In this study we assess whether using a polymerase chain reaction (PCR)-based rapid diagnostic tool to detect VAP-associated pathogens and resistance genes in the lower respiratory tract, in combination with CPIS scoring, microbiological tests and the levels of PTX-3, SP-D, s-TREM, IL-1β, and IL-8 in serum and/or lower respiratory tract aspirate, could improve the accuracy of VAP diagnosis and follow-up in critically-ill children. The gene discussed is PTX3; the disease is ventilator-associated pneumonia.