.93 +/- 5.83%. L. monocytogenes cells previously exposed to acid decontaminants (citric acid and peroxyacids) showed, when placed in acid TSB, a higher (P < 0.05) percentage of survival (average 38.80 +/- 30.52%) than control and pre-exposed to non-acidic decontaminants strains (22.82 +/- 23.80%). Similar (P > 0.05) survival percentages were observed in previously exposed to different decontaminants and control Salmonella strains. The GAD acid resistance system did not apparently play any role in the survival of L. monocytogenes or S. enterica at a low pH. This study demonstrates for the first time that prior exposure to acidic poultry decontaminants increases the percentage of survival of L. monocytogenes exposed to severe acid stress. These results have important implications for the meat industry when considering which decontaminant treatment to adopt.
Alicia Alonso-Hernando; Carlos Alonso-Calleja; Rosa Capita
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-06-21
Journal Detail:
Title:  Food microbiology     Volume:  26     ISSN:  1095-9998     ISO Abbreviation:  Food Microbiol.     Publication Date:  2009 Dec 
Date Detail:
Created Date:  2009-10-19     Completed Date:  2010-01-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8601127     Medline TA:  Food Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  905-9     Citation Subset:  IM    
Area de Nutrici??n y Bromatolog??a, Escuela Superior y T??cnica de Ingenier??a Agraria, Universidad de Le??n, 24400-Ponferrada, Le??n, Spain.
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MeSH Terms
Acids / pharmacology*
Chickens / microbiology
Colony Count, Microbial
Disinfectants / pharmacology*
Dose-Response Relationship, Drug
Drug Resistance, Bacterial / physiology*
Food Contamination / analysis,  prevention & control
Glutamate Decarboxylase / metabolism*
Glutamic Acid / metabolism
Hydrogen-Ion Concentration
Listeria monocytogenes / drug effects*,  enzymology,  growth & development
Meat / microbiology*
Microbial Sensitivity Tests
Salmonella enterica / drug effects*,  enzymology,  growth & development
Reg. No./Substance:
0/Acids; 0/Disinfectants; 56-86-0/Glutamic Acid; EC Decarboxylase

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