The present research is the first investigation regarding the Acanthamoeba genotypes in patients with respiratory problems suspected for lung cancer admitted to Kashan hospitals in Iran. The results of this study showed that, out of 97 BAL samples of suspected patients for cancer, 86.6% were positive to FLA and Acanthamoeba were confirmed in 73.2%. The prevalence of FLA in oral cavity of cancer patients in Kashan was reported 89% (Taghipour et al. 2021).
(Golestani et al. (2018). reported that the rates of Acanthamoeba in Beheshti Hospital dust, soil, and water samples in Kashan were 52.5%, 62.5%, and 50%, respectively. Furthermore, the contamination rates of rural drinking water of Kashan country to FLA and Acanthamoeba were 35.2% and 11.7%, respectively (Mostafaei et al. 2019). In a study conducted in Iran, Acanthamoeba infection was found in 100%, 98.4% BAL samples of immunocompromised patients with respiratory disorder by culture and molecular methods respectively (Eslamirad et al. 2020).
According to the results of Lanocha et al. (2009), Acanthamoeba were isolated from 3.13% of BAL samples of patients with immunodeficiency and the genotypes were identified as the T4. 19 cases of Acanthamoeba spp. has been reported from immunodeficiency patients with pneumonia in Poland, U.S.A and Australia, India, Japan and France (Kot et al. 2021). Based on a study that has been documented in Peru, Acanthamoeba spp. and two genotypes belonging to T4 and T15 were reported from nasal swap samples from healthy individuals (Cabello Vilchez et al. 2014).
However, the results of the present study are higher than the results of other researchers (Lanocha et al. 2009; Kot et al. 2021), but lower than Eslamirad et al. (2020). The high prevalence of FLA and Acanthamoeba in this study may be due to modification in culturing of the BAL samples, that agreement with the results of Taghipour et al. (2021). As such, the high rate of FLA and Acanthamoeba in BAL samples in this study may probably due to the climatic conditions of the Kashan desert region; dry climate, low rainfall, seasonal storms and dust. In addition, the high contamination rate of drinking water and dust of Kashan may cause this high prevalence rate (Golestani et al. 2018; Mostafaei et al. 2019)
In this study, for the first time, 18 Acanthamoeba genotypes were identified in BAL specimens of pulmonary patients and deposited in the GeneBank database. In addition, the similarity of them was 98–100% to the recorded isolates in the GeneBank. Other genotypes such as T1, T4, T5, T10, T11, T12, and T15 have been reported from clinical specimens around the world (Kot et al. 2021; Cabello Vilchez et al. 2014; Walochnik et al. 2008; Booton et al.2005; Memari et al. 2016). Our previous studies in Kashan were in agreement with the results of the present study regarding the T4 genotype (Golestani et al. 2018; Mostafaei et al. 2019). The presence of the T4 genotype in the BAL sample reveals risk factors for transmission of the parasite to health officials (Niyyati et al. 2009; Kot et al. 2021).
The results of the present study indicated that higher rates of Acanthamoeba infection in patients aged more than 66 years (85%, P = 0.025). Furthermore, the prevalence of Acanthamoeba among patients less than diploma was higher than others, the difference was statistically significant (p. value = 0.035). The result of Kot et al. (2021) study showed that most patients with Acanthamoeba pneumonia had weight loss and respiratory failure, which is consistent with the results of the present study. We also found that the rate of Acanthamoeba infection was higher in diabetic patients (90%), but the difference was not significant. Diabetes has been reported as one of the risk factors for Acanthamoeba infection (Shimmura-Tomita etal. 2018).
Some case reports regarding Acanthamoeba pneumonia with immunodeficient status have been published (Shin and Im 2004). The death of cancer patients due to unidentified encephalitis has been reported in several studies in Iran (Edrisiian et al. 2008).
In the present study, the T4 genotype was detected in BAL samples of cancer patients. This genotype was identified in dust samples of Beheshti Hospital in Kashan, which has 98% similarity with T4 genotype of the current study.
T4 is the predominant genotype in GAE and pulmonary Acanthamobiasis. Since the T4 genotype is a potential pathogen in patients with immunocompromising conditions, differential diagnosis of Acanthamoeba is should be more considered in these patients (Bloch and Schuster 2005; Shin and Im 2004; Kalra et al. 2020). Hence, physicians and health professionals should be more attentive to this lethal infection and diagnostic options, especially in suspected encephalitis.