Distribution of Microbial Keratitis After Penetrating Keratoplasty According to Early and Late Postoperative Periods

Abstract

Objectives: The aim of this study was to investigate the distribution of microbial agents in the early and late postoperative periods in patients with microbial keratitis (MK) after penetrating keratoplasty (PK). Materials and Methods: The records of 36 patients who were clinically diagnosed as having MK after PK were retrospectively reviewed. Culture results were obtained from microbiology records and the organisms that were produced were noted. A case was deemed as viral keratitis based on the clinical appearance, negative cultures, and response to antiviral treatment. Keratitis development times were evaluated in 2 categories: early (within the first year) and late (after year 1) postoperative period. Mann-Whitney U and Kruskal-Wallis tests were used to compare numerical variables that did not show normal distribution and chi-square test was used to compare categorical variables. Results: The majority of MK cases were of bacterial origin (55.5%, n=20), followed by viral (41.7%, n=15) and fungal (2.8%, n=1). Of the 15 cases of early postoperative MK, 10 were bacterial, 4 were viral, and 1 was fungal; however, among cases of late postoperative MK, 10 were bacterial and 11 were viral. The majority (65%) of early and late bacterial infections were caused by gram-positive strains (most commonly staphylococci). Gram-positive bacteria caused keratitis significantly earlier than gram-negative bacteria (p=0.037). Viral and gram-negative bacterial MK was more frequent in the late postoperative period, but the difference was not statistically significant. Conclusion: In our study, bacterial keratitis was more common in post-keratoplasty MK than viral and fungal keratitis. Gram-positive bacteria were the most common causative agents. The increased incidence of gram-negative bacterial agents and viral keratitis in the late postoperative period can be explained by long-term topical steroid use.

Post penetrating keratoplasty infectious keratitis: Clinico-microbiological profile and predictors of outcome

“…Infectious keratitis following PKP can occur in the early (<1 year) or late (> 1 year) post-operative period as described by previous studies. 10,16 Chen et al 14 noted that 57.1% of their patients developed graft infection within 1 year of PKP while 46.3% of patients had early graft infection in the study by Sun et al 10 In our study 62.82% patients developed early infection. The possible reasons for higher chance of developing early infections in the graft could be higher dose of topical steroids, presence of multiple sutures, a healing graft-host junction and decreased corneal sensitivity in the first year following PKP.…”

Clinical Outcomes of Infectious Keratitis Associated with Contact Lens Wear Following Penetrating Keratoplasty: A Case Series

“…as the most common causative agent of microbial keratitis following PK. 10,21 Ozlap et al found that 55.5% of cases of microbial keratitis after PK were of bacterial origin, followed by 41.7% viral and 2.8% fungal. 21 This case series identi ed a higher rate of fungal keratitis (33.3%) than reported in the literature.…”

“…In addition, the prevalence of microbial keratitis after penetrating keratoplasty without the use of contact lens has been reported as between 1.8% and 12.1%. 21 This makes it di cult to determine any direct causation or correlation between postoperative contact lens wear following PK and the development of infectious keratitis.…”

Post-Keratoplasty Microbial Keratitis in the Era of Lamellar Transplants—A Comprehensive Review

“…There are several well-established risk factors for recurrent infections in therapeutic grafts: fungal origin, big ulcer size (diameter of at least 60 mm), graft size (diameter of at least 8.5 mm), endophthalmitis, limbal involvement, perforated cornea, endothelial or retro-iris exudates [23]. Still, the most common origin of repeated microbial infections is bacteria (>50%), followed by viruses and fungi [60]. The recurrence rate varies from 2-3% to 41% in different analyses [2,23,59,62].…”

“…Table 4 summarizes the available literature on the time of PKMK onset after corneal transplant derived from the last 18 years of original research. Notably, fungal etiology brings about bacterial and viral infections [60]. Interestingly, contaminated donor tissue tends to manifest corneal ulcer early (within the first 2 months) [56].…”