INTRODUCTION

Top Abstract Introduction Case Report Materials & Methods Results & Discussion References

Gram-negative organisms are the causes of 16 to 18.5% of all cases of culture-proven postsurgical endophthalmitis (1, 3, 4, 11) and of up to 30% of posttraumatic cases in rural areas (2). A variety of gram-negative bacilli have been reported to cause postsurgical endophthalmitis; the most common include Pseudomonas spp., Haemophilus influenzae, Proteus spp., Serratia marcescens, Morganella morganii, Citrobacter spp., Escherichia coli, and Klebsiella pneumoniae.

The earliest case reports of postsurgical endophthalmitis caused by Enterobacter cloacae were published in 1966 (12) and 1975 (5). Other than these two cases, only two other separate cases of postsurgical endophthalmitis secondary to E. cloacae infection have been reported, and those were in 1992 (4) and 1993 (6). E. cloacae has more commonly been reported as a causative agent of posttraumatic endophthalmitis, often as part of a mixed infection (2, 11). Irrespective of the etiology, the clinical picture at presentation is usually that of a severe, rapidly progressive disease with acute onset which results in a poor final visual outcome and often loss of the eye. We report on four cases of endophthalmitis in patients treated at Moorfields Eye Hospital between June 1995 and August 1996.

	CASE REPORTS

Top Abstract Introduction Case Report Materials & Methods Results & Discussion References

The patients' clinical details are presented in Table 1. The details of the standard treatment protocol have been reported previously (8), and brief descriptions are provided in Table 1.

Patient 1. An 89-year-old lady underwent uncomplicated cataract surgery and was admitted 3 days later with a clinical picture of endophthalmitis. She was treated with intensive topical gentamicin, cefuroxime, and dexamethasone hourly, and she received one subconjunctival injection of gentamicin and cefuroxime and intravenous flucoxacillin and ciprofloxacin over the next 5 days. At 10 days postsurgery, clinical deterioration was evidenced by the visual acuity in the left eye, which was perception of light and the presence of a dense relative afferent pupillary defect (RAPD). Examination revealed pus in the anterior chamber and a dense fibrin plaque over the pupil. No fundal details or red reflex was visible.

Patient 2. A 50-year-old man with poorly controlled insulin-dependent diabetes was referred for management of recurrent and persistent vitreous hemorrhage in his left eye. Vitrectomy with delamination and endolaser treatment were undertaken on 25 May 1996. At the end of surgery Betamethasone (0.1%) and cefuroxime were injected subconjunctivally. The patient was then seen 1 week later with a clinical picture suggestive of endophthalmitis, but he had in fact suffered ocular pain and rigors since the first postoperative day. Ocular examination revealed visual acuity of poor perception of light, evidence of intraocular inflammation, no fundal view, or a RAPD. Ultrasound examination at this stage revealed no evidence of retinal detachment.

Patient 3. A 24-year-old man had suffered a shotgun injury to his right eye 2 months previously. After primary repair in Nigeria, he was left with perception of light vision in a comfortable eye. According to the patient, two pellets seen on orbital X ray at the time were not found at the time of surgery. Shortly after his arrival in the United Kingdom, 17 days prior to admission to Moorfields Eye Hospital, his right eye was red and tender with a visual acuity of no light perception.

Patient 4. Patient 4 was a 70-year-old diabetic man who had previously undergone combined cataract extraction, lens implant, and trabeculectomy with mitomycin C of the right eye in July 1993 and the left eye in September of the same year. In the case of the left eye, four subconjunctival injections of 5-fluorouracil had been administered in the early postoperative period in order to improve the chances of success by reducing the scarring response stimulated by the surgical procedure. Following uncomplicated surgery, postoperative visual acuity had been recorded as 6/9 in the left eye. The patient had suffered from diabetes mellitus since 1993, and at the time of admission with endophthalmitis he was poorly controlled on oral hypoglycemic medication, with a random glucose level of 17 mmol and 2% glycosuria.

	MATERIALS AND METHODS

Top Abstract Introduction Case Report Materials & Methods Results & Discussion References

Methods. The methodology for the sampling of intraocular fluids has been reported previously (8). Briefly, at the time of admission intraocular fluids (aqueous and vitreous fluids) were collected under sterile conditions and were processed immediately. Intraocular samples were examined by Gram and Giemsa staining and were cultured on blood agar, in brain heart infusion broth, and in Robertson's cooked meat broth. Because the volumes of the samples obtained were often small, Gram staining was performed only if the volume of the intraocular fluids obtained was greater than 100 µl for aqueous fluid and 200 µl for vitreous fluid. The fluids were cultured under both aerobic and anaerobic conditions. No aerobic organism was thought to be responsible for causing endophthalmitis unless it was isolated from an intraocular sample with heavy growth on one solid medium or the same organism was isolated from more than one medium. Anaerobic growth on any anaerobic medium was considered significant. All cultures were maintained for 14 days. If no organism was grown, the sample was considered culture negative even in the presence of organisms seen on Gram staining.

	RESULTS AND DISCUSSION

Top Abstract Introduction Case Report Materials & Methods Results & Discussion References

Antibiotic susceptibilities. The antibiotic susceptibilities of the isolates obtained from the cultures of aqueous and vitreous fluid from patients 2, 3, and 4 were identical. Each of seven isolates obtained from these four patients demonstrated resistance to ampicillin, erythromycin, and vancomycin. Each of these isolates was found to be sensitive to chloramphenicol, cefuroxime, cefotaxime, ciprofloxacin, ofloxacin, amikacin, gentamycin, tobramycin, ticarcillin, mezlocillin, and tetracycline.

Discussion. Between 11% (postoperative) (15) and 30% (posttraumatic) (2) of culture-positive cases of bacterial endophthalmitis are caused by gram-negative bacilli. The disease usually has an acute onset and is rapidly progressive. Gram-negative organisms are highly virulent, their toxins and proteases cause extensive damage to ocular tissues, and ocular infections with these organisms result in a poor final visual outcome for the majority of patients (4-7, 13). The damage is compounded by the sequelae of intraocular inflammation and the host's subsequent healing response. All four patients described here were seen in a 14-month period, and all infections were caused by E. cloacae, which is not considered a common cause of gram-negative endophthalmitis (1, 11, 15). The infections were characterized by a delay in intraocular sampling and treatment, because the patients themselves did not seek attention in the early stages of the infection. Earlier presentation may have resulted in a better final visual outcome.