. 2021 May 13;21:161. doi: 10.1186/s12890-021-01527-1

Table 1.

Ventilator-associated pneumonia diagnostic algorithms utilized in this study

Published Criteria (citation)	Systemic Criteria	Chest Criteria	Chest Radiography Criteria	Microbiologic Criteria
CDC/NHSN (25)	- Inflammatory response Temperature > 38 °C WBC > 12,000/mm³ or < 4,000/mm³ - OR new antimicrobial agent is started for ≥ 4 days → Infection-related ventilator-associated complication	After a period of stability or improvement on the ventilator (≥ 2 calendar days of stable or ↓ F_iO₂ or PEEP): - Minimum daily F_iO₂ ↑ ≥ 0.20 lasting 2 days - Or minimum daily PEEP values ↑ ≥ 3 cm H₂O lasting 2 days → Ventilator-associated condition	–	Microbiologic quantitative ( +), OR histologic ( +), OR ( +) for legionella, influenza, RSV, adenovirus, or parainfluenza virus AND Gram-stain evidence ≥ 25 neutrophils/lpf and ≤ 10 epithelial cells/lpf → Probable VAP
CPIS^a (26)	Fever: - 38.5–38.9 (1 point) - ≥ 39 or < 36.5 (2 points) WBC: - < 4,000/mm³ or > 11,000/mm³ (2 points)	- Secretions but not purulent (1 point) - Purulent secretions (2 points) - P_aO₂/ F_iO₂ < 240 without ARDS (2 points)	Diffuse infiltrate (1 point) Localized infiltrate (2 points) Progressive infiltrate (without cardiac disease or ARDS) (+ 2)	Positive (1 point)
HELICS^b (27)	At least 1 criterion: - Temperature > 38 °C (with no other cause) - WBC > 12,000/mm³ or < 4,000/mm³ - If age > 70 years: AMS without other cause	At least 1 of following criteria (2 clinical pneumonia only = PN4 and PN5): New onset purulent sputum or change in sputum character (color, odor, quantity, consistency) Cough or dyspnea or tachypnea Suggestive auscultation (rales or bronchial breath sounds, rhonchi, wheezing) Worsening gas exchange (O₂ desaturation, increasing F_iO₂ requirements or ventilation demands)	Image suggestive of pneumonia. (≥ 2 serial chest X-rays or CT scans with suggestive imaging for patients with underlying cardiac or pulmonary disease)	PN1 – ( +) quantitative Cx from minimally contaminated LRT specimen ^c PN2 – ( +) quantitative Cx from possibly contaminated LRT specimen ^d PN3 – Alternative methods: ^e ( +) blood or pleural Cx, pleural or pulmonary abscess, histology, or pathogen antigen or antibody testing PN4 – ( +) sputum Cx or non-quantitative LRT specimen Cx PN5 – No positive results
Johanson (28)	Temperature > 38.5 °C WBC > 12,000/mm³	Purulent secretions	New or progressive consolidation	–

Published Criteria (citation)

Systemic Criteria

Chest Criteria

Chest Radiography Criteria

Microbiologic Criteria

CDC/NHSN (25)

- Inflammatory response

Temperature > 38 °C

WBC > 12,000/mm³ or < 4,000/mm³

- OR new antimicrobial agent is started for ≥ 4 days

→ Infection-related ventilator-associated complication

After a period of stability or improvement on the ventilator (≥ 2 calendar days of stable or ↓ F_iO₂ or PEEP):

- Minimum daily F_iO₂ ↑ ≥ 0.20 lasting 2 days

- Or minimum daily PEEP values ↑ ≥ 3 cm H₂O lasting 2 days

→ Ventilator-associated condition

–

Microbiologic quantitative ( +), OR histologic ( +), OR ( +) for legionella, influenza, RSV, adenovirus, or parainfluenza virus

AND

Gram-stain evidence ≥ 25 neutrophils/lpf and ≤ 10 epithelial cells/lpf

→ Probable VAP

CPIS^a

(26)

Fever:

- 38.5–38.9 (1 point)

- ≥ 39 or < 36.5 (2 points)

WBC:

- < 4,000/mm³ or > 11,000/mm³ (2 points)

- Secretions but not purulent (1 point)

- Purulent secretions (2 points)

- P_aO₂/ F_iO₂ < 240 without ARDS (2 points)

Diffuse infiltrate (1 point)

Localized infiltrate (2 points)

Progressive infiltrate (without cardiac disease or ARDS) (+ 2)

Positive (1 point)

HELICS^b

(27)

At least 1 criterion:

- Temperature > 38 °C (with no other cause)

- WBC > 12,000/mm³ or < 4,000/mm³

- If age > 70 years: AMS without other cause

At least 1 of following criteria (2 clinical pneumonia only = PN4 and PN5):

New onset purulent sputum or change in sputum character (color, odor, quantity, consistency)

Cough or dyspnea or tachypnea

Suggestive auscultation (rales or bronchial breath sounds, rhonchi, wheezing)

Worsening gas exchange (O₂ desaturation, increasing F_iO₂ requirements or ventilation demands)

Image suggestive of pneumonia. (≥ 2 serial chest X-rays or CT scans with suggestive imaging for patients with underlying cardiac or pulmonary disease)

PN1 – ( +) quantitative Cx from minimally contaminated LRT specimen ^c

PN2 – ( +) quantitative Cx from possibly contaminated LRT specimen ^d

PN3 – Alternative methods: ^e ( +) blood or pleural Cx, pleural or pulmonary abscess, histology, or pathogen antigen or antibody testing

PN4 – ( +) sputum Cx or non-quantitative LRT specimen Cx

PN5 – No positive results

Johanson

(28)

Temperature > 38.5 °C

WBC > 12,000/mm³

Purulent secretions

New or progressive consolidation

–

AMS: altered mental status; ARDS: acute respiratory distress syndrome; CDC/NHSN: centers for disease control and prevention national health safety network; CPIS: clinical pulmonary infection score; Cx: culture; F_iO₂: fraction of inspired oxygen; HELICS: hospital in Europe link for infection control through surveilance; LRT: lower respiratory tract; P_aO₂: partial pressure of oxygen in arterial blood; RSV: respiratory syncytial virus; VAP: ventilator associated pneumonia; WBC: white blood cell

^aScore > 6 is suggestive of VAP

^bVAP diagnosis if criteria met and invasive respiratory device (even intermittently) in the 48 h preceding the onset of infection

^cEither: (1) Broncho-alveolar lavage (BAL) with a threshold of ≥ 104 cfu/mL or ≥ 5% of BAL obtained cells contains intracellular bacteria on direct microscopic exam; (2) Protected brush (PB Wimberley) with a threshold of ≥ 103 cfu/mL; (3) Distal protected aspirate (DPA) with a threshold of ≥ 103 cfu/mL

^dQuantitative culture of LRT specimen (e.g., endotracheal aspirate) with a threshold of 106 cfu/mL

^eEither: (1) positive blood culture not related to another source of infection; (2) positive growth in culture of pleural fluid; (3) pleural or pulmonary exam shows evidence of pneumonia; (4) positive exams for pneumonia with virus or particular germs (Legionella, Aspergillus, mycobacteria, Mycoplasma, Pneumocystis carinii). The latter may include: (A) positive detection of viral antigen or antibody from respiratory secretions (e.g., EIA, FAMA, shell vial assay, PCR); (B) positive direct exam or positive culture from bronchial secretions or tissue; (C) seroconversion (ex: influenza viruses, Legionella, Chlamydia); or (D) detection of antigens in urine (Legionella)