Abstract
Purpose: :
Biofilm formation in contact lens cases may predispose to the development of contact lens related keratitis. To better understand the composition of contact lens case biofilm, we used 16S ribosomal RNA (rRNA) gene sequencing to examine cases from patients with mild keratitis, keratitis with focal infiltrate, and contact lens related ulcers, as well as cases from asymptomatic controls.
Methods: :
Contact lens cases were obtained from 5 patients with mild diffuse keratitis, 8 with keratitis and focal infiltrates, and 4 with contact lens related ulcers. Eight cases from asymptomatic soft contact lens wearers were processed as controls. Biofilms were removed from lens cases by scraping and sonication, and DNA was extracted using the Mo Bio Microbial DNA Isolation Kit. Universal primers were used to amplify the bacterial 16S rRNA gene, PCR products were purified, cloned into the pCR 4-TOPO vector (Invitrogen), then re-amplified and sequenced. Sequences were classified by BLAST analysis against GenBank. Each sequence was matched with at least one database entry at the genus level (identity >95%).
Results: :
The number of bacterial types isolated from the case correlated with increasing severity of disease (Spearman rank order correlation Δ<0.000001). There was a statistically significant difference between the number of bacterial types identified and the four clinical groups: normal, mild keratitis, keratitis with focal infiltrate and corneal ulcer, p=0.0006. All the affected groups exhibited more bacterial types than the controls (Mann-Whitney U test, p=0.0013). Presenting visual acuity was correlated with number of bacteria identified (p=0.011). Achromobacter and tenotrophomonas were predominant isolates.
Conclusions: :
Bacterial diversity from contact lens cases was correlated with severity of disease and presenting visual acuity, and was greater than asymptomatic controls. Achromobacter and Stenotrophomonas are prominent residents of contact case biofilms.
Keywords: keratitis • contact lens • bacterial disease