EFFICACY OF AN AUTOGENOUS VACCINE AGAINST HIGHLY VIRULENT STAPHYLOCOCCUS AUREUS INFECTION IN RABBITS

The efficacy of an autogenous vaccine consisting of a whole cell suspension of formalin killed bacteria in sterile buffered saline against Staphylococcus aureus infections was determined, using a well-established rabbit skin infection model. Thirteen 8 wk old rabbits were vaccinated twice subcutaneously with a 2 wk interval while 10 rabbits were injected twice with formalised PBS (sterile phosphate buffered saline). Two weeks after the last injection, 10 vaccinated and all PBS-injected rabbits were inoculated intradermally with 10(8) cfu of a S. aureus strain (KH 171)which had been shown to be highly virulent for rabbits. Three vaccinated animals served as negative controls and were intradermally injected with sterile buffered saline. All rabbits were examined daily for the development of skin lesions until 14 d after the experimental infection when all rabbits were euthanised. All animals experimentally infected with S. aureus developed skin abscesses within 24 h post-inoculation, but in the vaccinated group the maximum abscess diameter was significantly lower than in the non-vaccinated group (P=0.048). This difference between autovaccinated and non-vaccinated groups increased over time (P < 0.001). These results indicate that vaccination with an inactivated whole cell bacterin may be useful for control of staphylococcosis in rabbits but does not prevent abscess formation in animals inoculated with a high dose of a highly virulent S. aureus strain.