Breakthrough Aspergillus fumigatus and Candida albicans double infection during caspofungin treatment: laboratory characteristics and implication for susceptibility testing.
Caspofungin is used for the treatment of acute invasive candidiasis and as salvage treatment for invasive aspergillosis. We report characteristics of isolates of Candida albicans and Aspergillus fumigatus detected in a patient with breakthrough infection complicating severe gastrointestinal surgery and evaluate the capability of susceptibility methods to identify candin resistance. The susceptibility of C. albicans to caspofungin and anidulafungin was investigated by Etest, microdilution (European Committee on Antibiotic Susceptibility Testing [EUCAST] and CLSI), disk diffusion, agar dilution, and FKS1 sequencing and in a mouse model. Tissue was examined by immunohistochemistry, PCR, and sequencing for the presence of A. fumigatus and resistance mutations. The MICs for the C. albicans isolate were as follows: >32 microg/ml caspofungin and 0.5 microg/ml anidulafungin by Etest, 2 microg/ml caspofungin and 0.125 microg/ml anidulafungin by EUCAST methods, and 1 microg/ml caspofungin and 0.5 microg/ml anidulafungin by CLSI methods. Sequencing of the FKS1 gene revealed a mutation leading to an S645P substitution. Caspofungin and anidulafungin failed to reduce kidney CFU counts in animals inoculated with this isolate (P > 0.05 compared to untreated control animals), while both candins completely sterilized the kidneys in animals infected with a control isolate. Disk diffusion and agar dilution methods clearly separated the two isolates. Immunohistochemistry and sequencing confirmed the presence of A. fumigatus without FSK1 resistance mutations in liver and lung tissues. Breakthrough disseminated aspergillosis and candidiasis developed despite an absence of characteristic FKS1 resistance mutations in the Aspergillus isolates. EUCAST and CLSI methodology did not separate the candin-resistant clinical isolate from the sensitive control isolate as well as did the Etest and agar methods.
Arendrup
Maiken Cavling
MC
Unit of Mycology and Parasitology, Statens Serum Institut, Copenhagen S, Denmark. mad@ssi.dk
Garcia-Effron
Guillermo
G
Buzina
Walter
W
Mortensen
Klaus Leth
KL
Reiter
Nanna
N
Lundin
Christian
C
Jensen
Henrik Elvang
HE
Lass-Flörl
Cornelia
C
Perlin
David S
DS
Bruun
Brita
B
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001228:Aspergillosis / Q000188:drug therapy* / Q000235:genetics; D001232:Aspergillus fumigatus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D002177:Candidiasis / Q000188:drug therapy* / Q000235:genetics; D000077336:Caspofungin; D015169:Colony Count, Microbial; D054714:Echinocandins / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007150:Immunohistochemistry; D007274:Injections, Intraperitoneal; D055666:Lipopeptides; D051379:Mice; D008815:Mice, Inbred Strains; D008826:Microbial Sensitivity Tests / Q000379:methods; D016133:Polymerase Chain Reaction
D000935:Antifungal Agents; D054714:Echinocandins; D055666:Lipopeptides; D000077336:Caspofungin