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Privasnik, A.
Pathogenicity of Candida albicans strains with Galleria mellonella, a model organism for fungal infections
[ Diplomarbeit ] Medical University of Graz; 2013. pp. 51 [OPEN ACCESS]


Authors Med Uni Graz:
Buzina Walter

Background: In the last decades previously undocumented manifestations of Candida infections appeared, and the incidence, especially in the last two decades, increased dramatically on account of more susceptible hosts. Despite the use of antifungal agents, candidemia is still the most frequent life-threatening fungal disease. Denture stomatitis is recently considered to be the most common form of oral candidiasis and oropharyngeal candidiasis (OPC) is still the most frequent opportunistic infection affecting up to 90% of HIV infected individuals. The objective of this work was to determine whether there is a difference in survival of the greater wax moth Galleria mellonella infected with either invasive or superficial isolates of Candida albicans. Methods: For these investigations 20 different clinical C. albicans strains were used. They were isolated from various patients from either oral infection sites (n= 10, considered as superficial) or from systemic candidiasis (n= 10, considered as invasive), namely blood culture. Larvae of G. mellonella were injected with 20 ¿l of a C. albicans suspension (concentration 2,5x109 cfu/ml) through the last, left proleg directly into the haemocoel. Consequently the infected larvae were kept in a petri dish covered with a kimwipe and incubated at 25°C for a maximum of seven days. Survival assays were carried out daily. Larvae were considered dead when they displayed no movement in response to touch and were removed from the petri dish. Killing curves were plotted and statistical analyses were performed. Results: We discovered that it is possible for the fungus to proliferate inside the haemocoel of the larvae and to colonize and kill the caterpillar. However, the results indicate that there is no statistically significant difference between superficial and invasive isolates of C. albicans (p=0.6). The killing curves of superficial and invasive isolates show similar linear curve progression. Discussion: The insect model organism G. mellonella represents a suitable alternative model for the evaluation of Candida pathogenesis. The finding that superficial isolates have the potential to cause elevated morbidity, if systemically disseminated, requires prompt therapeutic intervention of superficial C. albicans infection, especially in debilitated hosts.

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