A Case-Control Study of Detection of the Potentially Pathogenic Acanthamoeba Strains From the Oral Cavity of Diabetic Patients, Cancer Patients, and Healthy Individuals in Iran

Background and aims: Acanthamoeba is a genus of free-living amoebae (FLA) that can cause granulomatous amoebic encephalitis and amoebic keratitis. This study aimed to identify Acanthamoeba strains among diabetic and cancer patients and healthy individuals. Methods: In this cross-sectional study, ۳۲۴ sterile cotton swab samples were collected from the oral cavity of ۱۰۸ diabetic patients, ۱۰۶ cancer patients undergoing chemotherapy, and ۱۱۰ healthy individuals from June to October ۲۰۱۸ in Shahrekord, Iran. Samples were cultured onto ۱.۵% non-nutrient agar, and the Acanthamoeba spp. were investigated with morphological, molecular (polymerase chain reaction targeting ۱۸SrRNA), and pathogenicity assays. Results: FLA was found in ۱۳۰/۳۲۴ (۴۰.۱%) oral cavity samples of individuals. Microscopic results using Giemsa staining revealed that ۱۴/۳۷ (۳۷.۸%) and ۳۱/۹۳ (۳۳.۳%) FLA isolated from healthy individuals and immunocompromised patients were identified as Acanthamoeba spp. Moreover, the PCR confirmed the existence of Acanthamoeba spp. in ۴.۷% of patients and ۳.۶% of controls. In addition, the PCR demonstrated that Acanthamoeba spp. were isolated in ۶.۶%, ۸.۲%, and ۶.۳% of cancer patients, diabetic patients, and healthy individuals, respectively. According to the sequence analysis of PCR products of ۱۸S rRNA, the T۴ (۱۰ isolates) and T۵ (۳ isolates) genotypes of Acanthamoeba were identified in two groups. Finally, nine isolates genotyped as T۴ were positive for potential pathogenic assays. Conclusion: The presence of the potentially pathogenic Acanthamoeba T۴ genotype in both immunocompromised patients and healthy individuals indicated that it may pose a risk factor for immunocompromised individuals.