Background: ACANTHAMOEBA keratitis develops by pathogenic ACANTHAMOEBA such as A. PALESTINENSIS. Indeed this species is one of the known causative agents of amoebic keratitis in Iran. Mannose Binding Protein (MBP) is the main pathogenicity factors for developing this sight threatening disease. We aimed to characterize MBP gene in pathogenic ACANTHAMOEBA isolates such as A. PALESTINENSIS.Methods: This experimental research was performed in the School of Public Health, Tehran University of Medical Sciences, Tehran, Iran during 2007-2008. A. PALESTINENSIS was grown on 2% non-nutrient agar overlaid with Escherichia coli. DNA extraction was performed using henol-chloroform method. PCR reaction and amplification were done using specific primer pairs of MBP. The amplified fragment were purified and sequenced. Finally, the obtained fragment was deposited in the gene data bank.Results: A 900 bp PCR-product was recovered after PCR reaction. Sequence analysis of the purified PCR product revealed a gene with 943 nucleotides. Homology analysis of the obtained sequence showed 81% similarity with the available MBP gene in the gene data bank. The fragment was deposited in the gene data bank under accession number EU678895 Conclusion: MBP is known as the most important factor in ACANTHAMOEBA pathogenesis cascade. Therefore, characterization of this gene can aid in developing better therapeutic agents and even immunization of high-risk people.

Introduction: ACANTHAMOEBA is an opportunistic protist, which is ubiquitously distributed in the environment. Infection with ACANTHAMOEBA spp. poses threat to human health, such as, ACANTHAMOEBA keratitis (AK) that is a vision-threatening infection of the cornea. This study aimed to identify the species of ACANTHAMOEBA strains isolated from cornea of keratitis patients by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Methods: ACANTHAMOEBA isolates investigated in this cross-sectional study, were collected from patients referring to Farabi Eye Reference Center. All 10 isolates were subjected to species identification using DNA based method. BspLI (NlaIV) and HpyCH4IV restriction enzymes were used to categorize the PCR amplified DNA by PCR-RFLP method. Results: Six samples were identified as ACANTHAMOEBA PALESTINENSIS and 4 isolates as ACANTHAMOEBA culbertsoni, which implies that all the isolates belong to pathogenic strains of ACANTHAMOEBA. Conclusion: ACANTHAMOEBA can enter the corneal tissue and survive in the eye, which results in AK. To the authors' knowledge, no study is available on species identification of this genus using these enzymes and technique. This is the first time in Iran that ACANTHAMOEBA isolates are subjected to species identification using PCR-RFLP method.

ACANTHAMOEBA species are vision-threatening agents by causing cornea infections known as ACANTHAMOEBA keratitis. A 5 year-old kid with the complaints of erythema, eyelid edema, inflammation, limitation of eye movements in the right eye, and having no history of wearing contact lenses or trauma, was diagnosed of ACANTHAMOEBA conjunctivitis through laboratory examinations in the Ophthalmology clinic. The visual sharpness of the patient improved after the treatment. A 44 year-old female patient suffering from pain, stinging, irritation, and inability to see in the left eye with the history of wearing contact lenses or trauma was diagnosed of ACANTHAMOEBA keratitis through laboratory examinations. The agent was isolated and identified as "A. castellani" in the Genotype "T2". Examination of the left eye on the 15th day of treatment indicated that all complaints disappeared except for the cataract originated visual loss. However, the first diagnosis of ACANTHAMOEBA keratitis appeared in the literature on a case with no history of wearing contact lenses and trauma it is found to be attention grabbing. We think that ACANTHAMOEBA should not be ignored among microbial agents that cause eye infection with or without trauma and contact lens usage history.

ACANTHAMOEBA keratitis (AK) is a serious, potentially sight-threatening corneal infection caused by a pathogenic free-living amoeba. Contact lens wear is the major risk factor in its etiology. This article will review previous studies on the parasitology, epidemiology, pathogenesis, clinical presentations, diagnosis and therapeutic options. This article review previous studies up to 2004 indexed in Medline with the key words: "ACANTHAMOEBA" and "keratitis", Articles with original, clinical, evidence-based and remarkable findings were selected. Data from about 30 articles were extracted. The first cases of AK were reported more than 30 years ago. Its incidence has gradually increased due to the widespread use of contact lenses. Different approaches have been developed to improve diagnosis. Various medications including aromatic diamidines, cationic antiseptics, aminoglycosides, and imidazole derivatives have been proposed for treatment of AK. The medical treatment protocol at Labbafmejad Center, is also introduced. Finally, different surgical modalities which should be considered in case of medically non-responsive AK are discussed. These include epithelial debridement, cryotherapy, lamellar keratectomy and finally penetrating keratoplasty. Although treatment of AK is difficult and time-consuming, early diagnosis and initiation of proper management has a vital role in final visual prognosis and globe integrity.

AbstractIntroduction: Chlorine is an effective disinfection agent to kill pathogenic microorganisms in the municipal water treatment system. However, despite treatment, studies have shown that ACANTHAMOEBA is isolated from different water sources in Iran. In this study, the effect of standard concentrations of chlorine used in urban water treatment systems was evaluated on the survival of ACANTHAMOEBA castellanii and its ultrastructure. Materials and methods: ACANTHAMOEBA trophozoites and cysts were exposed to different concentrations (1-10 ppm) of calcium hypochlorite at different times (30 minutes, 1 and 2 hours). Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to study the ultrastructural changes of amoebic trophozoite.Results: This study showed that conventional chlorine concentrations could not completely eliminate A. castellanii trophozoites and cysts. Cysts were more resistant to different chlorine concentrations and compared to trophozoites, fewer cysts were killed at the same chlorine concentration and exposure time. Alteration of the cell membrane permeability, decrease in the number of pseudopodia, increase in mitochondria, vacuolation of the cytoplasm, and changes in the endoplasmic reticulum were the main ultrastructural changes in the chlorine-treated amoeba.Conclusion: This study showed that standard chlorine concentrations used as a disinfectant could not eliminate the trophozoites and cysts of A. castellanii. Due to the pathogenicity of the amoeba and its role as the reservoir and transmission of microbial agents, revising the guidelines for using disinfectants such as chlorine in the treatment of urban water systems is highlighted by this study.

ACANTHAMOEBAis a free-living amoeba that is an opportunistic pathogen of humans and animals.Its prognosis is potentially poor that requires fast diagnosis and successful treatment. There are two phases in its life cycle: an active trophozoite form and the double-walled resistant cyst. This amoebic genus is the causative agent of two severe diseases in humans: ACANTHAMOEBA keratitis (AK) and fatal granulomatous amoebic encephalitis (GAE).ACANTHAMOEBA cysts almost remain viable after treatments and lead to serious and frequent recurrence of infection. Resistance of the double walled cysts is mainly due to cellulose molecules presented in the inner layer of the cysts. Thus, cellulose degradation or inhibiting the cellulose synthesis offers a potential strategy for effective treatment ofACANTHAMOEBA. In this non-systematic review we aimed at providing an overview of the cellulose structure, its role in skeletal structure and also physicochemical activity of the protozoa and present it as new drug target for the treatment of amoebic infection. Overall, the degradation of the cyst wall will make amoeba susceptible to chemotherapeutic drugs, and at least inhibition ofACANTHAMOEBA excystment, consequently it prevents the recurrence of infection. Furthermore, cellulose synthesis inhibitors cause current drugs to affect onACANTHAMOEBA in lower time and concentrations. Therefore, using compounds or drugs that inhibit the synthesis of cellulose can be a new treatment for amoebic infections.