The Pathogenicity of Staphylococcus aureus in Rabbits

Abstract

Seven groups of rabbits were inoculated by different doses of standard Staphylococcus aureus (29213) that ranged between l5><l05- 50><10‘° cfu/one ml. Two of these groups were run as untreated groups receiving 3>< 106 and 50>< 101° , fifth groups received treatment by different doses of oxytetracycline or gentamicin antibiotics at the inoculation time or after 24 hours from inoculation. The eighth group was inoculated by sterile nonnal saline and considered as control, this group showed absence of mortality, and there were no pathological lesions or histopathological changes. One of the untreated groups; that inoculated with high dose of the bacterium 50>< 101° , showed 100% mortality rate within 24 hours from inoculation , pathological changes were observed during post mortem examination; the -inoculated group showed presence of liver congestion and urine retention, abscess formation was also observed . The Staphylococcus aureus bacterium was re-isolated from the heart of all members of this group and from liver, gall bladder, intestine and urine of the majority of the members of the group, some of lung and faecal specimens showed positive isolation of the bacterium while all specimens that collected from abscesses revealed negative isolation of the bacterium .Cardiovascular changes, lymphocytic infiltration, renal damage and other histopathological changes were detected. Rabbits that inoculated with 3>< 106 cfu/ml were survived till one week when were killed for further bacteriological and histopathological investigations. The bacterium was isolated from all samples collected from abscess and from most of samples collected from heart, liver, lungs and urine. The most characteristic histopathological features of the member of these group were necrosis of IV