Nocardia are aerobic, gram-positive, acid-fast filamentous bacteria. Nocardia asteroides belongs to the family Actinomycetales and is not a commensal in either humans or animals.1 They are soil saprophytes and are found in water and decaying organic matter. They gain entry to the eye through trauma or a foreign body. They have been isolated from keratitis, scleritis and even endophthalmitis cases. However, exogeneous Nocardia infection after cataract surgery is rare. We report two cases of Nocardia infection after phacoemulsification. Both cases had a good treatment outcome with early surgical intervention.
We report two patients who underwent uneventful clear corneal temporal incision phacoemulsification with a foldable intraocular lens by the same surgeon (SH), on the same day one after the other. Both patients were doing well on postoperative day one and were treated with a combination of ofloxacin 0.3% eye drops and prednisolone acetate 1% eye drops. Both patients presented with wound infection at the sideport site with no evidence of posterior segment involvement. Steroid drops were discontinued at presentation. Patient 1 had a well-controlled diabetes while patient 2 had hypertension and ischemic heart disease well controlled on medical therapy.
A 67-year-old female patient presented 17 days after surgery with complaints of pain, redness, watering and reduction of vision of two days duration. Cornea showed a small stromal infiltrate with a 2 + anterior chamber reaction but no hypopyon. She was empirically started on oral ciprofloxacin and hourly fortified antibiotic eye drops (cefazolin 5% and tobramycin 1.4%). On follow-up the infiltrate worsened and there was a 3 mm hypopyon [Fig. 1]. The patient underwent an incisional corneal biopsy with an anterior chamber tap. The material so obtained was subjected to smears and cultures, but all reports were negative. The treatment was empirically changed to vancomycin 5% and amikacin 4% eye drops, however, she continued to worsen. A therapeutic keratoplasty with anterior chamber wash was performed using a 5-mm trephine (PG). The corneal button was sent for histopathology and microbiology, however both were negative. At the same time the second patient's samples showed a rich growth of Nocardia asteroides. Therefore, after keratoplasty the patient was treated with oral co-trimoxazole and amikacin 4% eye drops [Fig. 2]. At one year follow-up patient has an opaque graft with a best corrected vision of 20/60.
A 62-year-old male patient presented 34 days after surgery with similar complaints. Cornea showed a 2 mm stromal infiltrate with a 1 mm hypopyon. He was started on similar treatment as the first case. He worsened and the corneal infiltrate increased in size to 3 mm along with a 2 mm hypopyon. The patient underwent an incisional corneal biopsy and an anterior chamber tap. Nocardia was identified presumptively on Gram stain as gram-positive branching filaments which were weakly acid-fast using Kinyoun's modification of acid-fast stain. The cultures confirmed Nocardia asteroides sensitive to co-trimoxazole, cefuroxime, ceftazidime, cefotaxime, gentamicin, tobramicin, amikacin, ciprofloxacin, ofloxacin, imipenem and vancomycin.
The treatment was changed to oral co-trimoxazole and amikacin 4%, gatifloxacin 0.3% and co-trimoxazole eye drops were started. The patient however continued to worsen and there was scleral involvement with iris prolapse [Fig. 3]. A therapeutic keratoplasty (6 x 6.5 mm) with AC wash was done (NG). The excised button was sent for culture, which was positive for Nocardia asteroides. At one year follow-up [Fig. 4] the patient had a best corrected vision of 20/40, the graft was opaque with peripheral anterior synechiae at 6 O’clock.
A review of the ophthalmic literature in the English language using PubMed revealed six reports of infection after self-sealing tunnel incision.234567 These are due to bacterial and fungal etiologies. In a series of 24 cases of Nocardia endophthalmitis, 11 wound-related infections were noted by Prajna et al.,8 however, only one of these was present in the self-sealing phacoemulsification incision. Thus Nocardia wound infection after phaco emulsification cataract surgery is rare.
The clinical features of tunnel infections are nonspecific and are often noncontributory of the possible etiological agent. Therefore, a detailed microbiological workup is mandatory. However, since the infiltrate is usually deep and not amenable to routine corneal scrapings, corneal biopsy becomes necessary in these cases.
Nocardia isolates from keratitis are most sensitive to trimethoprim-sulfamethoxazole,1 amikacin8 and cefazolin.9 Medical therapy has been reported to be successful in superficial Nocardia keratitis,1 however, it often fails in deep-seated corneal infections and in intraocular infections.8 This could be due to the failure of antibiotics to penetrate deep into the abscess cavity or due to the high load of infection. In patients unresponsive to medical treatment, a therapeutic keratoplasty should be considered. Reports of penetrating keratoplasty in Nocardia infections have however been associated with poor visual outcome89 except for the report by Chen.10 Early presentation after onset, prompt recognition and appropriate management may be associated with a better outcome.89 Use of topical and / or systemic corticosteroids in Nocardia infections can prolong the duration of treatment and worsen prognosis.9 We believe that the first case, despite negative reports also had Nocardia infection in view of the identical clinical course and outcome. Microbiological testing has limitations and is sometimes negative, despite best efforts. Contamination of the side port knife due to some breakdown in sterility measures must have been responsible for the first case. The same knife was then re-used without resterilization for the second case. Patients presented 17 and 34 days after surgery and this latent period is similar to the one reported earlier.8 Despite the organism being sensitive to antibiotics in vitro there was no clinical response to medical therapy, however surgical intervention was successful. We feel early surgery may be preferable in deep-seated Nocardia infections which show no response to appropriate medical therapy.
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