A case of leg cellulitis caused by multidrug-resistant Streptococcus pseudoporcinus

A 94-year-old woman was admitted to our hospital with a 5-day history of painful redness in the left lower leg. She was diagnosed with cellulitis and initiated antibiotic therapy with cefazolin. After two days, she presented with an extremely high fever (39.9°C), high C-reactive protein level (256 mg/L; normal, < 3), and signs of disseminated intravascular coagulation. In bacteriological examination, Streptococcus pseudoporcinus was detected from her lower leg wound purulence. An antibiogram revealed multidrug resistance except for cefepime, carbapenems, and vancomycin. We changed the antibiotics to cefepime and vancomycin according to the antibiogram and administered immunoglobulin concurrently. As the result of these therapies, her conditions gradually resolved over two weeks. S. pseudoporcinus, one of the β-hemolytic Streptococcus species recently described, has been isolated from the genitourinary tract of women. To our knowledge, this is the first case of cellulitis caused by S. pseudoporcinus. Typically, most antibiotics indicate adequate drug susceptibilities of S. pseudoporcinus, but in our case, multidrug resistance contributed to the prolonged duration of treatment. Because the colonization of S. pseudoporcinus in healthy individuals is not rare, it could become an important pathogen in elderly people and in those who have underlying medical conditions, as with other β-hemolytic Streptococci.