Exploring how bacterial keratitis infections have evolved following the COVID-19 pandemic

Researchers have examined the incidence, microbiological profile and antibiotic resistance of bacterial keratitis at a single Madrid hospital

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A clinician wearing a surgical mask and face shield stands in a hospital

Getty/Tempura

Selina Powell

13 October 2026

A corneal specialist has highlighted a “significant shift” in the microbiological profile of bacterial keratitis infections following the COVID-19 pandemic.

Ophthalmologist, Nerea Saenz-Madrazo, delivered a presentation examining bacterial keratitis infections at a single Madrid hospital during the European Society of Cataract and Refractive Surgeons Congress (ESCRS, 11-15 September, Excel London).

Saenz-Madrazo and colleagues evaluated changes in incidence, microbiological profile and antimicrobial resistance among 124 bacterial keratitis presentations before (2018–2019), during (2020–2021) and after (2022–2024) the pandemic at Hospital General Universitario Gregorio Marañón.

The researchers found that gram-positive bacteria dominated bacterial keratitis cases before and during the COVID-19 pandemic – at 88% and 81% respectively.

However, the proportion of gram-positive cases dropped in the post-pandemic period to 55%.

Conversely, the proportion of cases involving gram-negative bacilli more than tripled following the pandemic – from 12% before the pandemic to 45% after.

The proportion of cases involving bacteria that were resistant to Ciprofloxacin also close to tripled over the period – from 7% before the pandemic to 20% after.

Speaking with OT, Saenz-Madrazo shared that fewer people came to emergency departments during the pandemic.

“Severe cases of bacterial keratitis were coming, but they were presenting later. We were fighting against more resistant species,” she said.

Saenz-Madrazo highlighted the need to monitor the microbiological profile of bacterial keratitis in order to use the most effective therapies.

“As part of our study, we found that antibiotic resistance to the most widespread antibiotic increased,” the ophthalmologist said.

“Our take home message is that we have to review which strains we are fighting against, and which is the proper antibiotic to use. We have to be prepared to change our approach if something is not working,” she said.