Lung Abscess and Bacteremia Caused by Neisseria flavescens and Streptococcus sanguis in Patient with Idiopathic Hypereosinophilic Syndrome / 대한임상미생물학회지

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.

Native Valve Infective Endocarditis due to Staphylococcus lugdunensis Confirmed by 16S Ribosomal RNA Sequencing / 감염과화학요법

Staphylococcus lugdunensis is a Gram-positive, coagulase-negative Staphylococcus (CNS) species that is found as a skin commensal and has been implicated in fulminant invasive diseases such as infective endocarditis. S. lugudunensis infections resemble Staphylococcus aureus infections in terms of virulence, tissue destruction and clinical course. Although correct identification and determination of the susceptibility profile are important, some commercial systems may misidentify S. lugdunensis. We report a case of native valve infective endocarditis caused by S. lugdunensis, which was misidentified by the Vitek 2 system but identified correctly by 16S ribosomal RNA (rRNA) gene sequencing in a 72-year-old male patient. The patient had multiple vegetations on his mitral valve, and the largest one was found on the posterior mitral valve leaflet. It was 2.5 cm in size and hypermobile. Diffuse valvular abscess was also observed. He had persistent bacteremia for appoximately 8 days, which was resolved after immediate surgery and antibiotic therapy. When a patient with severe sepsis syndrome grows S. aureus or CNS other than S. lugdunensis on a commercial automatic culture system, the possibility of S. lugdunensis should be considered and further confirmatory testing such as 16S rRNA sequencing may be very useful.