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Query: UMLS:C0022568 (keratitis)
 5,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acanthamoeba is an opportunistic protozoan that is widely distributed in the environment and is well recognized to produce serious human infections, including a blinding keratitis and a fatal encephalitis. This review presents our current understanding of the burden of Acanthamoeba infections on human health, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be targets for therapeutic interventions and/or the development of preventative measures.
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PMID:Acanthamoeba: biology and increasing importance in human health. 1677 87

The free-living amoebae from genus Acanthamoeba are the causative agents of granulomatous amebic encephalitis (GAE), a chronic progressive disease of the central nervous system; amebic keratitis (AK), a chronic eye infection; amebic pneumitis (AP), a chronic lung infection, and skin infection. Chemotherapy of Acanthamoeba infection is problematic. The majority of infections have been fatal. Only a few cases are reported to have been treated successfully with very highly toxic drugs. The therapy might be succeed, if the diagnosis and therapy is made at very early stage of infection. In our experiments we used the following plant extracts: Solidago virgaurea, Solidago graminifolia, Rubus chamaemorus, Pueraria lobata, and natural plants products as ellagic acid and puerarin. Those therapeutic agents and plants extracts have been tested in vitro for amebicidal or amebostatic activity against pathogenic Acanthamoeba spp. Our results showed that methanol extracts obtained from plants are active against axenic pathogenic Acanthamoeba sp. trophozoites in vitro at concentration below 0.1 mg/ml. Further studies are needed to investigate whether these extracts are also effective in vivo in animal model of infection with Acanthamoeba sp.
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PMID:[Amebicidal plants extracts]. 1686 6

The free-living amoebae are ubiquitous organisms. They are found in humid soil and all water reservoirs, i.e. fresh, sea, freezing and hot water. They mainly feed on bacteria. Pathogenic properties of amoebae and the mechanisms underlying pathological changes induced during human infection have not yet been fully elucidated. They are the causative agents of primary amoebic meningo-encephalitis (PAM), granulomatous amebic encephalitis (GAE), a chronic progressive disease of the central nervous system, amebic keratitis (AK), a chronic eye infection; amebic pneumitis (AP), a chronic lung infection, and skin infection. Only a few isolates are strongly and permanently pathogenic to humans. Some isolates lose their pathogenic properties after one passage. It has been assumed that such "temporary", unstable pathogenic properties of the amoebae may be caused by internal factors carried by them. It is generally known that the free-living amoebae may be naturally infected with pathogenic bacteria, which have the ability to survive for a long time and to proliferate in the amoebae cells. The role of the amoeba in the process of maintaining, propagating and transmitting human pathogens has not been well recognized. It has been suggested that some infections can be acquired by inhaling aerosols containing amoebae cells filled with bacteria. The presence of bacteria inside the free-living amoebae possess a great challenge to organisations responsible for testing and inspecting the quality and cleanliness of surface waters, swimming pools and drinking water intakes.
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PMID:[Free-living amoebae as vehicles of pathogenic bacteria]. 1700 31

Free-living amebae appertaining to the genus Acanthamoeba, Naegleria and Balamuthia are the most prevalent protozoa found in the environment. These amebae have a cosmopolitan distribution in soil, air and water, providing multiple opportunities for contacts with humans and animals, although they only occasionally cause disease. Acanthamoeba spp. are the causative agent of granulomatous amebic encephalitis, a rare and often fatal disease of the central nervous system, and amebic keratitis, a painful disease of the eyes. Keratitis usually follows a chronic course due to the delay in diagnosis and subsequent treatment. The clear increase in Acanthamoeba keratitis in the last 20 years is related to the use and deficient maintenance of contact lenses, and to swimming while wearing them. The expected incidence is one case per 30,000 contact lens wearers per year, with 88% of cases occurring in persons wearing hydrogel lenses. This review presents information on the morphology, life-cycle and epidemiology of Acanthamoeba, as well as on diagnostic procedures (culture), appropriate antimicrobial therapy, and prevention measures.
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PMID:[Keratitis due to Acanthamoeba]. 1712 68

The pathogenic mechanism of granulomatous amebic encephalitis (GAE) and amebic keratitis (AK) by Acanthamoeba has yet to be clarified. Protease has been recognized to play an important role in the pathogenesis of GAE and AK. In the present study, we have compared specific activity and cytopathic effects (CPE) of purified 33 kDa serine proteinases from Acanthamoeba strains with different degree of virulence (A. healyi OC-3A, A. lugdunensis KA/E2, and A. castellanii Neff). Trophozoites of the 3 strains revealed different degrees of CPE on human corneal epithelial (HCE) cells. The effect was remarkably reduced by adding phenylmethylsulfonylfluoride (PMSF), a serine proteinase inhibitor. This result indicated that PMSF-susceptible proteinase is the main component causing cytopathy to HCE cells by Acanthamoeba. The purified 33 kDa serine proteinase showed strong activity toward HCE cells and extracellular matrix proteins. The purified proteinase from OC-3A, the most virulent strain, demonstrated the highest enzyme activity compared to KA/E2, an ocular isolate, and Neff, a soil isolate. Polyclonal antibodies against the purified 33 kDa serine proteinase inhibit almost completely the proteolytic activity of culture supernatant of Acanthamoeba. In line with these results, the 33 kDa serine proteinase is suggested to play an important role in pathogenesis and to be the main component of virulence factor of Acanthamoeba.
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PMID:Comparison of specific activity and cytopathic effects of purified 33 kDa serine proteinase from Acanthamoeba strains with different degree of virulence. 1717 May 74

Herpes simplex virus (HSV) infection triggers apoptosis in infected cells. However, proteins synthesized later in infected cells prevent apoptotic cell death from ensuing. In vivo data showing that apoptosis accompanies herpes stromal keratitis and encephalitis suggest that apoptotic modulation plays a role in the development of herpetic disease. Tremendous progress has been made toward identifying the viral factors that are responsible for inducing and inhibiting apoptosis during infection. However, the mechanisms whereby they act are still largely unknown. Recent studies have illustrated a wide diversity in the cellular response to HSV-triggered apoptosis, emphasizing the importance of host factors in this process. Together, these findings indicate that apoptosis during HSV infection represents an important virus-host interaction process, which likely influences viral pathogenesis.
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PMID:Apoptosis during herpes simplex virus infection. 1722 92

Acanthamoeba is an opportunistic protozoan pathogen that can cause blinding keratitis as well as fatal granulomatous encephalitis. One of the distressing aspects in combating Acanthamoeba infections is the prolonged and problematic treatment. For example, current treatment against Acanthamoeba keratitis requires early diagnosis followed by hourly topical application of a mixture of drugs that can last up to a year. The aggressive and prolonged management is due to the ability of Acanthamoeba to rapidly adapt to harsh conditions and switch phenotypes into a resistant cyst form. One possibility of improving the treatment of Acanthamoeba infections is to inhibit the ability of these parasites to switch into the cyst form. The cyst wall is partially made of cellulose. Here, we tested whether a cellulose synthesis inhibitor, 2,6-dichlorobenzonitrile (DCB), can enhance the effects of the antiamoebic drug pentamidine isethionate (PMD). Our findings revealed that DCB can block Acanthamoeba encystment and may improve the antiamoebic effects of PMD. Using in vitro assays, the findings revealed that DCB enhanced the inhibitory effects of PMD on Acanthamoeba binding to and cytotoxicity of the host cells, suggesting the cellulose biosynthesis pathway as a novel target for the improved treatment of Acanthamoeba infections.
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PMID:Cellulose biosynthesis pathway is a potential target in the improved treatment of Acanthamoeba keratitis. 1722 99

Ocular infection with herpes simplex virus (HSV) causes a vision-impairing inflammatory reaction called herpetic stromal keratitis. In murine models, herpetic stromal keratitis lesions appear to be immunopathologic, mediated by CD4(+) T cells of Th1 phenotype. To provide insight about cytokine networks and signaling events involved in the development of aggressor CD4(+) T cells, ocular HSV infection was followed in mice deficient in Stat4 (Stat4(-/-) mice), the signal transducer for the cytokine interleukin-12 (IL-12). After ocular HSV infection of Stat4(-/-) and control BALB/c mice, clinical, histologic, and immunologic analyses were carried out. Further, to evaluate the involvement of Stat4 in the development of this aggressor population, naive CD4(+) T cells from Stat4(-/-) and BALB/c mice were adoptively transferred to C.B-17 SCID mice 1 day after corneal infection. Although Stat4(-/-) mice demonstrated increased susceptibility to lethal encephalitis and facial lesions, interestingly, these mice had less severe stromal keratitis in comparison to control animals. Adoptive transfer of naive CD4(+) T cells from Stat4(-/-) mice failed to produce disease in infected SCID recipients. The data imply a significant role of Stat4-mediated signaling events in the generation of an aggressor CD4(+) T cell population in stromal keratitis pathogenesis.
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PMID:Role of Stat4-mediated signal transduction events in the generation of aggressor CD4+ T cells in herpetic stromal keratitis pathogenesis. 1726 45

Acanthamoeba species are known to cause 2 well-described entities: (1) granulomatous amoebic encephalitis (GAE), which usually affects immunocompromised hosts, and (2) keratitis, which typically follows trauma associated with contamination of water or contact lenses. Less common manifestations include pneumonitis and a subacute granulomatous dermatitis. We describe a case of granulomatous dermatitis secondary to Acanthamoeba infection in a lung transplant recipient and a successful outcome following treatment with lipid formulation of amphotericin B and voriconazole. We believe this is the second case report describing disseminated Acanthamoeba infection in a lung transplant recipient. We also describe successful outcome with a combination of lipid formulation of amphotericin B and voriconazole, drugs that have not been previously reported to treat Acanthamoeba.
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PMID:A case of successful treatment of cutaneous Acanthamoeba infection in a lung transplant recipient. 1731 73

The evolution of antiviral therapy began with developments in the management of influenza and herpes simplex keratitis in the 1960s and early 1970s. However, the field exploded with the successful treatment of herpes simplex encephalitis, herpes zoster and genital herpes simplex virus infections, all occurring in the late 1970s and early 1980s. These advances have contributed to the development of therapies for HIV that have transformed the lives of infected patients in recent years. The clinical fruit of all of these research advances has been an armamentarium of drugs that can be used to successfully treat a variety of viral illnesses. In addition to HIV/AIDS, current antiviral therapy focuses primarily on herpesviruses, hepatitis viruses and influenza. Notably, considerable progress remains to be made in these areas. Moreover, a variety of additional viral diseases currently require the development of specific therapies.
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PMID:Current non-AIDS antiviral chemotherapy. 1740 37


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