Corneal bacterial microbiome in patients with keratoconus using next-generation sequencing-based 16S rRNA gene analysis.

PURPOSE: To investigate the corneal bacterial microbiome in patients with keratoconus using next-generation sequencing and develop a new perspective on the pathogenesis of the disease. METHODS: This prospective observational study included 10 patients with keratoconus who underwent corneal crosslinking procedure and 10 healthy controls who underwent photorefractive keratectomy. Patients included in the study were aged 18 years or older. The demographic and clinical characteristics of participants were recorded. Corneal epithelial samples were collected between March 2021 and June 2021. Isolated bacterial DNA from corneal epithelial samples was analyzed using 16 S ribosomal RNA gene analysis. The relative abundance rates at the phylum and genus levels were calculated. Alpha diversity parameters were assessed. RESULTS: Eleven phyla and 521 genera of bacteria were identified in all participants. At the phylum level, Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were most abundant in both groups. There were no statistical differences between the two groups except Bacteriodetes (p < 0.05). At the genus level, the relative abundance rates of twenty bacteria were significantly different between keratoconus and healthy corneas (p < 0.05). Aquabacterium was the most abundant genus in patients with keratoconus, while Shigella was the most abundant genus in healthy controls. Alpha diversity parameters were lower in patients with keratoconus, although the difference did not reach statistical significance (p > 0.05). CONCLUSIONS: Our preliminary study revealed that there are similarities and differences in the corneal microbiome between keratoconus and healthy individuals. Further research is required on the relationship between the abnormal corneal microbiome composition and the pathogenesis of keratoconus.

Infectious keratitis in keratoconus with corneal hydrops without contact lens wear: a case report.

PURPOSE: Infectious keratitis after contact lens use is a known complication in cases of corneal hydrops. A case of infectious keratitis is reported in a case of keratoconus with corneal hydrops without any known predisposing factors. METHODS: Infectious keratitis was diagnosed in a 58-year-old man with spontaneous onset of pain, redness, photophobia, and decreased vision. There was no history of contact lens use or any ocular allergy. Noncoagulase staphylococci were cultured from the corneal scrapings, and treatment was started with fortified antibiotics. RESULTS: Response to treatment was noted, and the patient is awaiting keratoplasty. CONCLUSIONS: This case report highlights the occurrence of infectious keratitis in a case of keratoconus with corneal hydrops without any antecedent history of contact lens use.

In vitro model of infectious crystalline keratopathy: tissue architecture determines pattern of microbial spread.

PURPOSE: To develop an in vitro model of infectious crystalline keratopathy using human corneal buttons and to test the hypothesis that the compactness of the corneal stroma determines the pattern of microbial spread. METHODS: Twenty human corneal buttons obtained after penetrating keratoplasty for keratoconus (KC) and eight human corneal buttons obtained from eye bank (EB) donor eyes were maintained in organ culture. Fourteen buttons (10 KC and 4 EB donors) were maintained in a turgid state (swollen, edematous) and 14 in a nonturgid state (compact, normal state of deturgescence) by the omission or addition of 5% dextran to the culture medium. Eight KC and four EB nonturgid buttons and eight KC and four EB turgid buttons were inoculated with Streptococcus viridans (Lancefield group G, gram-positive) organisms. Two KC nonturgid and two KC turgid buttons were inoculated with Klebsiella oxytoca (gram-negative) organisms. Bacterial migration and spread in the tissue were observed by light and electron microscopy. RESULTS: Of the nonturgid buttons, six KC buttons and all four EB buttons inoculated with S. viridans and both KC buttons inoculated with K. oxytoca demonstrated an arborizing, crystallike pattern of bacterial spread. In the turgid buttons, five KC and all four EB buttons inoculated with S. viridans and both KC buttons inoculated with K. oxytoca demonstrated globular, amorphous colonies. This was in complete contrast to the needlelike branching appearance seen in nonturgid corneal buttons. Electron microscopy confirmed an interlamellar spread of the bacterial colonies. CONCLUSIONS: This is the first in vitro model of bacterial keratitis. It demonstrates that the pattern of spread of bacteria within corneal tissue is largely determined by the compactness of the corneal stroma. Altering tissue architecture changed the pattern of bacterial migration and spread. This model has considerable potential in further understanding host-microbe interactions and microbial spread that occurs during infection.

Transplante de córnea "a quente" em úlcera micótica: estudo clínico, microbiológico e histopatológico / Corneal transplantation a chaud in mycotic ulcer: clinical, microbiological and histopathological study

De uma amostra de 954 córneas recebidas no Registro Brasileiro de Patologia Ocular, durante um período de 6 anos (1982-1988), 63 córneas eram provenientes de 63 pacientes submetidos a ceratoplastia penetrante "a quente", decorrente de úlcera corneana micótica. O grupo mais acometido foi o dos homens 77,8%), na faixa etária entre 31 a 40 anos (28,6%). Nos 25 casos onde foi realizado o estudo clínico completo, a atividade profissional mais freqüente foi a de agricultor (44%), com antecedentes do transplante "a quente" foi obtido em 23 casos, e em 2 pacientes (8%) foi necessária a evisceraçäo devido a progressäo da infecçäo micótica. A acuidade visual obtida, em um seguimento médio de 11 meses, foi igual ou maior que 20/60 em 8 pacientes (32%), entre 20/200 e conta dedos em 6 (24%), percepçäo e projeçäo luminosa em 2(8%) e sem percepçäo luminosa em 4(76%). O agente etiológica mais freqüente, no estudo microbiológico realizado nos 63 casos, foi o Fusarium sp, responsável por 24 casos (38,1%). Nos 63% pacientes, o diagnóstico de ceratite micótica só foi possível em 24(38,1%) pelo exame histopatológico do botäo corneano, devido a exames microbiológicos negativos