Delayed post-op endophthalmitis could be due to propionebacterium acne ( most common sourse of contamination  from patient's flora- eyelids, conj., etc.

Delayed postoperative endophthalmitis is reported to result from Propionibacterium acnes, Staphylococcus epidermidis, and fungi, like Candida species. Clinical features of P.acnes endophthalmitis are  reported in literature. However, history, clinical examination, bacteriological work-up, and response to therapy offers definite etiological clue.

Review  old records of the patient. Most of the times the patient has history of chronic inflammation after surgery, which never settled or sometimes there could be plaque in the capsular bag in these patients which was missed. There could also be history of some precipitating event like suture removal. The incidence of slow growing organisms, fungal infections stays high. Immediate vitreous biopsy in these patients with cultures from undiluted vitreous biopsy samples could clinche the diagnosis.