A family cluster of five cases of group A streptococcal pneumonia.

A cluster of 5 family members, a mother and 4 children, were hospitalized for severe group A Streptococcus (GAS) pneumonia. Three family members had complications: sepsis (1), empyema (2), and a sterile parapneumonic effusion (1). Two additional family members had symptoms of upper respiratory tract infection, and 1 was hospitalized for these symptoms. GAS was isolated from the blood of 1 patient, the pleural fluid of 2 patients, and the oropharynx of 6 patients. Pulsed field gel electrophoresis testing revealed an identical deoxyribonucleic acid pattern in all 7 isolates. Genotyping revealed the speA gene and serotyping the T-1, M-1 serotype in all isolates. This family cluster of invasive GAS disease is the largest reported to date, with an attack rate of 41.7% (5 of 12 family members). This report provides further support for antibiotic prophylaxis of close contacts of individuals with invasive GAS disease.