| Sagenomella keratitidis | |
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| Species: | S. keratitidis |
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| Sagenomella keratitidis Sung-Yaon Hsieh et al. (2009) | |
Sagenomella keratitidis is a hyphomycete discovered as its own species in 2008 by Sung-Yaon Hsieh et al. at the Institute of Plant and Microbial Biology and the National Taiwan University Hospital. [1]
Studies prior to 2009 showed evidence of fungal keratitis development with the use of contact lenses, but very little evidence of the development of keratitis associated with contact lens wear. [1] Fungal keratitis associated with contact lens wear is quite rare when compared to microbial keratitis. Fungal keratitis accounts for only 5% of keratitides. [2] The majority of Sagenomella species are soil-associated. S. keratitidis is the first species that is associated with the human eye. [1] It was discovered in 2010 that Sagenomella can be grouped into three distinct categories, and these groups are not all descended from a common ancestor. [3] DNA sequence analysis studies showed that S. keratitidis is most closely related to Sagenomella sclerotialis with two species showing 99% DNA homology. [1] The researchers in Taiwan [1] proposed the genus Sagenomella based on growth pattern and morphology. [1]
S. keratitidis has very slow growth on a range of cultures, making experiments involving isolation and purification very difficult. [1] It has translucent, linked ameroconidia [1] and very small conidiophores— its unusually small, few conidiophores are the reason why the colonies are white rather than gray. [1] S. keratitidis species have spherical, phialidic conidia. [1] [3] Sagenomella species are closely related to Acremonium , but distinguished by their linked conidia. [4] Sagenomella species are also distinguished from Acremonium species by their sharp-tipped, abruptly-ending conidia. [4] S. keratitidis lacks chlamydospores. [1] S. keratitidis may superficially resemble another member of its genus,S.humicola, under a microscope, but can be distinguished from S.humicola because of its extremely slow growth and lack of chlamydospores. [1]
The species of genus Sagenomella generally grow between the temperatures of 20-23 °C on malt extract agar, and are known for their slow growth. [4] Little is known so far about the physiology of S. keratitidis but its close relative, S.chlamydospora, grows best between a temperature of 37 °C and 40 °C, above which it does not survive. [5] Ideal growth for Sagenomella species is at 27 °C. [4] S. keratitidis was found to grow better on media that had been modified with yeast. [1]
Sagenomella species normally cause unspecific symptoms and infections of Sagenomella are difficult to diagnose because this is an uncommon genus of fungus. [5] S. keratitidis was found to cause inflammation of the cornea, or keratitis, in an individual who wore contact lenses. [1] So far, this has been the only case of keratitis found to be caused by S. keratitidis. [1] S. keratitidis is not as pathogenic as other members of the same genus, such as S.chlamydospora, which can cause serious mycosis in canines. [5] Canine S.chlamydospora infections can cause the animal to limp, experience pain in its spine, and feel a general lack of energy. If left untreated, these infections can spread to humans. [5]
S. keratitidis is a human eye pathogen, unlike its other genus counterparts, whose habitat is either soil, manure, or fodder. [1] Although rare, it may occur due to poor sanitation in individuals who wear contact lenses. [1]