title: In vitro efficacy of nikkomycin Z against the human isolate of the microsporidian species Encephalitozoon hellem.
abstract: Since 1985 microsporidia have been recognized as a cause of emerging infections in humans, mainly in immunocompromised human immunodeficiency virus-positive subjects. As chitin is a basic component of the microsporidian infective stage, the spore, we evaluated in vitro the susceptibility of a human-derived strain of Encephalitozoon hellem to nikkomycin Z, a peptide-nucleoside antibiotic known as a competitive inhibitor of chitin synthase enzymes. Transmission electron microscopy showed that this drug, at 25 microgram/ml, reduced the number of parasitic foci by about 35% +/- standard deviation after 7 days of culture (P < 0.0001) and induced cell damage of both mature and immature spores and also other sporogonic and merogonic stages. In particular, an irregular outline of the cell shape and an abnormally condensed cytoplasm in meronts and sporonts were documented. Also, the polar tubule and the polaroplast membranes appeared disarrayed in the sporoblast stage. The spore wall showed an enlarged endospore and delaminated exospore. Mature spores had a complete cytoplasmic disorganization and a swollen and delaminated cell wall. No ultrastructural cell damage was observed in uninfected control cultures treated with the drug.
authors.affiliation: Department of Evolutionary Biology, University of Siena, Pavia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Bigliardi
authors.forename: A M
authors.initials: AM
authors.lastname: Bernuzzi
authors.forename: S
authors.initials: S
authors.lastname: Corona
authors.forename: S
authors.initials: S
authors.lastname: Gatti
authors.forename: M
authors.initials: M
authors.lastname: Scaglia
authors.forename: L
authors.initials: L
authors.lastname: Sacchi
mesh_terms: D000617:Aminoglycosides; D000704:Analysis of Variance; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D016819:Encephalitozoon / Q000187:drug effects* / Q000648:ultrastructure; D006801:Humans; D021261:Parasitic Sensitivity Tests
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000981:Antiprotozoal Agents; C011952:nikkomycin