Morphological Characterization and Genotyping of Acanthamoeba Isolates From Oral and Nasal Samples of Cancer Patients in Kashan, Iran.

Background: Acanthamoeba species are recognized as the most prevalent free-living amoebae (FLA). They can cause granulomatous amebic encephalitis (GAE) and pulmonary and ocular infections. The present study aimed to isolate and identify Acanthamoeba genotypes in cancer patients referred to Kashan's hospitals in Central Iran. Methods: This cross-sectional study was conducted with oral and nasal swab samples collected from a hundred cancer patients referred to Kashan's Beheshti and Yasrebi hospitals during 2019-2020. The samples were cultured in 1.5% non-nutrient agar (NNA) with heat-killed Escherichia coli and examined for "FLA." A polymerase chain reaction (PCR) assay amplifying the 18S rRNA gene was performed, and Acanthamoeba-positive isolates were subjected to nucleotide sequencing to identify their genotypes. Results: The prevalence of Acanthamoeba infection was 51% in the oral cavity and 38% in the nasal samples of cancer patients. The most frequent Acanthamoeba cysts were (51.3%) wrinkled polygonal and sized 9.55-11.5 μm (Group II). Acanthamoeba genotypes T4, T11, and T5 were identified in the oral cavity samples, whereas T4 and T11 were detected in the nasal samples. Conclusion: The prevalence of Acanthamoeba infection in oral and nasal cancer patients was higher in Kashan, Iran, compared to other countries. Due to the high rate of oral Acanthamoeba contamination, oral sampling is recommended for better detection of this protozoan. Since T4 is the predominant genotype that can cause serious diseases in high-risk groups, increasing physicians' awareness of infections associated with Acanthamoeba and preventive and control measures are strongly suggested.