Clinical and microbiological features of Streptococcus anginosus group infections: a 7-year retrospective study in Vietnam

Abstract

Introduction: The Streptococcus anginosus group (SAG) is emerging as a significant cause of invasive infections, yet data from Vietnam remain scarce. This study characterized the clinical features and outcomes of SAG infections in Ho Chi Minh City.

Methodology: We retrospectively reviewed patients with culture-confirmed SAG infections at the Hospital for Tropical Diseases (January 2017–August 2023). Demographics, clinical, and microbiological data were analyzed.

Results: A total of 82 patients (mean age 50.6 ± 16.8 years; 64.6% male) with culture-confirmed SAG infections were included. Comorbidities were present in 56.1% of patients, with diabetes mellitus being the most common (23.2%). S. anginosus was the most frequently isolated species (43.9%), followed by S. constellatus (34.1%) and S. intermedius (22.0%). Bacteremia (35.4%) and intra-abdominal infections (31.7%, mainly hepatic abscesses) were the predominant clinical presentations. Polymicrobial infections occurred in 14.6% of cases, primarily among patients with bacteremia and skin or soft tissue infections. All isolates remained susceptible to ceftriaxone and vancomycin, and 94.3% to ampicillin, but susceptibilities were lower to penicillin (84.3%), erythromycin (65.7%), clindamycin (54.3%), and tetracycline (54.3%). Despite a 92.7% cure rate, 19.5% required drainage procedures, and the 28-day mortality rate was 6.1%.

Conclusions: In this cohort, SAG infection most often present as occult bacteremia or hepatobiliary abscess, frequently in patients with comorbidities, but not restricted to immunocompromised hosts. Empirical β-lactam therapy (ampicillin or ceftriaxone) remains appropriate, although rising penicillin and macrolide resistance and the 15% polymicrobial rate, may warrant broader initial coverage when deep soft-tissue foci are suspected.