An update onAcanthamoebakeratitis: diagnosis, pathogenesis and treatment

Abstract

Free-living amoebae of the genus Acanthamoeba are causal agents of a severe sight-threatening infection of the cornea known as Acanthamoeba keratitis. Moreover, the number of reported cases worldwide is increasing year after year, mostly in contact lens wearers, although cases have also been reported in non-contact lens wearers. Interestingly, Acanthamoeba keratitis has remained significant, despite our advances in antimicrobial chemotherapy and supportive care. In part, this is due to an incomplete understanding of the pathogenesis and pathophysiology of the disease, diagnostic delays and problems associated with chemotherapeutic interventions. In view of the devastating nature of this disease, here we present our current understanding of Acanthamoeba keratitis and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be potential targets for improved diagnosis, therapeutic interventions and/or for the development of preventative measures. Novel molecular approaches such as proteomics, RNAi and a consensus in the diagnostic approaches for a suspected case of Acanthamoeba keratitis are proposed and reviewed based on data which have been compiled after years of working on this amoebic organism using many different techniques and listening to many experts in this field at conferences, workshops and international meetings. Altogether, this review may serve as the milestone for developing an effective solution for the prevention, control and treatment of Acanthamoeba infections.

Bacterial Keratitis Risk Factors, Pathogens and Antibiotic Susceptibilities: A 5- Year Review of Cases at Dubai hospital, Dubai

“…Contact lens related keratitis is the major risk factor in patients needing corneal transplantation [21]. Variety of contact lens markets, environmental issues like water storage and disinfection are known to aggravate the contact lens infection [22]. Also, inappropriate lens wear and absence of awareness of lens usage and care are some other risk factors for corneal ulcer among contact lens wearers [23].…”

Detection of Acanthamoeba on the ocular surface in a Spanish population using the Schirmer strip test: pathogenic potential, molecular classification and evaluation of the sensitivity to chlorhexidine and voriconazole of the isolated Acanthamoeba strains

“…The Schirmer test strips were seeded less than 24 h after collection onto 2% nonnutrient agar (NNA) plates with a layer of heat-inactivated Escherichia coli at 28 uC and were monitored daily for the presence of free-living amoebae as previously described (Lorenzo- Morales et al, 2005Morales et al, , 2015. The isolates were cultured axenically in 75 cm 2 culture tissue flasks without shaking, at 28 uC, in PYG medium [0.75% (w/v) proteose peptone, 0.75% (w/v) yeast extract, and 1.5% glucose] supplemented with 20 mg ml 21 gentamicin.…”

“…Attempts to correlate pathogenicity with certain genotypes continue to be made although it has been shown that 90% of Acanthamoeba isolates that produce infections belong to the T4 genotype, suggesting that the abundance of T4 isolates in human infections is most likely due to their greater virulence and/or other properties that enhance their transmissibility, as well as to their decreased susceptibility to chemotherapeutic agents (Khan, 2006;Lorenzo-Morales et al, 2013, 2015.…”

Gaseous nitric oxide for the local treatment of bacterial keratitis in mice

“…This is due to low hygiene standards and water quality with a greater risk of infection in poor countries. In addition, the widespread use of contact lenses and associated complications in wealthier countries contributes to severe keratitis (2,3). Staphylococcus aureus and Pseudomonas aeruginosa are two predominant gram-positive and gram-negative bacterial strains responsible for causing this disease (1,4,5).…”