Pneumonia is a lower respiratory tract infection classified by cause and setting. Bacterial pneumonia, commonly due to Streptococcus pneumoniae, often requires antibiotics such as ceftriaxone from a reliable ceftriaxone injection supplier. Viral pneumonia may result from influenza or respiratory syncytial virus and typically needs supportive care. Atypical pneumonia, caused by organisms like Mycoplasma pneumoniae, presents with milder, diffuse symptoms. Fungal pneumonia occurs in immunocompromised patients and involves pathogens like Histoplasma. Clinically, pneumonia is also categorized as community-acquired, hospital-acquired, or ventilator-associated, each differing in microbial profile, resistance patterns, and therapeutic strategy.