Table 1. Comparison between ventilator-associated infection definitions (5,6,8,9).

Diagnostic criteria	VARIa (CDC 2008)			Infective events of VAE (CDC 2013)
	VAT	VAP		PVAP	IVAC-plus
Clinical	Suspicion of infectiong	One of the following: worsening gas exchangek; tachypnea or dyspnea; change in sputum characteristicsl; rales or bronchial breath sounds; apnea in pediatric patients		Increase in FiO2 ≥0.20 or in PEEP ≥3 cmH2O with a previous period of stability or improvement ≥2 days	Increase in FiO2 ≥0.20 or in PEEP ≥3 cmH2O with a previous period of stability or improvement ≥2 days
	In infants ≤1 year old: respiratory distress; apnea; bradycardiah	And at least one: suspicion of infectiong; altered mental status in adults ≥70 years old; bradycardiah or tachycardiam in infants ≤1 year old		And suspicion of infectiong	And suspicion of infectiong
				And beginning of a new antibiotic	And beginning of a new antibiotic
				Pediatric patients: increase in FiO2 ≥0.20 or in PEEP ≥1 cmH2O or increase in FiO2 ≥0.15 plus PEEP ≥1 cmH2O with a previous period of stability/improvement ≥1 day
Chest X-ray	Absence of radiologic criteria for pneumonia	New or progressive infiltrate, consolidation or cavitation		Not included	Not included
		Pneumatocele in infants ≤1 year old
Microbiology	Purulent sputumi and positive endotracheal aspirate culturej	Significative growth of a pathogen in respiratory samplesj		Significative growth of a pathogen in respiratory samplesj	Not included
		>5% Cells with intracellular bacteria in bronchoalveolar lavage		Insufficient growth of a pathogenic microorganism plus purulent sputumi
		Pathogenic microorganism in pleural fluid cultures		Pathogenic microorganism in pleural fluid cultures
		Histopathologic evidence of lung infectionn		Histopathologic evidence of lung infectionn
		Positive growth in blood cultureo		Positive test for pathogenic virus in respiratory samples
				Positive test for Legionella species

^g, suspicion of infection: fever (≥38 °C) or hypothermia (≤36 °C) or leukocytosis (≥12,000 cells/mL in adults or ≥15,000 cells/mL in ≤12 years old) or leukopenia (≤4,000 cells/mL); ^h, bradycardia in children ≤1 year old: <100 beats per minute; ⁱ, purulent sputum: ≥25 neutrophils with <10 squamous epithelial cells per low power field; ^j, significative growth in respiratory samples: endotracheal aspirate: ≥10⁵ CFU/mL, bronchoalveolar lavage: ≥10⁴ CFU/mL, lung tissue: ≥10⁴ CFU/g, protected specimen brush: ≥10³ CFU/mL; ^k, worsening gas Exchange: Increased oxygen requirements or in ventilator demand (mandatory criteria for infants ≤1 year old); ^l, change in sputum characteristics: New onset of purulent respiratory secretions or increase in its production or in suctioning requirements; ^m, tachycardia in infants ≤1 year old: >170 beats per minute; ⁿ, histopathologic evidence of lung infection: abscess formation or foci of consolidation with intense polymorphonuclear accumulation or positive quantitative culture of parenchyma or evidence of parenchyma invasion by fungus or virus; ^o, in absence of other recognized focus. VARI, ventilator-associated respiratory infection; VAE, ventilator-associated events; VAT, ventilator-associated tracheobronchitis; VAP, ventilator-associated pneumonia; PVAP, possible-ventilator associated pneumonia; IVAC-plus, infectious-ventilator associated complication plus.