[Diagnosis of nosocomial pneumonia: conventional and new indicators].

Nosocomial pneumonia is difficult to diagnose. Clinical criteria, saliva and tracheal specimen cultures can be sensitive to bacterial pathogeny, they are however nonspecific in patients with assisted mechanical ventilation; on the other hand, blood and pleural liquid cultures have very poor sensitivity. Fever and leukocytosis are not constant signs and are not compulsory for diagnosing nosocomial pneumonia (NP). Interleukine 1 (IL-1) is a proinflammatory cytokine produced by macrophages, but research studies failed to indicate some connection to the incidence or clinical outcome in nosocomial pneumonia. Tumoral necrosis factor (TNF) is considered one of the most important mediators of endotoxin induced effects: studies on acute inflammatory conditions such as severe sepsis indicated a link between the homozygosity of TNFb2 and the mortality or the incidence of nosocomial pneumonia in trauma patients. Procalcitonin (PCT) is a parameter different from other markers currently available to evaluate inflammatory response. PCT is induced by bacterial inflammation selectively and also appears in sepsis and in MODS. PCT values higher than 0.5 ng/mL always indicate acute infection or septic inflammation.