Molecular identification of Acanthamoeba genotypes isolated from oral cavity of heart transplant patients in Iran

Abstract

Heart transplant is one of the accepted treatments for some patients with advanced heart failure. Of note, transplant surgeries may cause different infections and complications for patients during the post-transplant period. A wide variety of opportunistic organisms caused these infections including bacteria, fungi, viruses, and protozoa particularly Free-living amoebae (FLA). This study aims to study the presence of pathogenic FLA from the oral cavity of post-heart transplant recipients. Throat swabs were collected from 80 patients who underwent post-heart transplant surgery. All swabs were immediately cultured in non-nutrient agar (2%). PCR and sequencing of 18S rRNA gene (DF3 region) of Acanthamoeba isolates were performed using genus-specific primers. Genetic associations among sequenced genotypes inferred by the 18S rRNA gene obtained by MEGA X and a phylogenetic tree were constructed using the maximum likelihood algorithm and Kimura 2-parameter model. Out of 80 samples collected from post-heart transplant patients, six (7.5%) samples showed positive outgrowth of Acanthamoeba based on the page key and sequencing of the DF3 region. Sequence similarity of ASA1 by basic local alignment search tool(n) showed that five isolates (ANHT1, ANHT2, ANHT3, ANHT4, and ANHT5) belonged to Acanthamoeba T5 genotype corresponding to A. lenticulata and one strain (ANHT6) belonged to the T4 genotype. To the best of our knowledge for the first time, a comprehensive study of Acanthamoeba genotypes isolated from throat samples of heart transplant recipients is described. Heart transplantation patients can be colonized by FLA and are therefore at risk of developing an invasive infection. Physicians' awareness of central nervous system infections related to FLAs and preventive and control measures of patients with compromised immune status due to heart transplant surgery are of utmost importance.