| Objective:Mycotic keratitis (or keratomycosis) is a common disease of ophthalmology. The earlier period symptoms are not typical. It is difficult to distinguish from bacterial keratitis . So it is not easy to diagnose certainly in the earlier period. In recent 40 years,the incidence of mycotic keratitis(or keratomycotis) has been obviously increased. The reasons of it were as follows: ①The environment fungi intruded after the traumas of cornea.② The use of antibiotics disturbed the symbiosis between bacteria and fungi.③The local use of corticoid decreased the resistance of cornea tissue .Then fungi would be propagated.④The use of metabolism medicine or immune inhibitor decreased the immunity of the host.⑤The generally use of pesticide and chemical combination make fungi in soil changed. The pathogenic abilities of fungi increased. The common pathogenic strains of mycotic keratitis were Fusarium, next were Aspergillus and Penicillium. The disease developed very fast .If it was not be controlled in time, the cornea would be perforted. Endophthalmitis would happen,too. In the end , the patient would be blind. So ,the early diagnosis and treatment became urgent. But the succeed of treatmentand the resume of eyesight were depended on early, rapid and correct diagnosis. But there was not a laboratory method of early diagnosis up to the present. Now the usually detection of fungi was by microscope and cultivition. There were 10% KOH ,Acridine orange staining ,LPCB staining, Gram staining and CFW staining. The patient would suffered from scraping cornea. Cultivition was time-consuming( about 2 weeks) and it might be contaminated. Someone did experiment with animal and observed clinically through confocal microscope. But the good imaging function of it needed closely cooperation with the patient. Any little eye motion would blur the imaging. So it did not adapt to children, handicapped and the patient whose cornea had been perforated. Biopsy of cornea was used when the inspection of microscope and cultivition were all negtive. But it was limited because of being wound. The method of polymerase chain reaction(PCR) was sensitive ,differential and rapid. People liked it very much as soon as it appeared. Amplified fragment length polymorphism (AFLP) was regarded as the most effective molecule marker method so far. It was the integrated technique of PCR with RFLP. The basic principle was selective amplification of restricted fragment of genome DNA. The binding site was the base sequence of connecting fragment close together. In theory, in spite of how complex the genomic DNA was, the polymorphism can be inspectedamong them by AFLP. At present , Chenhong, Zhulihuang et al used AFLP to establish the fingerprinting of eight species of pathogenic Candida. The author used PstI to cut the genome DNA and used two primers to amplificate. In the end, they got clean, different strains and the fingerprinting among Candida were obviously separated. They selected eight strains of Candida albicans to do AFLP. It was revealed that the difference in DNA patterns of Candida between different species were more significant than those between different strains within one species. The result was agreed to the consequence of the RAPD typing of Candida albicans obtained by Lidongmei et al. Boekhout et al used AFLP to difference the DNA typing of two species of Cryptococcus neoformans of different geography distributed,serotype and the ecosystem origin. They confirmed that every Cryptococcus neoformans had three AFLP genotype. In the two species, there was a hybridization genotype. The author thought that the appearance of the new genotype was due to the use of antifungal medicine. It altered the toxicity and susceptibility to antifungal medicine of Cryptococcus neoformans. And the heredity materials transformed . Reyno-Lopez-GE et al used AFLP to detect the difference of methylated DNA of dimorphic fungi in the process of the transformation of phases. The experiment made clear that the methylated DNA was existed widespre... |
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