Multiple myeloma (MM) is the second most common hematological malignancy and is a type of plasma cell neoplasm. In MM, abnormal monoclonal plasma cell proliferation causes not only B-cell dysfunction and hypogammaglobulinemia but also abnormalities in other immune cells, such as T cells, dendritic cells, and natural killer (NK) cells [1]. In patients with MM, these abnormalities increased their susceptibility to infections. While several novel drugs have significantly improved the prognosis of patients with MM in the last decade, long-term treatment is generally required, which increases the risk of various infections [1]. Streptococcus agalactiae, also known as Group B Streptococcus (GBS), colonizes approximately 50% of healthy adults’ gastrointestinal, urinary, and genital tracts and occasionally causes opportunistic infections [2]. In the last 20 years, adult invasive GBS infections are said to have increased two-to four-fold [3]. Toxic shock-like syndrome (TSLS) is a rare fulminant infection caused by the Streptococcus species, similar to the Staphylococcus aureus or Streptococcus pyogenes toxic shock syndrome [4]. TSLS mostly occurs in those with S. agalactiae infections originating from cellulitis or necrotizing fasciitis or emerging as overwhelming post-splenectomy infection, presenting multiple organ failure, including impaired consciousness, acute kidney injury, liver dysfunction, and coagulopathy [5].

This paper describes a case of S. agalactiae bacteremia resulting in multiple organ failure due to TSLS during chemotherapy for relapsed MM.