Opportunistic free-living amoebal pathogens

Novel Plant-Based Metabolites as Disinfectants against Acanthamoeba castellanii

“…With the escalation in global warming and increasing global water shortages, it is likely that infections due to waterborne pathogens including free-living amoebae will rise, with many members of the public resorting to private storage tanks to house water, especially in the developing world [ 5 , 42 ]. Medicinal chemists have introduced a number of compounds that may be used to treat a variety of endoparasites; however, there are a limited number of compounds which are efficacious against free-living amoeba infections, for use as disinfectants or as therapy, due to factors such as the inability of the drugs to cross the blood–brain barrier, as well as the robust nature of the cyst stage of these amoebae and its ability to endure harsh conditions [ 12 , 13 ]. Furthermore, the pharmaceutical industry has not placed a high priority on the development of new antiparasitic treatments, as many parasitic infections occur in underdeveloped countries.…”

“…Subsequently, the number of A. castellanii was assessed using a haemocytometer. The starting A. castellanii inoculum (5 × 10 5 ) was adjusted by enumerating with a haemocytometer and then used for several tests [ 12 , 13 ].…”

“…Amoebae cultured in RPMI alone was taken as a negative control, and 0.25 percent sodium dodecyl sulphate (SDS) was used as a positive control. Finally, 0.1% Trypan blue was added to each well, and viable amoebae trophozoites were counted using a haemocytometer [ 12 , 13 ].…”

“…Antimicrobial topical treatments are available for AK infection and usually comprise a combination of propamidine isethionate and neomycin or chlorhexidine, while contact lens disinfectants often include chlorhexidine [ 2 ]. Notably, a plethora of studies have shown that many of the contact lens disinfectants commercially available in the market are ineffective against Acanthamoeba [ 9 , 10 ], suggesting the need to identify the compound(s) that are biologically relevant, cost effective, effective against cysts and trophozoites, and nontoxic, and which can be used as disinfectants and/or therapeutic agents [ 11 , 12 , 13 , 14 , 15 , 16 ].…”

Copper Metabolism in Naegleria gruberi and Its Deadly Relative Naegleria fowleri

“…N. gruberi and N. fowleri are unicellular organisms living worldwide in freshwater environments ( De Jonckheere, 2004 ; Mull et al, 2013 ). N. gruberi is considered to be the best safe system to study the pathogenic “brain-eating amoeba” N. fowleri , which can infect people and cause primary amoebic meningoencephalitis (PAM), a rare but almost always fatal disease ( Mungroo et al, 2021 ). The genomes of these organisms suggest canonical aerobic metabolism, such as the employment of cytochromes and ubiquinone in the respiratory chain, as well as properties of anaerobic metabolism, such as Fe-hydrogenase ( Tsaousis et al, 2014 ), which is typically utilized in metabolic processes of organisms adapted to anaerobic conditions ( Fritz-Laylin et al, 2011 ; Herman et al, 2021 ).…”