Microbial keratitis following penetrating keratoplasty

PURPOSE: To investigate the prevalence of microbial keratitis, predisposing risk factors and treatment modalities in patients who developed keratitis following penetrating keratoplasty (PK). PATIENTS AND METHODS: The records of 285 patients who had undergone PK betw een January 1991 and December 1995 in a tertiary care center were reviewed. Patients who developed postoperative microbial keratitis were evaluated fo r predisposing risk factors, microbiological etiology, response to broad sp ectrum antibiotic therapy and subsequent PK. Patients were mainly treated w ith fortified topical antibiotics with or without repeat PK. RESULTS: Of the 285 patient records reviewed, microbial keratitis developed in 21 eyes of 21 patients (7.4%). Seventy-one percent of infections occurr ed within 6 months after grafting. Keratitis initially began from the donor -recipient border in 16 cases (76.2%) and were central or paracentral in 5 patients. Predisposing risk factors included loose or exposed suture (9), s uture removal (I), persistent epithelial defect (3), graft failure (3), con tact lens wear (1), Stevens-Johnson syndrome (I). Fifteen (71.4%) patients were culture-positive consisting of Streptococcus pneumoniae (7), Staphyloc occus aureus (5), Pseudomonas aureginosa (2), and Hemophilus influenzae (I) . Forty-three percent of patients were successfully treated with medical th erapy only. Seven patients underwent second PK for visual rehabilitation an d 4 for tectonic purposes. After medical and surgical therapy, graft clarit y was achieved in 17 (81%) of patients. CONCLUSIONS: The microbial keratitis following PK is a major postoperative problem affecting the long term prognosis. Careful selection of patients, a nd preoperative and postoperative control of risk factors, may decrease the frequency of this complication. Several factors, including loose or expose d sutures, epithelial defects, ocular surface disorders, and graft failure, may predispose patients to develop microbial keratitis following PK.