The article highlights the increased incidence, severity, and mortality of bacterial infectious diseases in older adults, often presenting atypically and complicating diagnosis. Aging-related immune changes (immunosenescence) and chronic conditions heighten susceptibility and worsen outcomes. Pneumonia and urinary tract infections are most common, with diagnostic challenges due to nonspecific symptoms like confusion or functional decline. Effective prevention, timely diagnosis, and tailored treatment, including rational antibiotic use, are critical to improve prognosis in this vulnerable population.