[Multiple erythema annulare centrifugum associated with knee monoarthritis revealing Capnocytophagacanimorsus infection]. / Erythème annulaire centrifuge multiple et monoarthrite révélateurs d'une infection à Capnocytophaga canimorsus.

INTRODUCTION: Capnocytophagacanimorsus (C. canimorsus), a commensal Gram-negative bacillus found in the oral cavity of dogs and cats, is pathogenic for humans, with the most common clinical manifestations being septicemia, meningitis and endocarditis. Herein we report a case of CC bacteremia manifesting as multiple plaques of erythema annulare centrifugum associated with monoarthritis of the knee. PATIENTS AND METHODS: A 66-year-old man consulted for a skin rash and monoarthritis of the right knee with fever following an insect bite on his right hallux. Cutaneous examination revealed numerous erythematous annular plaques on the trunk and limbs with centrifugal extension. Analysis of synovial fluid from the right knee showed an inflammatory liquid with a sterile bacteriological culture and PCR was negative for Borrelia. C. canimorsus bacteria were isolated from blood cultures. 16S RNA PCR performed on the synovial fluid was positive for the same organism. The patient's history revealed that his hallux wound had been licked by his dog. DISCUSSION: C. canimorsus most frequently affects immunosuppressed subjects. Cutaneous signs are seen in half of all cases, most frequently presenting as cellulitis, pathological livedo or thrombotic purpura. We report herein a case of CC bacteremia in an immunocompetent patient manifesting as multiple plaques of erythema annulare centrifugum, an unusual sign, and monoarthritis of one knee.

Microbial elements as the initial triggers in the pathogenesis of polymorphic light eruption?

The primary trigger of polymorphic light eruption (PLE) remains to be uncovered. We hypothesize that PLE may be initiated by elements resulting from UV-induced damage to microbial communities of the skin, leading to a cascade of events eventually resulting in the skin rash of the disease. One mechanism by which epidermal injury by UV radiation could trigger PLE are danger signals such as damage or pathogen associated molecular patterns DAMP/PAMPs or commensal-associated molecular patterns (CAMPs). Such triggers could be produced due to UV-induced stress on microbial communities of the skin and exacerbate inflammatory responses by inducing the innate immune system through antimicrobial peptides (AMPs) such as psoriasin, RNase7, HBD-2 and LL-37. These AMPs also actively take part in initiating adaptive immunity. That signals derived from microbial rather than human elements may initiate PLE is supported by series of observations, including the PLE-protective effect of topically applied microbial-derived DNA repair enzymes.