Abstract
BACKGROUND: Group A streptococcus infection during pregnancy can be concerning. It may cause toxic shock syndrome, which can be fatal. Here, we report a rare case of a pregnant woman who developed infectious sacroiliitis due to group A streptococcus infection. To the best of our knowledge, this case is the first of its kind to be reported. CASE PRESENTATION: A 32-year-old multiparous Japanese woman presented with fever and right buttock pain at 28 weeks of gestation. Based on our clinical findings and investigations, she was diagnosed with group A streptococcus bacteremia and infectious sacroiliitis caused by group A streptococcus. A cardiotocography performed to assess the fetal status showed fetal tachycardia. To prevent the patient from progressing to toxic shock syndrome caused by group A streptococcus, we performed an emergency cesarean section. The patient and her infant had a good course after the cesarean section. CONCLUSION: A pregnant woman diagnosed with group A streptococcus infection needs to be monitored closely because a timely decision to deliver the fetus before rapid deterioration to toxic shock syndrome is crucial.