Acanthamoeba

We aimed to identity Helicobacter pylori endosymbiont in Acanthamoeba-positive samples in natural and laboratory conditions.

Overall, 134 samples were collected from hospital environments. Microscopic and PCR test were used for detection of Acanthamoeba and H. pylori. The real-time PCR method was used to check the active presence of H. pylori within Acanthamoeba under natural conditions from hospital samples and in co-culture laboratory conditions.

The rate of contamination of hospital samples with Acanthamoeba was 44.7%. Out of 42 Acanthamoeba PCR-positive samples, 13 isolates (31%) were positive in terms of H. pylori endosymbiont according to sampling location. H. pylori is able to penetrate and enter the Acanthamoeba parasite.

H. pylori is able to contaminate Acanthamoeba in natural and laboratory conditions. The presence of pathogenic Acanthamoeba in various hospital environments and the hiding of Helicobacter as an endosymbiont inside it can pose a serious threat to the health of hospitalized patients.

 Conventional treatment of Acanthamoeba typically involves a combination drug strategy, but its efficacy in clinical settings remains incomplete. Evaluating the therapeutic potential of existing drugs is a way used to introduce effective treatments for infectious agents. This study aimed to assess the in vitro anti-Acanthamoeba effect of valproate (VPA).

 An experimental study was conducted using Acanthamoeba cysts belonging to the T4 and T5 genotypes. Cysts collected from the culture medium were exposed to gentamicin, polymyxin, and three different concentrations of VPA for varying durations (1, 4, 6, and 24 hours). The treated cysts were stained with trypan blue, and the percentage of growth inhibition was calculated. Additionally, the viability of treated cysts was assessed by culturing them on non-nutrient agar plates for one month.

 The Acanthamoeba cysts of T4 and T5 genotypes showed susceptibility to VPA. The minimal cysticidal concentration (MCC) of VPA for maximum growth inhibition in both single and combination drug assays were 100 and 3 mg/ml, for durations of 24 and 4 hours, respectively. The growth inhibition observed in the groups exposed to gentamicin and polymyxin differed significantly from the growth inhibition in the group treated with ≥100 mg/ml VPA (P< 0.05).

 VPA enhances the effects of gentamicin and polymyxin on Acanthamoeba. Combining a low concentration of VPA (≥3 mg/ml) with gentamicin and polymyxin increases the potency and speed of action of these antibiotics.

Due to the opportunism character of Acanthamoeba, the presence of this parasite in the thermal water of recreational baths and hospital environments can be a risk to the health of staff, patients and others. The aim of this study was to investigate the distribution of potentially pathogenic Acanthamoeba genotypes isolated from the hospital environment and the thermal water of recreational baths in Markazi Province, central Iran.

Overall, 180 samples including thermal water from recreational baths in Mahallat City and dust, soil and water from different hospitals of Arak, Farahan and Komijan cities, central Iran were collected. The presence of Acanthamoeba was investigated using microscopic examination and molecular methods. The PCR and sequencing was performed based on a specific 18S fragment of ribosomal DNA.

Based on the microscopic survey, totally 134 positive samples were detected including 35% in thermal water samples and 44.7% in hospital samples. In molecular analysis, 53.5% of the samples were identified as Acanthamoeba and 46.7% as Protacanthamoeba bohemica. The genotypes were detected as T4 (33.3%), T2 (10%), T11 (6.7%), and T5 (3.3%).

The T4 was the most common genotype found in hospitals sampling sites while the T2 genotype and P. bohemica were detected in thermal water sampling sites.

Different genotypes of Acanthamoeba have been abundantly isolated in environmental samples such as water, soil, and dust, as well as in different hospital departments and eyewash stations. This protozoan is a potential hazard for immunocompromised patients and contact lens wearers. The aim of the present study was isolation and genotyping of environmental and corneal isolates of Acanthamoeba in Hamadan, west of Iran.

During 2018-2020, a total of 104 environmental samples including, water, soil, and dust and 16 corneal scraping samples were collected and investigated for the presence of Acanthamoeba using morphological and molecular identification tools. Genotypes were determined using sequence analysis of the diagnostic fragment 3 (DF3) from Acanthamoeba-specific amplimer S1 (ASA.S1) gene. Phylogenetic tree was constructed with the MEGA7 software using Neighbor-Joining method.

The presence of Acanthamoeba spp. was determined in 87.5% of water, 53.1% of soil, and 25% of dust samples. From 30 dust samples collected from eight wards of three hospitals, 7 (23.3%) were contaminated with Acanthamoeba. Sequencing analysis of environmental samples revealed that the T4 genotype was the most prevalent (92.6%) one. Genotypes T2 (1.9%), T2/T6 (1.9%), and mixed T4 and T2/T6 (3.7%) were also identified in environmental samples. Acanthamoeba was seen in none of the examined corneal scraping samples from patients with suspected keratitis.

The widespread occurrence of this potentially pathogenic amoeba in most hospital wards and environmental resources and areas of the region highlights a strong need to increase awareness regarding this ubiquitous amoeba among susceptible individuals, such as immunocompromised patients and contact lens wearers.

Acanthamoeba is a free-living amoeba that has been found on surfaces, air, water and various environmental sources around the world. It enters the human body through the respiratory tract via the nose. Of note, amoebae are well known to act as a reservoir for various pathogenic microorganisms including bacteria and viruses such as Adenoviruses and Mimivirus. Given that SARS-CoV-2 of the Coronaviridae family is transmitted through the respiratory tract, and the Trojan horse nature of Acanthamoeba, it has been suggested that amoebae act as a vector in the transmission of SARS-CoV-2. The aim of this study was to provide an opinion of the possibility of the coexistence of Acanthamoeba with SARS-CoV-2.

Free-living amoebae (FLA) such as Acanthamoeba spp., are considered as opportunistic and pathogenic protozoans.  Acanthamoeba granulomatous encephalitis (AGE) is a serious threat for immunodeficient patients and Acanthamoeba keratitis (AK) for contact lens users. We aimed to identify the presence of free living amoebae in nasal swabs of patients and contact lens users in Qazvin, Iran.

During 2019, 251 nasal and oral swabs (including the pharynx and mouth) were collected from patients with diabetes, AIDS and those under periodic dialysis in Qazvin, Iran. In addition, 27 soft contact lenses were collected from the participants. Following DNA extraction, PCR and sequencing were conducted to identify the genotypes of the amoeba. Phylogenetic analysis of the identified sequences was performed using MEGA 7 software.

A strain of Acanthamoeba belonging to the T3 genotype was isolated from hemodialysis patients. Two specimens of Acanthamoeba with T3 genotype were isolated from keratitis patients.

The clinicians should pay attention to the possible complication of this organism because this amoeba is potentially pathogenic for immunocompromised patients. Since the amoeba is present in environmental resources, the use of contact lenses should be accompanied by considering proper hygiene.

Members of the protozoan genusAcanthamoebaare free-living amoebas and the primary causative agent of amoebic keratitis and granulomatous encephalitis. Amoebic keratitis mainly occurs in individuals who wear soft contact lenses following trauma and exposure to contaminated sources. As the survival, growth, and multiplication of this protozoan increases in biofilms, which is the microbial accumulation, several cases of amoebic keratitis have been reported as co-infections with bacteria, especiallyPseudomonas aureginosa.Pseudomonasimproves the binding of this protozoan to soft lens surfaces by its special surface enzymes, resulting inAcanthamoebakeratitis and sometimes mixed infection. Biofilm accumulates microorganisms, including bacteria and fungi, on living and non-living surfaces. The firm attachment of these microbial accumulations to the surface can cause various diseases and resistance to treatment. The critical point is that bacteria have less destructive effects in the plantonik state, and when the specific signals of these microbiome cause the recall of other microorganisms and their interaction, they lead to problems. Unfortunately, the ocular defense barrier, which includes the eyelids, lacrimal glands, andtears, cannot kill microbial agents when microorganisms accumulate and adhere firmly to the lens surfaces.Due to the great importance of AK, especially in medical contact lens users, biofilm formation is an important issue that has been considered in recent years. Biofilm formation-induced drug resistance, which is caused by the disproportionate density of microorganisms on the inner and outer surfaces of the biofilm. There are several ways to prevent the formation of biofilms on the surfaces of contact lenses, including the use of antimicrobial peptides and various antibiotics and coating them on the inner surface of contact lenses to slow-release of antibiotics and prevent biofilm formation. In the present review article, we aimed to introduce biofilms asone of the important risk factors for developing Acanthamoebakeratitis and prevention ways of biofilms formation.

Acanthamoebae are a causative agent of Acanthamoeba keratitis (AK) in immunocompetent individuals. Since access to propamidine isethionate (Brolene®) as a first-line treatment has been limited in recent years, in the current study, we examined the effects of pentamidine isethionate against trophozoite and cyst forms of Acanthamoeba.

This experimental study was conducted in the Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran, during 2019-2020. Pentamidine isethionate at concentrations of 50, 100, 200, 400, 600, 800, and 1000 µM were tested against trophozoites and cyst stages of T4 genotype, at 24- and 48-hour incubation period, and the viability was determined by trypan blue staining. In addition, the cytotoxic effect of the drug was examined in Vero cells using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay.

The 50% inhibitory concentration (IC50) of pentamidine isethionate on trophozoite after 24 and 48h were 97.4 µM and 60.99 µM. These results on cyst after 24 and 48h were 470 µM and 175.5 µM, respectively. In MTT assay, the drug showed an inhibitory effect on Vero cell growth with IC50 values of 115.4 µM and 87.42 µM after 24h and 48h, respectively.

Pentamidine isethionate exhibited an inhibitory effect on trophozoite and cyst. Given that the trophozoicidal activity of the drug is in the safe dose, it could be suggested as an alternative in patients with AK; however, further investigation is needed in an animal model to confirm the data.

Acanthamoeba spp. as opportunistic microorganisms are widespread in a wide range of environmental sources in the world and may cause severe diseases in immune-deficient patients. The aim of this study was to determine the prevalence and genotypes of Acanthamoeba spp. in hemodialysis patients in Shahrekord county of Chaharmahal and Bakhtiari province.   In this cross-sectional study, 79 oral swabs were collected from the mouth of patients with chronic renal disorder undergoing hemodialysis from June to October 2018. The samples were then cultured on non-nutrient agar and examined by Giemsa staining, polymerase chain reaction (PCR), sequencing, and tolerance testing methods.   Morphological investigations indicated that 30.4% (24/79) of the subjects were infected with some free-living amoebae (FLA), and the PCR showed that only 3 samples contained Acanthamoeba spp. The sequencing of the latter samples demonstrated that these isolates belonged to T2 and T4 genotypes. After performing the assay tolerance test, 2 of these 3 isolates were related to T4 genotypes representing a high pathogenic potance.   The infection of hemodialysis patients with some of Acanthamoeba spp. particularly, the T4 genotype should be considered important for these patients. Therefore, it is recommended that dialysis machines and dialysis units in hospitals be checked and disinfected periodically.

Acanthamoeba is a globally dispersed protozoan that can cause different clinical manifestations in infected individuals. Various drugs have been proposed against its drugresistant forms.

The present study examined silver nanoparticles (NPs) with a good anti-parasitic background. More precisely, the study focused on evaluating the anti-parasitic effect of silver nano-scale particles on protozoan trophozoite and cysts by microscopic counting and flow cytometry after exposure to different concentrations.

To this end, MTT assay and IC50 were used to assess the macrophage toxicity and cysts/trophozoites, respectively.

Based on the results, 100 ppm silver NPs had better anti-parasitic effects than 80 ppm concentration and even the standard treatment of Acanthamoeba on both trophozoite and cystic phases. Macrophages toxicity at 100 ppm concentration was similar to the control group.

In general, further studies should be conducted to confirm the present results given the significant effects of silver NPs against trophozoite and parasite cysts.

To determine the causative organisms and associated risk factors for infectious keratitis in South Texas.

This retrospective study was performed at a tertiary teaching hospital system in South Texas. Medical records of all patients who presented with infectious keratitis from 2012 to 2018 were reviewed. Only patients with culture-proven bacterial, fungal, and Acanthamoeba keratitis were included.

In total, 182 eyes of 181 patients had culture-proven bacterial, fungal, or Acanthamoeba keratitis. The age of patients ranged from 3 to 93 years, with a mean of 48.3 ± 20.8 years. The most common etiologic agent was bacteria, with 173 bacterial cultures (95.1%) recovered, followed by 13 fungal cultures (7.1%), and 3 Acanthamoeba cultures (1.6%). Of the 218 bacterial isolates, coagulase-negative Staphylococcus was the most common (25.7%), followed by Pseudomonas aeruginosa (23.4%), Staphylococcus aureus (11.0%), and Moraxella (7.8%). Fusarium was the most common fungal isolate (46.2%). The most common risk factors for infectious keratitis included contact lens wear (32.4%), underlying corneal disease (17.6%), trauma (14.3%), and ocular surface disease (13.7%).

Bacteria are the most common cause of infectious keratitis in this patient population, with coagulase-negative Staphylococcus and Pseudomonas as the most common isolates. The prevalence of culture-positive fungal keratitis is significantly lower than that of bacterial keratitis. Contact lens wear is the most common risk factor associated with infectious keratitis in South Texas.

Free-living amoeba (FLA) are widely distributed in different environmental sources. The most genera of the amoeba are Acanthamoeba, Naegleria and Vermamoeba. The most common consequences of the infections in immune-deficient and immunocompetent persons are amoebic encephalitis and keratitis. The aim of this study was to investigate the presence of Acanthamoeba spp. and Naegleria spp., isolated from the main agricultural water canal in Qazvin.

Totally, 120 water specimens were collected and later the specimens were cultured and cloned to identify positive samples. PCR amplification and sequencing were carried out to identify the isolated species as well as the genotypes of amoeba.

According to morphological surveys, 41.7% (50/120) of water specimens were positive for FLA. Molecular analysis revealed that 68.6% and 31.4% of Acanthamoeba specimens were identified as T3 and T4 genotypes, respectively. Also, two species of Naegleria named as N. lovaniensis (57.1%) and Naegleria spp. (42.8%) were identified. The results of pathogenicity assays demonstrated that 38.5% of T3 and 61.5% of T4 genotypes of Acanthamoeba were highly pathogenic parasites.

The water flowing in the agricultural canal of the area is contaminated with potential pathogenic FLA, therefore, it is recommended that more attention to be paid towards proper treatment of water sources to prevent possible risk of the disease.

Acanthamoeba is a resistant protozoan that causes severe diseases, such as GAE and CAK. Because many medications are ineffective on the parasite, the quest to find alternative drugs is in progress.

This research was aim13 ed to assess the performance of the black and green tea extracts on Acanthamoeba.

The clinical isolate of Acanthamoeba was cultured on non-nutrient agar plates. The black and green tea extracts were prepared via maceration, dried by rotary evaporation, and stored at 4 °C. The main component of the extracts (caffeine) was recognized using GC-MS analysis. The effects of three concentrations of black and green tea extracts were evaluated on the parasite and compared with the control and current drug.

Black and green tea extracts have lethal effects on Acanthamoeba cysts and the performance was more than that shown by the control and the current anti-keratitis drug. Moreover, the effectiveness of the tea extracts was tim 25 e- and dose-dependent (P < 0.0001). There was no significant differences between the performance of black and green tea (P > 0.05).

Black 13 and green tea extracts demonstrated the potential to inhibit the Acanthamoeba parasite, but the use of tea extract in clinical applications requires further study.