Incipient empyema as an embolic complication of group A streptococcal septic arthritis in a patient with concomitant influenza B infection

A 43-year-old healthy male presented with left ankle septic arthritis. Surgical specimens cultured Streptococcus pyogenes (group A Streptococcus, GAS) and IV benzylpenicillin was commenced. In the setting of coryzal symptoms, a chest radiograph and nasopharyngeal swab revealed a left-sided pleural effusion and influenza B infection, respectively. Persisting fevers, rising CRP, and increasing breathlessness led to repeat chest radiography showing a rapidly enlarging left-sided effusion. Following intercostal catheter insertion with intrapleural fibrinolytic therapy, 6 L of haemorrhagic fluid was drained leading to defervescence and clinical improvement. At follow-up 4 weeks later, he was asymptomatic with a normal chest radiograph. Similar to previous reported cases of GAS empyema, this case was associated with concurrent viral respiratory tract infection, but is unusual as it arose through haematogenous seeding from an extra-thoracic source. This case reminds clinicians to be aware of the strongly pyogenic nature of GAS and its significance as a potential cause of pleural infection, especially in patients with concomitant viral respiratory infections.