[Black nails caused by Proteus mirabilis]

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  • 1Hautklinik, Abteilung Dermatologie und Venerologie, Universitäts-Klinik Göttingen, von-Siebold-Strasse 3, 37075 Göttingen.

Der Hautarzt; Zeitschrift Fur Dermatologie, Venerologie, Und Verwandte Gebiete
|July 31, 2001
PubMed

Insights

Black nails in two individuals were caused by Proteus mirabilis bacteria producing hydrogen sulfide. This chemical reaction with metals in the nail caused the discoloration, which resolved with treatment.

Area of Science:

  • Microbiology
  • Dermatology
  • Occupational Health

Background:

  • Proteus mirabilis is a gram-negative bacillus.
  • Hydrogen sulfide (H2S) production by bacteria can lead to chemical reactions.
  • Nail discoloration can have various etiologies.

Observation:

  • Two cases of black nails were observed in individuals with occupations involving wet work: a motor mechanic and a petrol pump attendant.
  • The black discoloration persisted for months.
  • The condition resolved after topical treatment with chinosol, tincture of iodine, and chloramphenicol solution.

Findings:

  • Proteus mirabilis, a hydrogen sulfide-producing bacterium, was identified as the cause of black nails.
  • Hydrogen sulfide reacts with trace metals (e.g., zinc, nickel, iron, copper) in the nail plate, forming black metal sulfides.
  • Prolonged exposure to wet and dirty conditions facilitates bacterial colonization.

Implications:

  • This study highlights an unusual presentation of Proteus mirabilis infection.
  • Occupational exposure to wet environments may increase the risk of this nail condition.
  • Understanding the mechanism of metal sulfide formation is crucial for diagnosis and treatment.

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