Candida parapsilosis
There are a bunch of Candida out there (Can da da, not can dee da)
When I was a young whippersnapper all clinical isolates of candida were C. albicans, but there has been a slow shift away from C. albicans to non-albicans Candida causing disease.
Like the patient in the ICU leaking bile into his peritoneum. He is growing C. parapsilosis and has had a fever and increased white count, so it is probably the real deal.
But what to treat him with?
C. parapsilosis has higher MIC’s to fluconazole, so I get nervous with that agent, although he will probably be just fine if I use it, given that he has no other issues with his immune system.
The echinocandidins are a good bet, and as a rule all the Candida are sensitive, except, it turns out, some C. parapsilosis, which isn’t your fathers C. parapsilosis.
C. parapsiolsis is actually three in one, the trinity of Candida: C. parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis. My lab can’t tell the difference, but depending on which one it really is, there is different susceptibilities to the various antifungals.
Voriconazole or posaconazole may be a good choice.
Decisions decisions, and the problem is no clinical trials, just in vitro susceptibility, to guide therapy. I think I will call a psychic.
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Diagn Microbiol Infect Dis. 2008 Sep;62(1):106-9. Epub 2008 Jun 13.
Significant differences in drug susceptibility among species in the Candida parapsilosis group.
Candida parapsilosis family has 3 proposed species: C. parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis. C. parapsilosis sensu stricto had significantly higher caspofungin (CAS) and anidulafungin MICs than C. orthopsilosis or C. metapsilosis; C. metapsilosis was least susceptible to fluconazole. C. parapsilosis sensu stricto more frequently displayed (37%) paradoxical growth in CAS (P < or = 0.02). These species susceptibility differences could affect therapeutic choices.
J Med Microbiol. 2009 Feb;58(Pt 2):185-91.
Molecular differentiation and antifungal susceptibilities of Candida parapsilosis isolated from patients with bloodstream infections.
The genetic heterogeneity and antifungal susceptibility patterns of Candida parapsilosis isolated from blood cultures of patients were investigated in this study. Randomly amplified polymorphic DNA (RAPD) analysis generated 5 unique profiles from 42 isolates. Based on the major DNA fragments of the RAPD profiles, the isolates were identified as RAPD type P1 (29 isolates), P2 (6 isolates), P3 (4 isolates), P4 (2 isolates) and P5 (1 isolate). Sequence analysis of the internal transcribed spacer (ITS) gene of the isolates identified RAPD type P1 as C. parapsilosis, P2 and P3 as Candida orthopsilosis, P4 as Candida metapsilosis, and P5 as Lodderomyces elongisporus. Nucleotide variations in ITS gene sequences of C. orthopsilosis and C. metapsilosis were detected. Antifungal susceptibility testing using Etests showed that all isolates tested in this study were susceptible to amphotericin B, fluconazole, ketoconazole, itraconazole and voriconazole. C. parapsilosis isolates exhibited higher MIC(50) values than those of C. orthopsilosis for all of the drugs tested in this study; however, no significant difference in the MICs for these two Candida species was observed. The fact that C. orthopsilosis and C. metapsilosis were responsible for 23.8 and 4.8 % of the cases attributed to C. parapsilosis bloodstream infections, respectively, indicates the clinical relevance of these newly described yeasts. Further investigations of the ecological niche, mode of transmission and virulence of these species are thus essential.
Eukaryotic pathogens are such a pain. I think I shall turn the tables by consuming mushrooms and beer.