The role of Acanthamoeba spp. in biofilm communities: a systematic review

Abstract

Acanthamoeba spp. have always caused disease in immunosuppressed patients, but since 1986, they have become a worldwide public health issue by causing infection in healthy contact lens wearers. Amoebae of the Acanthamoeba genus are broadly distributed in nature, living either freely or as parasites, and are frequently associated with biofilms throughout the environment. These biofilms provide the parasite with protection against external aggression, thus favoring its increased pathogeny. This review aims to assess observational studies on the association between Acanthamoeba spp. and biofilms, opening potential lines of research on this severe ocular infection. A systematic literature search was conducted in May 2020 in the following databases: PubMed Central ® /Medline, LILACS, The Cochrane Library, and EMBASE ® . The studies were selected following the inclusion and exclusion criteria specifically defined for this review. Electronic research recovered 353 publications in the literature. However, none of the studies met the inclusion criterion of biofilm-producing Acanthamoeba spp., inferring that the parasite does not produce biofilms. Nonetheless, 78 studies were classified as potentially included regarding any association of Acanthamoeba spp. and biofilms. These studies were allocated across six different locations (hospital, aquatic, ophthalmic and dental environments, biofilms produced by bacteria, and other places). Acanthamoeba species use biofilms produced by other microorganisms for their benefit, in addition to them providing protection to and facilitating the dissemination of pathogens residing in them.

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

“…In our study, from 69 biofilm samples collected from showerheads and kitchen and bathroom sinks, 18 were positive for FLA. Among the positive samples, Acanthamoeba strains were more prevalent than other FLA, which is in accordance with previous studies [16,22,38]. A previous study in Iran reported the presence of FLA in biofilm and dust from hospital wards hosting immunodeficient patients.…”

“…Furthermore, the Acanthamoeba genus has been found in a wide variety of natural habitats, including biofilms. Previously, the relationship between Acanthamoeba species and biofilms in different places (hospital, aquatic, ophthalmic, and dental environments) revealed that amoebae use biofilms for their survival and the dissemination of pathogens in nature [16].…”

“…According to the literature review, FLA and notably Acanthamoeba spp. have been detected in various biofilms around the world [14][15][16].…”

“…Furthermore, household biofilms are an important reservoir for Acanthamoeba spp. and bacterial endosymbionts in other FLA, which can cause amoebic keratitis in high-risk people during cleaning of lenses, exposure to ocular trauma, and showering while wearing contact lenses [16].…”

Isolation and identification of potentially pathogenic free-living amoeba in dental-unit water samples

“…Many studies have shown that FLAs are able to form biofilm in water supply systems by adhering to each other on a surface (Barbeau & Buhler 2001;Pinto et al 2021). In this regard, dental-unit hydraulic systems contain a high number of long and narrow pipes made of nylon or polyvinyl chloride (Göksay et al 2008).…”