Bloodstream Infection Caused by Erysipelothrix rhusiopathiae in an Immunocompetent Patient

Erysipelothrix rhusiopathiae is a facultative anaerobe Gram-positive bacillus, which is considered a zoonotic pathogen. E. rhusiopathiae causes erysipeloid, mainly in occupational groups such as veterinarians, slaughterhouse workers, farmers, and fishermen. Two cutaneous forms (localised and generalised) and a septicaemic form have been described. Here, we report the isolation of a strain of E. rhusiopathiae from a 56-year-old immunocompetent obese male admitted to Fondazione IRCCS Policlinico San Matteo Pavia (Italy). Blood cultures were collected and Gram-positive bacilli were observed. E. rhusiopathiae grew and was identified. Antimicrobial susceptibility tests were performed and interpreted with EUCAST breakpoints (PK-PD). The strain was susceptible to all the antibiotics tested, while it was intrinsically resistant to vancomycin. The clinical diagnosis of E. rhusiopathiae can be challenging, due to the broad spectrum of symptoms and potential side effects, including serious systemic infections such as heart diseases. In the case described, bacteraemia caused by E. rhusiopathiae was detected in a immunocompetent patient. Bacteraemia caused by E. rhusiopathiae is rare in immunocompetent people and blood cultures were proven to be essential for the diagnosis and underdiagnosis of this pathogen, which is possible due to its resemblance to other clinical manifestations.