Hairy Tongue in a 27-Year-Old Woman with Gram-Negative Bacterial Infection in the Oral Cavity: A Case Report

Black hairy tongue (BHT) is a benign hyperkeratotic disorder that is frequently overlooked in critically ill patients.A 27-year-old woman developed BHT after 46 days of broad-spectrum antibiotics for anti-NMDA-receptor encephalitis complicated by hypoxic-ischaemic encephalitis, tracheostomy and ventilator-associated pneumonia with Enterobacter hormaechei and Klebsiella pneumoniae. Despite empirical oral care with 3% hydrogen peroxide, the dorsal tongue lesion persisted and saliva pH remained acidic (5.3). Culture of the hairy plaque yielded the same Gram-negative species. Intervention with 2% sodium-bicarbonate-soaked swabs, dedicated suctioning devices and passive mandibular exercises normalised oral pH (> 6.6) and resolved the lesion within 14 days.Monitoring and correcting oral pH allows targeted, effective management of BHT and may reduce cross-infection risk in tracheostomised patients.