A rare case of empyema caused by Streptococcus constellatus in a healthy young adult: A case report

Abstract

Streptococcus constellatus (S. constellatus) is a Gram-positive, non-spore-forming, immobile, and catalase-negative coccus. Its growth is enhanced in the presence of CO2, while growth is reduced under aerobic conditions, with some strains requiring anaerobic conditions for optimal growth. A member of the Streptococcus anginosus group (SAG), S. constellatus is naturally found in the flora of the oral cavity, gastrointestinal system, and urogenital system. Although typically considered a commensal organism, it can become an opportunistic pathogen in immunocompromised individuals, leading to severe invasive infections. Among these infections, empyema is rare, with only a limited number of case reports in the literature. This study presents the first reported case from the Nakhchivan region. This study presents a rare case of empyema caused by S. constellatus in a healthy individual. The patient presented with classical symptoms of bacterial empyema, including fever, chest pain, and shortness of breath. During the diagnostic process, microbiological investigations confirmed that the cause of the infection was S. constellatus. “Microbiological culture analysis revealed that the isolated bacterium exhibited beta-hemolytic properties; following antibiotic susceptibility testing, an effective targeted treatment protocol was established. With appropriate antibiotic selection, the infection was quickly controlled, and the patient experienced rapid clinical improvement.” This case emphasizes the need to consider S. constellatus as a rare cause of empyema and highlights the importance of early diagnosis in such cases. Early diagnosis plays a critical role not only in controlling the infection but also in optimizing the response to treatment. In conclusion, this case report underscores the importance of recognizing S. constellatus as an agent of empyema, contributing a rare infection to the literature. Furthermore, it addresses the challenges encountered in the diagnosis and treatment of such infections and provides significant contributions to clinical practice. This case reiterates the necessity of considering atypical pathogens in the management of serious infections like empyema. © 2025, Refik Saydam National Public Health Agency (RSNPHA). All rights reserved.