CASE REPORT: Multidrug-resistant Pseudomonas keratitis and sequential endophthalmitis treated with chlorhexidine and piperacillin-tazobactam

Abstract

To report the clinical course and treatment strategies employed in management of a case of multidrug-resistant Pseudomonas aeruginosa keratitis progressing to endophthalmitis. The drug-resistant strain was later traced to use of contaminated EzriCare Artificial Tears in a multi-state cluster outbreak. A 57-year-old male patient with a history of Descemet stripping automated endothelial keratoplasty was referred for a culture-positive Pseudomonas corneal ulcer in the right eye that had been treated with several weeks of topical moxifloxacin, fortified vancomycin and tobramycin, and intravitreal injections for endophthalmitis. His cornea was cultured off of antibiotics and grew only rare Propionibacterium acnes. Topical antibiotics and steroids were reduced, but his condition rapidly deteriorated with leading to corneal melt, perforation, and endophthalmitis. Repeat corneal cultures and sensitivity analyses revealed growth of a strain of Pseudomonas aeruginosa that was resistant to fluoroquinolones, aminoglycosides, cephalosporins, monobactams, and carbapenems, and only intermediate susceptibility to piperacillin-tazobactam. The patient underwent a therapeutic penetrating keratoplasty and was subsequently initiated on an intensive regimen of topical chlorhexidine and polymyxin-B/trimethoprim. He also underwent a pars plana vitrectomy with anterior chamber washout, followed by serial injections of intravitreal piperacillin-tazobactam at a dose of 225 mg/0.1 mL. After 8 weeks of intensive treatment, there was gradual with healing of his ocular surface, regression of his hypopyon and posterior inflammation, and no signs of recurrent infection. A public health investigation ultimately revealed that his infection was one of several cases involved in a multistate cluster outbreak of extensively drug-resistant Pseudomonas ocular infections that were traced to the use of contaminated EzriCare Artificial Tears. Multidrug-resistant keratitis and endophthalmitis caused by multidrug-resistant Pseudomonas keratitis requires consideration of nonconventional antimicrobial agents and experimental therapeutic alternatives. Topical chlorhexidine and intravitreal piperacillin-tazobactam are currently nonconventional therapies in the context of bacterial keratitis and endophthalmitis, but were safe and effective in the management of multidrug-resistant Pseudomonas aeruginosa ocular infection.