Bacterial causes of CAP vary by age, comorbidities, and local resistance patterns. Commonly discussed organisms include Streptococcus pneumoniae and Haemophilus influenzae. In certain contexts, Staphylococcus aureus becomes more relevant, particularly after viral infections. Klebsiella pneumoniae and other Gram-negative pathogens may be more prominent in selected risk profiles. Within the atypical group, Mycoplasma pneumoniae can cause CAP-like illness. Empiric treatment is built around these probabilities and refined when test results support de-escalation. This approach improves clinical outcomes while reducing unnecessary broad-spectrum antibiotic exposure.