In vitro activity and synergism of amphotericin B, azoles and cationic antimicrobials against the emerging pathogen Trichoderma spp.
OBJECTIVE
The uncommon fungal pathogen Trichoderma shows increasing medical importance particularly in immunocompromised patients. Despite systemic antifungal therapy, prognosis of Trichoderma infection is poor regardless of the type of infection and the therapy used. The aim of the present study was to evaluate the in vitro activity and synergism of double antifungal combinations including amphotericin B, voriconazole, fluconazole, chlorhexidine digluconate and Akacid plus against 15 isolates of Trichoderma longibrachiatum and 1 isolate of Trichoderma harzianum.


METHODS
Individual MICs were determined by using broth microdilution method following the NCCLS M38-A guidelines with standard RPMI 1640 broth. Synergy tests were performed using the chequerboard method.


RESULTS
All clinical Trichoderma strains showed reduced susceptibility to fluconazole (MICs>or=64 mg/L) and amphotericin B (MICs=2 mg/L), whereas lower MICs of 0.5-1 mg/L were detected for voriconazole. Akacid plus reached the lowest MIC values in a range of 0.06-0.5 mg/L, 4- to 32-fold higher MICs were found for chlorhexidine. No antagonism was observed for any of the antifungal combinations tested. Interaction of amphotericin B and azoles was indifferent (fractional inhibitory concentration index, FICI 2-4). The combination of one azole and one cationic biocide showed different degree of synergism (FICI 0.07-2.03). Interaction of Akacid plus and chlorhexidine resulted in synergism for each Trichoderma isolate (FICI-range 0.05-0.5).


CONCLUSIONS
These results demonstrate no interaction between antifungals and some degree of synergism between azoles and cationic antimicrobials against Trichoderma spp.
Kratzer
Christina
C
Department of Internal Medicine I, Division of Infectious Diseases and Chemotherapy, Medical University of Vienna, Währinger Gürtel, 18-20, 1090 Vienna, Austria.
Tobudic
Selma
S
Schmoll
Monika
M
Graninger
Wolfgang
W
Georgopoulos
Apostolos
A
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology; D021821:Communicable Diseases, Emerging / Q000382:microbiology; D004357:Drug Synergism; D015725:Fluconazole / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009181:Mycoses / Q000382:microbiology*; D011108:Polymers / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D014242:Trichoderma / Q000187:drug effects* / Q000302:isolation & purification; D065819:Voriconazole
C512857:AKACID Plus; D000935:Antifungal Agents; D023181:Antimicrobial Cationic Peptides; D001393:Azoles; D006146:Guanidines; D011108:Polymers; D011743:Pyrimidines; D014230:Triazoles; D000666:Amphotericin B; D015725:Fluconazole; D065819:Voriconazole; C010882:chlorhexidine gluconate; D002710:Chlorhexidine