Comparison of Culture-Positive and -Negative Microbial Keratitis

Abstract

Objectives: To evaluate and compare the risk factors, presenting features, and outcomes of patients with culture-positive and culturenegative microbial keratitis (MK) who presented to a tertiary referral center. Materials and Methods: We conducted a retrospective review of the medical records of 314 patients who were diagnosed with MK in our clinic between 2012 and 2019. Results: Among 314 patients, 142 had positive cultures (45.2%). The mean ages of the culture-positive and -negative patients at the time of diagnosis were 51.39±21.31 (range, 14-90) years and 56.68±21.34 (7-94) years, respectively (p=0.028). The mean best corrected visual acuity (BCVA) of the culture-positive and -negative patients were1.74±1.25 (0-3.1) LogMAR and 1.91±1.23 (0-3.1) LogMAR prior to treatment and increased to 1.21±1.30 (0-3.1) LogMAR and 1.27± 1.29 (0-3.1) LogMAR at last visit, respectively. There was no statistically significant difference between culture-positive and -negative patients’ BCVA levels at presentation or last visit. Ninety-two patients (64.7%) were infected with bacteria and 50 patients (35.2%) with fungi. The most common pathogen was Pseudomonas aeruginosa (18.3%), followed by Streptococcus pneumoniae (11.2%) and Fusarium spp. (11.2%). Keratitis foci were either centrally or paracentrally located in 105 eyes (73.9%) of culture-positive patients and 149 eyes (86.6%) of culture-negative patients. Multiple foci were present mostly in culture-positive patients (p=0.001). There was no significant difference between the culture-positive and -negative groups in terms of hypopyon presence (p=0.364). The proportion of contact lens (CL) wearers was 33% (n=47) among culturepositive MK patients and 13.3% (n=23) among culture-negative MK patients, respectively (p<0.001). Culture positivity was found to be significantly higher in keratitis associated with CL use (p=0.0001). Conclusion: Microbiological analysis and culture evaluation are important steps in order to manage proper treatment in microbial keratitis. Prognosis mostly depends on the infectivity of the microbiological agent.

Comparison of culture-positive and culture-negative severe infectious keratitis leading to hospitalization: a tertiary referral center experience

“…Furthermore, other factors such as age and sex did not differ significantly between the groups. Similar results were reported by Bhandage et al (12) and Yarımada et al (20) who found that the initial and final visual acuity did not differ between the CP and CN groups.…”

Estimated direct and indirect health care costs of severe infectious keratitis by cultured organisms in Thailand: An 8-year retrospective study

“…These results suggest a trend towards worse visual outcomes in culture-positive IK, but the difference did not reach statistical significance in their study. Yarimada et al [ 21 ], in their study of 314 IK patients, found no statistically significant difference in BCVA between culture-positive and culture-negative patients at the end of the follow-up (p = 0.716). The mean BCVA for culture-positive patients was 1.21 ± 1.30 LogMAR, while it was 1.27 ± 1.29 LogMAR for culture-negative patients.…”

“…This finding was consistent with our study, which found that BCVA at presentation was statistically significantly worse in culture-positive patients than in culture-negative patients (p-value 0.001). However, some studies have found differences in BCVA at presentation between patients with culture-positive and culture-negative IK, but no statistically significant difference [ 21 , 22 ]. In the study by Bhadange et al [ 22 ], which included 60 patients with IK, the mean BCVA at the last follow-up was 1.83 LogMAR for culture-positive IK and 2.34 LogMAR at presentation for culture-negative IK.…”

Microbial keratitis: Causative organisms, susceptibilities and trends at a tertiary eye hospital in South Africa

“…21 Wearing contact lenses is a risk factor for microbial keratitis. 22 There were no fungal organisms isolated in the 2018 study compared with Koetsie et al, where 3.0% of the total organisms were fungi; this seems to be a substantial change. 2 Proxenos et al, who conducted a similar study in Durban, South Africa, had 2.5% fungal growths (n = 5/199) in corneal scrapes (although their study period was over four years -2016 to 2019).…”