Influence of bacterial suspension storage in the inflammatory response in mice

Abstract

The preparation of bacterial suspension is an important procedure used in laboratories for inflammatory evaluation protocols and can be obtained by different methods that need or not need step storage. The aim of this work was investigate the influence of storage of Staphylococcus aureus suspension in bacterial viability and its influence in bacteria-induced inflammation in vivo. The bacterial suspension of S. aureus ATCC 6538 was prepared accordingly to 4^th degree of McFarland’s Scale by visual comparison. This suspension was used to determine by CFU counting the bacterial viability and for administration to the animals to induce septic arthritis and peritonitis. Twenty four hours of storage reduced the S. aureus CFU. As a consequence of reduced bacterial viability, was detected reduced mechanical hyperalgesia, edema and leukocyte recruitment in septic arthritis and leukocyte recruitment and cytokine production bacterial peritonitis. These results demonstrate that storage of bacterial suspension affected bacterial viability, which resulted in diminished inflammatory response in vivo, raising the importance of standard procedures for bacterial suspension preparation. A conceivable approach would be to determine the number of CFU at a specific McFarland’s scale degree, which will allow the preparation and use a bacterial suspension in the same day for in vivo testing.