One regimen is an intravenous antipseudomonal beta-lactam such as cefepime, imipenem, meropenem or piperacillin/tazobactam, plus an IV antipseudomonal fluoroquinolone such as levofloxacin. Another is an IV antipseudomonal beta-lactam such as cefepime, imipenem, meropenem or piperacillin/tazobactam, plus an aminoglycoside such as gentamicin or tobramycin, plus a macrolide (such as azithromycin) or a nonpseudomonal fluoroquinolone such as ciprofloxacin.For mild-to-moderate CAP, shorter courses of antibiotics (3–7 days) seem to be sufficient.Some patients with CAP will be at increased risk of death despite antimicrobial treatment. A key reason for this is the hosts exaggerated inflammatory response. There is a tension between controlling the infection on one hand and minimizing damage to other tissues on the other. Some recent research focuses on immunomodulatory therapy that can modulate the immune response in order to reduce injury to the lung and other affected organs such as the heart. Although the evidence for these agents has not resulted in their routine use, their potential benefits are promising. Hospitalization
Some CAP patients require intensive care, with clinical prediction rules such as the pneumonia severity index and CURB-65 guiding the decision whether or not to hospitalize.
Pseudomonas aeruginosa, an uncommon cause of CAP, is a difficult bacteria to treat. Bacteria and fungi typically enter the lungs by inhalation of water droplets, although they can reach the lung through the bloodstream if an infection is present. In the alveoli, bacteria and fungi travel into the spaces between cells and adjacent alveoli through connecting pores. The immune system responds by releasing neutrophil granulocytes, white blood cells responsible for attacking microorganisms, into the lungs. The neutrophils engulf and kill the microorganisms, releasing cytokines which activate the entire immune system. This response causes fever, chills and fatigue, common symptoms of CAP. The neutrophils, bacteria and fluids leaked from surrounding blood vessels fill the alveoli, impairing oxygen transport. Bacteria may travel from the lung to the bloodstream, causing septic shock (very low blood pressure which damages the brain, kidney, and heart). Parasites
A variety of parasites can affect the lungs, generally entering the body through the skin or by being swallowed. They then travel to the lungs through the blood, where the combination of cell destruction and immune response disrupts oxygen transport. Diagnosis
Patients with symptoms of CAP require evaluation. Diagnosis of pneumonia is made clinically, rather than on the basis of a particular test. Evaluation begins with a physical examination by a health provider, which may reveal fever, an increased respiratory rate (tachypnea), low blood pressure (hypotension), a fast heart rate (tachycardia) and changes in the amount of oxygen in the blood.