September 2018

CORNEA

Presentation spotlight
Post-cataract Nocardia does not have to mean trouble


by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer


Nocardia infiltrate in the main incision of the cataract 1 month after surgery
Source: Nicolas Alejandre Alba, MD

 

If diagnosed in time and treated promptly, Nocardia infections of the eye can
be quickly cured

Nocardia rarely cause eye infections. Nonetheless, keratitis, scleritis, conjunctivitis, canaliculitis, orbital cellulitis, and endophthalmitis have all been associated with Nocardia infections of the eye. The clinical picture at times is not unlike infections caused by other, more commonly found organisms, and the causative agent in these infections can therefore be missed. A new report that documents a case of a Nocardia infection in a post-cataract patient highlights how best to diagnose, or rather not misdiagnose, these potentially dangerous eye infections.
This study presented the case of a 68-year-old male patient who underwent uneventful cataract surgery. The patient had good visual acuity 6 weeks after the surgery with no signs of ocular inflammation. Then an epithelial defect at the incision site of the self-healing corneal tunnel was observed 2 months following surgery, arousing concern. The examining physician observed corneal infiltrate and anterior chamber fogginess (flare) due to leaked proteins and inflammatory cells.
Nocardia infections of the eye have been associated with non-specific punctate epitheliopathy or ulcer with margins lined with yellow/white pinhead size superficial infiltrates. Infiltrates can have a wreath-like appearance and satellite lesions that are mostly found adjacent to the sites of corneal trauma. An unrelated study that correlated the clinical presentation of Nocardia keratitis with the time to diagnosis concluded that the characteristic clinical picture of Nocardia was very much dependent on the early presentation of the infection.1
According to Nicolas Alejandre Alba, MD, Hospital Universitario Fundacion Jimenez Diaz, Madrid, Spain, who presented the case report at the 22nd ESCRS Winter Meeting, there are important steps the treating physician needs to take in order to get to the root of the infection and stop it from spreading.

Where to begin

“The first line of management in any case of corneal infection is to take corneal scrapes,” Dr. Alejandre Alba said. “Then, while waiting for the test results, something should be done against the infection. We began our management of this patient with ceftazidime and vancomycin treatment.”
Within 48 hours after the initiation of treatment, staining revealed a filamentous gram positive bacterium, which prompted a treatment change to amikacin and moxifloxacin for 21 days, plus oral co-trimoxazole for 10 days. The modified (5% sulfuric acid) Ziehl-Neelsen acid fast stain was positive, and Nocardia nova was confirmed 8 days later.
Nocardia are aerobic, gram- positive, non-motile, branching, filamentous bacteria, found in soil, mud, water, dust, and decaying vegetation. Pathogenic species have been found in home dust, beach sand, garden soil, and swimming pools. They do not belong to the normal flora of the eye.
An antibiogram revealed that the particular strain found in this patient was resistant to ciprofloxacin. Dr. Alejandre Alba opted not to change the treatment regimen because of the good clinical evolution of the case. There was a complete resolution of the infection after treatment was completed, with no relapses after more than 1 year of follow-up and a BCVA of 20/20.

Treatment success

Gauging treatment success may not always be straightforward, Dr. Alejandre Alba said. “The epithelial healing may not be an appropriate indicator for improvement in Nocardia keratitis. It is not the best way to determine how progression is going because the infection can progress in spite of epithelial healing. In the case of this patient, progression to endophthalmitis was a concern. We adjusted our treatment plan to include antibiotics that were reported to obtain good results,” he said.
Nocardia show good susceptibility to amikacin and sulfonamides. Twenty Nocardia species that were isolated from ocular infections were sensitive to amikacin, according to the results of one study that investigated speciation and susceptibility of Nocardia from ocular infections.2 Another investigation that focused on Nocardia specific infections revealed the drug of choice to be amikacin.1 In yet another investigation, amikacin resolved infections in four out of seven study eyes with Nocardia infections, with six out of the seven eyes requiring surgical intervention. The investigators concluded that early surgical intervention, before anterior chamber involvement, was key.3
Dr. Alejandre Alba added oral co-trimoxazole to his treatment regimen, as an added measure of protection, as has been documented by one study in which a Nocardia farcinica infection was successfully treated by the agent based on cultured drug sensitivities. The investigators thought that Nocardia farcinica keratitis should be considered in the differential diagnosis of common, contact lens-related keratitis.4
“The use of topical steroids in the treatment of Nocardia ulcers seems to worsen the outcomes. We therefore did not include them in out treatment plan,” Dr. Alejandre Alba explained. Studies on the subject of corticosteroids in Nocardia infected eyes corroborate this assertion. One such study compared the clinical course of Nocardia keratitis with keratitis resulting from other bacterial organisms to assess the effect of corticosteroids. The multicenter, randomized, controlled trial included a study population of 500 patients with bacterial keratitis randomized 1:1 to topical steroids or placebo. The study outcomes seemed to indicate that corticosteroids were associated with worse outcomes in Nocardia patients, showing less overall improvement in visual acuity than non-Nocardia ulcers.5
“My take-home messages for the management of Nocardia infections are first of all to take corneal scrapes, which can be important not only in the presence of central ulcers but also in atypical presentations. I would avoid using corticosteroids in Nocardia keratitis and in severe cases of infection, the combination of different treatment strategies can be useful,” Dr. Alejandre Alba said.

References

1. Lalitha P, et al. Nocardia keratitis: species, drug sensitivities, and clinical correlation. Cornea. 2007;26:255–9.
2. Reddy AK, et al. Speciation and susceptibility of Nocardia isolated from ocular infections. Clin Microbiol Infect. 2010;16:1168–71.
3. Sharma D, et al. Nocardia infection following intraocular surgery: report of seven cases from a tertiary eye hospital. Indian J Ophthalmol. 2017;65:371–375.
4. Sharma N, O’Hagan S. The role of oral co-trimoxazole in treating Nocardia farcinica keratitis: a case report. J Ophthalmic Inflamm Infect. 2016;6:23.
5. Lalitha P et al. Nocardia keratitis: clinical course and effect of corticosteroids. Am J Ophthalmol. 2012;154:934–939.

Editors’ note: Dr. Alejandre Alba has no financial interests related to his comments.

Contact information

Alejandre Alba: nalejandre@fjd.es

Post-cataract Nocardia does not have to mean trouble Post-cataract Nocardia does not have to mean trouble
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