The burden of antimicrobial resistance in biofilm-forming Staphylococcus spp. from Vernal Keratoconjunctivitis patients' eyes

Vernal keratoconjunctivitis (VKC) is a chronic allergic ocular surface disease with seasonal recurrences and severe forms showing vision threatening complications. The purpose of the study is to understand the prevalence and diversity of biofilm-forming bacteria and antimicrobial resistance in VKC compared to healthy individuals (HC). For this, conjunctival swab samples were collected from VKC (n = 26) and HC (n = 23), of which culture positive samples were 77 % and 78.26 % respectively. The 16S rRNA gene sequencing revealed a significant increase in bacterial diversity in VKC compared to HC (p < 0.05), identifying 16 and 9 bacterial species, respectively. <i>Staphylococcus epidermidis</i> emerged as the predominant bacterium in both groups, with relative abundances of 52.8 % in HC and 30.2 % in VKC (p < 0.001). Biofilm formation was observed in 64.15 % of bacterial species in VKC and 31 % in HC (p < 0.001). Scanning electron microscopy analysis confirmed temporal biofilm formation by <i>Staphylococcus</i> spp. in both groups. Minimum inhibitory concentration testing showed that biofilm forming <i>Staphylococcus</i> spp. from VKC exhibited multidrug resistance (>2 antibiotics) more frequently than those from HC. Additionally, <i>Staphylococcus</i> spp. in VKC demonstrated higher resistance to fluoroquinolones compared to HC. These findings indicate a significantly greater prevalence of biofilm-forming and antimicrobial resistant <i>Staphylococcus</i> bacteria in VKC Patients compared with HC.