Caspofungin in vitro and in vivo activity against Brazilian Pythium insidiosum strains isolated from animals.
OBJECTIVE
The present study evaluated the susceptibility of 27 clinical isolates of Pythium insidiosum to caspofungin in vitro and correlated the results with the therapeutic response in vivo in rabbits with experimental pythiosis.


METHODS
The macrodilution method was performed in accordance with the CLSI document M38-A technique. Three reading criteria for MICs were adopted: MIC0, MIC1 and MIC2 (100%, 90% and 50% growth inhibition, respectively). The minimum fungicidal concentration was also determined. Ten rabbits inoculated with viable P. insidiosum zoospores were divided into two groups: group 1 (control) and group 2 (treated with caspofungin at a dosage of 1 mg/kg/day for 20 consecutive days).


RESULTS
Of the isolates 51.8% had an MIC0 of 64 mg/L, 88.8% of isolates had an MIC1 between 8 and 64 mg/L and 62.9% of isolates had a minimum fungicidal concentration of 64 mg/L. In the in vivo assay, growth of subcutaneous lesions reduced during treatment, but rapidly resumed when treatment was stopped.


CONCLUSIONS
The results showed that caspofungin has limited fungistatic activity against P. insidiosum. This work is the first study to analyse the susceptibility of this oomycete to inhibitors of beta-glucans of the cellular wall.
Pereira
Daniela Isabel Brayer
DI
Laboratório de Pesquisas Micológicas, Departamento de Microbiologia e Parasitologia, Universidade Federal de Santa Maria, Campus Universitário, Prédio 20, 4139, 97105900 Santa Maria, RS, Brazil.
Santurio
Janio Morais
JM
Alves
Sydney Hartz
SH
Argenta
Juliana Siqueira
JS
Pötter
Luciana
L
Spanamberg
Andréia
A
Ferreiro
Laerte
L
D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001938:Brazil; D000077336:Caspofungin; D004285:Dogs; D054714:Echinocandins / Q000494:pharmacology*; D005260:Female; D006736:Horses; D007239:Infections / Q000188:drug therapy; D055666:Lipopeptides; D008297:Male; D011775:Pythium / Q000187:drug effects*; D011817:Rabbits; D012756:Sheep; D012871:Skin Diseases / Q000188:drug therapy