Acanthamoeba Keratitis: The Emerging Vision-Threatening Corneal Disease

Some Acanthamoeba species are distributed in natural and man-made environments, in a wide range of soil and aquatic habitats, also in clinical settings. The amphizoic organisms can exist as facultative parasites - causative agents of serious human disease, Acanthamoeba keratitis. The vision-threatening eye disease occurring particularly in contact lens wearers is reported with increasing prevalence in different regions of the world. The amoebic keratitis is difficult to diagnose as clinical symptoms are similar to those observed in other eye diseases. Moreover, bacterial, viral, fungal, and amoebic co-infections frequently occur; also amoebae act as carriers for ~ 20 species pathogenic for humans, e.g. from Pseudomonas, Legionella, Mycobacterium and Escherichia genera; thus the corneal disease is frequently misdiagnosed. Complex etiology, late proper recognition of amoebic infections, and the exceptional resistance of Acanthamoeba cysts to chemicals are important factors influencing diagnostic and therapeutic difficulties. Surgical interventions are needed as an alternative treatment in refractory Acanthamoeba keratitis. It should be taken into consideration that the knowledge and awareness of increasing threat generated by the amphizoic amoebae are still insufficient. This compilation presents selected aspects of eye disease that is becoming the increasingly significant for human health worldwide

Molecular identification of Trichomonas tenax in the oral environment of domesticated animals in Poland – potential effects of host diversity for human health

Introduction The protozoan Trichomonas tenax is considered to be a human specific flagellate of the oral cavity, found in humans with poor oral hygiene and advanced periodontal disease. Morphological variability and great similarity between species occurring in humans and animals, complicate the specific identification of trichomonads, using microscopic examination and other standard parasitological techniques. Objective The aim of the study was to search for and identify T. tenax in domesticated animals using molecular methods. The obtained data were assessed in terms of potential effects of a spread of the species deriving from the animals in the human environment. Material and methods 301 animals: 142 dogs, 57 cats and 102 horses, were examined in terms of their mouth status and occurrence of trichomonads. ITS1–5.8S rRNA-ITS2 region was amplified and sequenced. Results Finally, 7 dogs, 3 cats and 1 horse were diagnosed positive for T. tenax by PCR. In the oral cavity of 9 /11 animals, gingivitis and dental plaque accumulation were diagnosed. 9 /11 sequences of trichomonad isolates showed 100% identity with T. tenax sequence derived from the GenBank. The sequences of 2 isolates differed by substitutions. Conclusions It was proved that T. tenax , considered so far as a human specific parasite, can also inhabit the oral cavity of dog, cat and horse. To summarize, T. tenax was detected in the mouths of different domesticated animals, indicating that in Poland it can colonize a wider range of hosts than previously known. The owners of 3 dogs showed oral tissue inflammation of different intensity and were also positive for T. tenax ; therefore, oral trichomonosis spread from humans to domestic animals and conversely should be taken into consideration

Amoebicidal or amoebostatic influence of disinfectants used in health facilities and laboratories on corneal strains of Acanthamoeba

Different Acanthamoeba species are amphizoic organisms distributed in wide range of habitats in natural and man-made environments; they are also detected on surfaces of equipment and accessories in health facilities. Some strains of the amoebae are causative agents of the vision-threatening human disease Acanthamoeba keratitis, mainly reported in contact lens wearers. An exceptional high resistance of Acanthamoeba trophozoites and particularly cysts to chemicals, disinfectants and drugs is believed as influencing difficulty resulting in unsuccessful therapeutic management. As Acanthamoeba keratitis is the serious medical problem worldwide, different chemicals with possible activity against environmental and clinical Acanthamoeba strains are tested. In our study, selected disinfectants used in health care settings and laboratories were tested and their efficacy against the corneal strains Acanthamoeba castellanii and A. polyphaga , and environmental A. castellanii Neff strain was assessed. Comparative assessment of results of the assays show that, apart from amoebistatic effects, the disinfectants indicated expected cysticidal efficacy

Effect of povidone iodine, chlorhexidine digluconate and toyocamycin on amphizoic amoebic strains, infectious agents of Acanthamoeba keratitis – a growing threat to human health worldwide

Introduction Free-living amoebae, ubiquitous in outer environments, in predisposing circumstances may exist as parasites, infectious agents of Acanthamoeba keratitis. In recent decades, the vision-threatening corneal infection is a growing human health threat worldwide, including Poland. The applied therapy is often ineffective due to diagnostic mistakes, various pathogenicity of Acanthamoeba strains and high resistance of cysts to drugs; many agents with possible anti-amoebic activity are still being tested. In the presented study, selected chemicals are investigated in terms of their in vitro effect on corneal and environmental Acanthamoeba strains. Material and methods Samples of a corneal isolate from a patient with severe Acanthamoeba keratitis,of assessed on the basis of genotype associations of 18S rRNA and the type strain, Acanthamoeba castellanii Neff cultivated in bacteria-free condition, were exposed to povidone iodine, chlorhexidine digluconate or toyocamycin. In vitro population dynamics of the strains were monitored and compared to those of control cultures. Results All chemicals showed anti-amoebic effects with different degrees of effectiveness. Significant differences were observed in the in vitro population dynamics, and the morpho-physiological status of A. castellanii Neff T4 and corneal strains determined as A. polyphaga T4 genotype, exposed to povidone iodine or toyocamycin, in comparison with chlorhexidine taken as reference. Conclusions Time-dependent amoebstatic in vitro effects were demonstrated for all agents, in particular, the results of assays with povidone iodine are promising. No significant stimulation of encystation appeared; however, as cysticidal efficacy of chemicals is expected, complementary research is needed on different Acanthamoeba strains with modified agent concentrations and method application

Identification of infectious microbiota from oral cavity environment of various population group patients as a preventive approach to human health risk factors

Introduction and objective. This study presents the results of comparative investigations aimed to determine microbiota that can occur in the oral environment in different human populations. The objective of the research was to identify pathogenic oral microbiota, the potential cause of health complications in patients of different population groups. Materials and method. The study included 95 patients requiring dental or surgical treatment; their oral cavity environment microbiota as risk factors of local and general infections were assessed. Results. In clinical assessment, differences occurred in oral cavity conditions between patients with malformations of the masticatory system, kidney allograft recipients and individuals without indications for surgical procedures. The presence of various pathogenic and opportunistic bacterial strains in oral cavities were revealed by direct microscopic and in vitro culture techniques. Conclusions. Colonization of oral cavities of patients requiring surgical treatment by the potentially pathogenic bacteria constitutes the threat of their spread, and development of general infections. Assessment of oral cavity infectious microbiota should be performed as a preventive measure against peri-surgical complications

Tannic Acid-Modified Silver Nanoparticles in Conjunction with Contact Lens Solutions Are Useful for Progress against the Adhesion of Acanthamoeba spp. to Contact Lenses

Acanthamoeba spp. are amphizoic amoebae that are widely distributed in the environment and capable of entering the human body. They can cause pathogenic effects in different tissues and organs, including Acanthamoeba keratitis (AK), which may result in a loss of visual acuity and blindness. The diagnostics, treatment, and prevention of AK are still challenging. More than 90% of AK cases are related to the irresponsible wearing of contact lenses. However, even proper lens care does not sufficiently protect against this eye disease, as amoebae have been also found in contact lens solutions and contact lens storage containers. The adhesion of the amoebae to the contact lens surface is the first step in developing this eye infection. To limit the incidence of AK, it is important to enhance the anti-adhesive activity of the most popular contact lens solutions. Currently, silver nanoparticles (AgNPs) are used as modern antimicrobial agents. Their effectiveness against Acanthamoeba spp., especially with the addition of plant metabolites, such as tannic acid, has been confirmed. Here, we present the results of our further studies on the anti-adhesion potential of tannic acid-modified silver nanoparticles (AgTANPs) in combination with selected contact lens solutions against Acanthamoeba spp. on four groups of contact lenses. The obtained results showed an increased anti-adhesion activity of contact lens solutions in conjunction with AgTANPs with a limited cytotoxicity effect compared to contact lens solutions acting alone. This may provide a benefit in improving the prevention of amoebae eye infections. However, there is still a need for further studies on different pathogenic strains of Acanthamoeba in order to assess the adhesion of the cysts to the contact lens surface and to reveal a more comprehensive picture of the activity of AgTANPs and contact lens solutions

Examination of Oral Microbiota Diversity in Adults and Older Adults as an Approach to Prevent Spread of Risk Factors for Human Infections

The oral cavity environment may be colonized by polymicrobial communities with complex, poorly known interrelations. The aim of this study was to determine oral microbiota diversity in order to prevent the spread of infectious microorganisms that are risk factors for human health complications in patients requiring treatment due to various disabilities. The study examined Polish adults aged between 40 and 70 years; parasitological, microbiological, and mycological data collected before treatment were analyzed. The diversity of oral microbiota, including relatively high prevalences of some opportunistic, potentially pathogenic strains of bacteria, protozoans, and fungi detected in the patients analyzed, may result in increasing risk of disseminated infections from the oral cavity to neighboring structures and other organs. Increasing ageing of human populations is noted in recent decades in many countries, including Poland. The growing number of older adults with different oral health disabilities, who are more prone to development of oral and systemic pathology, is an increasing medical problem. Results of this retrospective study showed the urgent need to pay more attention to the pretreatment examination of components of the oral microbiome, especially to the strains, which are etiological agents of human opportunistic infections and are particularly dangerous for older adults

Emerging Threats for Human Health in Poland: Pathogenic Isolates from Drug Resistant Acanthamoeba Keratitis Monitored in terms of Their In Vitro Dynamics and Temperature Adaptability

Amphizoic amoebae generate a serious human health threat due to their pathogenic potential as facultative parasites, causative agents of vision-threatening Acanthamoeba keratitis (AK). Recently, AK incidences have been reported with increasing frequency worldwide, particularly in contact lens wearers. In our study, severe cases of AK in Poland and respective pathogenic isolates were assessed at clinical, morphological, and molecular levels. Misdiagnoses and the unsuccessful treatment in other ophthalmic units delayed suitable therapy, and resistance to applied chemicals resulted in severe courses and treatment difficulties. Molecular assessment indicated that all sequenced pathogenic corneal isolates deriving from Polish patients with AK examined by us showed 98–100% homology with Acanthamoeba genotype T4, the most prevalent genotype in this human ocular infection worldwide. In vitro assays revealed that the pathogenic strains are able to grow at elevated temperature and have a wide adaptive capability. This study is our subsequent in vitro investigation on pathogenic Acanthamoeba strains of AK originating from Polish patients. Further investigations designed to foster a better understanding of the factors leading to an increase of AK observed in the past years in Poland may help to prevent or at least better cope with future cases