In this work, the development of resistance and the recovery of growth after several consecutive cycles of
high hydrostatic pressure (HPP) were for the first time evaluated in different strains of Staphylococcus
aureus. Three strains of this important and highly resilient to HPP foodborne pathogen were used: a nonenterotoxigenic
ATCC 6538 strain, treated with 600 MPa for 30 min at 20 C, and the toxigenic strains
2153 MA (with enterotoxin A) and 2065 MA (with the enterotoxins A, G and I), treated with 600 MPa for
15 min at 20 C. After the first treatment, surviving colonies were used to produce new bacterial cultures.
This procedure was repeated nine times more for each bacterium or until total inactivation occurred. The
inactivation profile of non-enterotoxic strain and the two enterotoxic strains did not change after
consecutive cycles, but the toxic strain with three enterotoxins was completely inactivated after the
fourth cycle. The three strains did not recover their viability after 14 days. The results indicate that HPP
effectively inactivates non-toxigenic and toxigenic strains of S. aureus after a single treatment. The
surviving bacteria did not develop resistance after 10 cycles of pressurization and did not recover their
viability after 14 days of incubation.
In this work, the development of resistance and the recovery of growth after several consecutive cycles ofhigh hydrostatic pressure (HPP) were for the first time evaluated in different strains of Staphylococcusaureus. Three strains of this important and highly resilient to HPP foodborne pathogen were used: a nonenterotoxigenicATCC 6538 strain, treated with 600 MPa for 30 min at 20 C, and the toxigenic strains2153 MA (with enterotoxin A) and 2065 MA (with the enterotoxins A, G and I), treated with 600 MPa for15 min at 20 C. After the first treatment, surviving colonies were used to produce new bacterial cultures.This procedure was repeated nine times more for each bacterium or until total inactivation occurred. Theinactivation profile of non-enterotoxic strain and the two enterotoxic strains did not change afterconsecutive cycles, but the toxic strain with three enterotoxins was completely inactivated after thefourth cycle. The three strains did not recover their viability after 14 days. The results indicate that HPPeffectively inactivates non-toxigenic and toxigenic strains of S. aureus after a single treatment. Thesurviving bacteria did not develop resistance after 10 cycles of pressurization and did not recover theirviability after 14 days of incubation.
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