Abstract
Abstract: :
Purpose: To identify major pathogens associated with the development of microbial keratitis after penetrating keratoplasty (PK); to determine associated factors in patients who develop this postoperative complication, the time between initial PK and onset of microbial keratitis, and visual outcomes after resolution of infection. Methods: A retrospective study of patients treated by the Duke University Eye Center Cornea Service from January 1, 1999 to December 1, 2004 was conducted to identify patients who developed microbial keratitis after penetrating keratoplasty. Patients who developed postoperative microbial infections were evaluated for the identity of the pathogen, antimicrobial treatment, need for repeat PK, visual acuity at last follow up appointment, and conditions associated with the development of microbial keratitis in the corneal graft. Confirmation of microbial infection was carried out by laboratory analysis including gram stain, KOH, and fungal and bacterial culture. Results:A total of 23 cases of microbial keratitis within the corneal graft were identified. Median interval between PK and microbial keratitis was 15 months. Five infections (22%) occurred within the first 6 months after PK, while 16 (70%) occurred greater than 12 months after PK. Associated factors included epithelial defect, broken or loose sutures, and graft failure. Pathogenic organisms included Pseudomonas aeruginosa (6), coagulase–negative Staphylococcus (4), Curvilaria (3), Candida and Fusarium (2), and Serratia marcescens (1), Streptococcus pneumoniae (1), Streptococcus viridans (1), Aspergillus (1), Bacillus (1), Corynebacterium species (1). All patients were treated with fortified multi–drug antibiotic therapy, and therapy was tailored based on culture results. Eight patients (35%) underwent repeat PK. Mean post–infection visual acuity at the time of last follow up was 20/200. Conclusions: Microbial infections following PK carry significant morbidity with respect to visual outcomes and are major postoperative problems. The most common pathogen identified was Pseudomonas aeruginosa. Several factors including epithelial defect, loose sutures, and graft failure are associated with the development of microbial keratitis following corneal transplantation. Identification of associated factors, time course of infection onset, and knowledge of common pathogens is crucial to the successful treatment of these serious infections.
Keywords: cornea: clinical science • keratitis • microbial pathogenesis: clinical studies