Are Thermotolerant and Osmotolerant Characteristics of Species an Indicator of Pathogenicity?

OBJECTIVE

The aim of this study was to evaluate the pathogenicity of strains with T4, T5, T11, and T12 genotypes by comparing the osmotolerance and thermotolerance characteristics of strains isolated from genotype groups, within species with the same genotype, and from environmental and keratitis cases.

METHODS

In this study, after axenic cultures of 22 strains with T4 (Neff, A, B, D, E), T5, T11, and T12 genotypes isolated from clinical and environmental samples, thermotolerance (37 °C, 39 °C and 41 °C) and osmotolerance (0.5 M, 1 M) tests were performed.

RESULTS

All strains showed growth ability at 37 °C and 0.5 M osmolarity. While all five strains isolated from patients with keratitis showed growth ability at 37 °C and 0.5 M osmolarity, no growth was detected at 41 °C and 1 M osmolarity. When the tolerance characteristics of the strains with the same genotype were evaluated, the strains with the T5 and T4E genotypes showed the same characteristics. When strains with the T4 genotype were evaluated in general, 31.25% of the strains were found to grow at 39 °C and 6.25% at 41 °C. Of the T4Neff strains, only one strain did not show the ability to reproduce at 39 °C and showed a different feature from the other strains. While the strain with the T11 genotype grew at all temperatures, the strain with the T12 genotype did not grow at 41 °C.

CONCLUSION

According to our research results, we believe that tolerance to 39 °C and 1 M mannitol is not an indicator of pathogenicity. More studies with strains are required to clarify this issue.