Home›Ophthalmology› Prospective observational study on antifungal resistance in fungal keratitis in South India
Prospective observational study on antifungal resistance in fungal keratitis in South IndiaWhy Common Eye Infection Treatments Are Failing More Patients
medRxivPublished April 23, 2026Study authors: Fingerhut, L.; Vigneshwar, R.; Burte, F.; Devi, M. V.; Nagarajan, R. S.; Karpagam, R.; Prajna, V.; M…DOI ↗Editorial oversight: Dr. Lars van Dijk, PhD · Surgical, Procedural & Diagnostic
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Key Takeaway
Consider species-specific antifungal susceptibility testing for fungal keratitis in endemic regions.
This is a prospective observational study from a cornea clinic in Madurai, South India, evaluating antifungal resistance in 153 patients with culture-positive fungal keratitis. The study assessed minimum inhibitory concentrations (MIC) for isolates and their association with clinical outcomes.
Key findings show high resistance rates among Fusarium spp. isolates (n=81): 38.3% resistant to natamycin, 93.8% to amphotericin B, 97.5% to voriconazole, and 76.5% to econazole. For Aspergillus spp. isolates (n=33), resistance was 66.7% to natamycin, 87.9% to amphotericin B, 6.1% to voriconazole, and 0% to econazole. Natamycin resistance was significantly correlated with poor clinical outcome (relative risk 1.7, P=0.0034, 95% CI: 1.2-2.6).
The authors note that the data support species-specific MIC thresholds for clinical utility. Limitations were not reported, but the study is specific to a South Indian population and time period (May-August 2025). Causality is not inferred; only associations are reported.
Practice relevance is restrained, emphasizing the need for tailored antifungal strategies based on local resistance patterns.
Why Eye Drops Fail Now
But these medicines are not working as well as before. A new report shows that the germs causing these infections are getting stronger. They are learning how to survive the drugs meant to kill them.
For years, doctors believed certain drops would stop the infection. They assumed the medicine would work on most patients. But here is the twist. The fungi are changing faster than we thought.
How Germs Evade Medicine
Think of the medicine like a key trying to open a lock. The fungus is the lock. Over time, the lock changes shape. Now the key no longer fits. This is called resistance.
Researchers looked at 153 patients in South India. They tested the fungi against four common drugs. The study took place over four months in 2025.
The results were alarming. Most fungi resisted at least one drug. Some types of fungi resisted almost all of them. One type called Fusarium was very hard to kill.
This doesn’t mean this treatment is available yet.
The study found that resistance to one specific drug linked to worse results. Patients with resistant infections were more likely to have poor outcomes. One drug, natamycin, showed a clear link to failure.
One Drug Linked to Risk
Experts say this data changes how we look at eye infections. It suggests we cannot use the same drug for everyone. We need to know exactly which germ is causing the problem first.
This research is not ready for every clinic yet. If you have an eye infection, see a specialist immediately. Do not try to treat it with old home remedies.
Steps to Protect Your Sight
This study only looked at one hospital in India. Results might be different in other parts of the world. We need more data to be sure.
Scientists will test new drugs and better testing methods. Approval for new treatments takes time and careful review. But this work helps doctors prepare for the future.
Objectives: Our primary objective was to identify the rate of anti-fungal resistance (including multidrug resistance) of fungal isolates cultured from fungal keratitis patients in South India. Our secondary objective was to identify associations between antifungal resistance and patient outcome. Subjects/Methods: 153 patients attending the cornea clinic at Aravind Eye Hospital, Madurai (May-August 2025) with culture positive fungal keratitis were enrolled in the study. Cultured isolates were evaluated for natamycin, amphotericin B, voriconazole and econazole MIC (n=151-153). MIC data were analysed by Kruskal-Wallis test followed by Dunn's multiple comparisons test. Patient disease outcome relative to isolate resistance was analysed by fisher's exact test (n=91). Results: There were high levels of resistance to all four antifungals, which were significantly elevated in Fusarium spp. and Aspergillus spp. isolates compared to other fungal genera (P<0.0001). Resistance of Fusarium spp. isolates (n=81) to: natamycin: 38.3%; amphotericin B: 93.8%; voriconazole: 97.5% and econazole: 76.5%. Resistance of Aspergillus spp. isolates (n=33) to: natamycin: 66.7%; amphotericin B: 87.9%; voriconazole: 6.1%; and econazole: 0%. Overall, fungal resistance to natamycin significantly correlated with a poor clinical outcome, P=0.0034, relative risk 1.7 (95% CI: 1.2-2.6). Conclusions: The majority of fungal isolates were resistant to multiple antifungals; none of the Fusarium isolates were susceptible to all four drugs, 15% were resistant to all of them. Resistance towards natamycin may worsen clinical outcome, particularly for infections caused by Aspergillus, even when susceptible to azoles. Our data supports the need for species specific MIC thresholds to have increased clinical utility.
