Streptococcus pneumoniae, group A beta-hemolytic streptococci, Neisseria gonorrhoeae, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae (group B), Salmonella choleraesuis, Pasteurella multocida, Acinetobacter calcoaceticus, and Plesiomonas shigelloides. It may also be associated with a history of splenectomy. In rare cases, it may be caused by the use of medications that promote blood clotting, low platelet counts, primary antiphospholipid syndrome, renal vein thrombosis or steroid use. While the exact mechanism of disease is not clear, activation of several cytokine mediators appears to lead to sepsis and shock.

A characteristic skin rash with a typical evolution occurs in approximately 75% of patients with Waterhouse-Friderichsen syndrome.

• In its early stages, the rash consists of small, pink macules or papules.
• These are rapidly followed by petechial lesions, which gradually transform into large, purpuric, coalescent plaques in late stages of the disease.

Treatment may include antibiotics and glucocorticoids. Other treatment is symptomatic and supportive.

In Waterhouse-Friderichsen syndrome, the case fatality rate is 55-60%, particularly when the diagnosis is delayed. Death typically results from sepsis, despite aggressive treatment.