Molecular identification of Acanthamoeba spp., Balamuthia mandrillaris and Naegleria fowleri in soil samples using quantitative real-time PCR assay in Turkey; Hidden danger in the soil!

Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri are pathogenic free-living amoeba (FLA) and are commonly found in the environment, particularly soil. This pathogenic FLA causes central nervous system -affecting granulomatous amebic encephalitis (GAE) or primary amebic meningoencephalitis (PAM) and can also cause keratitis and skin infections. In the present study, we aimed to determine the quantitative concentration of Acanthamoeba spp., B. mandrillaris, and N. fowleri in soil samples collected from places where human contact is high by using a qPCR assay in Izmir, Turkey. A total of 45.71% (n = 16) of Acanthamoeba spp., 20% (n = 7) of B. mandrillaris, and 17.4% (n = 6) of N. fowleri were detected in five different soil sources by the qPCR assay. The quantitative concentration of Acanthamoeba spp., B. mandrillaris, and N. fowleri in various soil sources was calculated at 10 x 105 -6 x 102, 47 x 104 to 39 x 103, and 9 x 103 - 8 x 102 plasmid copies/gr, respectively. While the highest quantitative concentration of Acanthamoeba spp. and B. mandrillaris was determined in garden soil samples, N. fowleri was detected in potting soil samples. Three different genotypes T2 (18.75%), T4 (56.25%), and T5 (25%) were identified from Acanthamoeba-positive soil samples. Acanthamoeba T4 genotype was the most frequently detected genotype from soil samples and is also the most common genotype to cause infection in humans and animals. To the best of our knowledge, the present study is the first study to identify genotype T5 in soil samples from Turkey. In conclusion, people and especially children should be aware of the hidden danger in the garden and potting soil samples that come into contact most frequently. Public health awareness should be raised about human infections that may be encountered due to contact with the soil. Public health specialists should raise awareness about this hidden danger in soil.

Automated summary

In this study, soil samples were collected from Izmir, Turkey, and a qPCR assay was used to determine the quantitative concentration of pathogenic free-living amoeba (Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri) in the soil. The results showed that these organisms were present in different soil samples at high concentrations. Therefore, people should be aware of the potential infection risks associated with contact with soil, especially in garden and potting soil samples.