High-volume ITS sequencing into a diagnostic supplement for fungal corneitis

fungal cornealitis is a highly blinding type of corneitis caused by pathogenic fungi. With the widespread use of antibiotics and glucoticoids, the incidence of them continues to increase. Culture has been used as a gold standard for diagnosing fungal corneitis, but the actual diagnosis is not satisfactory.
in the DNA of the nuclear organism, the ITS sequence, as a non-coding region, has relatively large differences in length and sequence between species and can therefore be used for the classification and identification of different fungal genus. Professor
Qingdao Eye Hospital, affiliated with Shandong First Medical University, based on the conclusions of previous studies on microbiomes on the eye table, Professor Huang and his team recently published a study in scientific reports to discuss and analyze the pathogenic diagnosis of fungal cornealitis.
Huang's team conducted a sample study on 35 patients who were treated at Qingdao Eye Hospital affiliated with Shandong First Medical University and diagnosed with fungal corneitis. ITS high-flux sequencing of conjunctival swabs and corneal scraper tissue in these patients assumed that the relatively highest level of fungi in sequencing results was pathogenic, and the positive and consistent rates of culture and sequencing for diagnosis of pathogenic bacteria were evaluated.
results show that the high-volume ITS sequencing method to some extent questions the accuracy of fungal culture pathogenic bacteria identification, and the high-volume ITS sequencing method can be used as a supplementary method to identify the pathogenic diagnosis of fungal cornealitis.
researchers suggest that although culture has long been considered the gold standard for the diagnosis of fungal corneitis pathogens, it still has many disadvantages. First, different myceliums sometimes exhibit similar appearances, while the same genus can exhibit different morphological characteristics, so the judgment of culture results depends heavily on the experience of the examiner. Second, fungi usually grow slowly. Third, some pathogenic fungi are not suitable for the general-purpose fungal mediums currently used in hospitals. Fourth, some empirical treatment or treatment before a patient is admitted to the hospital can reduce the activity of the fungus and affect the culture results. Fifth, the result of the culture method may be the genus of the medium most suitable for the selected medium in the symboxic fungal community of the eye.
Compared with culture, high-volume sequencing is not affected by fungal activity and requires only a small amount of DNA, and is highly sensitive and specific.
However, there are still shortcomings in high-volume sequencing, for example, ITS sequencing depends on the integrity of the database, but there are still some defects in the public sequence database; There are fungal groups, so the high-flux ITS sequencing method can only be used to identify fungal corneitis pathogenic bacteria, not to confirm fungal corneitis;
huang pointed out that this study does not mean that there is no need to cultivate microorganisms in the future, culture and sequencing methods are not only complementary, but also interdependent. On the one hand, sequencing can make people understand the symbiotic microbiome from a macro perspective, and there can be extensive research and application space for the pathogenic diagnosis and pathogenicity of diseases, on the other hand, the further study of symbiotic microbiome depends on culture method. (Source: Liao Yang Zhao Yingzo, China Science Journal)
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