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EVALUATION OF INTESTINAL INVASION IN GERM‐FREE MICE CHALLENGED WITH ACID‐ADAPTED AND NONACID‐ADAPTED SALMONELLA ENTERITIDIS SE86 AND SALMONELLA TYPHIMURIUM ST99
Author(s) -
PEREZ KARLA J.,
MARTINS FLAVIANO S.,
CARA DENISE C.M.,
NICOLI JACQUES R.,
TONDO EDUARDO C.
Publication year - 2012
Publication title -
journal of food safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 43
eISSN - 1745-4565
pISSN - 0149-6085
DOI - 10.1111/j.1745-4565.2011.00355.x
Subject(s) - salmonella enteritidis , salmonella , microbiology and biotechnology , biology , virulence , microorganism , inoculation , serotype , bacteria , immunology , biochemistry , genetics , gene
The aim of the present study was to evaluate intestinal invasion in germ‐free mice by acid‐adapted and nonacid‐adapted Salmonella ( S .) Enteritidis SE86 and S . Typhimurium ST99. The microorganisms were cultivated in brain heart infusion broth supplemented with glucose in order to promote a gradual pH decrease and acid adaptation during the stationary phase. Acid‐adapted and nonacid‐adapted S . Enteritidis SE86 and S . Typhimurium ST99 were administered orally to germ‐free mice, which were kept under aseptic conditions. Feces and intestinal portions were examined by microbiological and histopathological examinations, respectively, during a 12‐day period. A mortality curve was constructed during the same period. The results indicated a similar rapid multiplication of all microorganisms after inoculation; however, mice inoculated with acid‐adapted SE86 showed a higher mortality rate (fourth day) and more severe lesions than animals challenged with ST99. Histopathological analysis showed greater severity of infection caused by SE86 than ST99. The latter microorganism did not cause the death of animals, even 12 days after inoculation. Acid‐adapted SE86 demonstrated a greater virulence in the mice, and this capacity might be related to the survival of this microorganism through the stomach acid barrier. PRACTICAL APPLICATIONS In the Rio Grande do Sul state, southern Brazil, a specific strain of S . Enteritidis (SE86) has been identified as the main causative agent of more than 90% of the salmonellosis cases investigated by the Surveillance Service during the last decade. When compared with other Salmonella serovars, this strain has shown a higher acid adaptation capacity when exposed to sublethal acid levels. Since the stomach acid barrier is one of the most important defenses against foodborne pathogens, acid adaptation can be very important for virulence of such microorganisms. This study focused on investigating in vivo the influence of SE86 acid adaptation capability on its pathogenic characteristics to explain why this microorganism is predominantly involved in foodborne salmonellosis in southern Brazil.