Silicone oil tamponade in managing recalcitrant endophthalmitis after cataract surgery secondary to Clostridium intestinale

Background

Cataract surgery is the most performed operation in the USA, with the number of surgeries performed annually on the rise.1 Complications after cataract surgery are rare, but potentially devastating as in cases of postoperative endophthalmitis. The incidence of postoperative endophthalmitis in cataract surgery averages around 2 in 1000 cases or 0.2%.1

The source of infection in postoperative endophthalmitis is predominantly organisms of the lids and conjunctiva that gain access to the eye during surgery or through the corneal wound postoperatively.2 Most isolated organisms are gram positive (94%) with the majority of those being coagulase-negative Staphylococci (70%).3 Rarer organisms, not typically found on the eye surface or adnexal structures, have also been reported to cause postoperative endophthalmitis, including exogenous organisms from the operating room.4 These can include gram-positive spore-forming bacilli such as the aerobic Bacillus species or the anaerobic Clostridium species. More commonly, however, these bacilli are associated with cases of endophthalmitis resulting from penetrating injuries to the eye, particularly those that involve organic material.5

Clostridium species are a rare cause of endophthalmitis and tend to be associated with poor visual outcomes.5 For example, endophthalmitis secondary to Clostridium perfringens often fails medical and surgical management, ultimately resulting in loss of the eye.6 In this report, we describe a case of endophthalmitis secondary to C. intestinale, an aerotolerant gram-positive spore-forming bacilli. It is believed to be an organism of gastrointestinal colonisation, and to date has only been reported as the source of one human infection, a case of bacteraemia.7 To our knowledge, this is the first report in the literature of C. intestinale causing endophthalmitis. Herein, we describe the clinical course of this patient, which was initially refractory to conventional management of endophthalmitis but resolved after pars plana vitrectomy (PPV) and silicone oil tamponade with excellent visual outcomes.

Case presentation

A woman in her seventh decade of life was referred to the retina service for evaluation of acutely decreased vision in the right eye, 2 weeks after uncomplicated sutureless cataract extraction by phacoemulsification through a clear corneal incision, and monofocal one-piece Tecnis ZCB00 intraocular lens (Abbott Medical Optics, Santa Ana, California, USA) placement in the capsular bag. She had no medical history and ocular history was only notable for refractive error and presbyopia, she had no preoperative corneal abnormality. Following surgery, she was using gatifloxacin 0.5% and prednisolone acetate 1% four times daily as directed. Her examinations on postoperative day 1 and week 1 were as expected, without signs of infection, and she achieved a visual acuity (VA) of 20/15.

On presentation to the retina service on postoperative week 2, VA in the right eye was decreased to 20/50 with normal intraocular pressure, marked anterior chamber fibrinoid reaction without hypopyon, and 3+ vitreous cell with debris limiting posterior view. Given poor posterior view, the patient underwent ophthalmic B-scan ultrasonography to rule out alternate diagnoses and to monitor the course of the vitritis over time (figure 1). The patient did not have any associated eye pain.

Treatment

The fulminant inflammation after recent intraocular surgery was concerning for endophthalmitis, so an anterior chamber paracentesis and vitreous tap were obtained and sent for gram stain, aerobic, anaerobic and fungal cultures. The patient was empirically treated at that time with intravitreal vancomycin (1 mg/0.1 mL) and ceftazidime (2.25 mg/0.1 mL) and monitored daily for changes in ophthalmic examination. The next day, her vision was 20/300 with development of a small hypopyon, which resolved the following day with slight improvement of VA to 20/200.

The gram stain from the anterior chamber paracentesis resulted positive for rare polymorphonuclear leucocytes, without organisms, and the patient’s examination over the next couple of days remained stable. On postoperative week 3, 1 week after intravitreal antibiotics, the patient’s VA worsened to 20/400, with increased anterior chamber inflammation, a recurrent hypopyon, and vitritis (figure 2). Anterior chamber paracentesis and vitreous tap were repeated and again sent for gram stain and culture. Intravitreal injections of vancomycin (1 mg/0.1 mL) and ceftazidime (2.25 mg/0.1 mL) were also repeated, with the addition of voriconazole (100 μg/0.1 mL) due to lack of improvement and concern for possible fungal infection. At this point, all cultures were without growth. Two days later, vision worsened to counting fingers and a 25-gauge PPV (Alcon Constellation, Fort Worth, Texas, USA) with partial air-fluid exchange was performed, thoroughly removing the vitreous, with repeated administration of intravitreal vancomycin (1 mg/0.1 mL), ceftazidime (2.25 mg/0.1 mL) and voriconazole (100 μg/0.1 mL). Given concern for vision loss in a patient with an undiagnosed panuveitis suspicious for endophthalmitis, a surgical vitreous sample was sent for diagnostic testing covering a significantly broadened differential. The sample was sent for cytology, aerobic, anaerobic and fungal cultures, in addition to herpes simplex viruses 1 and 2, varicella zoster virus and cytomegalovirus PCR testing, acid-fast bacilli smear and culture, and mycobacteriology.

The same day, after the patient underwent vitrectomy, 9 days after the initial ocular sample was taken, preliminary culture results from the initial anterior chamber paracentesis grew non-perfringens Clostridium species, which was sent to an outside laboratory for confirmation, identification and sensitivity testing. All other anterior chamber and vitreous sample testing resulted negative. On post vitrectomy day 1, the patient had a marked improvement in VA to 20/30, and only mild residual anterior chamber inflammation without vitritis. However, on post vitrectomy day 3, the patient’s VA dropped to 20/200, with recurrent anterior chamber and vitreous inflammation concerning for recurrence of endophthalmitis. The patient was admitted to the hospital for an infectious disease consultation and systemic intravenous ceftazidime, vancomycin and metronidazole were initiated to target the unknown Clostridium species. The following day, she underwent repeat 25-gauge PPV, during which minimal residual vitreous was noted, with injection of intravitreal vancomycin (1 mg/0.1 mL), amikacin (200 μg/0.05 mL) and tamponade with 5000-centistoke silicone oil injected in the typical fashion with a viscous fluid injector. Two days later, the patient’s vision improved to 20/30 with only mild residual intraocular inflammation and new fibrotic membrane over the intraocular lens (IOL). She was discharged on a 2-week course of oral metronidazole per infectious disease recommendations.

Outcome and follow-up

Confirmatory testing identified the pathogen as C. intestinale, and the isolate was found by minimum inhibitory concentration to be susceptible to vancomycin, piperacillin/tazobactam, ertapenem, clindamycin and metronidazole, indicating that these antibiotics at reasonable doses prevented microbial growth, and had intermediate susceptibility to penicillin, which had a minimum inhibitory concentration of 1 μg/mL. The patient was followed closely for 4 months without infectious recurrence, after which silicone oil was removed. One month after silicone oil removal, the eye remained quiet, and uncorrected VA remained 20/20 (figure 3). At her most recent follow-up, at 13 months after her cataract surgery, the affected eye remains quiescent, without new ocular diagnoses, with an uncorrected VA of 20/20.