Toxigenic strains of Staphylococcus epidermidis and their experimental corneal pathogenicity in rabbits.

Thirty strains of Staphylococcus epidermidis, ten each from normal conjunctival sacs, corneal ulcer cases and from those who developed postoperative endophthalmitis, were examined for their dermonecrotic and haemolytic activities. Dermonecrosis was studied on rabbit skin whereas haemolysis was determined against sheep, guinea pig, rabbit and human erythrocytes. None of the cell free filtrates from strains derived from normal sacs showed any evidence of toxin production. Four strains from corneal ulcer cases and five from postoperative infections produced + to + + + dermonecrosis whereas haemolytic activity was exhibited by one strain in the former and by two in the latter. Only those strains that were highly dermonecrotoxic were haemolytic. Experimental corneal lesions in the rabbit were mild by strains from normal sacs. Those showing highest dermonecrotoxic reaction, irrespective of their source, produced identical and most severe corneal pathology when compared to those producing minimal necrosis.