Ocular Surface Microbiota in Contact Lens Users and Contact-Lens-Associated Bacterial Keratitis

Abstract

Our objectives were to investigate whether the conjunctival microbiota is altered by contact lens wear and/or bacterial keratitis and to explore the hypothesis that commensals of conjunctival microbiota contribute to bacterial keratitis. Swab samples from both eyes were collected separately from the inferior fornix of the conjunctiva of non-contact-lens users (nparticipants = 28) and contact lens users (nparticipants = 26) and from patients with contact-lens-associated bacterial keratitis (nparticipants = 9). DNA from conjunctival swab samples was analyzed with 16S rRNA gene amplicon sequencing. Pathogens from the corneal infiltrates were identified by cultivation. In total, we identified 19 phyla and 283 genera; the four most abundant genera were Pseudomonas, Enhydrobacter, Staphylococcus, and Cutibacterium. Several pathogens related to bacterial keratitis were identified in the conjunctival microbiota of the whole study population, and the same bacteria were identified by both methods in the conjunctiva and cornea for four patients with contact-lens-associated bacterial keratitis. The overall conjunctival microbiota profile was not altered by contact lens wear or bacterial keratitis; thus, it does not appear to contribute to the development of bacterial keratitis in contact lens users. However, in some individuals, conjunctival microbiota may harbor opportunistic pathogens causing contact-lens-associated bacterial keratitis.

Ocular surface microbiota in patients with varying degrees of dry eye severity

“…The microbiota plays a key role in maintaining the OS microenvironment balance under normal physiological conditions. The microbiota constitution can differ under certain conditions, such as DE, personal habits, rubbing eyes, antibiotic usage, use of contact lenses, infectious conditions, systemic diseases, and perioperative management [7,9,10,21,[27][28][29] . DE alters the frequency and density of specific bacterial groups.…”

“…Alterations in OS microbiota can significantly affect the dynamic balance of OS microecology through quorumsensing [5] . The ocular microbiota may be disrupted under certain conditions, such as DE, use of contact lenses, antibiotic treatment, and infections; additionally, impaired OS integrity in patients with DE promotes the pathogenic role of the microflora [6][7][8][9] . Some pathogenic bacteria such as Staphylococcus aureus and Propionibacterium are associated with DE [3,10] .…”

Spectrum and resistance in bacterial infections of the ocular surface in a German tertiary referral center 2009–2019

“…In line with our results, Steger et al in Basel found a significantly higher ratio of gram-negative bacterial isolates in contact lens samples (71%) than in of conjunctival swabs of patients with bacterial keratitis (37%) [ 16 ]. This association between gram-negative bacterial infection and wearing contact lenses is well known, and possibly caused by biofilm formation [ 21 – 24 ].…”

Cutibacterium (Formerly Propionibacterium) acnes Keratitis: A Review

“…More classical causes of microbial keratitis, such as Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae, are also often found in the conjunctival microbiota of healthy patients. 43,47 Like these species, C. acnes has attributes that can make it pathogenic. Suzuki et al 28 found that C. acnes caused a potent delayed-type hypersensitivity reaction when injected into the corneal stroma of rats.…”