Failed Treatment of Multidrug-resistant Acinetobacter Baumannii Keratitis Mistaken for a Mixed Infection

Purpose: To report treatment failure of multidrug-resistant Acinetobacter baumannii keratitis in a patient wearing contact lenses for a long time. Case summary: A 48-year-old man using daytime soft lenses for 20 years was transferred due to decreased visual acuity and eye pain. Slit-lamp biomicroscopy showed a large corneal epithelial defect and stromal infiltration, but no hypopyon. Treatment was initiated with moxifloxacin, polyhexamethylene biguanide eye drops, and oral antibiotics. Corneal infiltration worsened, corneal scrapings and culture were performed. Gram staining showed Gram-positive bacteria, potassium hydroxide (KOH) hyphae-positive, and culture yielded Bacillus. He was hospitalized and vancomycin, voriconazole, and amphotericin B eye drops were administered. Oral antifungal agents were also prescribed. The corneal epithelial defect was restored from temporal side for a while, and then deteriorated with an endothelial plaque. Therefore, voriconazole and amphotericin B were injected intracamerally. All four repeated culture tests were negative. Despite total conjunctival flap, the patient complained of severe pain and eventually underwent evisceration. In the culture of intraocular contents, Acinetobacter baumannii, which is resistant to all drugs except minocycline, was detected. Conclusions: In patients wearing contact lens for a long time, not only mixed infection with acanthamoeba and fungi, but also gram-negative bacteria should be considered first, and multidrug-resistant Acinetobacter baumannii should also be considered.