Infectious Diseases: What You May Have Missed in 2025

This article highlights clinical trials on infectious diseases published in 2025 that we believe are highly relevant to internal medicine physicians who are not infectious diseases specialists. Selected studies address prevention and treatment strategies across infectious diseases. We highlight 2 studies of sexually transmitted infections (STIs): one examining the effectiveness of treating male partners to reduce recurrence of bacterial vaginosis and another study of doxycycline as postexposure prophylaxis against bacterial STI. A strategy for using methanamine hippurate to prevent recurrent urinary tract infections (UTIs) in older women is included in our review. We review the updated evidence supporting the effectiveness of COVID-19, respiratory syncytial virus, and influenza vaccines for the 2025–2026 season, and a modified messenger RNA influenza vaccine, which showed superior efficacy with an acceptable safety profile. In HIV care, a study of dual antiretroviral maintenance therapy showed that dolutegravir and lamivudine was noninferior to triple therapy at 48 weeks. A meta-analysis supporting shorter antibiotic courses for pyelonephritis and complicated UTIs provides important information for antibiotic stewardship strategies. In serious infections, dalbavancin was noninferior to standard therapy for Staphylococcus aureus bacteremia, whereas cefiderocol expanded treatment options for gram-negative bloodstream infections without clear superiority, particularly in carbapenem-resistant pathogens. Finally, a study found that elevated C-reactive protein identifies patients most likely to benefit from adjunctive corticosteroids in community-acquired pneumonia.