Parasitic Biofilm:
Parasitic biofilms
are structured microbial communities formed by protozoan parasites that adhere
to surfaces and are embedded within an extracellular matrix (ECM). These
biofilms provide protection against the host immune response and antimicrobial
treatments, contributing to persistent infections. Unlike bacterial and fungal
biofilms, parasitic biofilms are less studied, but emerging research highlights
their role in chronic parasitic diseases. They exhibit key characteristics such
as strong adherence to host tissues or medical devices, ECM production composed
of polysaccharides, proteins, and extracellular DNA, and increased drug
resistance compared to planktonic cells. Parasitic biofilms also contain
heterogeneous cell populations, including trophozoites, cysts, and amastigotes,
which aid in survival and immune evasion by shielding parasites from
phagocytosis and complement-mediated killing.
Medically relevant
parasites that form biofilms include Giardia lamblia, which colonizes
the intestinal epithelium and contributes to chronic giardiasis; Trichomonas
vaginalis, which produces biofilms in the vaginal mucosa, leading to
recurrent infections and increased resistance to metronidazole; and Leishmania
species, which form biofilm-like aggregates in sand fly vectors, facilitating
transmission. Additionally, Plasmodium falciparum exhibits
biofilm-like behavior in sequestration within blood vessels, promoting malaria
pathogenesis, while Trypanosoma cruzi forms biofilms in the gut of
insect vectors and possibly within host tissues, contributing to Chagas disease
progression. The formation of parasitic biofilms follows a structured process,
starting with attachment to host surfaces via adhesion molecules and lectins,
followed by ECM production that embeds parasites and promotes aggregation. As
the biofilm matures, it develops a structured architecture with metabolic and
developmental heterogeneity, and eventually, parasites disperse to colonize new
infection sites.
Parasitic biofilms
pose significant clinical challenges due to their enhanced drug resistance and
immune evasion strategies. Standard antiparasitic treatments such as
metronidazole, miltefosine, and quinolines are often ineffective against
biofilm-associated parasites. Novel therapeutic approaches, including
biofilm-disrupting agents like DNase and quorum sensing inhibitors, combination
therapies, and host-targeted immunomodulators, are being explored to counteract
biofilm-mediated resistance. Understanding the role of biofilms in parasitic
infections is crucial for developing new strategies to combat chronic and
recurrent parasitic diseases.
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