Contact lenses contamination by Acanthamoeba spp. in Upper Egypt

Background Acanthamoeba spp. are one of the free-living amoeba that spread worldwide causing keratitis. Owing to the increase in the use of lenses, whether for medical or cosmetic purposes, the incidence of disease increases every year. Contamination of the lenses with the Acanthamoeba trophozoites or cysts may lead to eye infection and cause sight-threatening keratitis in human. We isolated Acanthamoeba spp. from new lenses, used lenses, and contact lens disinfecting solutions and identified them based on morphological characteristics and molecular test. Methods New and used lenses and contact lens disinfecting solutions were cultured on monogenic media. Light and scanning electron microscope was used to identify Acanthamoeba spp. morphological features. Genotype identification was also evaluated using PCR sequencing of 18S rRNA gene specific primer pair JDP1 and JDP2. Results A hundred samples were examined, 29 (29%) were infected with Acanthamoeba spp. That belonged to two strains of Acanthamoeba (Acanthamoeba 41 and Acanthamoeba 68). 18S rRNA of the Acanthamoeba 41 had 99.69% sequence identity to Acanthamoeba castellanii clone HDU-JUMS-2, whereas Acanthamoeba 68 had 99.74% similar pattern to that of Acanthamoeba sp. isolate T4 clone ac2t4 that are morphologically identified as Acanthamoeba polyphaga. The obtained data revealed that the isolated strains belong to T4 genotype that was evolutionarily similar to strains isolated in Iran. Conclusions Cosmetic lenses and disinfectant solutions are a major transmissible mode for infection. This genotype is common as the cause of Acanthamoeba keratitis. To avoid infection, care must be taken to clean the lenses and their preservative solutions and prevent contamination with the parasite.

Mycobacterium avium Subsp. hominissuis Interactions with Macrophage Killing Mechanisms

Non-tuberculosis mycobacteria (NTM) are ubiquitously found throughout the environment. NTM can cause respiratory infections in individuals with underlying lung conditions when inhaled, or systemic infections when ingested by patients with impaired immune systems. Current therapies can be ineffective at treating NTM respiratory infections, even after a long course or with multidrug treatment regimens. NTM, such as Mycobacterium avium subspecies hominissuis (M. avium), is an opportunistic pathogen that shares environments with ubiquitous free-living amoeba and other environmental hosts, possibly their evolutionary hosts. It is highly likely that interactions between M. avium and free-living amoeba have provided selective pressure on the bacteria to acquire survival mechanisms, which are also used against predation by macrophages. In macrophages, M. avium resides inside phagosomes and has been shown to exit it to infect other cells. M. avium’s adaptation to the hostile intra-phagosomal environment is due to many virulence mechanisms. M. avium is able to switch the phenotype of the macrophage to be anti-inflammatory (M2). Here, we have focused on and discussed the bacterial defense mechanisms associated with the intra-phagosome phase of infection. M. avium possesses a plethora of antioxidant enzymes, including the superoxide dismutases, catalase and alkyl hydroperoxide reductase. When these defenses fail or are overtaken by robust oxidative burst, many other enzymes exist to repair damage incurred on M. avium proteins, including thioredoxin/thioredoxin reductase. Finally, M. avium has several oxidant sensors that induce transcription of antioxidant enzymes, oxidation repair enzymes and biofilm- promoting genes. These expressions induce physiological changes that allow M. avium to survive in the face of leukocyte-generated oxidative stress. We will discuss the strategies used by M. avium to infect human macrophages that evolved during its evolution from free-living amoeba. The more insight we gain about M. avium’s mode of pathogenicity, the more targets we can have to direct new anti-virulence therapies toward.

Molecular Identification of Pathogenic Free-Living Amoeba from Household Biofilm Samples in Iran: A Risk Factor for Acanthamoeba Keratitis

Free-living amoeba (FLA) are ubiquitously distributed in the environment. However, they are also the causative agents of opportunistic infections in humans and other animals. A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. Moreover, FLA have been detected in various biofilms around the world. Therefore, the present study aimed to check for presence of FLA in samples from household biofilms in Iran and to characterize them at the molecular level. A total of 69 biofilm samples collected from showerheads, kitchen areas, and bathroom sinks were analyzed. Positive samples for FLA were characterized at the morphological and molecular levels. Furthermore, the results of morphology analysis indicated that 26.08% (18/69) of biofilm samples were positive for Acanthamoeba spp., Vermamoeba genus, and Vahlkampfiids. According to sequence analysis, five strains of Acanthamoeba isolates related to the T4 genotype and two strains belonged to the T2 genotype. In addition, the pathogenic potential of Acanthamoeba-positive isolates was conducted using the tolerance ability test. The results of BLASTn of Vermamoeba sequences were similar to what was expected for Vermamoeba vermiformis. The above-mentioned reasons revealed that the relative high contamination of household biofilm samples with FLA may pose a risk for people using soft contact lenses and for patients with traumatic cataract. Our finding proposes that filtration should be performed in shower heads and indicates the need to monitor people at increased risk of Acanthamoeba keratitis.

High occurrence of Acanthamoeba spp. in the water samples of public swimming pools from Kerman Province, Iran

Acanthamoeba spp. is a free-living amoeba that can cause major infections in humans, including keratitis and granulomatous encephalitis. Thus, water resources play an important role in transmitting Acanthamoeba spp. infection to humans. The purpose of this study was to investigate the presence of Acanthamoeba spp. in public swimming pools from three cities of Kerman Province, southeastern Iran. Eighty water samples of 20 public indoor swimming pools were taken from Kerman, Jiroft, and Kahnauj cities. Water temperature (°C), pH, and free chlorine concentration (ppm) were measured. Filtration and cultivation were applied on non-nutrient agar medium. The polymerase chain reaction was applied by using the genus-specific primers (JDP1 and JDP2) on positive samples; these primers can amplify the 423–551 bp fragment. Eighteen of the 20 swimming pools (including 32/80; 40% samples) were contaminated with Acanthamoeba spp. All swimming pools of Jiroft and Kahnauj and 88.2% of swimming pools in Kerman were contaminated. As such, all 32 Acanthamoeba isolates were amplified using the JDP primer pairs. Two genotypes, T3 and T4, were also identified. The present research is the first to report Acanthamoeba spp. in public swimming pools from Kerman Province. Due to high occurrence of this protozoan, it is recommended to use warning signs around swimming pools to create awareness of this infection.

Effect of a Commercial Disinfectant CLORICAN® on Acanthamoeba spp. and Naegleria fowleri Viability

Swimming pool water treatment by chemicals is an essential step to avoid microbial proliferation and infections namely caused by free living amoeba such as, for example, primary amebic meningoencephalitis and Acanthamoeba keratitis. In the present study, a commercial reactive, CLORICAN, based on chlorine dioxide, was evaluated against Acanthamoeba spp. and Naegleria fowleri. We observed that CLORICAN could eliminate in a short period of incubation time both amoebae. Furthermore, Naegleria fowleri’s trophozoites were more sensitive than those of Acanthamoeba spp. By means of inverted microscopy, the chlorine dioxide was found to greatly affect morphology shape by increasing the cell size shrinkage.

Anaerobic derivates of mitochondria and peroxisomes in the free-living amoeba Pelomyxa schiedti revealed by single-cell genomics

Pelomyxa schiedti is a free-living amoeba belonging to the group Archamoebae, which encompasses anaerobes bearing mitochondrion-related organelles (MROs) - hydrogenosomes in free-living Mastigamoeba balamuthi and mitosomes in the human pathogen Entamoeba histolytica. Anaerobic peroxisomes, another adaptation to anaerobic lifestyle, were identified only recently in M. balamuthi. We found evidence for both these organelles in the single-cell-derived genome and transcriptome of P. schiedti, and corresponding vesicles were tentatively revealed in electron micrographs. In silico reconstructed MRO metabolism seems similar to that of M. balamuthi harboring respiratory complex II, electron-transferring flavoprotein, partial TCA cycle running presumably in reductive direction, pyruvate:ferredoxin oxidoreductase, [FeFe]-hydrogenases, glycine cleavage system, and sulfate activation pathway. The cell disposes with an expanded set of NIF enzymes for iron sulfur cluster assembly, but their localization remains unclear. Quite contrary, out of 67 predicted peroxisomal enzymes, only four were reported also in M. balamuthi, namely peroxisomal processing peptidase, nudix hydrolase, inositol 2-dehydrogenase, and D-lactate dehydrogenase. Other putative functions of peroxisomes could be pyridoxal 5′-phosphate biosynthesis, amino acid and carbohydrate metabolism, and hydrolase activities. Future experimental evidence is necessary to define functions of this surprisingly enzyme-rich anaerobic peroxisome.