Xanthomonas maltophilia Endophthalmitis After Cataract Surgery

Xanthomonas maltophilia, previously known as Pseudomonas maltophilia and Stenotrophomonas maltophilia, is a gram-negative motile bacillus that can be isolated from human, animal, and environmental sources.¹ It may cause potentially life-threatening opportunistic systemic infections.^1,2 Most isolates demonstrate multidrug resistance, making it a highly virulent organism. Postoperative endophthalmitis caused by X maltophilia is rare. To date, only 2 case reports have been published.^3,4 We describe 4 additional patients with postoperative X maltophilia endophthalmitis treated between January 1, 1996, and March 31, 1999, at the Bascom Palmer Eye Institute, Miami, Fla (Table 1).

An 80-year-old woman was evaluated for increasing pain and decreased vision in the left eye, 2 weeks after uneventful clear-corneal phacoemulsification and posterior chamber intraocular lens (IOL) insertion. Her medical history was unremarkable. Visual acuity in the affected eye was hand movements. Clinical findings included a 5% hypopyon and marked vitritis. Vitreous tap was performed through the pars plana, and the patient was given intravitreal injections of ceftazidime, 2.25 mg; vancomycin hydrochloride, 1.0 mg; and dexamethasone sodium phosphate, 0.4 mg. On the first day after the initial treatment, a combined regimen was started with topical fortified ceftazidime, vancomycin, and 1% prednisolone acetate, every hour, and 1% atropine sulfate, 3 times daily. No systemic antibiotic therapy was used. Gram stain of the vitreous aspirate revealed many neutrophils, but no organisms were identified. Three days later, X maltophilia was isolated from the culture that was resistant to ceftazidime but sensitive to amikacin sulfate (Table 2). However, her clinical condition continued to improve, with resolution of the hypopyon; visual acuity returned to 20/50 OS. A small amount of retained lens cortex was noted at the 6-o'clock position. Gradual tapering of topical medications was begun.

Three weeks after the initial treatment, she returned with visual acuity in the left eye of light perception and recurrent hypopyon. Vitreous tap was performed and intravitreal injections of amikacin sulfate, 0.4 mg, and dexamethasone sodium phosphate, 0.4 mg, were given. Cultures of the vitreous aspirate were again positive for X maltophilia. During the next 48 hours, she developed worsening intraocular inflammation; the visual acuity remained light perception. Pars plana vitrectomy was performed and intravitreal injections of amikacin sulfate, 0.4 mg, and dexamethasone sodium phosphate, 0.4 mg, were administered. During the vitrectomy, the silicone plate posterior chamber IOL dislocated into the vitreous cavity but was positioned into the anterior chamber with a plan to exchange the IOL at a later date. At the 9-month follow-up visit, visual acuity was 20/50 OS and the vitritis resolved (Figure 1).

A 70-year-old woman was referred with increasing pain and redness in her left eye. One month earlier, she underwent phacoemulsification and insertion of a posterior chamber IOL. Her early postoperative course was uneventful, and she recovered 20/25 OS visual acuity by week 2. However, she had persistent anterior chamber reaction (2+) with retained lens cortex at the 5-o'clock position and was given a sub-Tenon injection of dexamethasone sodium phosphate, 40 mg, by her ophthalmologist. Two days later, the visual acuity in the left eye decreased to hand movements. Clinical findings included a 5% hypopyon, vitritis, and no view of the retina. A vitreous aspirate was performed, and she was given intravitreal injections of ceftazidime, 2.25 mg; vancomycin hydrochloride, 1.0 mg; and dexamethasone sodium phosphate, 0.4 mg. Cultures of the vitreous aspirates were positive for X maltophilia that was resistant to ceftazidime but sensitive to amikacin (Table 2). However, the patient had an excellent response to intravitreal ceftazidime treatment and 3 months later, best-corrected visual acuity was 20/30 OS and the vitritis resolved.

A 46-year-old man developed pain and irritation 5 days after undergoing extracapsular cataract extraction and posterior chamber IOL implantation in his left eye. In Venezuela, he was diagnosed as having postoperative endophthalmitis and was treated with vitreous tap and intravitreal injections of amikacin and cefazolin sodium. Vitreous cultures were reported to yield gram-negative rods and were read as possible Escherichia coli. Initially, the patient showed improvement in clinical signs but developed recurrent inflammation after 6 weeks and was referred to the Bascom Palmer Eye Institute for further management of his condition.

Best-corrected visual acuity was 20/200 OS. The cornea was slightly edematous, with anterior chamber cells (2+ to 3+) but no hypopyon. The posterior chamber IOL was in the bag with fluffy white cortical material for about 3 clock-hours. Dilated fundus examination revealed vitritis (2+) with optic disc hyperemia and cystoid macular edema. The patient underwent an uncomplicated pars plana vitrectomy, partial capsulectomy, and received intravitreal injections of ceftazidime, 2.25 mg, and vancomycin hydrochloride, 1.0 mg. Several days later, X maltophilia was isolated from the culture of vitreous aspirates that was sensitive to ceftazidime but resistant to amikacin (Table 2). The vitritis resolved; visual acuity improved to 20/30 OS at the 8-month follow-up visit.

A 48-year-old man underwent an uneventful extracapsular cataract extraction with insertion of posterior chamber IOL in his right eye in Nicaragua. Because of the marked intraocular inflammation on the fifth postoperative day, a clinical diagnosis of postoperative endophthalmitis was made and he was treated with subconjunctival gentamicin and topical tobramycin-prednisone drops every hour. Seventy-two hours after the first treatment, the patient was seen by us. Visual acuity in the operated eye was light perception with a 20% hypopyon and no view of the posterior pole. The patient underwent pars plana vitrectomy with intravitreal injection of ceftazidime, 2.25 mg; vancomycin hydrochloride, 1.0 mg; and dexamethasone sodium phosphate, 0.4 mg. In addition, he was started on a regimen of topical fortified ceftazidime, vancomycin, and 1% prednisolone acetate, every hour, and 1% atropine sulfate, 3 times daily. Vitreous cultures were positive for X maltophilia that was sensitive to ceftazidime but resistant to amikacin (Table 2). The initial favorable clinical response was followed 1 week later by increasing pain, decreased visual acuity in the right eye to hand movements, and increased hypopyon (30%). A second vitreous culture was taken and intravitreal injection of ceftazidime, 2.25 mg, was administered and the patient was given oral ciprofloxacin, 750 mg twice daily. Vitreous cultures were again positive for X maltophilia sensitive to ceftazidime. Five days later, the patient returned with increasing pain and subjective decrease in vision in the right eye, but the results of the ocular examination were unchanged. A third course of intravitreal injections of ceftazdime, 2.25 mg, and dexamethasone sodium phosphate, 0.4 mg, was administered and treatment with topical fortified antibiotics were continued. During the next 3 weeks, there was significant improvement in pain and inflammation but visual acuity remained poor at hand movements because of vitreous opacities. Pars plana vitrectomy was performed to clear the vitreous opacities. Vitreous cultures were not obtained and intravitreal antibiotic injections were not administered. Three weeks after the second vitrectomy, the vitritis resolved but visual acuity was 20/400 OD owing to persistent cystoid macular edema. The patient returned to Nicaragua and was lost to follow-up.

The first reported case of X maltophilia endophthalmitis was in a patient with acquired immunodeficiency syndrome following implantation of a ganciclovir implant.¹ This patient required multiple injections of amikacin and ciprofloxacin hydrochloride with only partial response. Two different vitreous aspirate cultures yielded X maltophilia that was sensitive to ceftazidime but resistant to all aminoglycosides, quinolones, and other β-lactam antibiotics. Treatment included removal of the ganciclovir implant, pars plana vitrectomy, and administration of intravitreal and systemic ceftazidime.

Kaiser et al⁴ recently reported a case of X maltophilia endophthalmitis 6 days after cataract extraction in an immunocompetent 76-year-old woman. The patient was initially treated with pars plana vitrectomy and intravitreal injections of vancomycin and tobramycin. Vitreous aspirate culture was positive for X maltophilia that was resistant to both of the initially administered antibiotics but was sensitive to ceftazidime, gentamicin, ciprofloxacin, ticarcillin, polymixin B, and sulfamethoxazole-trimethoprim. However, the patient responded extremely favorably to the initial treatment but had recurrence of inflammation 6 weeks later. A second pars plana vitrectomy, intravitreal ceftazidime injection, and treatment with topical and oral ciprofloxacin and sulfamethoxazole-trimethoprim sulfate was successful in clearing the vitritis.

In our study, the clinical course of X maltophilia endophthalmitis following cataract surgery in 4 immunocompetent patients is described. Patient 2 responded well to the initial intravitreal antibiotic therapy. The other 3 patients (cases 1, 3, and 4) had a course of recurrent infection similar to previously published cases.^3,4 The duration between the initial treatment and the first recurrence ranged from 7 to 45 days. In all patients, cure was achieved by pars plana vitrectomy and/or intravitreal antibiotic injection.

In a study by Stern et al,⁵ reported risk factors for recurrent postoperative endophthalmitis included infection with a gram-negative bacillus, host immunosuppression, slow-growing organisms, organisms with multiantibiotic resistance, and inadequate antibiotic exposure time. Antibiotic resistance may in part explain the recurrence in the cases reported by Chen et al³ and Kaiser et al⁴ and cases 1 and 3 in our study. The case by Kaiser et al⁴ and patient 1 in our case series did show favorable clinical response to initial intravitreal therapy despite organism resistance. Intravitreal injection of antibiotics provides high initial concentrations of antibiotics that are well in excess of the minimum inhibitory concentrations against susceptible organisms. However, in patient 4, the organism was sensitive to the ceftazidime but endophthalmitis still recurred. Cottingham and Forster⁶ hypothesized the concept of eradication time, which was the time after inoculation within which eyes had to be treated to be sterilized. Beyond the eradication time, the organism load is such that pars plana vitrectomy is required in addition to injection of intravitreal antibiotics. Our patient 4 may represent an infected eye treated after the eradication time had elapsed.

Three of the 4 cases (cases 1 through 3) had visible retained lens cortex that may cause intraocular inflammation mimicking endophthalmitis.⁷ It is also possible that the retained lens cortex may have played a role in facilitating growth of the organisms as has been described for postoperative Propionibacterium endophthalmitis.⁸

The antibiotic sensitivities of all vitreous isolates in our study are summarized in Table 2. All 4 isolates were sensitive to polymixin B and sulfamethoxazole-trimethoprim, while 3 of the 4 isolates were sensitive to ciprofloxacin. All isolates were resistant to gentamicin, while 2 of the 4 isolates were sensitive to amikacin, tobramycin, and ceftazidime; there was no cross-resistance between amikacin and ceftazidime.

The role of systemic antibiotics in the management of X maltophilia endophthalmitis is unclear. Kaiser et al⁴ used both oral ciprofloxacin and sulfamethoxazole-trimethoprim for treating their patient with Xmaltophilia endophthalmitis. In accord with the findings of the Endophthalmitis Vitrectomy Study Group⁹ showing no beneficial effect of systemic antibiotic treatment in the management of postoperative endophthalmitis, no systemic antibiotics were used in our study.

Endophthalmitis associated with gram-negative organisms usually has poor visual prognosis.^9,10 However, some gram-negative organisms may be less virulent, cause somewhat delayed-onset endophthalmitis, and have a better visual prognosis.¹¹ Despite the high recurrence rate, endophthalmitis caused by X maltophilia seems to be in the latter category since the visual acuity outcomes after treatment were generally favorable.

Our case series and the previously reported cases demonstrate that X maltophilia endophthalmitis may have a persistent and recurrent clinical course even when the organism is sensitive to the intravitreal antibiotics used. Hence, it is important to follow up these patient closely for recurrence, possibly repeating treatment with intravitreal antibiotics and pars plana vitrectomy when indicated.

Corresponding author: Harry W. Flynn, Jr, MD, Bascom Palmer Eye Institute, 900 NW 17th St, Miami, FL 33136 (e-mail: hflynn@miami.med.edu).