<i>Staphylococcus cohnii</i> Causing a Latent Endophthalmitis: A Case Report

<b>Objective:</b> We report a case of latent postoperative endophthalmitis caused by <i>Staphylococcus cohnii</i> in a 72-year-old woman. <b>Observation:</b> The patient was referred to the department of ophthalmology with blurry vision in her right eye 12 days after phacoemulsification. The clinical examination showed signs of endophthalmitis. A vitreous tap, with intraocular injection of ceftazidime, was performed, and topical dexamethasone and tobramycin were initiated. The postoperative follow-up showed reduction in the intraocular reaction, and the patient was afterwards discharged. After 6 months, her private ophthalmologist referred the patient again with signs of uveitis and macular edema. The clinical examination showed hypopyon and infiltrates on the posterior lens capsule which led to a vitrectomy with the removal of the posterior lens capsule infiltrate. With no signs of improvement at the postoperative follow-up, the intraocular lens was removed. <b>Results:</b> A pathological examination with H&E, Gram, and Periodic Acid Schiff showed gram-positive cocci in relation to the lens capsule. Polymerase chain reaction was performed, detecting DNA of <i>Staphylococcus cohnii</i>. <b>Conclusion and Importance:</b> <i>Staphylococcus cohnii</i> should be considered in cases of latent endophthalmitis. <i>Staphylococcus cohnii</i> is a gram-positive coagulase-negative bacterium that produces biofilm. Biofilm can promote adherence to implants leading to failure of therapy.