## Diagnosis: Neonatal Oral Candidiasis (Thrush) ### Clinical Presentation The white patch on the palate that does not wipe off (unlike milk residue) is pathognomonic for oral candidiasis. The mother's cracked nipples and engorgement suggest secondary candidal mastitis, a common complication. ### Investigation of Choice **Key Point:** KOH (Potassium Hydroxide) mount of an oral swab is the gold standard for confirming Candida albicans in oral thrush. **High-Yield:** KOH dissolves cellular material and leaves fungal elements (pseudohyphae and budding yeast) visible under low-power microscopy. This is rapid, inexpensive, and highly specific for candidiasis. ### Why KOH Mount Works | Feature | KOH Mount | Gram Stain | Culture | Wet Mount | |---------|-----------|-----------|---------|----------| | **Sensitivity** | High (80–90%) | Low | High | Low | | **Specificity** | High | Low (bacteria also gram-positive) | High | Very low | | **Speed** | Rapid (10–15 min) | Rapid | Slow (24–48 hrs) | Rapid but unreliable | | **Visualization** | Pseudohyphae, budding yeast | Cocci, no hyphae | Not applicable | Yeast not visible | | **Cost** | Minimal | Minimal | Moderate | Minimal | **Clinical Pearl:** The white patch of thrush is composed of pseudomycelium and epithelial cells; it does NOT wipe off easily (unlike milk residue, which wipes away), making the clinical diagnosis highly suggestive. KOH mount confirms it. **Mnemonic:** **THRUSH** = **T**hite patch, **H**ard to remove, **R**equires **U**nder microscope **S**pecific test (**K**OH), **H**yphae visible. ### Management Context Once confirmed, treat with nystatin oral suspension (100,000 IU/mL, 1 mL QID for infant; apply to all oral surfaces) and miconazole cream to mother's nipples to prevent reinfection cycle.
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