Journal of Antimicrobial Chemotherapy (1999) 44, 653-659
© 1999 The British Society for Antimicrobial Chemotherapy
In-vitro activity of rifabutin and albendazole singly and in combination with other clinically used antimicrobial agents against Pneumocystis carinii
Institute of Infectious Diseases and Public Health, University of Ancona, Italy
The in-vitro activity of rifabutin and albendazole alone and in combination with clarithromycin, etoposide, minocycline and pyrimethamine was investigated against four clinical isolates of Pneumocystis carinii. The susceptibility tests were performed by inoculation of the isolates on to cell monolayers and by determining the parasite count after 72 h incubation at 37°C. The culture medium was supplemented with serial dilutions of each agent. Albendazole tested alone was more active than rifabutin. Albendazole suppressed the growth of cysts and trophozoites by >50% at 4 mg/L. Rifabutin, at the same concentration, produced about 40% reduction in the mean cyst and trophozoite counts. Albendazole (4 mg/L) combined with etoposide 4 mg/L showed the highest anti-P. carinii activity, with a decrease of 86.3% and 90.1% in cyst and trophozoite counts, respectively. The greatest synergic interaction was detected when rifabutin (4 mg/L) was combined with clarithromycin (4 mg/L). Our study suggests that clinically used antimicrobial agents may be effective in inhibiting P. carinii growth in vitro and that, above all, some of these agents possess a positive interaction upon combination with other clinically used compounds. These findings may be useful in the establishment of a prophylaxis regimen for multiple opportunistic pathogens.
* Correspondence address. Clinica Malattie Infettive, c/o Azienda Ospedaliera Umberto I, Piazza Cappelli, 1, I-60121 Ancona, Italy. Tel: +39-71-596-3467; Fax: +39-71-596-3468; E-mail: cmalinf{at}popcsi.unian.it