Histology of retina overlying bacterial subretinal abscess and implications for treatment.

Abstract

To evaluate the state of the retina overlying a subretinal abscess and its contents by histopathologic analysis and electron microscopy (EM) and to determine implications for treatment. Case report of a patient with a subretinal abscess secondary to Klebsiella pneumoniae infection who underwent pars plana vitrectomy, PPL, endolaser, retinectomy, abscess drainage, and retinal biopsy. The retinal biopsy was analyzed histologically using special stains, and EM of the abscess contents was performed. Postoperatively, the retina remained attached, and the patient regained visual acuity of 20/60. Culture of the vitrectomy specimen yielded K. pneumoniae. Retinal biopsy revealed a partially intact inner retina with destruction of the outer retinal layers in the setting of acute inflammation. Results of gram, Grocott-Gomori methenamine-silver nitrate, and acid-fast staining of the retinal biopsy specimen were negative. EM of the abscess contents revealed cellular debris with scattered inflammatory cells but no bacteria. This case demonstrates that aggressive surgical management of a subretinal abscess due to K. pneumoniae in an eye can result in useful vision. Management included retinectomy of the retina overlying the abscess that revealed photoreceptor destruction with intraretinal inflammation. Drainage of a subretinal abscess without removal of the overlying retina may limit treatment effectiveness and spare retina that is not functional.