Eleven antimicrobials tested per os against a grasshopper pathogenic microsporidium (Fungi: Microsporidia).

JOHNY, S., C.E. LANGE, L.F. SOLTER, A. MERISKO, D. WHITMAN.

Bloomington, Illinois.

Congreso; 2006 North Central Branch Meeting, Entomological Society of America.; 2006

Entomological Society of America, North Central Branch.

Microsporidia are obligate protist pathogens that parasitize a wide range of invertebrate and vertebrate hosts.  Several species in the genus Encephalitozoon infect mammals, including humans.  There is an urgent need to find new therapies against these pathogens, because they are resistant to most antibiotics.  We tested 11 commercial antibiotics against an Encephalitozoon species that infects the grasshopper Romalea microptera.  Treatment with fumagillin or thiabendazole significantly reduced spore counts, whereas spore counts of grasshoppers fed with albendazole, ampicillin, chloramphenicol, griseofulvin, metronidazole, quinine, streptomycin, sulfadimethoxine, or tetracycline, were not significantly different from the infected controls. Quinine reduced the number of spores produced in the host but the reduction was not significant.  Streptomycin induced a non-significant antagonistic trend.  Although two antibiotics significantly reduced spore counts, in no case was the pathogen totally eliminated.  This study corroborates the difficulty researchers and physicians have had in treating microsporidia infections.  It also suggests that quinine and related alkaloid compounds should be further examined as possible therapeutic agents against this group of ubiquitous pathogens.  In addition, streptomycin and related compounds should be tested to determine if this widely used antibiotic enhances microsporidiosis.