The study aimed to investigate the relationship between ica genes and phenotypic biofilm formation in staphylococcal isolates causing conjunctivitis. Additionally, it examined their antibiotic resistance and the presence of selected virulence characteristics, namely adhesion to epithelial cells and in vitro cytotoxicity.

Out of the staphylococcal isolates involved in conjunctivitis, the ica genes were detected in 26.9% of Staphylococcus epidermidis (SE) isolates and in 42.3% of Staphylococcus aureus (SA) isolates. Only 15.3% of SE isolates tested positive for both the icaAD and the ica operon. Phenotypically, 19.2% of SE isolates exhibited strong biofilm production, with three of them being positive for both icaAD and the ica operon. On the other hand, approximately 26.9% of SA isolates were strong biofilm producers.

Methicillin resistance (MR) was observed in 34.6% of SE isolates and in 26.9% of SA isolates. Among the MR isolates, about 75% were found to be multidrug resistant. Additionally, SA isolates displayed a higher adhesion ability to host cells compared to SE isolates. Furthermore, SA isolates released a higher level of LDH (lactate dehydrogenase) than SE isolates, indicating a higher cytotoxicity potential.

In conclusion, staphylococci associated with conjunctivitis commonly demonstrated adherence abilities. However, there was a low prevalence of isolates positive for a complete and functional ica locus, as well as a low prevalence of strong biofilm producers. SA isolates exhibited greater adhesion to eukaryotic cells and were more cytotoxic compared to SE isolates.

To learn more about evaluation of the role of staphylococci in the pathomechanism of conjunctivitis check out article written by Agnieszka Magryś, one of the creators of KARVADERM.