Isolation and identification of pathogenic free-living amoeba from surface and tap water of Shiraz City using morphological and molecular methods

Hydra-Amoeba system: a double infection with a lethal ending

Within each ecosystem, organisms and populations maintain a complex set of relationships. These interactions can determine the distribution area of a species and play an essential role in its evolution. Parasites are ubiquitous components of nature and have a high influence on various aspects of the biology and ecology of organisms, affecting the populations of their hosts and, therefore, their communities and ecosystems. Free-living amoebae are unicellular organisms that can be found in water, soil or air. Some species are of great importance in human health. In Hydra, there are several reports of Hydramoeba hydroxena infections. In this work we present a double parasitosis: two concatenated infectious periods in the host polyp of Hydra vulgaris and Hydra vulgaris pedunculata for three freshwater bodies in the province of Buenos Aires, Argentina. Hydramoeba sp. and Acanthoamoeba sp. unchain a series of anatomical lesions that in all cases cause the death of the polyps due to total disintegration. This finding becomes important at a sanitary level due to the appearance of Acanthoamoeba sp. in waters associated with human recreational activities; For the Hydra genus, the importance lies at an ecological and evolutionary level, considering the possible impact on its natural populations.

In Vitro Cytopathogenic Activities of Acanthamoeba T3 and T4 Genotypes on HeLa Cell Monolayer

Amoebic keratitis and encephalitis are mainly caused by free-living amoebae of the genus Acanthamoeba, which consists of both pathogenic and nonpathogenic species. The global distribution, amphizoic properties and the severity of the disease caused by Acanthamoeba species have inspired the scientific community to put more effort into the isolation of Acanthamoeba, besides exploring the direct and indirect parameters that could signify a pathogenic potential. Therefore, this study was performed to characterize the pathogenic potential of Acanthamoeba isolated from contact lens paraphernalia and water sources in Malaysia. Various methodologies were utilized to analyze the thermotolerance and osmotolerance, the secretion level of proteases and the cytopathic effect of trophozoites on the cell monolayer. In addition, the in vitro cytopathogenicity of these isolates was assessed using the LDH-release assay. A total of 14 Acanthamoeba isolates were classified as thermo- and osmotolerant and had presence of serine proteases with a molecular weight of 45-230 kDa. Four T4 genotypes isolated from contact lens paraphernalia recorded the presence of serine-type proteases of 107 kDa and 133 kDa. In contrast, all T3 genotypes isolated from environmental samples showed the presence of a 56 kDa proteolytic enzyme. Remarkably, eight T4 and a single T3 genotype isolates demonstrated a high adhesion percentage of greater than 90%. Moreover, the use of the HeLa cell monolayer showed that four T4 isolates and one T3 isolate achieved a cytopathic effect in the range of 44.9-59.4%, indicating an intermediate-to-high cytotoxicity level. Apart from that, the LDH-release assay revealed that three T4 isolates (CL5, CL54 and CL149) and one T3 isolate (SKA5-SK35) measured an exceptional toxicity level of higher than 40% compared to other isolates. In short, the presence of Acanthamoeba T3 and T4 genotypes with significant pathogenic potential in this study reiterates the essential need to reassess the functionality of other genotypes that were previously classified as nonpathogenic isolates in past research.

Distribution and Current State of Molecular Genetic Characterization in Pathogenic Free-Living Amoebae

Free-living amoebae (FLA) are protozoa widely distributed in the environment, found in a great diversity of terrestrial biomes. Some genera of FLA are linked to human infections. The genus Acanthamoeba is currently classified into 23 genotypes (T1-T23), and of these some (T1, T2, T4, T5, T10, T12, and T18) are known to be capable of causing granulomatous amoebic encephalitis (GAE) mainly in immunocompromised patients while other genotypes (T2, T3, T4, T5, T6, T10, T11, T12, and T15) cause Acanthamoeba keratitis mainly in otherwise healthy patients. Meanwhile, Naegleria fowleri is the causative agent of an acute infection called primary amoebic meningoencephalitis (PAM), while Balamuthia mandrillaris, like some Acanthamoeba genotypes, causes GAE, differing from the latter in the description of numerous cases in patients immunocompetent. Finally, other FLA related to the pathologies mentioned above have been reported; Sappinia sp. is responsible for one case of amoebic encephalitis; Vermamoeba vermiformis has been found in cases of ocular damage, and its extraordinary capacity as endocytobiont for microorganisms of public health importance such as Legionella pneumophila, Bacillus anthracis, and Pseudomonas aeruginosa, among others. This review addressed issues related to epidemiology, updating their geographic distribution and cases reported in recent years for pathogenic FLA.

Prevalence of free-living amoebae in swimming pools and recreational waters, a systematic review and meta-analysis

Free-living amoebae (FLA) are cosmopolitan microorganisms known to be pathogenic to humans who often have a history of contact with contaminated water. Swimming pools and recreational waters are among the environments where the greatest human exposure to FLA occurs. This study aimed to determine the prevalence of FLA in swimming pools and recreational waters, through a systematic review and meta-analysis that included studies published between 1977 and 2022. A total of 106 studies were included and an overall prevalence of FLA in swimming pools and recreational waters of 44.34% (95% CI = 38.57–50.18) was found. Considering the studies published up to 2010 (1977–2010), between 2010 and 2015, and those published after 2010 (> 2010–2022), the prevalence was 53.09% (95% CI = 43.33–62.73) and 37.07% (95% CI = 28.87–45.66) and 45.40% (95% CI = 35.48–55.51), respectively. The highest prevalence was found in the American continent (63.99%), in Mexico (98.35%), and in indoor hot swimming pools (52.27%). The prevalence varied with the variation of FLA detection methods, morphology (57.21%), PCR (25.78%), and simultaneously morphology and PCR (43.16%). The global prevalence by genera was Vahlkampfia spp. (54.20%), Acanthamoeba spp. (33.47%), Naegleria spp. (30.95%), Hartmannella spp./Vermamoeba spp. (20.73%), Stenamoeba spp. (12.05%), and Vannella spp. (10.75%). There is considerable risk of FLA infection in swimming pools and recreational waters. Recreational water safety needs to be routinely monitored and, in case of risk, locations need to be identified with warning signs and users need to be educated. Swimming pools and artificial recreational water should be properly disinfected. Photolysis of NaOCl or NaCl in water by UV-C radiation is a promising alternative to disinfect swimming pools and artificial recreational waters.

Molecular identification and phylogenetic analysis of free-living amoeba in the water resources of Arak, Iran

The aim of the present study was to detect free-living amoeba (FLA) in the water resources of Arak, Iran using molecular tools. A total of 154 samples were collected from different water supplies. Molecular analyses, sequencing, and phylogenetic study were conducted to confirm the species and genotypes of FLA. Fisher exact test was used to determine the significance. Of 154 water samples, 19 (12.3%) samples were tested positive for FLA. Three genotypes of Acanthamoeba including T4, subtype D, and T5 were identified among the isolates. The pathogenicity assay showed that the isolate of Acanthamoeba in drinking water was highly pathogenic. Three species of Naegleria, including N. australiensis, N. pagei, and N. gruberi were found among the samples. Six isolates of Vermamoeba were identified as V. vermiformis. Meanwhile, three other species including Vannella sp., Vahlkampfia avara, and Stenamoeba polymorpha were also recovered from the water samples. Statistical analysis showed a significant difference between the various water resources contaminated with FLA. This is the first study to reveal the presence of S. polymorpha in water sources in Iran. According to the findings of the present study, health officials should be beware of potential public health impacts of FLA in water resources.

Cooccurrence of Five Pathogenic Legionella spp. and Two Free-Living Amoebae Species in a Complete Drinking Water System and Cooling Towers

Pathogenic Legionella species grow optimally inside free-living amoebae to concentrations that increase risks to those who are exposed. The aim of this study was to screen a complete drinking water system and cooling towers for the occurrence of Acanthamoeba spp. and Naegleria fowleri and their cooccurrence with Legionella pneumophila, Legionella anisa, Legionella micdadei, Legionella bozemanii, and Legionella longbeachae. A total of 42 large-volume water samples, including 12 from the reservoir (water source), 24 from two buildings (influents to the buildings and exposure sites (taps)), and six cooling towers were collected and analyzed using droplet digital PCR (ddPCR). N. fowleri cooccurred with L. micdadei in 76 (32/42) of the water samples. In the building water system, the concentrations of N. fowleri and L. micdadei ranged from 1.5 to 1.6 Log₁₀ gene copies (GC)/100 mL, but the concentrations of species increased in the cooling towers. The data obtained in this study illustrate the ecology of pathogenic Legionella species in taps and cooling towers. Investigating Legionella’s ecology in drinking and industrial waters will hopefully lead to better control of these pathogenic species in drinking water supply systems and cooling towers.

Isolation and identification of potentially pathogenic free-living amoeba in dialysis fluid samples of hydraulic systems in hemodialysis units

BACKGROUND

Free-living amoeba (FLA), including Acanthamoeba, Naegleria, Balamuthia and Vermamoeba, have been isolated from water, sand, soil, dust and air. Numerous studies considered that FLA are a significant cause of neurological and ocular complications in high-risk groups, including immunocompromised individuals. The present study aimed to identify morphological and molecular characteristics of FLA isolates in dialysis fluid samples of hydraulic systems in hemodialysis units in Iran.

METHODS

A total of 328 dialysis fluid samples were collected from 16 dialysis machines, including 164 samples before hemodialysis sessions (after cleaning) and 164 samples after hemodialysis sessions (before cleaning). Filtration and cultivation were performed on non-nutrient agar medium. Also, PCR and sequencing were applied by using the genus-specific primers along with a common primer set on positive samples.

RESULTS

Both morphology and molecular investigations showed that 22.5% (74/328) of dialysis fluid samples were positive for FLA. There was a positive relationship between the high frequency of FLA after hemodialysis sessions (before cleaning) compared with before hemodialysis sessions (after cleaning) (OR=2.86; 95% CI 1.5 to 5.45). Considering the PCR assay, 16.46% (54/328) samples were identified as Acanthamoeba spp. (belonging to T3 and T4 genotypes), 5.18% (17/328) as Vermamoeba vermiformis and 0.91% (3/328) as Vahlkampfiidae family (Naegleria australiensis, Naegleria pagei and Allovahlkampfia).

CONCLUSION

The present results support a need to improve filtration and purification methods for dialysis fluid of hydraulic systems in hemodialysis units. They also highlight the relevance of periodic screenings for FLA-related diseases in hemodialysis patients.

Isolation and Molecular Identification of Acanthamoeba and Naegleria from Agricultural Water Canal in Qazvin, Iran

Background:

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 immuno-competent 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.

Methods:

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.

Results:

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 sp. (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.

Conclusion:

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.

Adaption of microbial communities to the hostile environment in the Doce River after the collapse of two iron ore tailing dams

In November 2015, two iron ore tailing dams collapsed in the city of Mariana, Brazil. The dams' collapse generated a wave of approximately 50 million m³ of a mixture of mining waste and water. It was a major environmental tragedy in Brazilian history, which damaged rivers, and cities 660 km away in the Doce River basin until it reached the ocean coast. Shortly after the incident, several reports informed that the concentration of metals in the water was above acceptable legal limits under Brazilian laws. Here the microbial communities in samples of water, mud, foam, and rhizosphere of Eichhornia from Doce River were analyzed for 16S and 18S rRNA-based amplicon sequencing, along with microbial isolation, chemical and mineralogical analyses. Samples were collected one month and thirteen months after the collapse. Prokaryotic communities from mud shifted drastically over time (33% Bray-Curtis similarity), while water samples were more similar (63% Bray-Curtis similarity) in the same period. After 12 months, mud samples remained with high levels of heavy metals and a reduction in the diversity of microeukaryotes was detected. Amoebozoans increased in mud samples, reaching 49% of microeukaryote abundance, with Discosea and Lobosa groups being the most abundant. The microbial communities’ structure in mud samples changed adapting to the new environment condition. The characterization of microbial communities and metal-tolerant organisms from such impacted environments is essential for understanding the ecological consequences of massive anthropogenic impacts and strategies for the restoration of contaminated sites such as the Doce River.

Vermamoeba vermiformis CDC-19 draft genome sequence reveals considerable gene trafficking including with candidate phyla radiation and giant viruses

Vermamoeba vermiformis is a predominant free-living amoeba in human environments and amongst the most common amoebae that can cause severe infections in humans. It is a niche for numerous amoeba-resisting microorganisms such as bacteria and giant viruses. Differences in the susceptibility to these giant viruses have been observed. V. vermiformis and amoeba-resisting microorganisms share a sympatric lifestyle that can promote exchanges of genetic material. This work analyzed the first draft genome sequence of a V. vermiformis strain (CDC-19) through comparative genomic, transcriptomic and phylogenetic analyses. The genome of V. vermiformis is 59.5 megabase pairs in size, and 22,483 genes were predicted. A high proportion (10% (n = 2,295)) of putative genes encoded proteins showed the highest sequence homology with a bacterial sequence. The expression of these genes was demonstrated for some bacterial homologous genes. In addition, for 30 genes, we detected best BLAST hits with members of the Candidate Phyla Radiation. Moreover, 185 genes (0.8%) best matched with giant viruses, mostly those related to the subfamily Klosneuvirinae (101 genes), in particular Bodo saltans virus (69 genes). Lateral sequence transfers between V. vermiformis and amoeba-resisting microorganisms were strengthened by Sanger sequencing, transcriptomic and phylogenetic analyses. This work provides important insights and genetic data for further studies about this amoeba and its interactions with microorganisms.

Isolation and identification of Acanthamoeba genotypes and Naegleria spp. from the water samples of public swimming pools in Qazvin, Iran

Free-living amoeba (FLA), including Acanthamoeba and Naegleria are facultative parasites in humans. The amoeba have widespread distribution in various water sources. The aim of this study was isolation and molecular identification of Acanthamoeba and Naegleria isolated from swimming pools and also hot and cold tub waters in Qazvin province. The samples (166 water samples) were cultured to isolate and identify positive specimens. PCR (polymerase chain reaction) amplification, sequencing and phylogenetic analysis were conducted to confirm the isolated species and genotypes of amoeba. According to morphological characterizations, 18.6% of specimens were identified as FLA, which in 71% were Acanthamoeba by PCR method. Molecular analysis revealed that 36.3%, 18.1% and 4.5% of Acanthamoeba specimens were identified as T3, T4 and T11 Acanthamoeba genotypes, respectively. Protacanthamoeba bohemica (27.2%) and Acanthamoeba sp. (4.5%) were found among the specimens. The results of osmo-tolerance and thermo-tolerance assays demonstrated that 50% of T3 and 25% of T4 genotypes of Acanthamoeba were highly pathogenic parasites. The molecular approach showed the presence of Naegleria lovaniensis (9%) in hot tub water of swimming pools. This study demonstrated that the swimming pools and hot tub water in Qazvin province were contaminated with Acanthamoeba and Naegleria species.

Fungal and parasitic contamination of indoor public swimming pools in Arak, Iran

BACKGROUND

Swimming is a popular exercise for different types of people at different ages. Public swimming pools are places where fungal infections can be easily transferred. The purpose of this study is to evaluate the quality of mycological, parasitological, and physicochemical parameters of swimming pools of Arak city.

METHODS

This cross-sectional study was done for 12 months from April 2013 to March 2014 in six indoor active swimming pools of Arak city (A, B, C, D, E, and F). Samples were collected in four seasons, two times/season; each time, two samples were obtained from six specified locations (shallow level pool, deep level pool, dressing rooms, showers, margin of pool walls, and foot-washing sink) from each pool with a total of 576 samples. Physicochemical parameters including water temperature, pH, turbidity, and the residual chlorine were measured on-site. In order to isolate and detect the fungal agents, special filters and culture Sabouraud's dextrose agar, chloramphenicol, and mycosel agar media were applied. Furthermore, non-nutrient agar medium enriched with Escherichia coli was used to detect and to separate the eggs of the worms, cysts, and parasitic protozoa from centrifuges of samples. In order to investigate their sediment, optical microscope and culture media were used.

RESULTS

We found that 456 (79.1%) samples were positive regarding the fungal elements, and 516 fungal species were isolated. The most common isolates were saprophytic species (8.74%), yeast species (25%), and dermatophyte species (2.5%). The most contaminated surfaces were foot-washing sinks and showers. In this study, Acanthamoeba parasites were isolated from one pool only. All the investigated physicochemical parameters of pool water except for the temperature were found to be in the standard range.

CONCLUSIONS

Existence of saprophytic fungi and yeast in pools' water is plausible to be considered as an indicator of water resistance to the detergent agents. This high degree of contamination is due to the huge number of visitors, the complexity of construction, the choice of materials, and the long opening hours. Isolation of dermatophytes and Acanthamoeba parasite from the pools' area and foot-washing sink reveals the important role of the public swimming pools in disease transmission.

Genotyping determination of Acanthamoeba strains: an original study and a systematic review in Iran

This study aimed to detect the presence of Acanthamoeba spp. in different water resources of Zahedan, southeast of Iran, and also systematically reviewed all publications regarding Acanthamoeba in Iran (2005-2018). Fifty water samples were collected from different water resources in Zahedan. The positive samples were identified morphologically and subjected to polymerase chain reaction (PCR) using fragments of 18S rRNA. In the systematic review, data collection using particular terms was carried out using the following electronic databases including Science Direct, ISI Web of Science, MEDLINE, EBSCO, Scopus, and Google Scholar. A total of 17 (34%) samples were positive for Acanthamoeba spp., and nucleotide sequencing indicated that 15 samples (88.23%) belonged to the T4 genotype and the rest belonged to the T5 genotype. A total of 39 studies reported genotyping of Acanthamoeba spp. from various geographical areas of Iran and revealed that T4 (35 studies), T5 (19 studies), T3 (11 studies), T11 (8 studies), and T2 (6 studies) genotypes were the most prevalent in Iran. The T4 genotype of Acanthamoeba is a prevalent free-living amoeba and widely distributed not only in Zahedan but also in other provinces of Iran. Phylogenetic analysis reveals that A. castellanii and A. griffini predominantly colocalize with the T4 genotype.

Vermamoeba vermiformis - A Free-Living Amoeba with Public Health and Environmental Health Significance

Many case reports emphasize the fact that Free-Living Amoebae (FLA) can relatively easily get in contact with humans or animals. The presence of several facultative parasitic FLA in habitats related to human activities supports their public health relevance. While some strains of Acanthamoeba,Naegleria fowleri,Balamuthia mandrillarisand several other FLA have been described as facultative human pathogens, it remains controversial whetherVermamoeba vermiformisstrains may have a pathogenic potential, or whether this FLA is just an incidental contaminant in a range of human cases. However, several cases support its role as a human parasite, either as the only etiological agent, or in combination with other pathogens. Additionally, a wide range of FLA is known as vectors of microorganisms (endocytobionts), hereby emphasizing their environmental significance. Among those FLA serving as hosts for and vectors of (pathogenic) endocytobionts, there are also descriptions ofV. vermiformisas a vehicle and a reservoir of those endocytobionts. The involvement in animal and human health, the role as vector of pathogenic microorganisms and the pathogenicity in cell cultures, led to the assumption thatV. vermiformisshould be considered relevant in terms of public health and environmental health.

Isolation and Genotyping of Acanthamoeba from Soil Samples in Markazi Province, Iran

AIM:

A previous study confirmed the contamination of water sources with this parasite in Arak, Markazi Province, Iran. The current study investigated soil sources and determined the predominant genotype of Acanthamoeba in this region of Iran.

MATERIAL AND METHODS:

Forty-eight soil samples, collected from different regions of Arak, Markazi province, Iran, were evaluated in this study. The samples were processed and identified by culturing on a specific medium, performing PCR assay, and sequencing the PCR products. Finally, using the NCBI database, the genotypes were determined.

RESULTS:

Of 48 soil samples, 33.3% and 31.25% were contaminated with Acanthamoeba according to the culture and molecular assays, respectively. The majority of these isolates belonged to the T4, T5 and T6 genotypes of Acanthamoeba.

CONCLUSION:

The genotypes of most isolates from soil samples in Arak similar to other regions of Iran belong to T4 genotype of this parasite. New sequence accession numbers include MG066681 and MG298785-MG298794.

Vermamoeba vermiformis: a Free-Living Amoeba of Interest

Free-living amoebae are protists that are widely distributed in the environment including water, soil, and air. Although the amoebae of the genus Acanthamoeba are still the most studied, other species, such as Vermamoeba vermiformis (formerly Hartmannella vermiformis), are the subject of increased interest. Found in natural or man-made aquatic environments, V. vermiformis can support the multiplication of other microorganisms and is able to harbor and potentially protect pathogenic bacteria or viruses. This feature is to be noted because of the presence of this thermotolerant amoeba in hospital water networks. As a consequence, this protist could be implicated in health concerns and be indirectly responsible for healthcare-related infections. This review highlights, among others, the consequences of V. vermiformis relationships with other microorganisms and shows that this free-living amoeba species is therefore of interest for public health.

Isolation and identification of Acanthamoeba from pond water of parks in a tropical and subtropical region in the Middle East, and its relation with physicochemical parameters

Background

Free-living amoeba (FLA) are wide-spread protozoa that are found in different environmental sources including water, soil, dust, hospital units and ventilation areas. These amoebas can act as opportunistic or non-opportunistic pathogens. Among FLAs, some genera such as Acanthamoeba are important because of their potential pathogenic ability in humans. The purpose of this study is to identify of Acanthamoeba isolated from pond water of parks in a tropical and subtropical region in the Middle East, and its relation with physicochemical parameters.From August to December 2015, 90 samples were collected from pond water of parks of 13 regions of Mashhad City. Physicochemical parameters were measured in situ. After filtering, the samples were cultured on Bacto-agar enriched with Escherichia coli. PCR analysis was conducted on the culture-positive samples, and then the PCR products were sequenced. Statistical analysis was performed by SPSS software and Fisher’s Exact and Mann-Whitney test.

Results

Among the samples that were examined, 19 samples (21.1%) were positive for Acanthamoeba. The sequencing revealed that Acanthamoeba isolates belonged to T4 genotype of Acanthamoeba. There was no significant relationship between physicochemical parameters and the presence of Acanthamoeba.

Conclusion

The prevalence of Acanthamoeba in pond water of parks was relatively high, but there was no significant relationship between physicochemical parameters and the presence of Acanthamoeba.

Contamination of swimming pools and hot tubs biofilms with Acanthamoeba

The members of Acanthamoeba genus are ubiquitous amoeba which could be a pathogenic parasite. The amoeba is resistant to the common chlorine concentration that used for disinfecting the swimming pool water. Therefore, the pools can be suitable environments for the survival and multiplication of the amoeba. In this cross sectional study, 10 indoor recreational water centers from different regions of Tabriz city were selected and sampling was done from fixed and floating biofilms of the swimming pools and hot tubs. The samples were cultured and monitored for the presence of amoeba cyst or trophozoite. For molecular identification of Acanthamoeba, PCR (polymerase chain reaction) and sequencing were conducted based on genus specific fragment of 18S ribosomal DNA (Rns). Acanthamoeba contamination was observed in 6 centers of 10 recreational centers. Based on the amoeba isolation from fixed and floating biofilms, 2 (20%) swimming pools, and 5 (50%) hot tubs were contaminated. Based on the type of the sample, the highest contamination was found in the hot tub water (40%) and the least was found in the swimming pools water (10%) and fixed biofilms of the swimming pools (10%). Out of 8 isolates, 5 (62.5%) were shown expected product in PCR amplification. Sequence analysis showed that Acanthamoeba isolates belonged to the T3 and T4 genotypes. The study revealed a high degree of contamination in the indoor recreational water centers in Tabriz city. So, it is essential to pay closer attention to the hygiene of swimming pools and hot tubs.

Genotyping of Acanthamoeba spp. from water sources from Northwestern Iran

Acanthamoeba spp. are free-living amoebae which are ubiquitously distributed worldwide and can be found in the wide range of environments, particularly in various types of water sources, where they able to cause important health problems. In the present study, cultures containing Acanthamoeba from water samples were obtained from our earlier survey. For an analysis of the genetic pattern of Acanthamoeba isolates, DNA sequencing of nuclear small-subunit rRNA gene (18S rRNA or Rns) was applied. A phylogenetic analyses of the isolates displayed that all of them were belonged to the potentially pathogenic T4 genotype. This investigation provides further evidence that the T4 genotype is the most prevalent in water samples and demonstrates that there is a need for taking more consideration to water sources in order to prevent complications associated with pathogenic Acanthamoeba spp.

Phylogeography, genetic variability and structure of Acanthamoeba metapopulations in Iran inferred by 18S ribosomal RNA sequences: A systematic review and meta-analysis

OBJECTIVE

To verify phylogeography and genetic structure of Acanthamoeba populations among the Iranian clinical isolates and natural/artificial environments distributed in various regions of the country.

METHODS

We searched electronic databases including Medline, PubMed, Science Direct, Scopus and Google Scholar from 2005 to 2016. To explore the genetic variability of Acanthamoeba sp, 205 sequences were retrieved from keratitis patients, immunosuppressed cases and environmental sources as of various geographies of Iran.

RESULTS

T4 genotype was the predominant strain in Iran, and the rare genotypes belonged to T2, T3, T5 (Acanthamoeba lenticulata), T6, T9, T11, T13 and T15 (Acanthamoeba jacobsi). A total of 47 unique haplotypes of T4 were identified. A parsimonious network of the sequence haplotypes demonstrated star-like feature containing haplogroups IR6 (34.1%) and IR7 (31.2%) as the most common haplotypes. In accordance with the analysis of molecular variance, the high value of haplotype diversity (0.612-0.848) of Acanthamoeba T4 represented genetic variability within populations. Neutrality indices of the 18S ribosomal RNA demonstrated negative values in all populations which represented a considerable divergence from neutrality. The majority of genetic diversity belonged to the infected contact lens and dust samples in immunodeficiency and ophthalmology wards, which indicated potential routes for exposure to a pathogenic Acanthamoeba sp. in at-risk individuals. A pairwise fixation index (F_ST) was from low to high values (0.02433-0.41892). The statistically F_ST points out that T4 is genetically differentiated between north-west, north-south and central-south metapopulations, but not differentiated between west-central, west-south, central-south, and north-central isolates.

CONCLUSIONS

An occurrence of IR6 and IR7 displays that possibly a gene flow of Acanthamoeba T4 occurred after the founder effect or bottleneck experience through ecological changes or host mobility. This is the first systematic review and meta-analysis providing new approaches into gene migration and transmission patterns of Acanthamoeba sp, and targeting at the high-risk individuals/sources among the various regions of Iran.

Occurrence of Infected Free-Living Amoebae in Cooling Towers of Southern Brazil

This study determined the occurrence of potentially pathogenic free-living amoebae (FLA) and bacteria associated with amoebae in air-conditioning cooling towers in southern Brazil. Water samples were collected from 36 cooling systems from air-conditioning in the state of Rio Grande do Sul, Brazil. The organisms were identified using polymerase chain reaction (PCR) and sequencing automated. The results showed that these aquatic environments, with variable temperature, are potential "hot spots" for emerging human pathogens like free-living amoebae and bacteria associated. In total, 92% of the cooling-tower samples analyzed were positive for FLA, and Acanthamoeba was the dominant genus by culture and PCR. Amoebal isolates revealed intracellular bacteria in 39.3% of them and all were confirmed as members of the genus Pseudomonas. The results obtained show the important role of cooling towers as a source of amoebae-associated pathogens.

Free-living amoebae in the water resources of Iran: a systematic review

Free-living amoebae (FLA) are a group of protozoa with the capabilities of growth in the environment and invasion to the human body which have been isolated from different water sources. Acanthamoeba, Naegleria, and Balamuthia are the most important FLA. These cause a variety of severe complications of eye and central nervous system. Despite the fact that various studies have demonstrated the prevalence of FLA in different parts of Iran, there is no comprehensive evaluation and conclusion regarding the pollution of various water sources in Iran. This review was carried out to achieve the prevalence pattern of FLA in water resources across Iran to design appropriate health strategies. For this purpose, 8 online databases in English and Persian and also graduate thesis and national parasitology congresses were studied. The key words such as "free living amoebae", "Acanthamoeba", "Naegleria", "Hartmannella", "Balamuthia", "Sappinia", "Vermamoebae", "Valkampfia", "water resources", "water" and "Iran" were used to search articles between 1990 to 2017. From a total of 236 articles found, 38 reliable articles were included in the study. From the total number of investigated studies, the estimated prevalence was obtained as 36% among 2430 samples. Although Acanthamoeba prevalence has been considered as a priority, most kinds of free-living amoebae were found in all kinds of water resources. Due to the lack of free-living amoebae prevalence in more than a quarter of the Iranian provinces, more studies are recommended to achieve a better perspective to make comprehensive decisions to improve the hygiene of water resources.

Vermamoeba vermiformis-Aspergillus fumigatus relationships and comparison with other phagocytic cells

Free living amoebae (FLA) are protists ubiquitously present in the environment. Aspergillus fumigatus is a mould responsible for severe deep-seated infections, and that can be recovered in the same habitats as the FLA. By conducting coculture experiments and fungal incubation with amoebal supernatants, we report herein that Vermamoeba vermiformis, a FLA present in hospital water systems, promotes filamentation and growth of A. fumigatus. This finding is of particular importance to institutions whose water systems might harbor FLA and could potentially be used by immunocompromised patients. Also, the relationships between V. vermiformis and A. fumigatus were compared to those between this fungus and two other phagocytic cells: Acanthamoeba castellanii, another FLA, and macrophage-like THP-1 cells. After 4 h of coincubation, the percentages of the three phagocytic cell types with adhered conidia were similar, even though the types of receptors between FLA and macrophagic cell seemed different. However, the percentage of THP-1 with internalized conidia was considerably lower (40 %) in comparison with the two other cell types (100 %). Thus, this study revealed that interactions between A. fumigatus and these three phagocytic cell types show similarities, even though it is premature to extrapolate these results to interpret relationships between A. fumigatus and macrophages.

Genotypic, physiological, and biochemical characterization of potentially pathogenic Acanthamoeba isolated from the environment in Cairo, Egypt

Acanthamoebae are the most common opportunistic amphizoic protozoa that cause life-threatening granulomatous amoebic encephalitis in immunocompromised individuals and sight-threatening amoebic keratitis (AK) in contact lens wearers. The present work aimed to determine the presence of Acanthamoeba isolates in different environmental sources: water, soil, and dust in Cairo, Egypt and to characterize the pathogenic potential of the isolated Acanthamoeba using physiological and biochemical assays as well as determination of the genotypes in an attempt to correlate pathogenicity with certain genotypes. The study included the collection of 22 corneal scrapings from patients complaining of symptoms and signs indicative of acanthamoeba keratitis (AK) and 75 environmental samples followed by cultivation on non-nutrient agar plates preseeded with E. coli. Positive samples for Acanthamoeba were subjected to osmo- and thermo-tolerance assays and zymography analysis. Potentially pathogenic isolates were subjected to PCR amplification using genus-specific primer pair. Isolates were classified at the genotype level based on the sequence analysis of Acanthamoeba 18S rRNA gene (diagnostic fragment 3). The total detection rate for Acanthamoeba in environmental samples was 33.3 %, 31.4 % in water, 40 % in soil, and 20 % in dust samples. Three and two Acanthamoeba isolates from water and soil sources, respectively, had the potential for pathogenicity as they exhibited full range of pathogenic traits. Other 12 isolates were designated as weak potential pathogens. Only ten of the environmental isolates were positive in PCR and were classified by genotype analysis into T4 genotype (70 %), T3 (10 %) and T5 (20 %). Potential pathogens belonged to genotypes T4 (from water) and T5 (from soil) while weak potential pathogens belonged to genotypes T3 (from water) and T4 (from water and soil). Additionally, T7 genotype was isolated from keratitis patients. There is a considerable variation in the response of Acanthamoeba members of the same genotype to pathogenicity indicator assays making correlation of pathogenicity with certain genotypes difficult. Presence of potentially pathogenic Acanthamoeba isolates in habitats related directly to human populations represent a risk for human health. Isolation of Acanthamoeba genotype T7 from AK cases, which is commonly considered as nonpathogenic, might draw the attention to other Acanthamoeba genotypes considered as non pathogenic and reevaluate their role in production of human infections. To our knowledge, this is the first study on the presence and distribution of Acanthamoeba genotypes in the environment, Cairo, Egypt.