A 34-year-old otherwise healthy male presented with asymptomatic, greenish discoloration of the nail plate that had set in over a period of 4 weeks. The discoloration began at the distal margin extending to the middle of the nail plate. The patient did not report any history of trauma or onychosis. Before the lesions appeared, he was an epidemic prevention volunteer who wore PPE (Figure 1A) for at least 10 h daily. He washed his feet for an average of two to three times per shift during the outbreak of the Omicron variant of severe acute respiratory syndrome coronavirus (SARS-CoV-2) in Shanghai.
Physical examination revealed greenish black discoloration from the middle to distal parts of the first and third toenails of the left foot (Figure 1B). A white scale was observed on the distal part of the big toenail plate on the left foot (Figure 1C). Neither onycholysis nor paronychia was observed around the affected nails. Direct fluorescence microscopy and fungal culture of nail scrapings were negative; however, bacterial culture of the nail scrapings was positive for P. aeruginosa. Subsequently, drug sensitivity tests were performed, which revealed sensitivity to fluoroquinolones including ciprofloxacin and levofloxacin.
GNS was diagnosed based on these findings, and the patient was instructed to stop wearing PPE, to wash his feet daily, and to keep his feet dry. Based on previous literature and drug sensitivity tests, he was prescribed treatment that included the application of topical nadifloxacin in combination with acetic acid twice daily. At the 2-month follow-up, discoloration of the nail was significantly reduced (Figures 1D,E).