A49-40 IVIG in Group A Streptococcal Bacteremia Complicated by Clostridioides Difficile Colitis and Shock

Abstract Introduction Group A Streptococcus (GAS), a gram-positive, beta-hemolytic bacterium, commonly causes pharyngitis and skin infections. In severe cases, it can lead to necrotizing fasciitis and streptococcal toxic shock syndrome (STSS) which has up to 26% mortality rate within 24 hours. Patients with gastrointestinal symptoms are even twice as likely to die within the first 7 days. We present a case of GAS bacteremia complicated by Clostridioides difficile colitis and septic shock, treated with intravenous immunoglobulin (IVIG) as an adjunctive therapy. Case Description 60-year-old male with a history of squamous cell carcinoma on chemotherapy, recent port placement, diabetes mellitus, and hypertension presented with fever, vomiting, and diarrhea. Blood cultures were obtained, and empiric IV antibiotics (vancomycin, cefepime, and metronidazole) were initiated. On hospital day two, he developed new-onset rapid atrial fibrillation, respiratory distress, and hypotension requiring ICU transfer. He was started on norepinephrine, vasopressin, and amiodarone drip and intubated for airway protection. Blood cultures grew Streptococcus pyogenes and stool PCR was positive for Clostridioides difficile. Antibiotics were adjusted to oral vancomycin, IV ceftriaxone, and clindamycin. Given his immunosuppression and septic shock, a three-day course of IVIG therapy was initiated. His vasopressor requirements declined within 12 hours and stopped entirely within 48 hours. Clindamycin was discontinued by Day 4 due to colitis, and he was transferred out of the ICU in stable condition. Discussion The role of IVIG in the treatment of invasive GAS infections remains controversial. The anti-superantigen antibodies in the IVIG neutralize the circulating superantitoxin preventing toxins from binding to immune cells and, thereby interrupting the vicious cycle of the cytokine storm and helping to reverse shock and stabilize organ function. Observational studies show no significant difference in outcomes, but a small randomized controlled trial reported a 3.6-fold higher mortality rate in the placebo group compared to the IVIG-treated group. A pooled analysis of five nonrandomized studies showed that IVIG, when added to clindamycin, reduced mortality from 33.7% to 15.7%. In our case, IVIG was used as adjunctive therapy in a patient with worsening septic shock, concurrent C. difficile colitis, and pancytopenia. The patient’s rapid clinical improvement following IVIG initiation suggests a potential survival benefit in select critically ill patients with toxin-mediated GAS infections. This abstract is funded by: None