RESUMO
Neisseria flavescens has been rarely reported as a pathogen in the literature. We experienced a case of N. flavescens bacteremia and lung abscess co-infected with Streptococcus sanguis in patient with idiopathic hypereosinophilic syndrome. A 15-year-old boy was diagnosed with idiopathic hypereosinophilic syndrome complicated with pulmonary thromboembolism. He was given systemic steroids and thrombolytics. After 8 weeks of therapy, a lung abscess appeared on the plain chest radiograph. We treated him with empirical antibiotics and carried out surgical drainage. Two types of microorganisms were cultured from both blood and pus samples, obtained in the first day of hospitalization. Pus was aspirated from the lung abscess with an aseptic technique. Neisseria species and S. sanguis were identified using traditional methods. To confirm the identity of the Neisseria species, we conducted further testing using 16S ribosomal ribonucleic acid sequencing whereupon N. flavescens was identified. This is the first case report of pulmonary infection caused by N. flavescens. We suggest that N. flavescens may act as a pathogen.