Evaluation of antifungal susceptibility and clinical characteristics in fungal keratitis in a tertiary care center in North India.

PURPOSE

To study the antifungal susceptibility of common corneal pathogenic fungi to antifungal agents in the North Indian population.

METHODS

Prospective study of the antifungal sensitivity testing (natamycin, amphotericin B, voriconazole, itraconazole, fluconazole, posaconazole, caspofungin, micafungin) of fungal isolates from 50 cases of culture positive fungal keratitis by using E test method. Details noted included demographic data, visual acuity, clinical details, grade of keratitis, healing time, and success in medical management.

RESULTS

Of 50 patients with fungal keratitis (mean age: 40.28 ± 16.77 years), 12 eyes healed within 3 weeks, 14 had a delayed healing response, and 24 had chronic keratitis. Among the 15 cases of Fusarium isolates, 93.3% were sensitive to natamycin, while 40% to amphotericin B; 66.6% to voriconazole, 13.4% to itraconazole and fluconazole each. 80% of Fusarium cases (n = 12) showed susceptibility to posaconazole. Among Aspergillus flavus isolates, 53.4% (n = 8) were sensitive to natamycin, with only 40% (n = 7) showing sensitivity to amphotericin B and good susceptibility to azoles. MIC against susceptible Fusarium spp. for natamycin was 3-16 μg/mL, amphotericin B: 1-8 μg/mL, voriconazole: 0.5-1.5 μg/mL, itraconazole: 0.5-12 μg/mL, posaconazole: 0.094-1.5 μg/mL. MIC against Aspergillus flavus was natamycin: 8-32 μg/mL, amphotericin B: 0.5-16 μg/mL, voriconazole: 0.025-4 μg/mL, itraconazole: 0.125-8 μg/mL, posaconazole: 0.047-0.25 μg/mL; against Aspergillus niger isolates, to natamycin was 6 μg/mL (n=1), amphotericin B 8-12 μg/mL (n = 3), voriconazole: 0.125-0.19 μg/mL (n = 3), itraconazole: 0.38-0.75 μg/mL, posaconazole: 0.064-0.19 μg/mL and against Aspergillus fumigatus (n = 1), was natamycin4 μg/mL, amphotericin B - 8 μg/mL, voriconazole 0.25 μg/mL, itraconazole 1 μg/mL, and posaconazole 0.19 μg/mL. MIC against susceptible Acremonium spp. for natamycin was 1.5-16 μg/mL, amphotericin B: 0.5-8 μg/mL, voriconazole: 0.19-3 μg/mL, itraconazole: 0.125 μg/mL, posaconazole: 0.125-0.5 μg/mL and against susceptible Curvularia was natamycin 0.75-4 μg/mL, amphotericin B 0.5-1 μg/mL, voriconazole 0.125-0.19 μg/mL, itraconazole 0.047-0.094 μg/mL, posaconazole 0.047-0.094 μg/mL. MIC against Mucor spp.+ Rhizopus spp. (n = 1) was natamycin: 8 μg/mL, amphotericin B: 0.75 μg/mL, posaconazole: 1.5 μg/mL. MIC against of Alternaria (n = 1) was voriconazole: 0.19 μg/mL, posaconazole: 0.094 μg/mL. MIC against Penicillium (n=1) was natamycin: 8 μg/mL, voriconazole: 0.25 μg/mL, itraconazole: 0.5 μg/mL, and Posaconazole: 0.125 μg/mL.

CONCLUSION

Our observations highlight the variations in susceptibility to antifungal agents. Posaconazole seems to be effective with low MIC against common corneal pathogenic fungal isolates.