Table 1 Classification of ventilator-acquired pneumonia by the HELICS criteria

Code	Diagnostic method
PN1	Positive quantitative culture from minimally contaminated LRT specimen—BAL ⩾10⁴ CFU
PN2	Positive quantitative culture of LRT (tracheal aspirate) or sputum—not available within our laboratory
PN3	Positive culture related to no other source—positive pleural fluid culture OR pulmonary abscess with positive needle aspiration OR positive histology OR positive exams for virus
PN4	Positive sputum culture or non-quantitative LRT (tracheal aspirate) specimen culture
PN5	No positive microbiology including BAL with <10⁴ CFU

All patients meet clinical criteria (radiographic changes, pyrexia or leucocytosis/leucopenia and clinical signs of chest infection such as increased volume or purulence of sputum, crepitations and deterioration in oxygenation). Adapted from IPSE (Improving Satety in Europe).21
BAL, bronchoalveolar lavage; CFU, colony-forming units; HELICS, Hospitals in Europe Link for Infection Control through Surveillance; LRT, lower respiratory tract.