First report of a mixed infection due to Acanthamoeba genotype T3 and Vahlkampfia in a cosmetic soft contact lens wearer in Iran

Isolation and morphological and molecular characterization of waterborne free-living amoebae: Evidence of potentially pathogenic Acanthamoeba and Vahlkampfiidae in Assiut, Upper Egypt

Free-living amoebae (FLA) are gaining attention due to the increasing number of related grave central nervous system (CNS) and sight-threatening eye infections and their role as Trojan horses for many bacteria and viruses. This study was conducted in Assiut City, Egypt to detect the presence of FLA in different water sources using morphological and molecular approaches and determine their potential pathogenicity. A total of 188 water samples (100 tap, 80 tank, and 8 swimming pool samples) were collected, cultivated on non-nutrient agar seeded with Escherichia coli, and inspected for FLA. Thermo- and osmo-tolerance assays were performed to determine their pathogenicity. Polymerase chain reaction and sequence analysis were performed to confirm the identification and analyze the genotype. Overall, 52 samples (27.7%) were positive for FLA. Of these, 20.7% were identified as Acanthamoeba, 1.6% as Vahlkampfiidae, and 5.3% as mixed Acanthamoeba and Vahlkampfiidae. Seven species of Acanthamoeba were recognized, of which A. triangularis, A. polyphaga, A. lenticulata, and A. culbertsoni are thermo- and osmo-tolerant, and A. astronyxis, A. comandoni, and A. echinulata are non-thermo- and non-osmo-tolerant. The phylogeny analysis revealed T4 and T7 genotypes. Among Vahlkampfiids, 61.5% were identified as thermo- and osmo-tolerant Vahlkampfia, and 30.8% were identified as non-pathogenic Naegleria. One isolate (7.7%) was identified as potentially pathogenic Allovahlkampfia, as confirmed by sequencing. This is the first report documenting the occurrence and phylogeny of waterborne FLA (Acanthamoeba/Vahlkampfiidae) in Assiut, Egypt. The presence of potentially pathogenic FLA highlights the possible health hazards and the need for preventive measures.

Amoebicidal effect of Allium cepa against Allovahlkampfia spelaea: A keratitis model

Allovahlkampfia spelaea (A. spelaea) is a free-living amoeba, proved to cause Acanthamoeba-like keratitis with quite difficult treatment. This study aimed to evaluate the amoebicidal effect of Allium cepa (A. cepa) on A. spelaea trophozoites and cysts both in vitro and in vivo using Chinchilla rabbits as an experimental model of this type of keratitis. Chemical constituents of the aqueous extract of A. cepa were identified using Liquid Chromatography-mass Spectrometry (LC-MS). In vitro, A. cepa showed a significant inhibitory effect on trophozoites and cysts compared to the reference drug, chlorhexidine (CHX) as well as the non-treated control (P < 0.05) with statistically different effectiveness in terms of treatment durations and concentrations. No cytotoxic effect of A. cepa on corneal cell line was found even at high concentrations (32 mg/ml) using agar diffusion method. The in vivo results confirmed the efficacy of A. cepa where the extract enhanced keratitis healing with complete resolution of corneal ulcers in 80% of the infected animals by day 14 (post infection)pi compared to 70% recovery with CHX after 20 treatment days. The therapeutic effect was also approved at histological, immune-histochemical, and parasitological levels. Our findings support the potential use of A. cepa as an effective agent against A. spelaea keratitis.

Isolation and identification of potentially pathogenic free-living amoeba in drinking, surface, and stagnant water sources from Alborz Province, Iran

Free-living amoebas (FLAs) can cause neurological and ocular complications in humans. Water supplies play a critical role in transmitting FLAs to humans. The aim of the present study was to investigate the presence of FLAs in various aquatic sources including drinking water, stagnant water, and surface water in Alborz province, northern Iran, using morphological and molecular techniques. A total of 70 water samples were collected from 34 drinking waters, 23 surface waters, and 13 stagnant waters. Filtration and cultivation were employed to isolate FLAs. PCR assay was applied by using the genus-specific primers on positive samples. Pathogenicity tests (osmo- and thermo-tolerance properties) were performed for Acanthamoeba spp., positive sample. Considering the morphological criteria, four positive samples of Acanthamoeba sp., three Vermamoeba sp., two mixed Vermamoeba sp. with Vahlkamfiids, and one mixed Acanthamoeba sp. with Vahlkamfiids were isolated. Five Acanthamoeba sp. isolates were amplified using the JDP primer pairs. Among them, two genotypes, T4 (three isolates) and T5 (two isolates) corresponding to A. lenticulata, were identified. Four V. vermiformis samples were confirmed using the sequencing. This study highlighted the occurrence of potentially pathogenic waterborne FLAs in water habitats associated with high human activity. The results of such research on the prevalence of FLAs, as a human hazard, should be communicated to health policymakers.

Diagnostic Considerations for Non-Acanthamoeba Amoebic Keratitis and Clinical Outcomes

Cases of amoebic keratitis involving species other than Acanthamoeba are hypothesised to be underdiagnosed and poorly understood. Amoebic keratitis is debilitating and associated with chronic visual impairment. Understanding associated symptoms of non-Acanthamoeba amoebic keratitis could facilitate new diagnostic procedures and enable prompt treatment, ultimately leading to improved patient outcomes. Thus, a review of the literature was undertaken surrounding non-Acanthamoeba amoebic keratitis. Cases were geographically widespread and mostly confined to contact lens wearers ≤ 30 years old exposed to contaminated water sources and/or demonstrating poor lens hygiene. Vermamoeba vermiformis (previously Hartmanella vermiformis) was the most common causative agent, and a moderate number of mixed keratitis cases were also reported. A crucial disease indicator was early onset stromal deterioration/ulcerations, reported in 10 of the studies, usually only occurring in advanced Acanthamoeba keratitis. Mixed infections were the most difficult to treat, often requiring keratoplasty after unsuccessful combination treatment regimens. New diagnostic measures for non-Acanthamoeba amoebic keratitis should consider early onset stromal disease as a key disease indicator. Deep corneal scrapes are also necessary for accurate amoebic identification. Moreover, a combination approach to diagnosis is advised and should involve culture, microscopy and PCR techniques. In vitro drug sensitivity tests should also be conducted to help develop patient-specific treatment regimes.

Genotype distribution of Acanthamoeba in keratitis: a systematic review

Acanthamoeba spp. are among the most worldwide prevalent protozoa. It is the causative agent of a disease known as Acanthamoeba keratitis, a painful and severe sight-threatening corneal infection that can lead to blindness. In recent years, the prevalence of Acanthamoeba keratitis has rapidly increased, growing its importance to human health. This systematic review aims to assess the distribution of Acanthamoeba sp. genotypes causing keratitis around the world, considering the sample collected type and the used identification method. Most of the cases were found in Asia and Europe. Not surprisingly, the T4 genotype was the most prevalent worldwide, followed by T3, T15, T11, and T5. Furthermore, the T4 genotype contains a higher number of species. Given the differences in pathology, susceptibility to treatment, and clinical outcome between distinct genotypes, it is essential to genotype isolates from Acanthamoeba keratitis cases to help to establish a better correlation between in vitro and in vivo activities, resulting in better drug therapies and successful treatment in cases of this important ocular infection.

Acanthamoeba Keratitis Versus Mixed Acanthamoeba and Bacterial Keratitis: Comparison of Clinical and Microbiological Profiles

PURPOSE

To compare the clinical profiles and outcomes of patients with Acanthamoeba keratitis with or without mixed bacterial infection.

METHODS

A retrospective analysis of microbiologically confirmed AK cases presenting to a tertiary care center over a 9-year period was conducted. Fourteen eyes in the coinfected group (group 1) and 24 eyes in the AK group (group 2) were analyzed to study the differences in these 2 groups of patients. The cases were diagnosed using a conventional microscopic analysis with staining techniques confirmed by cultural methods and were treated, which tailored to the microbiology report.

RESULTS

There was no difference in the demographic profile and presenting features in the 2 groups. Duration of symptoms and history of ocular trauma, contact lens wear, and previous steroid usage were also similar for both the groups. Dense central corneal infiltrate was the common presentation for both groups (7/14 vs. 16/24 in group 1 vs. group 2). Epithelial defect without dense stromal infiltrate was significantly more common in group 1 (42.9% vs. 4.2%, P = 0.003) as a presenting clinical feature. Hypopyon was present in 8/14 of group 1 versus 9/24 of group 2 eyes (P = 0.25). No significant difference was found in the final visual acuity in pure and mixed AK cases, and the need for surgical intervention was comparable. The most common bacterial pathogen isolated in the mixed group was the Staphylococcus species.

CONCLUSIONS

Bacterial coinfection is common in patients with Acanthamoeba keratitis. Coinfection did not point toward a worse clinical disease at presentation or outcome.

The Increasing Importance of Vermamoeba vermiformis

Vermamoeba vermiformis are one of the most prevalent free-living amoebae. These amoebae are ubiquitous and also thermotolerant. Of concern, V. vermiformis have been found in hospital water networks. Furthermore, associations between V. vermiformis and pathogenic bacteria have been reported, such as Legionella pneumophila. Moreover, V. vermiformis are well known to host viruses, bacteria, and other microorganisms and cases of keratitis due to V. vermiformis in conjunction with other amoebae have been reported. Despite the preceding, the medical importance of V. vermiformis is still an ongoing discussion and its genome has been only recently sequenced. Herein, we present a review of the current understanding of the biology and pathogenesis pertaining to V. vermiformis, as well as its' role as an etiological agent and trojan horse. An approach known as theranostics which combines both diagnosis and therapy could be utilized to eradicate and diagnose keratitis cases caused by such amoebae. Given the rise in global warming, it is imperative to investigate these rarely studied amoebae and to understand their importance in human health.

Free living amoebae isolation in irrigation waters and soils of an insular arid agroecosystem

The use of freshwater in agricultural systems represents a high percentage of total water consumption worldwide. Therefore, alternative sources of water for irrigation will need to be developed, particularly in arid and semi-arid areas, in order to meet the growing demand for food in the future. The use of recycled wastewater (RWW), brackish water (BW) or desalinated brackish water (DBW) are among the different non-conventional water resources proposed. However, it is necessary to evaluate the health risks for humans and animals associated with the microbiological load of these waters. Protozoa such as free-living amoebae (FLA) are considered an emerging group of opportunistic pathogens capable to cause several diseases in humans (e.g. cutaneous and ocular infections, lung, bone or adrenal gland conditions or fatal encephalitis). In the present study we evaluate FLA presence in three different irrigation water qualities (RWW, BW and DBW) and its survival in irrigated agricultural soils of an extremely arid insular ecosystem (Fuerteventura, Canary Islands, Spain). Samples were cultured on 2% Non-Nutrient Agar (NNA) plates covered with a thin layer of heat killed E. coli and checked daily for the presence of FLA. According to the prevalence of FLA, Vermamoeba vermiformis (53,8%), Acanthamoeba spp. (30,8%), Vahlkampfia avara (7,7%) and Naegleria australiensis (7,7%) were detected in the analysed water samples, while Acanthamoeba (83,3%), Cercozoa spp. (8,3%) and Vahlkampfia orchilla (8,3%) were isolated in irrigated soils. Only Acanthamoeba strains were isolated in no irrigated soils used as control, evidencing the capability of these protozoa to resist environmental harsh conditions. Additionally, all analysed water sources and the irrigated soils presented growth of several pathogenic bacteria. Therefore, the coexistence in water and soils of pathogenic bacteria and FLA, can mean an increased risk of infection in agroecosystems.

Evaluation of the occurrence of pathogenic free-living amoeba and bacteria in 20 public indoor swimming pool facilities

Recently, indoor swimming pool activities have increased to promote health-enhancing physical activities, which require establishing suitable protocols for disinfection and water quality control. Normally, the assessment of the microbial quality of the water in the pools only considers the presence of different bacteria. However, other less frequent but more resistant pathogens, such as free-living amoebas (FLA), are not contemplated in both existing recommendation and research activities. FLA represent a relevant human health risk, not only due to their pathogenicity but also due to the ability to act as vehicles of other pathogens, such as bacteria. Therefore, this work aimed to study the physicochemical characteristics and the occurrence of potentially pathogenic FLA and bacteria in water samples from 20 public indoor swimming facilities in Northern Portugal. Our results showed that some swimming pools presented levels of pH, free chlorine, and conductivity out of the recommended limits. Pathogenic FLA species were detected in two of the facilities under study, where we also report the presence of both, FLA and pathogenic bacteria. Our findings evidence the need to assess the occurrence of FLA and their existence in the same environmental niche as pathogenic bacteria in swimming pool facilities worldwide and to establish recommendations to safeguard the health of the users.

Isolation and identification of free-living amoebae isolated from well water in Istanbul

Free-living amoebae (FLA) are ubiquitous protozoa commonly found in water and soil environments. FLA belonging to various genera, including Acanthamoeba, Balamuthia, Naegleria, and Vermamoeba, can cause opportunistic and non-opportunistic infections in humans and animals such as keratitis or meningoencephalitis. In addition, some of them serve as hosts for a large number of pathogenic bacteria, yeasts, and viruses. The purpose of the present study was to assess the prevalence and molecular characterization of FLA in well water samples in İstanbul. Ten well water samples were collected from the taps and the presence of FLA was monitored both by the culture and polymerase chain reaction methods. FLA were isolated in 8 out of the 10 samples (80%) included in this study. Morphological analysis and partial sequencing of the 18S rDNA revealed the presence of Acanthamoeba genotypes T3 and T4, and Vermamoeba vermiformis in the investigated well water samples. This study reports for the first time the detection of Acanthamoeba genotype T3 in well water samples in İstanbul. The presence of potentially pathogenic amoebae in habitats related to human activities supports the relevance of FLA as a potential public health concern.

In vitro activity of Camellia sinensis (green tea) against trophozoites and cysts of Acanthamoeba castellanii

The effect of Camellia sinensis (green tea) on the growth of Acanthamoeba castellanii trophozoites was examined using a microplate based-Sulforhodamine B (SRB) assay. C. sinensis hot and cold brews at 75% and 100% concentrations significantly inhibited the growth of trophozoites. We also examined the structural alterations in C. sinensis-treated trophozoites using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). This analysis showed that C. sinensis compromised the cell membrane integrity and caused progressive destruction of trophozoites. C. sinensis also significantly inhibited the parasite's ability to form cysts in a dose-dependent manner and reduced the rate of excystation from cysts to trophozoites. C. sinensis exhibited low cytotoxic effects on primary corneal stromal cells. However, cytotoxicity was more pronounced in SV40-immortalized corneal epithelial cells. Chromatographic analysis showed that both hot and cold C. sinensis brews contained the same number and type of chemical compounds. This work demonstrated that C. sinensis has anti-acanthamoebic activity against trophozoite and cystic forms of A. castellanii. Further studies are warranted to identify the exact substances in C. sinensis that have the most potent anti-acanthamoebic effect.

Isolation and identification of free-living amoeba from the hot springs and beaches of the Caspian Sea

Free-living amoeba (FLA) such as Acanthamoeba, Naegleria, Balamuthia, and Vermamoeba have been identified from both natural and human-made environments such as Hot springs and spa. Naegleria fowleri causes Primary Amoebic Meningoencephalitis (PAM), while Acanthamoeba and Balamuthia cause chronic granulomatous encephalitis. Acanthamoeba also can cause cutaneous lesions and Amoebic Keratitis (AK) that is associated with contact lens use or corneal trauma. FLA are known to serve as host of and vehicles for diverse intracellular organisms. This study aimed was to identify the presence of FLA in the hot springs and beaches of the Caspian Sea in Ramsar tourist town located in the northern part of Iran. Water samples were collected in sterile bottles and were transferred to the laboratory. One litre of each sample passed through the nitrocellulose membrane filter. Each filter insert was then placed in non-nutrient agar plates already seeded with lawn culture of Escherichia coli. Positive samples were analyzed by morphological keys and Polymerase chain reaction (PCR) using 18S rDNA gene and ITS region to identify amoeba isolates. A total of 81 water sampled were tasted. After identified using the morphological key and PCR assay, 54 (66.6%) of the samples were positive for FLA. Ten of the samples were identified as Acanthamoeba (belong to T3, T4, and T5 genotypes), three as Vermamoeba vermiformis, four as Naegleria (3 N.australiensis and 1 N.grubery). Only one sample was positive Vahlkampfia. The presence of thermotolerant FLA in the Hot springs and beaches of the Caspian Sea as places for recreational purposes or wellness may be a potential health risk.

Isolation and Phylogenetic Analysis of Free-Living Amoebae (Acanthamoeba, Naegleria, and Vermamoeba) in the Farmland Soils and Recreational Places in Iran

PURPOSE

Free-living amoeba (FLA) including Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria are among the soil-born parasites. There are reports of FLA-related keratitis with a history of contact with soil and dust sources, particularly among the farmers. Due to lack of the previous studies on the farmland soils and a limited number of researches conducted on recreational soils in Iran, the present study was conducted.

METHODS

A total of 93 soil samples including farming lands and recreational places were tested for the presence of Acanthamoeba spp. Balamuthia mandrillaris, Naegleria, and Vermamoeba using morphological key and sequencing-based tools. Pathogenicity of Acanthamoeba positive strains was also evaluated. To verify genetic associations and taxonomic status of isolated amoeba, a phylogenetic tree was built by MEGA 5.05 software inferred by the 18S rRNA gene based on maximum likelihood algorithm.

RESULTS

Overall, 28 samples (30%) were contaminated with potentially pathogenic FLA, and according to the sequencing data, 17 strains were successfully sequenced. The isolated Acanthamoeba belonged to T2, T4, T5, mixed T4 and T5 contaminations, and T11. ITS sequencing revealed the occurrence of one strain of Naegleria canariensis. Four strains of Vermamoeba vermiformis were also confirmed. Morphological survey and PCR assay failed to show any positive results for Balamuthia mandrillaris. Pathogenic potential of the Acanthamoeba strains showed that T2, T4, and T11 genotypes were highly pathogenic, whereas T5 genotypes demonstrated lower pathogenic potential.

CONCLUSION

The results indicate that soil could be a serious hazard to human health, and therefore, further studies are expected to investigate the source of infection in patients developing FLA-related diseases. The present study is the first to investigate FLA in the farmland soils in Iran and the first to report the presence of N. canariensis in the country.

The Spectrum of Microbial Keratitis: An Updated Review

Background:

In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis.

Objective:

To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study.

Methods:

An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019).

Results:

Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis.

Conclusion:

The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

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.

Amebicidal effects of fenugreek (Trigonella foenum-graecum) against Acanthamoeba cysts

Trigonella foenum-graecum L. (TF) is known to the public as a chest emollient, mucous expectorant, laxative and is used to prevent maturation of boils and diabetes since ancient times. In this study, we aimed to determine the amebicidal effects against Acanthamoeba cysts. Plant extracts were prepared at concentrations of 1, 2, 4, 8, 16, and 32 mg/ml and were placed in a hemocytometer with cell counts 22 × 106 cell/ml. The fatty acid profiles of TF seeds were determined. Standard Acanthamoeba cysts were added and incubated at 25°C. The viability of the parasite was checked and recorded at hours 3, 24, 48, 72, 96, and 102. The values of lethal concentration doses (LD50 and LD90) were calculated using probit analysis. This study revealed that T. foenum-graecum prevented proliferation of the parasite at certain times. However, further for in vivo and controlled experimental studies are needed in order to find out how to use this plant as medication.

Thecamoeba quadrilineata (Amoebozoa, Lobosa) as a new member of amphizoic amoebae-first isolation from endozoic conditions

A free-living soil amoeba Thecamoeba quadrilineata (Carter, 1856) Lepşi, 1960 (Amoebozoa: Thecamoebidae) was isolated from endozoic conditions for the first time. Presence of amoebae was detected after 4 days following inoculation of the gut of the earthworm Lumbricus terrestris on agar plate with Escherichia coli. On the basis of our isolation, we consider T. quadrilineata as further amphizoic amoeba species. This study enlarges the range of amphizoic tendency in members of the genus Thecamoeba and stresses the need for further research on the pathogenic potential of Thecamoeba species.

In Vitro Evaluation of Adhesion of Two Acanthamoeba Strains to Cosmetic Contact Lenses

PURPOSE

To evaluate the factors affecting the adhesion of Acanthamoeba trophozoites to the surface of cosmetic contact lenses (CCLs).

METHODS

Acanthamoeba castellanii and A. hatchetti trophozoites were inoculated onto CCLs (hema copolymer [HM] [38.5% H2O], phemfilcon [PF] [55% H2O], polymacon [PM] [38% H2O], polyhema [PH] [%42 H2O], and hema [HM55] [55% H2O]), and the number of trophozoites adhered to the lens surfaces was assessed over time, that is, at 15 min, 1, and 24 hr. In addition, scanning electron microscopy (SEM) analysis of the lens surfaces was performed to evaluate the effect of lens surface topology on adhesion.

RESULTS

The number of amoeba adhered to the contact lens surface was found lower with PF and PH production materials, than lenses with HM, PM, and HM55 production materials (P<0.05). No significant difference was detected in amoebic strains adhered in all the contact lens types (P>0.05). No significant difference was found on average amoeba adhesion between contact lenses with hema production material but with different water contents (45%, 55%), to see the effect of water content on amoebic adhesion (P>0.05). As a result of SEM analysis, surface topology showed no effect on adhesion.

CONCLUSION

(1) Chemical composition of lenses seemed to be mostly responsible for the adhesion of Acanthamoeba. (2) Different numbers of trophozoites, obtained after the adhesion experiment, could also indicate that adherence capacity can also differ among Acanthamoeba species.

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.

Molecular identification of waterborne free living amoebae (Acanthamoeba, Naegleria and Vermamoeba) isolated from municipal drinking water and environmental sources, Semnan province, north half of Iran

The present study tested 80 samples of municipal, geothermal and recreational water samples for the occurrence of waterborne free living amoebae (FLA) including Acanthamoeba, Balamuthia mandrillaris, Vahlkampfiids and Vermamoeba in Semnan province, North half of Iran. Four sets of primers including JDP1,2 primers, ITS1,2 primers (Vahlkampfiids), 16S rRNABal primers (Balamuthia mandrillaris) and NA1,2 primers (Vermamoeba) were used to confirm the morphological identification. From the 80 water samples tested in the present study, 16 (20%) were positive for the outgrowth of free living amoebae based on the morphological page key. Out of the 34 municipal water samples, 7 (20.6%) were positive for outgrowth of Free living amoeba, belonging to Vermamoeba, Naegleria and Acanthamoeba using molecular tools. Three out of the six investigated hot springs were also contaminated with Naegleria spp. Sequencing of the ITS1,2 region of the Vahlkampfiid isolates revealed the highest homology with N. gruberi (2 isolates), N. australiensis (1 isolate) and N. pagei (3 isolates). This is the first report of N. gruberi in the country. Using morphological and molecular analysis, Balamuthia mandrillaris was undetected in all the water samples. The present study further confirmed the occurrence of potentially pathogenic waterborne free living amoebae in habitats with high human activity. It is of utmost importance that more studies are conducted to evaluate the niches of B. mandrillaris and N. fowleri in Iran and worldwide. Such investigations regarding the relevance of FLA as a hazard to humans, should be brought to the notice of the health authorities.

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.

Knowledge, Behavior, and Free-Living Amoebae Contamination of Cosmetic Contact Lens Among University Wearers in Thailand: A Cross-Sectional Study

OBJECTIVE

To assess the general knowledge, behavior, and presence of potentially pathogenic amoebae in cosmetic contact lens (CCL) wearers.

METHODS

One hundred CCL asymptomatic wearers were randomly selected. A questionnaire regarding their lens use, and a pair of their CCL was obtained. Identification of free-living amoeba (FLA) strains was based on morphological diagnosis, enflagellation tests (for non-Acanthamoeba strains), and sequencing of the small-subunit rRNA gene fragments.

RESULTS

Most (92%) of the participants surveyed were women, and the average age of the participants was 21.5±0.2 years. The CCL wearers generally showed a moderate (47%) or good (35%) level of knowledge, and good (51%) or excellent (40%) use of CCL. Two CCL samples were positive for Acanthamoeba genotype T3 or Vahlkampfia. The Acanthamoeba-contaminated CCL was from a wearer who used saline for treating lenses, and the Vahlkampfia-contaminated CCL was from a wearer who used CCL while swimming.

CONCLUSIONS

This is the first report of the presence of potentially pathogenic FLA in used CCL from asymptomatic wearers in Thailand. Although there was satisfactory knowledge and practice of lens care use, the public should be aware of CCL contaminated with potentially pathogenic FLA that can directly or indirectly cause keratitis.

Isolation and molecular characterization of a Naegleria strain from a recreational water fountain in Tenerife, Canary Islands, Spain

Free-Living Amoebae (FLA) are widely distributed protozoa in the environment and have been isolated from many sources such as dust, soil and water. Among the pathogenic genera included in this group Acanthamoeba spp., Naegleria fowleri and Balamuthia mandrillaris have been reported to be causative agents of lethal encephalitis, disseminated infections and keratitis. Naegleria fowleri is a pathogenic FLA species which causes Primary Amoebic Meningoencephalitis (PAM). At present there are not many available data on the distribution of Naegleria species in Spain from environmental sources. Therefore, the aim of this study was to evaluate the presence of this genus in recreational water sources in the island of Tenerife, Canary Islands, Spain. In this study, ten samples collected from recreational water fountains were checked for the presence of Naegleria spp. using morphological and molecular identification tools. From the analysed samples, only one sample (seawater fountain) was positive for Naegleria spp. interestingly, not many reports of Naegleria spp. in seawater are available in the literature and thus awareness should be raised among the environmental and public health professionals.

Prevalence of pathogenic free-living amoeba and other protozoa in natural and communal piped tap water from Queen Elizabeth protected area, Uganda

Background

Pathogenic water dwelling protozoa such as Acanthamoeba spp., Hartmannella spp., Naegleria spp., Cryptosporidium spp. and Giardia spp. are often responsible for devastating illnesses especially in children and immunocompromised individuals, yet their presence and prevalence in certain environment in sub-Saharan Africa is still unknown to most researchers, public health officials and medical practitioners. The objective of this study was to establish the presence and prevalence of pathogenic free-living amoeba (FLA), Cryptosporidium and Giardia in Queen Elizabeth Protected Area (QEPA).

Methods

Samples were collected from communal taps and natural water sites in QEPA. Physical water parameters were measured in situ. The samples were processed to detect the presence of FLA trophozoites by xenic cultivation, Cryptosporidium oocysts by Ziehl-Neelsen stain and Giardia cysts by Zinc Sulphate floatation technique. Parasites were observed microscopically, identified, counted and recorded. For FLA, genomic DNA was extracted for amplification and sequencing.

Results

Both natural and tap water sources were contaminated with FLA, Cryptosporidium spp. and Giardia spp. All protozoan parasites were more abundant in the colder rainy season except for Harmannella spp. and Naegleria spp. which occurred more in the warmer months. The prevalence of all parasites was higher in tap water than in natural water samples. There was a strong negative correlation between the presence of Acanthamoeba spp., Hartmannella spp., Cryptosporidium spp. and Giardia spp. with Dissolved Oxygen (DO) (P < 0.05). The presence of Cryptosporidium spp. showed a significant positive correlation (P < 0.05) with conductivity, pH and Total Dissolved Solids (TDS); whereas the presence of Giardia spp. had only a strong positive correlation with TDS. Molecular genotyping of FLA produced 7 Acanthamoeba, 5 Echinamoeba, 2 Hartmannella, 1 Bodomorpha, 1 Nuclearia and 1 Cercomonas partial sequences.

Conclusions

All water collection sites were found to be contaminated with pathogenic protozoa that could possibly be the cause of a number of silent morbidities and mortalities among rural households in QEPA. This implies that water used by communities in QEPA is of poor quality and predisposes them to a variety of protozoan infections including the FLA whose public health importance was never reported, thus necessitating adoption of proper water safety measures.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-016-0162-5) contains supplementary material, which is available to authorized users.

Ophthalmology hospital wards contamination to pathogenic free living Amoebae in Iran

The present study was conducted to determine the occurrence of potentially pathogenic free-living amoeba in ophthalmology wards in reference hospitals in Iran. Since an increasing number of Acanthamoeba Keratitis cases after eye surgery and eye trauma have been recently observed in this country, it could be possible that the disinfection procedures undertaken in the clinical setting may not have a good hygiene and disinfection procedures, hence the aim of this study. Therefore, 42 dust and biofilm samples were collected from different areas of ophthalmology wards and checked for the presence of FLA using morphological criteria, PCR based analysis and DNA sequencing. Of the 42 samples from dust and biofilm sources, 18(42.86%) isolates were found to contain FLA and 12(92.3%) isolates belonged to Acanthamoeba T4 genotype. Isolation of the pathogenic genotype T4 from medical instruments, including slit lamp in corneal wards, may be a threat for patients undergoing eye surgery in these wards. Other FLA isolated in this study included Acanthamoeba genotype T5, Vahlkampfia sp, Naegleria australiensis, Vermamoeba vermiformis and Echinamoeba exudans. To our knowledge, this is the first report of the presence of potentially pathogenic FLA in ophthalmology wards in Iran. Improved disinfection methods and monitoring of hospitals ward are thus necessary in this area in order to minimize the risk of infection in patients.

Detection and Molecular Characterization of Potentially Pathogenic Free-living Amoebae from Water Sources in Kish Island, Southern Iran

Amoebic keratitis, a sight-threatening corneal infection, mainly occurs in contact lens wearers who wash their eyes with tap water. The present research was conducted to identify the occurrence of potentially pathogenic free-living amoebae (FLA) in tap water sources on Kish Island, a tourist region in Iran. Amoebae were detected using a culture-enriched method and by polymerase chain reaction (PCR)/sequencing of the diagnostic fragment 3 region of the 18S rRNA gene of Acanthamoeba. In the case of other free-living amoebae species, PCR/sequencing analysis of the 18S rDNA was conducted. Results of this study showed the presence of Acanthamoeba belonging to T3, T4, T5, and T11 genotypes in tap water sources. Additionally, Vermamoebae vermiformis was detected in three water samples. This is the first report of the Acanthamoeba genotypes T3, T4, T5, and T11 and V. vermiformis species in tap water sources in a tourist region in Iran.

Morphological Features and In Vitro Cytopathic Effect of Acanthamoeba griffini Trophozoites Isolated from a Clinical Case

Light and transmission electron microscopy observations are reported on the structure and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from a clinical case. Live trophozoites were moderately active with a remarkable pleomorphism which changed from ovoid to quite elongated shapes. When moving, amoebae formed cytoplasmic projections such as wide lamellae and acanthopodia of diverse size and thickness which contain a significant amount of actin. Ultrastructurally, the cytoplasm showed the main organelles found in other free-living amoebae. Coincubation of trophozoites with MDCK cell monolayers resulted in a local damage to target cells after 24 h of interaction, suggesting that the cytopathic effect is contact-dependent. By transmission electron microscopy, amoebae appeared to engulf small portions of the MDCK cells; however, the cells that were not in contact with trophozoites had an unaltered morphology. When epithelial monolayers were incubated with conditioned medium for 24 h, small areas of cell injury were also observed. The phylogenetical analysis as well as the sequencing of the acquired amplified product for the DF3 region of the amoebae isolate confirmed that it belongs to genotype T3, which includes other pathogenic amoebae; besides the activity of two drugs currently used against Acanthamoeba was tested on A. griffini.

Influence of Acanthamoeba genotype on clinical course and outcomes for patients with Acanthamoeba keratitis in Spain

Genotype T4 is by far the most frequent genotype of Acanthamoeba keratitis (AK) and therefore has been considered the most virulent. This study included 14 cases of AK of genotype T4 and three cases of non-T4 genotype. We found that cases of non-T4 genotype had a worse response to medical therapy, greater need for surgical intervention, greater risk of extracorneal involvement, and remarkably poorer final visual outcome than those of T4 genotype, suggesting an association between Acanthamoeba virulence and genotype that requires additional case investigation.

Co-isolation of Vahlkampfia and acanthamoeba in acanthamoeba-like keratitis in a Spanish population

PURPOSE

To report the co-isolation incidence of Acanthamoeba and Vahlkampfia in amoebic keratitis from a tertiary care institution in Madrid, Spain.

METHODS

In this retrospective case series, 7 eyes of 7 consecutive patients with culture-proven or polymerase chain reaction-positive Acanthamoeba keratitis were seen at a tertiary care institution from January 2010 to April 2011, and their charts were reviewed.

RESULTS

Two of 7 patients showed mixed Acanthamoeba and Vahlkampfia keratitis. Good clinical response to the treatment was strongly correlated with early diagnosis, whereas delayed diagnosis resulted in poor response to the treatment in single or mixed infection.

CONCLUSIONS

Co-isolation of Vahlkampfia and Acanthamoeba in Acanthamoeba-like keratitis has recently been detected in our population. This finding should raise awareness of the existence of other amoeba different from Acanthamoeba causing keratitis. There are not enough cases yet to determine the impact of mixed amoebic keratitis in the prognosis of this disease.

Identification of free-living amoebae and amoeba-associated bacteria from reservoirs and water treatment plants by molecular techniques

The occurrence of free-living amoebae (FLA) was investigated in 83 water samples from reservoirs and water treatment plants, with culture positive in 64 of them (77.1%). Polymerase chain reaction (PCR) of partial 18S rRNA gene and ITS region was performed in order to identify amoeba isolates, and the presence of Legionella pneumophila , Mycobacterium spp., Pseudomonas spp., and Microcystis aeruginosa was investigated in 43 isolates of amoebae by multiplex PCR. Of the isolated amoebae, 31 were Acanthamoeba spp., 21 were Hartmannella vermiformis, 13 were Naegleria spp., and one was Vanella spp. T2, T4, and T5 genotypes of Acanthamoeba have been identified, and T4 isolates were grouped into five subgenotypes and graphically represented with a Weblog application. Inside amoebae, L. pneumophila was detected in 13.9% (6/43) of the isolates, and Pseudomonas spp. and Mycobacterium spp. were detected in 32.6% (14/43) and 41.9% (18/43), respectively. No statistical correlation was demonstrated between FLA isolation and seasonality, but the presence of intracellular bacteria was associated with warm water temperatures, and also the intracellular presence of Mycobacterium spp. and Pseudomonas spp. were associated. These results highlight the importance of amoebae in natural waters as reservoirs of potential pathogens and its possible role in the spread of bacterial genera with interest in public and environmental health.

Potentially pathogenic free-living amoebae isolated from hospital wards with immunodeficient patients in Tehran, Iran

This study investigated the occurrence of free-living amoebae (FLA) in immunodeficiency wards of hospitals in Tehran, Iran. A total of 70 dust and biofilm samples from wards serving transplant, pediatric (malignancies), HIV, leukemia and oncology patients of five university hospitals were collected and examined for the presence of FLA using culturing and molecular approaches. Based on the morphology of the amoebae in plate cultures, primer sets were applied for molecular identification of Acanthamoeba, vahlkampfiid amoebae and Hartmannella. Out of 70 samples, 37 (52.9%) were positive for FLA. Acanthamoeba belonged to the T4 genotype was the most prevalent isolate. Presence of the T4 genotype on medical instruments, including an oxygen mask in an isolation room of an immunodeficiency pediatric ward, should be of concern for health authorities. Acanthamoeba T5 genotypes, Hartmannella vermiformis, and Vahlkampfia avara were also present. These results highlight a clear need for greater attention to improved disinfection, especially where susceptible patients, such as those who are immune-suppressed, are served. To our knowledge, this is the first report of these FLA in immunodeficiency wards in Iran, and also the first to identify Acanthamoeba T5, Hartmannella, and Vahlkampfia in moist habitats, such as biofilms, in this country.