Isolation and molecular characterization of Acanthamoeba genotypes in recreational and domestic water sources from Jamaica, West Indies

Assessment of in vitro dynamics of pathogenic environmental Acanthamoeba T4 and T9 genotypes isolated from three recreational lakes in Klang Valley, Malaysia over the HaCaT cell monolayer

Free-living amoebae of the genus Acanthamoeba are causative agents of keratitis and amoebic encephalitis. They are widely found in various ecological environments. Therefore, the present study brings results that can help to better understand the genotypes of the environmental isolates and their pathogenicity. This study procured 26 Acanthamoeba isolates from three recreational lakes in 2022. Polymerase chain reaction amplification was performed on positive Acanthamoeba samples. The thermotolerance, osmotolerance, and cytopathogenicity in human keratinocyte (HaCaT) cells of the samples were also evaluated. The phylogenetic analysis demonstrated that 12 isolates were of genotype T4, two (T9), six (T17), four (T8), and one each from T5 and T11. The thermo- and osmotolerance assays indicated that eight Acanthamoeba samples were potentially pathogenic. Two T4 and one T9 genotype also recorded 33-, 42-, and 133-kDa serine-type proteases, respectively. The HaCaT cell monolayer revealed that three T4 and one T9 samples achieved cytopathic effects within the 50-100% range, hence significantly cytotoxic. The lactate dehydrogenase secretion results demonstrated that three (T4) and one (T9) sample exhibited exceptional toxicity (over 40%) compared to the other samples. The responses of Acanthamoeba members with similar genotypes to pathogenicity indicator assays varied considerably, rendering correlation of pathogenicity with specific genotypes challenging.

[First isolation of Acanthamoeba spp. in seawater from the southeast of Buenos Aires (SE, Argentina)]

Free-living amoebae (FLA) of the genus Acanthamoeba are ubiquitous and amphizoic protozoa that colonize aquatic and terrestrial habitats and can serve as reservoirs for other microorganisms. They are considered econoses that can cause severe and rare pathologies. Due to limited epidemiological data available, the objective of this study was to investigate the presence of Acanthamoeba in coastal wetlands of the southeast of Buenos Aires province and evaluate their association with bacteriological and environmental variables. From February 2021 to July 2022, 22 seawater samples were collected at different points along the coast of the city of Mar del Plata (Buenos Aires, Argentina). Environmental parameters were determined and physicochemical and bacteriological studies, morphological identification, cultures and molecular typification were conducted. Regardless of the environmental and bacteriological variables, the presence of Acanthamoeba spp. was molecularly confirmed in 54.54% of the samples, being the first report of these protozoa in seawater in Argentina.

Saline-Tolerant Pathogenic Acanthamoeba spp. Isolated from a Geothermal Power Plant

Few studies have been conducted in the cooling systems of power plants; they have focused on Naegleria fowleri, leaving a gap in the knowledge of other pathogenic free-living amoebae in this environment. The objective of this study was to determine the occurrence of saline-tolerant pathogenic Acanthamoeba in a geothermal power plant. The identification of isolated amoebae at genus level was carried out, observing their morphological characteristics; the determination of genotype and species of Acanthamoeba was performed via molecular biology (PCR). Water temperature ranged from 18 to 43 °C and conductivity from 4.0 × 104 to 8.7 × 104 μS/cm; this last value was greater than the seawater value. Only five amoeba genera were found. Acanthamoeba was in all the sampling sites, showing high saline tolerance. The high temperature, but mainly high conductivity, were the environmental conditions that determined the presence of pathogenic free-living amoebae in the hot water. All the strains of Acanthamoeba culbertsoni killed the mice, having a mortality of 40 to 100%. Acanthamoeba genotypes T10 and T5 were identified, T10 is rarely isolated from the environment, while T5 is more frequent. This is the first time that genotypes T5 and T10 have been reported in the environment in Mexico.

Molecular characterisation and potential pathogenicity analysis of Acanthamoeba isolated from recreational lakes in Peninsular Malaysia

The present study aims to identify the Acanthamoeba genotypes and their pathogenic potential in three recreational lakes in Malaysia. Thirty water samples were collected by purposive sampling between June and July 2022. Physical parameters of water quality were measured in situ while chemical and microbiological analyses were performed in the laboratory. The samples were vacuum filtered through nitrate filter, cultured onto non-nutrient agar and observed microscopically for amoebic growth. DNAs from positive samples were extracted and made to react with polymerase chain reaction using specific primers. Physiological tolerance tests were performed for all Acanthamoeba-positive samples. The presence of Acanthamoeba was found in 26 of 30 water samples by PCR. The highest rate in lake waters contaminated with amoeba was in Biru Lake (100%), followed by Titiwangsa Lake (80%) and Shah Alam Lake (80%). ORP, water temperature, pH and DO were found to be significantly correlated with the presence of Acanthamoeba. The most common genotype was T4. Temperature- and osmo-tolerance tests showed that 8 (30.8%) of the genotypes T4, T9 and T11 were highly pathogenic. The presence of genotype T4 in habitats related to human activities supports the relevance of this amoeba as a potential public health concern.

Occurrence of enteric and non-enteric microorganisms in coastal waters impacted by anthropogenic activities: A multi-route QMRA for swimmers

The purpose of this study was to evaluate the microbial characteristics of coastal waters which are impacted by anthropogenic pollution as well as estimate the health risks associated with exposure to enteric and non-enteric microorganisms during swimming. Fecal indicator bacteria were highly detected in samples. Moreover, pathogenic and opportunistic microorganisms were found, with the highest frequency for Pseudomonas aeruginosa followed by Adenovirus 40/41, Acanthamoeba spp., Salmonella enterica, and Cryptosporidium parvum. The median risk of gastrointestinal illness through ingestion of water was estimated to be above the benchmark value of 0.05 per event recommended by WHO. Cryptosporidium followed by Adenovirus, showed higher illness risks than Salmonella. The potential risks of Acanthamoeba and P. aeruginosa were estimated to be low for both dermal and ocular exposure routes. However, there are uncertainties about the infectious fraction of pathogens existing in coastal waters and the delivered dose of microorganisms from dermal/ocular exposure during recreational activities.

Acanthamoeba Keratitis Risk Factors for Daily Wear Contact Lens Users: A Case-Control Study

PURPOSE

This study was designed to establish risk factors for the development of Acanthamoeba keratitis (AK) for daily disposable (DD) contact lens (CL) users compared with daily wear (DW) reusable lens users and for risks unique to DD users. This is important because, in many major economies, CL use is the principal cause of microbial keratitis, of which AK accounts for approximately 50% of cases with sight loss. Determining these AK risks informs practitioner advice and consumer behavior.

DESIGN

Case-control study.

PARTICIPANTS

Cases and controls were recruited from an Accident and Emergency Department serving South-East England. Cases were new CL users with AK recruited retrospectively from January 2011 to February 2013 and prospectively thereafter until August 2014. Controls were recruited prospectively from February 2014 to June 2015.

METHODS

Analysis of a self-administered questionnaire.

MAIN OUTCOME MEASURES

Independent risk factors and population attributable risk percentage (PAR%) for AK.

RESULTS

A total of 83 AK cases and 122 controls were recruited; DD use was reported by 20 (24%) cases and 66 (54%) controls. In multivariable analyses adjusted for potential confounders, the odds of AK was higher for DW reusable soft lenses (odds ratio [OR], 3.84; 95% confidence interval [CI], 1.75-8.43) and rigid lenses (OR, 4.56; 95% CI, 1.03-20.19) than for DD lenses. Within the DD-using subset, AK was associated with the following modifiable risk factors: less frequent professional follow-up visits (OR, 10.12; 95% CI, 5.01-20.46); showering in lenses (OR, 3.29, 95% CI, 1.17-9.23); lens reuse (OR, 5.41; 95% CI, 1.55-18.89); and overnight wear (OR, 3.93; 95% CI, 1.15-13.46). The PAR% estimated that 30% to 62% of cases could be prevented by switching from reusable soft lens to DD lens use.

CONCLUSIONS

Acanthamoeba keratitis risks are increased > threefold in DW reusable lens users versus DD lens use. Acanthamoeba keratitis risks for DD lens users can be minimized by adherence to safe use guidelines (no reuse, overnight wear, or contamination by water). Safe CL use can be improved by increasing the prominence of risk avoidance information from manufacturers and regulators. Because AK accounts for half of severe keratitis in CL users, these measures can be expected to have public health benefits.

Investigation of Parasitic Infection in Crocodile Lizards (Shinisaurus crocodilurus) Using High-Throughput Sequencing

The highly endangered crocodile lizard (Shinisaurus crocodilurus) continues to be impacted by disease, especially in captive breeding populations. In this paper, based on high-throughput sequencing, we investigated parasitic infections in captive and wild crocodile lizard populations in the Daguishan National Nature Reserve and Guangdong Luokeng Shinisaurus crocodilurus National Nature Reserve. The results show that the overall parasitic infection rate in crocodile lizards was 33.33% (23/69). Four parasite genera were detected, including Eimeria, Cryptosporidium, Nematopsis, and Acanthamoeba, with infection rates of 15.94% (11/69), 17.39% (12/69), 7.25% (5/69), and 4.35% (3/69), respectively. Significant differences in the infection rate were found between the different parasite species (χ2 = 8.54, p < 0.05, chi-squared test). The parasitic infection rates in the captive and wild populations were 39.29% (22/56) and 7.69% (1/13), respectively, which were significantly different (p < 0.05, Fisher’s exact test). However, no significant differences in the infection rates of the four parasite genera were found between the captive and wild populations (p > 0.05, Fisher’s exact test). The parasitic infection rates in Daguishan and Luokeng were 34.09% (15/44) and 32.00% (8/25), respectively, which were not significantly different (p > 0.05, Fisher’s exact test). However, significant differences in terms of species were found in the two reserves (p < 0.01, Fisher’s exact test). Only Cryptosporidium infection showed a significant difference between the two regions (p < 0.01, Fisher’s exact test). Our results suggest that captive crocodile lizards are more susceptible to parasitic diseases than wild crocodile lizards and that Cryptosporidium infection varies by geographical region. This study provides basic information about the parasites of endangered crocodile lizards, as well as a reference for disease control and conservation.

Identification of Acanthamoeba spp. from water and soil of public parks in the north of Iran

Acanthamoeba, a free-living and opportunistic protozoan parasite, is a causative agent of severe human infections of the cornea and brain. The present study evaluated the distribution and genotyping of Acanthamoeba spp. in water and soil of recreational places in various areas in Guilan province in northern Iran. Eighty water and 20 soil samples were collected from the study area. Water samples were vacuum filtered through a 0.45 μm pore-size membrane filter. Soil samples were washed with sterile distilled water, and washings were similarly filtered, as mentioned for water samples. The filtered material was cultured on non-nutrient agar plates seeded with heat-killed Escherichia coli. Molecular analysis was performed by PCR and sequencing using specific primers for Acanthamoeba. Finally, 26 isolates were successfully sequenced. According to culture and PCR methods, 54% of water and 100% of soil samples were contaminated with Acanthamoeba. Based on the sequencing data, genotypes T4 (47%), T5 (35.29%), T3 (11.76%), and T11 (5.88%) were identified in water samples. Genotypes T4 (66.6%), T5 (22.2%) and T15 (11.1%) were identified in water samples. Most isolates might present a potential health hazard for humans in this region. To the best of our knowledge, this is the first comprehensive survey of water and soil of recreational areas in northern Iran and the first report on identifying genotype T15 from soil sources.

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.

Survey and first report of Acanthamoeba T4 genotype in natural spring water resources in the Black Sea, Turkey

Infection with Acanthamoeba spp. may result in granulomatous amoebic encephalitis and Acanthamoeba keratitis. Water is an important habitat where Acanthamoeba species thrive. Therefore, studying the occurrence of this free-living amoeba in water sources will help understand the infection dynamics. The aim of the study was to survey and report on the presence of Acanthamoeba spp. in water resources from the Ordu and Giresun provinces in Black Sea. Acanthamoeba spp. was found in 1/17 natural spring water samples from Ordu and in 2/18 from Giresun. Acanthamoeba species were not detected in any of the investigated tap water samples. Sequencing of the (SSU) rDNA gene resulted in the identification of haplotype I (Acanthamoeba genotype: KJ094684). T4 (8.6%) was the only isolated genotype in both Ordu and Giresun provinces. This is the first report of Acanthamoeba T4 genotype in natural spring water resources in the Black Sea. The occurrence of Acanthamoeba species in natural spring water sources should be considered as a potential risk for human infection, especially to high-risk populations.

Acanthamoeba species isolated from marine water in Malaysia exhibit distinct genotypes and variable physiological properties

The present study identifies the Acanthamoeba genotypes and their pathogenic potential in five marine waters in Malaysia. Fifty water samples were collected between January and May 2019. Physical parameters of water quality were measured in situ, whereas chemical and microbiological analyses were conducted in the laboratory. All samples had undergone filtration using nitrocellulose membrane and were tested for Acanthamoeba using cultivation and polymerase chain reaction by targeting the 18S ribosomal RNA gene. The pathogenic potential of all positive isolates was identified using physiological tolerance tests. Thirty-six (72.0%) samples were positive for Acanthamoeba. Total coliforms (p = 0.013) and pH level (p = 0.023) displayed significant correlation with Acanthamoeba presence. Phylogenetic analysis showed that 27 samples belonged to genotype T4, four (T11), two (T18) and one from each genotype T5, T15 and T20. Thermo- and osmo-tolerance tests signified that three (8.3%) Acanthamoeba strains displayed highly pathogenic attributes. This study is the first investigation in Malaysia describing Acanthamoeba detection in marine water with molecular techniques and genotyping. The study outcomes revealed that the marine water in Malaysia could be an integral source of Acanthamoeba strains potentially pathogenic in humans. Thus, the potential risk of this water should be monitored routinely in each region.

Amoebal coculture and enrichment methods as a proposal for water quality control in Brazil

Free living amoebae (FLA) can be found in different environments, where they feed on diverse microorganisms. Some bacteria preyed by FLA are called amoeba-resistant bacteria (ARB), as they can resist to lysosomal fusion and are capable of multiplying and evading FLA after internalization, propagating in the environment. Despite the health risks due to the existence of pathogenic and opportunistic species that are ARB and the pathogenicity of some FLA species, there are no water quality protocols to analyze the presence of ARB or FLA. In this sense, our study aimed to isolate FLA through amoebal enrichment and to identify ARB using amoebal coculture in water samples from a public park and two hospitals in southern Brazil. As a result, 9 different microorganisms genera have been identified through amoebal coculture, including fastidious Legionella spp. and Bosea vestrisii. From the positive samples for FLA, by amoebal enrichment, Acanthamoeba spp., Vermamoeba vermiformis and Naegleria spp. were identified in 14 amoebic isolates. The methodologies used in this work proved to be effective as simple and low-cost methods to be used in the implementation in water quality control of anthropogenic environments.

Evaluation of molecular characterization and phylogeny for quantification of Acanthamoeba and Naegleria fowleri in various water sources, Turkey

Free-living amoeba (FLA) is widely distributed in the natural environment. Since these amoebae are widely found in various waters, they pose an important public health problem. The aim of this study was to detect the presence of Acanthamoeba, B. mandrillaris, and N. fowleri in various water resources by qPCR in Izmir, Turkey. A total of (n = 27) 18.24% Acanthamoeba and (n = 4) 2.7% N. fowleri positives were detected in six different water sources using qPCR with ITS regions (ITS1) specific primers. The resulting concentrations varied in various water samples for Acanthamoeba in the range of 3.2x10⁵-1.4x10² plasmid copies/l and for N. fowleri in the range of 8x10³-11x10² plasmid copies/l. The highest concentration of Acanthamoeba and N. fowleri was found in seawater and damp samples respectively. All 27 Acanthamoeba isolates were identified in genotype level based on the 18S rRNA gene as T4 (51.85%), T5 (22.22%), T2 (14.81%) and T15 (11.11%). The four positive N. fowleri isolate was confirmed by sequencing the ITS1, ITS2 and 5.8S rRNA regions using specific primers. Four N. fowleri isolates were genotyped (three isolate as type 2 and one isolate as type 5) and detected for the first time from water sources in Turkey. Acanthamoeba and N. fowleri genotypes found in many natural environments are straightly related to human populations to have pathogenic potentials that may pose a risk to human health. Public health professionals should raise awareness on this issue, and public awareness education should be provided by the assistance of civil authorities. To the best of our knowledge, this is the first study on the quantitative detection and distribution of Acanthamoeba and N. fowleri genotypes in various water sources in Turkey.

Detection of potentially pathogenic free-living amoebae from the Caspian Sea and hospital ward dust of teaching hospitals in Guilan, Iran

Free-living amoebae (FLA) thrive in diverse environmental conditions. The present study aimed to define the FLA distribution from the Caspian Sea as well as from hospital ward dust from Guilan, Iran. Seawater (20) and hospital ward dust samples (100) were collected from May to June 2018. Seawater samples were vacuum filtered through a 0.45 μm pore-size membrane. Dust was collected using sterile gauze, washed with sterile distilled water, with washings collected thereafter. Washings were similarly filtered as seawater samples. FLA from the filtered material was cultivated in non-nutrient agar. Molecular analysis was performed by PCR and sequencing using specific primers for Acanthamoeba, Naegleria, and Vermamoeba/Hartmanella. Culture and PCR returned 50 and 65% positivity, respectively, for seawater samples where sequencing revealed Acanthamoeba T2, T5 and T6 genotypes and A. palestinensis and A. lenticulata, as well as N. dobsoni and N. clarki. In addition, 30% amoebic growth and 16% PCR detection were observed from hospital ward dust samples where sequencing revealed Acanthamoeba T2, T4 and T11 genotypes and A. castellanii, A. palestinensis and A. stevensoni as well as N. clarki. For both seawater and dust samples, Acanthamoeba was the dominant isolate. The detection of potentially pathogenic FLA from seawater may pose a threat to the public, while the presence of the same in dust spells threats to both hospital staff and patients, in particular, immunocompromised individuals. Public education, awareness, improved sanitation and hygiene, and the crafting of diagnostic strategies for the early detection of FLA in humans are necessary for the mitigation and management of potential human infection cases.

Genotyping by Sequencing of Acanthamoeba and Naegleria Isolates from the Thermal Pool Distributed Throughout Turkey

PURPOSE

The main goal of this study was genotyping of free-living parasites and sub-grouping of pathogenic or non-pathogenic amebae obtained from Turkey's thermal springs. In so doing, distribution and abundance of possible pathogenic or causative strain for humans, which are caused by Acanthamoeba and Naegleria strains, would be elaborated. The number of extensive studies on the general occurrence and distribution of parasitic strains is very high worldwide, but there has been a paucity of information with regard to Turkey.

METHODS

From a total of 434 obtained thermal pool samples, free-living amebas were isolated from 148 water samples using the non-nutrient agar (NNA) culture method. Subsequently, the cultivated samples were used for DNA isolation; then 102 obtained DNA samples were subjected to PCR amplification using various primers for samples of genera Acanthamoeba and Naegleria. Ultimately, estimation of genotype or subtype was evaluated by sequencing.

RESULTS

About 29 samples that belong to Acanthamoeba and Naegleria were estimated from a total of 102 amplified PCR samples. These eukaryotic PCR products which have Acanthamoeba genus appearance, generated 26 subtypes and 3 Naegleria samples. Among the 26 Acanthamoeba genotypes, 22 aligned sequences were matched with various GenBank reference samples, while the 4 divergent genotypes were not elaborated and marked as ND. Most of the Acanthamoeba genera were determined as likely dominating groups and clustered as T form within totally eight groups. Eight, seven and three subtypes were found as T4A, T15 and T11 genotypes, respectively while the remainings were ultimately found in four groups. Results confirming the predominance of T4A, which is known the most causative form, the presence in the pools. Despite being uncommon, N. fowleri, lovaniensis and australiensis were also observed among the surveyed pools.

CONCLUSION

The present study is descriptive and is not unique. However, this is the most comprehensive study of the molecular distribution sampling of thermophilic Acanthamoeba and Naegleria that confirmed and demonstrated their ubiquitous presence throughout Turkey. By this estimation, in some spas, the most and likely causative form Acanthamoeba including T4 and Naegleria fowleri has also been confirmed.

Isolation and molecular identification of free-living amoebae (Naegleria spp., Acanthamoeba spp. and Vermamoeba spp.) from mineral springs in Guilan Province, northern Iran

Free-living amoebae (FLA) include many genera which cause serious diseases such as sight-threatening keratitis, cutaneous ulcers and fatal encephalitis. This study was conducted due to the lack of research regarding genotypes Acanthamoeba, Naegleria and Vermamoeba in mineral springs of Guilan Province in northern Iran. Twenty-five water samples were collected from mineral springs in Guilan Province. After filtration through nitrocellulose membrane, samples were cultured on non-nutrient agar plates. The morphological key of Page was used to identify free-living amoebae (FLA) using an inverted microscope. Positive cultures were analyzed by polymerase chain reaction (PCR) and genotypes based on the NCBI database. Eleven (44%) samples were positive for Acanthamoeba, Naegleria and Vermamoeba. By sequencing the positive isolates, the strains were shown to belong to Acanthamoeba castellanii (three case isolates belonged to T4 genotype), three cases of Vermamoeba vermiformis, and two cases of N. australiensis, two cases of N. pagei and one case of N. gruberi. According to our research the occurrence of Acanthamoeba, Naegleria spp. and Vermamoeba spp. in mineral springs could be hazardous for high risk persons. Regular monitoring and posting warning signs of these waters by health planners could prevent free-living amoebae mediated diseases.

Occurrence and molecular characterisation of Acanthamoeba isolated from recreational hot springs in Malaysia: evidence of pathogenic potential

This study aimed to identify the Acanthamoeba genotypes and their pathogenic potential in five recreational hot springs in Peninsular Malaysia. Fifty water samples were collected between April and September 2018. Physical parameters of water quality were measured in situ while chemical and microbiological analyses were performed in the laboratory. All samples were filtered through the nitrocellulose membrane and tested for Acanthamoeba using both cultivation and polymerase chain reaction (PCR) by targeting the 18S ribosomal RNA gene. The pathogenic potential of all positive isolates was identified using thermo- and osmotolerance tests. Thirty-eight (76.0%) samples were positive for Acanthamoeba. Water temperature (P = 0.035), chemical oxygen demand (P = 0.026), sulphate (P = 0.002) and Escherichia coli (P < 0.001) were found to be significantly correlated with the presence of Acanthamoeba. Phylogenetic analysis revealed that 24 samples belonged to genotype T4, nine (T15), two (T3) and one from each genotype T5, T11 and T17. Thermo- and osmotolerance tests showed that 6 (15.79%) of the Acanthamoeba strains were highly pathogenic. The existence of Acanthamoeba in recreational hot springs should be considered as a health threat among the public especially for high-risk people. Periodic surveillance of hot spring waters and posting warning signs by health authorities is recommended to prevent disease related to pathogenic Acanthamoeba.

Isolation, identification, and phylogenetic analysis of potentially pathogenic free-living amoebae isolated from nasal and oral mucosa of HIV/AIDS patients in Iran

The burden of HIV/AIDS in Iran is not as high as in the other countries with high prevalence; however, the number of cases of HIV/AIDs is increasing in this region. According to a recent report, Iran had 5000 (1400-13,000) new cases of HIV infection with 4000 (2500-6200) AIDS-related deaths. Individuals affected by HIV/AIDS are highly susceptible for developing opportunistic infections, e.g. the cerebral complications related to pathogenic free-living amoebae and colonization of free-living amoebae (FLA) can be a serious hazard for patients living with HIV/AIDS. In the present study, a total of 70 oral and nasal mucosal samples were obtained from HIV/AIDS patients referred to the reference hospitals in Iran and tested for the presence of potentially pathogenic FLA using culture and PCR/sequencing-based methods. To discern the taxonomic status of Acanthamoeba genotypes a maximum likelihood phylogenetic tree was constructed and tolerance assays were performed for the positive Acanthamoeba strains. Among the patients with HIV/AIDS referred to the reference hospitals from 2017 to 2019, 7.1% were found positive for pathogenic free-living amoebae. Three strains (HA3, HA4, and HA5) belonged to the T4 genotype, one strain (HA1) was related to the T5 genotype assigned as A. lenticulata, and another strain (HA2) had high homology to Vermamoeba vermiformis. The tolerance assay used for Acanthamoeba strains (HA1, HA3, and HA4) classified these amoebae as highly pathogenic strains. For the most part, the encephalitis cases occurring in HIV/AIDS patients in Iran remain undiagnosed due to lack of awareness of the practitioners on the available diagnostic tools for this lethal infection; therefore, the true incidence of GAE in this region is unknown. A possible colonization with FLA should be considered in the differential diagnosis of suspected cases of CNS infections among HIV/AIDS patients. This study is the first worldwide comprehensive study attempting to isolate and identify the FLA colonization in HIV/AIDS patients. This study highlights the fact that clinicians should be aware of the differential diagnosis of cerebral disease related to FLA in patients with HIV/AIDS.

Thermotolerant Acanthamoeba spp. isolated from recreational water in Gorgan City, north of Iran

Acanthamoeba as free-living parasites are scattered ubiquitously, throughout the world. This study was aimed to evaluate the presence of Acanthamoeba spp. genotypes in the recreational water sources in Gorgan County, the capital of Golestan Province using both morphological and molecular approaches. Thirty water samples were collected from different recreational waters in Gorgan, the capital of Golestan Province, northern Iran during 2015-2016. Samples were filtered and followed by culture in non-nutrient agar. Acanthamoeba were identified both by morphological and molecular analysis. The pathogenical potential of positive cloned samples were also determined using tolerance test. Twenty-six percent of recreational water were identified as Acanthamoeba spp. based on the morphological analysis and from these positive samples, five samples were successfully sequenced after molecular studies. Phylogenetic analysis showed the clustering of four samples in T4 genotype group and only one sample as T15 genotype. Thermotolerance test revealed that all cloned samples were highly positive. Since the attractiveness of recreational places for people is increasing, the potential risk of this water should be monitored routinely in each region. More studies are needed to better evaluate the risk of this ubiquitous parasite for the human.

Occurrence of free-living amoebae (Acanthamoeba, Balamuthia, Naegleria) in water samples in Peninsular Malaysia

The aim of this study was to determine the occurrence of free-living amoebae (FLA) in Peninsular Malaysia and to compare different methodologies to detect them from water samples. Water samples were collected from tap water, recreational places, water dispensers, filtered water, etc. and tested for FLA using both cultivation and polymerase chain reaction (PCR) via plating assays and centrifugation methods. Amoebae DNA was extracted using Instagene matrix and PCR was performed using genus-specific primers. Of 250 samples, 142 (56.8%) samples were positive for presence of amoebae, while 108 (43.2%) were negative. Recreational water showed higher prevalence of amoebae than tap water. PCR for the plating assays revealed the presence of Acanthamoeba in 91 (64%) samples and Naegleria in 99 (70%) of samples analysed. All samples tested were negative for B. mandrillaris. In contrast, the centrifugation method was less effective in detecting amoebae as only one sample revealed the presence of Acanthamoeba and 52 (29%) samples were positive for Naegleria. PCR assays were specific and sensitive, detecting as few as 10 cells. These findings show the vast distribution and presence of FLA in all 11 states of Peninsular Malaysia. Further studies could determine the possible presence of pathogenic species and strains of free-living amoebae in public water supplies in Malaysia.

The many lives of nontuberculous mycobacteria

Nontuberculous mycobacteria (NTM) include species that colonize human epithelia, as well as species that are ubiquitous in soil and aquatic environments. NTM that primarily inhabit soil and aquatic environments include the Mycobacterium avium complex (MAC, M. avium and Mycobacterium intracellulare) and the Mycobacterium abscessus complex (MABSC, M. abscessus subspecies abscessus, massiliense, and bolletii), and can be free-living, biofilm-associated, or amoeba-associated. Although NTM are rarely pathogenic in immunocompetent individuals, those who are immunocompromised - due to either an inherited or acquired immunodeficiency - are highly susceptible to NTM infection (NTMI). Several characteristics such as biofilm formation and the ability of select NTM species to form distinct colony morphotypes all may play a role in pathogenesis not observed in the related, well-characterized pathogen Mycobacterium tuberculosis The recognition of different morphotypes of NTM has been established and characterized since the 1950s, but the mechanisms that underlie colony phenotype change and subsequent differences in pathogenicity are just beginning to be explored. Advances in genomic analysis have led to progress in identifying genes important to the pathogenesis and persistence of MAC disease as well as illuminating genetic aspects of different colony morphotypes. Here we review recent literature regarding NTM ecology and transmission, as well as the factors which regulate colony morphotype and pathogenicity.

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.

Isolation and molecular characterization of Acanthamoeba strains isolated from the oral cavity of immunosuppressed individuals in Tehran, Iran

Acanthamoeba spp. is an opportunistic protozoan parasite which is the causative agent of granulomatous amoebic encephalitis (GAE) and Acanthamoeba keratitis (AK). GAE usually occurs in immunocompromised patients which in most cases is fatal. The present study was conducted to determine the genotypes of Acanthamoeba isolated from patients with compromised immunological status. For this purpose, 90 samples from the oral cavity of these individuals were collected in different hospitals of Tehran, Iran using sterile cotton swabs. Samples were cultured in 2% Non-Nutrient Agar (NNA) plates in order to check for the presence of amoebae. Identification of isolates was carried out using both morphological and molecular tools. The pathogenic potential of the obtained strains was assessed by performing osmo- and thermotolerance assays as previously described. Genotyping of the isolates was carried out by PCR/sequencing of the DF3 region of the 18S rDNA gene of Acanthamoeba. From the 90 collected samples, 11 (13.4%) were positive for Acanthamoeba genus. Molecular analysis revealed the presence of genotypes T3, T4 and T11, although most of the isolates belonged to genotype T4. Only 3 of the isolates genotyped as T4 were positive for the pathogenic potential assays. To this end if the immunological status is considered as one of the key factors for the development of GAE due to Acanthamoeba in the previous reported cases, individuals suffering from the conditions mentioned in this study should be considered as a high risk group of population in Iran and worldwide.

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.

Isolation and identification of Acanthamoeba species from natural water sources in the northeastern part of Thailand

Acanthamoeba are found in the environment, particularly in water, all over the world. The genus is currently classified into 20 different genotypes, T1-T20. In this study, 63 natural water samples from 11 provinces in northeast Thailand were collected and cultured on non-nutrient agar plates. Positive samples by culture were subsequently analyzed by molecular methods. The identification of Acanthamoeba was based on morphological features and molecular techniques using PCR and DNA sequencing. The results showed that 10 samples out of 63 were positive (15.9 %). Phylogenetic analysis revealed that seven samples were T4, one sample was similar to T3, and the other two samples were similar to T5. This is the first report demonstrating the contamination of Acanthamoeba species in natural water sources in northeast Thailand.