Using the general guidelines presented in chapter 17 and figure 22.3, explain how you can tell for sure if a fungal isolate is the actual causative agent or merely a contaminant.
Figure 22.3

Pus, Vaginal Hair, Skin, Nails Blood, Fluid Concentrate Tissue Biopsies, Punches Cerebrospinal Secretions Use of Wood's light on hairs Digested to remove debris Negative stain for capsule (fig. 22.23) Clear Section Grind Digest Hot wet mount Inoculate animals. mount Negative Highlight with KOH mount (wet mount) Inoculate stain for capsule Direct stains animals. of specimenStain with Special stains fig. 22.11) Brighteners (fig. 22.4) Implant onto media selective and differential for fungi. Isolation on selective acid-Schiff (PAS). media incubate for 4 weeks 25 C or 30C selective media BHi Blood agar 37C 25-37 C 37"C Stain Culturing: incubation for up to 8 weeks Test for ig. 22.1). Inspect Selective agar Blood agar Room temperature 37 C 25 C or 30C (fig. 22.6a.b) macros for pigment, texture (fig. 22.8). mFm Observe after staining. Microscopic (fig. 22.22) (fig. 22.11) Perform hair infection test by inoculating sterile hair with culture di for conidial and hyphal Differential media (fig. 22.22b) .Biochemical tests (fig. 22.220) Antigen tests (fig. 22.18) Speclfic nucleic acid Differential media InoculateGerm tube test" (fig. 22.4) Biochemical tests animals Genetic probes Antigen tests probe Serological tests (ig. 17.10, 22.10) media (fig. 22.22b) Biochemical tests (fig. 22.22c)