Methicillin-resistant Staphylococcus aureus buckle infection complicated by endophthalmitis and presumed choroidal abscess in a patient with ulcerative colitis.

This patient presented with excessive pain, lid swelling, erythema, heat and limitations of extraocular movement (OD) nine days after a scleral buckle (SB) and pneumopexy surgery. Complicated buckle infection with endophthalmitis was impressed. Bacterial culture yielded methicillin-resistant Staphylococcus aureus. A choroidal abscess was identified 1 week after the episode. Complete visual recovery from hand motion to 20/30 (OD) was achieved with buckle removal, subconjunctival and intravitreal antibiotics. Endophthalmitis and choroidal abscess formation after SB surgery is extremely rare. Host factors including ulcerative colitis may play a role in causing the severe buckle infection of this patient.

1. Introduction

Scleral buckle (SB) surgery is a conventional repair procedure for rhegmatogenous retinal detachment. The reported incidence of buckle infection ranges 0.2–5.6%.1 Infective endophthalmitis after scleral buckling surgery is even lower (0.02–0.19%).23 Management typically requires prompt SB removal, which carries the risk of recurrent retinal detachment. Thus, the visual outcome of buckle infection may be poor because of retinal damage or recurrent detachment. In this paper, we present the clinical course of a patient with complicated methicillin-resistant Staphylococcus aureus (MRSA) buckle infection and discuss the possible host factors associated with the disease.

2. Case Presentation

A 46-year-old male with baseline visual acuity of 20/30 in both eyes (OU), had history of high myopia (spherical equivalent -12.0 diopters; OU), retinal break postfocal laser treatment (OU), and open angle glaucoma (OU) under regular follow up at our clinic. He moreover had ulcerative colitis (UC), which was well controlled with mesalamine. He presented to our clinic and had experienced floaters in the right eye (OD) for 1 week and an inferior visual field defect for 3 days. An examination revealed superior rhegmatogenous retinal detachment from the 10 o’clock to 2 o’clock direction without macular involvement. Lattice with atrophic holes from the 12 o’clock to 1 o’clock positions was identified. He underwent segmental SB surgery with scleral diathermy for retinal break localization and an intravitreal injection of perfluoropropane (C3F8). A Mira silicon sponge-507 was fixated at the superonasal sclera. Postoperative examination showed a well-attached retina, and the patient was discharge under stable condition.

Nine days postoperation, the patient presented to our clinic with excessive pain, chills, and headache. Erythema, lid swelling, heat, and limitation of extraocular movement were present. Visual acuity was limited to seeing hand motion only at 10 cm. The active cellular reaction was 4+ in the anterior chamber. A dilated fundus examination showed inferior vitreous opacities with an attached retina and an intraocular gas bubble of ~30%. The orbital computed tomography scan revealed a significant thickening of the right eyelid and the right superior rectus and levator palpebrae superioris muscles (Figure 1). Buckle infection complicated with orbital cellulitis and endophthalmitis was impressed. Empirical intravenous antibiotics of cefazolin and gentamicin were administered. The patient was started on hourly topical ciprofloxacin.

Figure 1

Orbital computed tomography without contrast of the right eye shows swelling of the periorbital tissue and fat stranding next to the buckle (arrow). An intraocular gas bubble from pneumatic retinopexy of right eye is also evident on the computed tomography image.

Emergent buckle removal surgery was arranged. During the operation, a peritomy was performed 120° superonasally. Purulent discharge was spontaneously drained from the superonasal quadrant. After removing the sponge implant and the underlying pus, the sclera beneath the buckle appeared soft and necrotic. Intra-vitreal vancomycin (1 mg/0.1 mL) and ceftriaxone (2 mg/0.1 mg) were injected, followed by subconjunctival injections of vanco-mycin (25 mg/0.5 mL) and ceftriaxone (100 mg/0.5 mL). The buckle and swab culture both yielded MRSA that was resistant to all antibiotics except vancomycin and teicloplanin. Hence, systemic antibiotics were shifted to teicloplanin and topical antibiotics were shifted to vancomycin. The anterior chamber reaction subsequently subsided. However, the fundus view remained impaired because of vitreous opacities. An elevated subretinal lesion located at the former buckle area over the superonasal region was identified 1 week postbuckle removal. An ultrasound B-scan (Figure 2A) revealed a dome-shaped elevation in the area. A choroidal abscess was also impressed. Intravitreal and subconjunctival injections of vancomycin were repeated every 2 days for a total of eight times to control the infection.

Figure 2

(A) Ultrasound B-scan of the right eye shows a dome-shaped choroidal elevation at the previous location of the removed buckle. Vitreous opacities are present. (B) At the 8-week follow up, the choroidal lesion (asterisk) has gradually flattened and the vitreous opacities are markedly decreased, which is consistent with resolution of the inflammatory process. (C) Optical coherence tomography reveals a thin epiretinal membrane over the right eye.

The patient responded well to vancomycin treatment. The vitreous opacities subsided and the choroidal abscess gradually flattened over an 8-week period, as shown by fundus examination and ultrasound B-scan in Figure 2B. Subsequent bacterial cultures of the eye discharge remained negative. Visual acuity of the patient improved dramatically to the baseline value of 20/30 at the 2-month follow up. The retina remained attached thereafter without any focal laser treatment. The patient underwent cataract surgery 48 months later, and visual acuity improved to 20/25. Follow-up optical coherence tomography (OCT) postcataract surgery showed a thin epiretinal membrane formation over the macular area of the right eye (Figure 2C).

3. Discussion

Our patient had MRSA infection that was associated buckle infection with endophthalmitis and presumed choroidal abscess. Scleral necrosis also occurred underneath the silicon sponge. Staphylococcus species are one of the most common organisms identified from an explanted SB and necrotic sclera.45 Methicillin-resistant Staphylococcus aureus ophthalmic infections are increasing. In a review by Blomquist,6 orbital cellulitis with endophthalmitis accounted for 4% of all MRSA ophthalmic infections. Apart from Staphylococcus aureus, other causative organisms in buckle infection include Staphylococcus epidermidis, Proteus mirabilis, and Pseudomonas aeruginosa.7

The possible route of bacterial entry in our patient may have been via contamination of the buckle implant or suture material. Ocular penetration during intravitreal injection of C3F8 may also pose a risk for endophthalmitis. However, standardized sterilization of the operating field with 5% povidone-iodine solution and soaking the silicon sponge in amikacin before placement were performed during surgery. Prophylactic amikacin irrigation of the implanted buckle and exposed orbital tissue and muscle cone was also performed before closing the wound. Despite administering all of the aforementioned preventive measures, our patient still experienced a SB infection. We reviewed the possible host factors and found that UC may have been associated with the complicated clinical course of our patient.

Oshima et al8 reviewed 287 Japanese patients (representing 293 eyes) who underwent SB surgery for rhegmatogenous retinal detachment. They found that the incidence of MRSA buckle infection was significantly higher in patients with atopic dermatitis [6 (18.8%) of 32 eyes] than in patients without atopic dermatitis [only 1 (0.4%) of 261eyes; p < 0.001]. Three patients developed endophthalmitis, which required a repeated intravitreal injection of antibiotics or emergent vitrectomy. The mean interval from initial surgery to onset of the disease was 7.2 ± 9.3 days, which was similar to our patient. Recent epidemiology studies documented an increased prevalence of atopic dermatitis in patients with inflammatory bowel disease.910 Ulcerative colitis may be more frequent in patients with atopic dermatitis than in the general population, and has an odds ratio of 6.0.10 Furthermore, advances in genome-wide association studies also suggest the susceptibility of shared genetic loci between atopic dermatitis and inflammatory bowel disease.9 Atopic dermatitis and UC involve dysfunction of the mucocutaneous barrier. The cytokine pattern in UC mucosa is primary Th2.11 Chronic inflammation of the epithelium and defective innate immunity result in poor bacterial clearance. This process may increase the risk of MRSA infection in these two groups of patients. We propose that soaking buckle implants in vancomycin and amikacin before and after buckle fixation and irrigating antibiotics around the exposed orbital tissue and muscle cone before wound closure may be feasible in reducing the risk of infection in patients with UC.

We also investigated the anti-inflammatory medication mesal-amine, which our patient used to control the activity of UC. According to our patient, he had stable disease activity under mesalamine alone. No steroid therapy was ever adopted. The presumed mechanism of mesalamine is that it diminishes inflammation by inhibiting the actions of cyclooxygenase and lipoxygenase, and thereby decreases the production of prostaglandins, leukotri-enes, and hydroxyeicosatetraenoic acids.12 However, a literature search found no significant association of mesalamine with opportunistic infections. A study by Toruner et al13 found that the odds of developing an opportunistic infection in patients taking mesalamine was 1.0, which was the same rate as in the reference group. Therefore, mesalamine is not a likely host factor related to the buckle infection in our patient.

Apart from aforementioned factors, pathological changes in highly myopic eyes include thinning of the sclera. Our patient had open angle glaucoma (OU) for years. This may provide indirect evidence that our patient had weakened biomechanical properties of the sclera. This predisposed our patient to increased susceptibility of deeper bacterial invasion through the sclera, which resulted in the formation of the choroidal abscess and endophthalmitis.14 In addition, the application of scleral diathermy for retinal break localization also reportedly weakens scleral strength.15 Limited coagulations were applied intraoperatively, and this may have contributed to the scleral defect in our patient.

The mainstay of buckle infection lies in promptly removing the buckle and suturing with subconjunctival or intravenous antibiotics to prevent scleral perforation. In our patient, buckle removal was performed promptly once the buckle infection was impressed. The endophthalmitis and presumed choroidal abscess subsided under aggressive systemic intravitreal and subconjunctival antibiotics. Excellent visual recovery was achieved. In conclusion, UC and high myopia may have been associated with the severe buckle infection of this patient. Careful preoperative evaluation, strict adherence to standard sterilization protocol, and close postoperative follow up are necessary to prevent and detect a postoperative infection early.