Journal of Antimicrobial Chemotherapy (2000) 45, 651-654
© 2000 The British Society for Antimicrobial Chemotherapy
In vitro anti-cryptosporidial activity of cationic peptides alone and in combination with inhibitors of ion transport systems
Institute of Infectious Diseases and Public Health, University of Ancona, Piazza Cappelli 1, 60121 Ancona, Italy
The anti-cryptosporidial activity of four cationic peptides alone and in combination with five ion transport system (ITS) inhibitors was investigated for six clinical isolates of Cryptosporidium parvum recovered from stools of AIDS patients. The susceptibility tests were performed by inoculating the protozoa on to cell monolayers and determining the parasite count after 48 h incubation at 37°C. The culture medium was supplemented with serial dilutions of cecropin P1, magainin II, indolicidin and ranalexin alone or in combination with amiloride and its analogues. No agent was able to inhibit parasite growth completely. The peptides had some inhibitory effect on parasite growth: cecropin P1, magainin II, indolicidin and ranalexin at a concentration of 50 µM produced 30.6, 33.2, 38.5 and 42.1% reductions, respectively, in schizont count. Conversely, the ITS inhibitors were scarcely effective. Positive interaction was demonstrated when the peptides were tested in combination with ITS inhibitors.
* Corresponding author. Tel: +39-071-596-3467; Fax: +39-071-596-3468; E-mail: cmalinf{at}popcsi.unian.it