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Editor,—We present a rare case of endophthalmitis due to Pasteurella multocida, a bacterium commonly pathogenic to animals but rare in humans. This is the first reported case of P multocida endophthalmitis in which the infection occurred as an immediate postoperative complication following an uneventful cataract surgery.
A 93-year-old white woman underwent endocapsular cataract extraction with posterior chamber intraocular lens in the right eye under local anaesthesia in August 1995. On the second postoperative day she developed endophthalmitis.
Vitreous biopsy/intravitreal antibiotic injection could not be done as the patient immensely disliked the idea of any further surgical or anaesthetic procedures and refused to consent. After much persuasion, she agreed to an aqueous tap which was done by her bedside. A conjunctival swab was also taken. She was given subconjunctival cefuroxime 150 mg, intensive topical cefuroxime 5% and fortified gentamicin drops, and intravenous cefuroxime 750 mg 8 hourly.
Cultures of the conjunctival swab and the anterior chamber material showed P multocida sensitive to chloramphenicol, penicillin, and cefuroxime. Despite antibiotic therapy, the eye became completely purulent within a few days (Fig 1). There was no sign of systemic infection clinically. The eye was eventually enucleated. A swab from the conjunctival sac of the opposite eye taken 20 days after the enucleation grew P multocida.
Hoffman et al 3 reported the third case in a 61-year-old man who developed the infection 8 years after phacoemulsification with implantation of an iris plane lens. There was no history of animal bite and the infection was considered to be endogenous. Pars plana vitrectomy was performed but the visual outcome was poor despite antibiotic therapy.
P multocida is a Gram negative coccobacillus which usually causes infection in animals such as cats, dogs, and cattle and it is a frequent commensal in animals. It is not a usual human commensal but it has been found as part of bacterial flora in the upper respiratory tract of apparently healthy people who have been exposed to animals with no history of injuries such as bites or scratches.4Human infection due to P multocida occurs more frequently after exposure to cats than dogs and presents as focal cellulitis at the site of injury caused by animals, chronic respiratory infections, intra-abdominal infections, or bacteraemia with or without metastatic lesions.4 Conjunctivitis5 and corneal ulcer following injury by a dog6 have also been reported.
Our patient has had a pet cat for 2 years and we believe that it is highly possible that the infection could have been acquired from the cat although there was no history of bites or scratches. Swabs from the nose and nasopharynx did not grow P multocida in our patient but it was cultured from the conjunctival sac of her other eye 20 days after the enucleation of the infected eye.
We thank to Dr L A Jewes for microbiology work and advice.