title: Evaluation of resistance development and viability recovery by toxigenic and non-toxigenic Staphylococcus aureus strains after repeated cycles of high hydrostatic pressure.
abstract: 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 non-enterotoxigenic 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.
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal; Department of Chemistry and QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: mines.baptista@ua.pt.
authors.forename: Inês
authors.initials: I
authors.lastname: Baptista
authors.affiliation: Department of Chemistry and QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: rui.queiros@ua.pt.
authors.forename: Rui P
authors.initials: RP
authors.lastname: Queirós
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: acunha@ua.pt.
authors.forename: Ângela
authors.initials: Â
authors.lastname: Cunha
authors.affiliation: Department of Chemistry and QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: smrocha@ua.pt.
authors.forename: Sílvia M
authors.initials: SM
authors.lastname: Rocha
authors.affiliation: Department of Chemistry and QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: jorgesaraiva@ua.pt.
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Saraiva
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal. Electronic address: aalmeida@ua.pt.
authors.forename: Adelaide
authors.initials: A
authors.lastname: Almeida
mesh_terms: D004768:Enterotoxins / Q000378:metabolism; D005516:Food Microbiology; D006874:Hydrostatic Pressure; D050296:Microbial Viability; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000145:classification / Q000254:growth & development* / Q000378:metabolism
chemical_list: D004768:Enterotoxins
keywords: Enterotoxins; High hydrostatic pressure (HPP); Resistance; Staphylococcus aureus; Viability growth recovery