Effect of temperature on the growth of ocular surface microflora in normal and keratitis cases

Relevance The study of temperature conditions for the growth of ocular surface (OS) microorganisms is important for ophthalmology, since standard methods of bacteriological diagnostics involve cultivation at 37 °C, which may not correspond to real conditions [1]. Infrared thermography allows for an objective assessment of OS temperature dysregulation, making it an important tool in the study of microbial composition and diagnostics of infectious processes [2]. Infectious keratitis (IK) is accompanied by changes in the heat exchange of the eye, which can affect the growth of pathogenic microorganisms. Taking this factor into account can improve the efficiency of diagnostics and treatment of eye infections [3–5]. Objective Study of the composition and properties of OS microorganisms under various temperature cultivation conditions in patients with IK and healthy volunteers. Identification of psychrotolerant microorganisms growing at room temperature. Material and methods Fifteen people were examined: 10 patients with IK and 5 healthy volunteers. Samples were cultured at 37 and 24°C. Biochemical, immunological and physicochemical methods, including mass spectrometry, were used. Visualization was performed by scanning electron microscopy (SEM), the temperature of the GP was assessed by infrared thermography. Results Psychrotolerant microorganisms that effectively grow at 24°C were identified. In the group of patients with IR, Acinetobacter lwoffii, Achromobacter xylosoxidans, Bacillus licheniformis, Enterococcus faecalis, Klebsiella spp., Micrococcus luteus, Pseudomonas luteola, Streptococcus spp. were more common. A relationship was found between temperature dysregulation of the GP and the characteristics of bacterial growth. Conclusion Standard cultivation conditions do not always reflect the real microbial composition of the GP. IR may be dominated by psychrotolerant microorganisms requiring diagnostics at room temperature, especially in cases of corneal trophic disorders. Keywords: ocular surface; infectious keratitis; microbiome; scanning electron microscopy; infrared thermography