Moraxella keratitis: risk factors, presentation, and management

Abstract

Editor, M oraxella accounts for approximately 5% of all corneal ulcers. (Varaprasathan et al. 2004) Moraxella keratitis can lead to severe ulceration and significant vision loss, and is often associated with compromised host immunity with chronic alcoholism, malnutrition, diabetes and poor sanitary habits considered as important predisposing factors. A retrospective chart review was performed on 21 patients of 21 culture-proven cases of Moraxella keratitis treated at University of Michigan W.K. Kellogg Eye Center from 1999 to 2007, and the predisposing factors, clinical presentation, and outcomes of management in these patients were evaluated. The following data were collected for each patient: age, gender, predisposing risk factors (ocular and systemic), ulcer location, slit-lamp examination, presenting and final visual acuity, and medical and surgical treatment plans and outcomes. All of the ulcers were cultured; positive Moraxella cultures showed evidence of many colonies. After clinical diagnosis, intensive medical treatment was started in all patients. The main outcomes are showed in Table 1. The mean age of the NINE male and 12 female patients was 59.9 (range 18–89) years. Predisposing ocular and systemic risk factors were identified in 61.9% of patients with systemic conditions (diabetes mellitus) being present in 23.8% of patients. Ocular risk factors were identified in 12 patients: seven patients had blepharitis; three patients had previously had corneal transplantation; three patients had a diagnosis of glaucoma; ectropion, lagophthalmos, herpes simplex virus keratitis, and proptosis were present in one patient each. No predisposing risk factor could be identified in 38.1% of cases, and none of the patients were alcoholics or malnourished. All patients were treated medically with various antibiotic combinations, use of tissue adhesive was necessary in four patients, two of whom subsequently required penetrating keratoplasty because of perforation and a total of seven patients required surgical procedures. Despite aggressive medical and surgical treatment, visual outcomes were poor. Final best corrected visual acuity improved to ≥20/100 in only four cases (19.0%) of central ulceration and four cases (19.0%) of paracentral ulceration. Moraxella keratitis has been characterized as a central ulceration with deep stromal involvement, hypopyon, and a tendency for perforation. (Fedukowicz & Horwich 1953) Heidemann et al. described ten cases which had predisposing ocular or systemic conditions.(Heidemann et al. 1987) However, Das et al. reported 95 cases of culture-proved Moraxella keratitis with only 13% with systemic risk factors.(Das et al. 2006) In the present study, there were no alcoholics or malnourished patients while diabetes was present in only five patients (23.8%). In fact, the diabetic patients did not have an unfavourable outcome, as measured by final best corrected visual acuity and need for additional surgery, when compared to the nondiabetics. More than 47.6% (10 of 21) of our patients were treated with single or multi-drug combinations of fluoroquinolones. Although the best outcomes were obtained with a multi-drug combination of a fluoroquinolone, cefazolin and fortified tobramycin, the results were less than ideal. Final best corrected visual acuity and need for surgery did not correlate with use of fluoroquinolone or multi-drug treatment. Moraxella keratitis must be suspected in patients with corneal ulceration regardless of the absence of systemic risk factors such as malnutrition and alcoholism. Close follow-up and observation are mandatory because of the significant risk of corneal perforation and vision loss despite aggressive medical and surgical therapy.