Final answer:
Fungal infections like ringworm caused by Trichophyton or Microsporum species appear as raised, boggy lesions with purulent nodules. Trichophyton rubrum infections present with specific culture characteristics and respond well to treatment. Diagnosis is made through culturing and microscopic examination.
Step-by-step explanation:
The symptoms described in the question relate to fungal infections caused by Trichophyton or Microsporum species, which are dermatophytes. These fungal pathogens can cause skin infections such as ringworm, presenting as raised, boggy lesions with purulent (pus-filled) nodules on the skin. The case mentioned with Sarah likely refers to an infection caused by Trichophyton rubrum, which is characterized by a culture with a granular texture and pale pink color on top with a red underside, clearing up within 2 weeks with appropriate treatment.
Diagnosis of these infections typically requires culturing the pathogen on media such as Sabouraud's agar, but can also include histologic examination and observation of macroscopic and microscopic morphology. For example, Sporothrix schenkii, causing sporotrichosis, can be cultured on potato dextrose agar and observed under a microscope after staining with lactophenol cotton blue for accurate identification.