Identification of virulence factors in contact lens associated bacteria: A physiological approach

Wearing contact lens requires awareness about possible contaminants, the causative agents of multiple complications. The present study focused on identification of potential pathogens and presence of virulence associated markers in contact lens associated bacteria.

Bacterial contaminants were isolated from contact lenses or cleaning solutions collected from University students. Isolates were identified using conventional methods followed by 16S rRNA gene sequencing and screened for the presence of virulence factors which included capsular presence, adhesion, serum resistance, iron chelation, haemagglutination and hemolysis. Moreover, antibiotic resistance profile was also monitored.

Contamination was observed in 79% (45 of 57) of lenses. Based on 16S rRNA sequencing Bacillus sp. was found to be most abundant (26%). The presence of at least three pathogenic characteristics was recorded in 75.8% isolates. Among the pathogenic characteristics, capsule presence was found to be the most prevalent character (73%) followed by hemolysin production (65%), serum resistance (61%), haemagglutination (56%), iron chelation (50%) and polystyrene adherence (42%). Multiple antibiotic resistance was recorded in 66.13% isolates. Cluster analysis on the basis of virulence markers separated all isolates in two groups. Potential pathogens and non-pathogens were found to be equally frequent among contaminants of contact lens cases.

The present work provides evidence that pathogenic bacteria can adhere and survive in contact lens or lens solution. It highlights the need for the development of new methods to protect contact lenses and lens care accessories. Drugs targeting capsule formation may offer a good option for treatment or use in cleaning solution.