The period reveals a shift toward antibody-based and early antimicrobial strategies as central to infection control. Researchers explore refined antibacterial serum therapy for pneumonia, identify growth-inhibitory substances from lactic streptococci, and document serological phenomena that underpin diagnostic and immunotherapeutic concepts. In parallel, bacterial genetics begins to emerge through in vitro transformation of pneumococcal types and the demonstration of antigenic plasticity, foreshadowing later molecular approaches that would underpin antibiotic discovery.