Summary

A 67-year-old Chinese man presented with acute loss of vision and pain in the left eye with hypopyon in the anterior chamber. The patient was afebrile with no systemic symptoms at presentation. Diagnosis of endogenous endophthalmitis was made with vitreous tap yielding Klebsiella pneumoniae. Pars plana vitrectomy was performed twice to clear the infection. Thorough investigations showed no septic foci. Whole body positron emission tomography CT revealed a rectal tumour and biopsy showed adenocarcinoma. He was treated with neoadjuvant chemoirradiation followed by surgery to resect the tumour. Vision in the left eye was hand movement at 12 months postoperatively. This case illustrates Klebsiella endogenous endophthalmitis might be a herald of occult colorectal cancer. Bacteria might gain access into bloodstream via mucosal defect in the tumour.