当前世界环境

Introduction

Free living amoebae includingAcanthamoeba,Hartmannella,Vahlkampfia,VannellaandNaegleriaare small amphizoic protozoan parasites which feed on natural environment contents such as bacteria and fungi. These organisms are resistant to extreme environmental conditions including unfavorable temperature, pH ranges and exposure to chemicals in cyst stage and they transfer to trophozoite when condition became favorable (Stockmanet al.,2011) (Pelletieret al., 2011)

Free living amoebae could be isolated from water resources, soil, sewage and even contact lens washing solution and dialysis machine(Marciano-Cabral et al.,2003). The most common cause of amoebic keratitis (AK) associated withAcanthamoebais improper usage of soft contact lenses such as taking shower or swimming in suspected water sources while wearing lenses (Martinez AJ et al.,1997)( Radford CF et al.,1992). The mentioned infection causes severe eye pain, uveitis wounds, photophobia and blindness (Dart, 1993).

Unlike amoebic keratitis, granulomatous amebic encephalitis (GAE) has been reported only from immunocompromised individuals. Indeed, normal immune system could prevent the parasite pathogenesis. Main routes of parasite entrance in GAE are cysts inhalation and contact of skin wounds with contaminated environmental sources (Marciano-Cabralet al., 2003).

Although some drugs like biguanide, diamidine and triazoles are choices for both diseases, treatment is difficult and it fails in majority of cases. It should be mentioned that other free living amoebae such asVahlkampfiaandHartmannellacould be the cause of infection in both immunocompetent and immunosuppressed patients. Interestingly there are several case reports in Iran during recent years regarding Ak due to Vahlkampfia and Hartmannell(Niyyati M et al.,2010). It should be mentioned that due to increasing number of high risk individuals and extended spread of pathogenicFLA, outbreaks can be predicted in future. Overall, occurrence of free living amoebae in recreational water bodies may constitute a source of amoebae for high risk people including contact lens wearers and immunosuppressed patients.

Kaleybar and Khomarlou cities are the centers of Kaleybar and Khodaafarin counties, respectively which both located in East Azerbaijan Province, northwest of Iran. Kaleybar and Khodaafarin are located 1240 meters above sea level. Both counties together have a population of 83814 in 2012 census (48837 and 34977 respectively). The counties total area is 3702 km². Kaleybar and Khodaafarin have a mountain climate with regular seasons.

Overall, there were no data regarding the occurrence of free living amoebae in water bodies in Kalaybar and Khodaafarin Counties thus the present research was conducted to clarify the presence of free living amoebae using morphological key. To the best of our knowledge this is the first report of occurrence of FLA in this region.

Material and Methods

Sampling

50 water samples (500–1500ml) were collected from different water resources of Kaleybar and Khodaafarin Counties in East Azarbayjan Province (Figure 1), in March and November 2014 including hot-springs (3 samples), cold-springs (29 samples), rivers (5 samples), wells (2 samples), refined drinking water (10 samples) and subterranean canal (1 sample). The samples were transferred to Protozoology laboratory, Shahid Beheshti University of Medical Science, Tehran, Iran and stored at room temperature.

Figure 1:Star show Kaleybar and Khodaafarin position in East Azerbaijan province Click here to View figure

Filtration and Cultivation

Approximately 250 ml of each sample filtered through cellulose nitrate membrane (pore size of membranes were equal 1.6µm).¹⁰After filtering middle part of each membrane were cut out and cultured. Culturing conducted on 1.5% non-nutrient agar containingEscherichia colibacteria. Plates were then incubated at room temperature up to two month.

Microscopic Examination and Cloning

Investigation of plates started after one week and continued daily up to two month. Positive samples were identified using light microscopy using x100 magnification. Cloning were then performed for elimination of bacteria and fungi contamination and also to isolate each clone of free living amoebae in mixed amoebae plates. Identification was based on page key and according to morphological criteria of each cloned amoebae.

Results

一个完全的l of 20 (%40) out of 50 samples were positive in microscopic examination. Isolated genera were belonged toAcathameobaegenus (Figure 2 and 3),Thechameoba(Figure 4),Hartmannella(Figure 5),ValkamphiidsandVannella(Figure 6).Acanthamoebawere detected by its double walled shape and flat trophozoite with obvious acanthopodia.Hartmannellidaewere identified by its wormy shape trophozoites and small round cysts.Vannellawere characterized by its fan shaped trophozoites andVahlkampfidshad round cysts measuring approximately 10 micron, their trophozoite were long and wormy shape.

Number and percentage of positive water resources and isolated amoebae are shown in table1 and table 2, respectively.

Table 1: positive samples of water resource (number and percentage)

Resource	Number of samples	Number of positive samples	Positive percentage
Cold spring	29	11	%38
Refined drinking water	10	3	%30
River	5	4	%80
Hot-spring	3	1	%33
Well	2	1	%50
Subterranean canal	1	0	%00
Total	50	20	%40

Table 2: Isolated free living amoeba from water samples and their percentage

Amoebae genus	Number of positive samples	Percentage
Acanthamoebae	12	%60
Thecameoba	2	%10
Harmannella	7	%35
Valkamphia	4	%20
Vannella	4	%20
Mix	9	%45

Figure 2: Acanthamoeba flat shape trophozoites (x100) Click here to View figure

Figure 3: Acanthamoeba cysts(x100) Click here to View figure

Figure 4: Clump of Thechamoeba trophozoites Click here to View figure

Figure 5: Hartmanellidae cysts (x100) Click here to View figure

Figure 6: Vannella with fan shape trophozoites (x100) Click here to View figure

Discussion

目前的研究调查occurrence of free living amoeba in Kaleybar and Khodaafarin Counties water resources by culture method and microscopic investigation. The present study showed 20 out of 50 (%40) water samples were contaminated to potentially pathogenic free living amoebae. About half (9 out of 20) of samples had mix contamination and various amoebae were detected. As expected the frequency ofAcanthamoebaspecies (12 samples out of 20 samples) were higher than others and the least occurance belonged toThechameoba(2 samples out of 20 positive samples). In addition present study suggests that different kind of water resources (cold spring, hot spring, refined drinking water, river and well) were contaminated to at least one amoeba, but the highest contamination was seen in rivers water with 4 positive samples out of a total of 5 samples. Although the subterranean canal sample result was negative but because of the low sample number (1 sample) this result cannot be reliable.

Based on Bagheri et al. study, 45 samples out of 94 tap water samples (%48) were contaminated withAcanthamoeba.¹¹In this study samples were collected from tap water of hospitals in different cities of Iran. According to our studyAcanthamoebacontamination was also higher in their research. High occurrence ofAcanthamoebais mainly due to its resistance to extreme environmental conditions. This level of resistance is contributed to morphological changes and development of cyst stage. Cyst form is resistant to a wide range of temperature, pH and osmalarity.

Ghadar-ghadr et al. reported %48 contamination of different kinds of water resources with free-living amoeba by using culturing, giemsa staining and microscopic investigation methods(Solhjoo K et al., 2012) Identified amoebae in their research wereNaegleria and Acanthamoeba.

Nazar et al. determined %32 contamination withAcanthamoebain water resources(Nazar M et al.,2011) Samples were collected from parks and public squares in this research. The mentioned study reported higher contamination toAcanthamoebain comparison to present study, however they did not identify other free living amoebae in their samples. Another research in Spain revealed that 48 out of 88 (%59.5) tap water containedAcanthamoeba.

Other identified amoebae in the present research wereHartmannellidaeandVahlkampfiidsboth are causative agents of amoebic keratitis in Iran and worldwide.^8,9Keratitis due toHartmannellaandVahlkampfiaalso showed poor prognosis and they could lead to loss of vision. Thus recreational water contamination to such amoebae could be a health hazard for high risk people and education to contact lens wears regarding avoidance of contact with suspected water is necessary.

As we see in present study free living amoebae can be found in different natural water resources associated with human activity in Kalaybar and Khodaafarin Counties with high frequency. This is the first study which showed water bodies contamination to free living amoebae in this region and this issue could reflect a potential hazard particularly for contact lens wearers and immunosuppressed patients. Posting of alarming sign in recreational water places could be an approached to prevent free living amoebae related infections. More researches should be implicated regarding molecular analysis of free living amoebae in this Counties.

Acknowledgment

Dr. Maryam Niyyati has been funded by young associated professor grant of Elite foundation.

Thanks are due to Mr. Kamandar Sheikhzadeh, Mr. Jabbar Dirineh, Mr. Seyed Ahmad Karamati and Mr. Amir Reza Javadi for their kind help in processing of the samples.

References

1. Stockman LJ, Wright CJ, Visvesvara GS, Fields BS, Beach MJ. Prevalence of Acanthamoeba spp. and other free-living amoebae in household water, Ohio, USA—1990–1992. Parasitology research. 2011;108(3):621-7. (Stockmanet al.,2011)
2. Pelletier JS, Miller D, Liang B, Capriotti JA. In vitro efficacy of a povidone–iodine 0.4% and dexamethasone 0.1% suspension against ocular pathogens. Journal of Cataract & Refractive Surgery. 2011;37(4):763-6. (Pelletieret al., 2011)
3. Khan NA, Tareen NK. Genotypic, phenotypic, biochemical, physiological and pathogenicity-based categorisation of Acanthamoeba strains. Folia parasitologica. 2003;50(2):97-104.
4. Marciano-Cabral F, Cabral G. Acanthamoeba spp. as agents of disease in humans. Clinical Microbiology Reviews. 2003;16(2):273-307.
5. Martinez AJ, Visvesvara GS. Free‐living, amphizoic and opportunistic amebas. Brain Pathology. 1997;7(1):583-98.
6. Radford CF, Lehmann OJ, Dart JK.Acanthamoebakeratitis: multicentre survey in England 1992–6. British journal of ophthalmology. 1998;82(12):1387-92.
7. Dart J. Disease and risks associated with contact lenses. The British journal of ophthalmology. 1993;77(1):49.(Dart, 1993)
8. Niyyati M, Lorenzo-Morales J, Rezaie S, Rahimi F, Martín-Navarro CM, Mohebali M, et al. First report of a mixed infection due toAcanthamoebagenotype T3 andVahlkampfiain a cosmetic soft contact lens wearer in Iran. Experimental parasitology. 2010;126(1):89-90.
9. Abedkhojasteh H, Niyyati M, Rahimi F, Heidari M, Farnia S, Rezaeian M. First Report of Hartmannella keratitis in a Cosmetic Soft Contact Lens Wearer in Iran. Iranian journal of parasitology. 2013;8(3):481.
10. Rezaeian M, Niyyati M, Farnia S, Haghi AM. Isolation ofAcanthamoebaspp. from different environmental sources. Iranian Journal of Parasitology. 2008;3(1):44-7.
11. Bagheri H, Shafiei R, Shafiei F, Sajjadi S. Isolation ofAcanthamoeba Spp. from drinking waters in several hospitals of Iran. Iranian journal of parasitology. 2010;5(2):19.
12. Sh G-g, Solhjoo K, MJ N-n, Rohi R, Zia-Jahromi S. Isolation and identification of free living amoeba (NaegleriaandAcanthamoeba) in Shiraz water resources by morphological criteria. Journal of Jahrom University of Medical Sciences. 2012;10(3):27.
13. Nazar M, Haghighi A, Niyyati M, Eftekhar M, Tahvildar-Biderouni F, Taghipour N, et al. Genotyping ofAcanthamoebaisolated from water in recreational areas of Tehran, Iran. Journal of water and health. 2011;9(3):603-8.
14. Lorenzo-Morales J, Lindo J, Martinez E, Calder D, Figueruelo E, Valladares B, et al. PathogenicAcanthamoebastrains from water sources in Jamaica, West Indies. Annals of tropical medicine and parasitology. 2005;99(8):751-8.