Current Evidence for Corynebacterium on the Ocular Surface

Abstract

Corynebacterium species are commonly found in the conjunctiva of healthy adults and are recognized as non-pathogenic bacteria. In recent years, however, Corynebacterium species have been reported to be potentially pathogenic in various tissues. We investigated Corynebacterium species on the ocular surface and reviewed various species of Corynebacterium in terms of their antimicrobial susceptibility and the underlying molecular resistance mechanisms. We identified a risk for Corynebacterium-related ocular infections in patients with poor immunity, such as patients with diabetes or long-term users of topical steroids, and in those with corneal epithelial damage due to trauma, contact lens wear, lagophthalmos, and trichiasis. The predominant strain in the conjunctiva was C. macginleyi, and the species associated with keratitis and conjunctivitis were C. macginleyi, C. propinquum, C. mastitidis, C. pseudodiphtheriticum, C. accolens, C. striatum, C. xerosis, and C. bovis. Overall, Corynebacterium species present on the ocular surface were resistant to quinolones, whereas those in the nasal cavity were more susceptible. The prevalence of fluoroquinolone-resistant Corynebacterium has not changed in the past 10 years; however, Corynebacterium species remain susceptible to third-generation cephems. In conclusion, the use of third-generation cephems should be a reasonable and pragmatic approach for treatment of ocular infections caused by Corynebacterium species.

The effect of topical ocular moxifloxacin on conjunctival and nasal mucosal flora

“…That difference was explained by the increased exposure to quinolone antibiotics on the conjunctival surface. Although antibiotic resistance and the amount of bacterial load for conjunctival and nasal flora has been previously reported as mentioned above 18 , 19 , alteration of conjunctival and correspondent nasal bacterial flora after short-term topical administration of ocular antibiotics has not been previously studied. As we only included the patients that were quinolone (moxifloxacin) sensitive, we were unable to obtain a percentage of ocular and nasal flora that were quinolone resistant and we hope that this can be topic of a further study.…”

“…However, a recent report by Hoshi et al 18 studied nasal flora in addition to conjunctival flora and showed an increased quinolone resistance in both nasal and conjunctival Corynebacterium profiles. A more recent review by Aoki et al 19 which also studied nasal flora in addition to conjunctival flora pointed out that Corynebacterium species present on the ocular surface were resistant to quinolones, whereas those in the nasal cavity were more susceptible. That difference was explained by the increased exposure to quinolone antibiotics on the conjunctival surface.…”

Categorization of the Ocular Microbiome in Japanese Stevens–Johnson Syndrome Patients With Severe Ocular Complications

“…For example, under steady-state conditions in mice, C. accolens does not cause inflammation; however, when this steady state is disrupted, C. accolens promotes inflammation via a bacterial cell wall component in an interleukin 23-dependent manner (Ridaura et al, 2018). Similarly, on the ocular surface, Corynebacterium species are commonly found in both healthy individuals and individuals with inflammatory ophthalmic conditions such as keratitis and conjunctivitis (Aoki et al, 2021). Indeed, C. accolens and C. amycolatum have been isolated from ocular samples obtained from patients with bacterial conjunctivitis and corneal ulcer, respectively (Eguchi et al, 2008;Sugumaran et al, 2020).…”

Draft Reference Genome Sequence of Corynebacterium mastitidis RC, an Ocular Commensal, Isolated from Mouse Conjunctiva

“…Corynebacterium is a Gram-positive, pleomorphic bacterium that exists frequently as a normal flora inhabiting skin, mucous membrane, and conjunctiva. Several Corynebacterium species have also been identified as either pathogens or opportunistic pathogens causing diseases like diphtheria, endocarditis, and mastitis ( 1 ). Genome sequences of two Corynebacterium mastitidis species, namely, one isolated from the milk of a sheep with subclinical mastitis ( 2 ) and the other isolated from a mouse with keratitis ( 3 ), are currently available in NCBI genome database.…”