Temporal Trends in Pathogens and Clinical Outcomes of Adult Deep Neck Infections: An 18-Year Multicenter Cohort Study of 12,063 Cases

Adult deep neck infection (DNI) is a potentially life-threatening condition associated with significant morbidity and mortality. Contemporary large-scale data characterizing long-term microbial evolution and clinical outcome trends in adult DNI remain limited. This study aimed to investigate temporal changes in bacterial pathogens, treatment strategies, and clinical outcomes of adult DNI across an 18-year period. This is a retrospective multicenter cohort study using the Chang Gung Research Database (CGRD) and a de-identified nationwide database from Taiwan’s largest medical system. Hospitalized adult patients (aged ≥18 years) with DNI from 2006 to 2023 were identified and stratified into two consecutive 9-year epochs (Epoch 1: 2006–2014, n = 5512; Epoch 2: 2015–2023, n = 6551). Demographics, comorbidities, treatment modalities, disease severity, and microbiological profiles were analyzed. Bacterial isolates were evaluated at genus and species levels, with methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) assessed separately. Among 12,063 adult DNI patients (Epoch 1: n = 5512; Epoch 2: n = 6551), antibiotic-only treatment increased (77.3% to 83.2%) and surgical intervention decreased (22.7% to 16.9%). Descending necrotizing mediastinitis decreased markedly (2.7% to 0.7%) and in-hospital mortality declined (7.7% to 6.4%). Poly-microbial infections increased substantially (45.3% to 53.7%). Among facultative anaerobic and aerobic isolates, the Streptococcus anginosus group (SAG) emerged as a clinically important pathogen. Among anaerobes, Prevotella displaced Peptostreptococcus as the dominant genus, with Peptostreptococcus micros (Parvimonas micra) and Prevotella buccae emerging as prominent species. Over 18 years, adult DNI in Taiwan demonstrated significant improvements in clinical outcomes, with marked reductions in mediastinitis and in-hospital mortality. Concurrently, poly-microbial infections increased, and the SAG, Peptostreptococcus micros (Parvimonas micra), Prevotella, and anaerobic organisms emerged as clinically important pathogens, underscoring the need for empiric antibiotic regimens providing broad aerobic and anaerobic coverage. Although microbiological profiles vary geographically, these findings provide a contemporary evidence base to guide empiric antibiotic selection, inform surgical decision-making, and identify high-risk adult patients with DNI.