Pneumonia is a lung infection caused by bacteria, viruses, fungi, or, less commonly, parasites. Common bacterial causes include Streptococcus pneumoniae, while viral pneumonia may result from influenza or respiratory syncytial virus. Risk factors include weakened immunity, chronic illness, smoking, and advanced age. Symptoms typically include persistent cough, fever, chills, chest pain during breathing, shortness of breath, fatigue, and production of phlegm. In severe cases, confusion and low oxygen levels may occur. Treatment depends on the cause and severity; for bacterial pneumonia, hospitals often rely on antibiotics sourced through a ceftriaxone injection wholesaler as part of standard care.