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Pneumonia (Ventilator-associated [VAP] and non-ventilator-
associated Pneumonia [PNEU]) Event
Table of Contents
Introduction .................................................................................................................................................. 1
Settings ......................................................................................................................................................... 2
Key Terms and Abbreviations ....................................................................................................................... 2
Definitions Specific to PNEU/VAP Surveillance ............................................................................................. 3
Guidance for Determination of Eligible Imaging Test Evidence ................................................................... 3
General Comments Applicable to All Pneumonia Specific Site Criteria ........................................................ 4
Reporting Instructions .................................................................................................................................. 5
Table 1: Specific Site Algorithms for Clinically Defined Pneumonia (PNU1) ................................................. 6
Table 2: Specific Site Algorithm for Pneumonia with Common Bacterial or Filamentous Fungal Pathogens
and Specific Laboratory Findings (PNU2) ...................................................................................................... 7
Table 3: Specific Site Algorithm for Viral, Legionella, and other Bacterial Pneumonias with Definitive
Laboratory Findings (PNU2) .......................................................................................................................... 8
Table 4: Specific Site Algorithm for Pneumonia in Immunocompromised Patients (PNU3) ........................ 9
Figure 1: Pneumonia Flow Diagram for Patients of Any Age ...................................................................... 10
Figure 2: Pneumonia Flow Diagram, Alternative Criteria for Infants and Children .................................... 11
Footnotes to Algorithms and Flow Diagrams ............................................................................................. 12
Table 5: Threshold values for cultured specimens used in the diagnosis of pneumonia ........................... 15
Numerator Data .......................................................................................................................................... 16
Denominator Data ...................................................................................................................................... 16
Data Analyses .............................................................................................................................................. 17
Table 6: VAP Measures Available in NHSN ................................................................................................. 18
References .................................................................................................................................................. 19
Introduction
In 2015 CDC conducted a point-prevalence survey in a sample of acute care hospitals in U.S. and
determined that of the 427 healthcare–associated infections identified, pneumonia was the most
common infection with 32% of those being ventilator associated.
1
Patients receiving invasive mechanical
ventilation are at risk for numerous complications, including pneumonia. Ventilator-associated
pneumonia (VAP) and other healthcare-associated pneumonias are important, common healthcare-
associated infections, but national surveillance for VAP has long been a challenge because of the lack of
objective, reliable definitions. Due to these challenges, in January 2013 the National Healthcare Safety
Network (NHSN) replaced surveillance for ventilator-associated pneumonia (VAP) in adult inpatient
locations with surveillance for ventilator-associated events (VAE).
2
Based on discussions with an expert
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working group in 2012-2013, NHSN also discontinued in-plan VAP surveillance in neonatal locations. As
of January 2014, in-plan VAP surveillance is only available in pediatric inpatient locations.
Settings
Surveillance may occur in any inpatient pediatric location where denominator data can be
collected, such as critical/intensive care units (pediatric ICUs), specialty care areas (SCA), step-down
units, wards, and long-term care units. In-plan surveillance for pediatric ventilator-associated
pneumonia (pedVAP) using the criteria found in this chapter is restricted to patients of any age in
pediatric locations only (excludes neonatal locations). In-plan surveillance conducted for mechanically-
ventilated patients in adult locations (regardless of age) will use the Ventilator-Associated Event (VAE)
protocol (see VAE chapter).
The PNEU definitions are still available for those units seeking to conduct off-plan PNEU surveillance for
mechanically-ventilated adult, pediatric, and neonatal patients and non-ventilated adult, pediatric, and
neonatal patients. The PNEU definitions are also available for secondary bloodstream infection
assignment when performing Central Line-Associated Bloodstream Infection (CLABSI) surveillance in
ventilated or non-ventilated patients of any age in any location. A complete listing of inpatient locations
and instructions for mapping can be found in Chapter 15 CDC Locations and Descriptions.
Note: Post-discharge surveillance for pedVAPs is not required. However, if discovered, any pedVAPs
with a date of event (DOE) on the day of discharge or day after discharge is attributed to the discharging
location and should be included in any pedVAPs reported to NHSN by the discharging location. No
additional ventilator days are reported.
Key Terms and Abbreviations
Refer to the NHSN Patient Safety Manual, Chapter 2 Identifying Healthcare-associated Infections (HAI)
for NHSN Surveillance and Chapter 16 General Key Terms for definitions of the following universal
concepts for conducting HAI surveillance.
I Date of event (DOE)
II Healthcare associated infection (HAI)
III Infection window period (IWP)
IV Present on admission (POA)
V Repeat infection timeframe (RIT)
VI Secondary BSI attribution period (SBAP)
VII Location of attribution (LOA)
VIII Transfer rule
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Definitions Specific to PNEU/VAP Surveillance
Pneumonia (PNEU) is identified by using a combination of imaging, clinical, and laboratory criteria. The
following pages detail the various criteria that may be used for meeting the surveillance definition of
healthcare-associated pneumonia (Tables 1, 2, 3, and 4 and Figures 1 and 2), general comments
applicable to all site-specific criteria, and reporting instructions. Table 5 shows threshold values for
cultured specimens used in the surveillance diagnosis of pneumonia.
Ventilator: Any device used to support, assist, or control respiration (inclusive of the weaning period)
through the application of positive pressure to the airway when delivered via an artificial airway,
specifically an oral/nasal endotracheal or tracheostomy tube.
Ventilation and lung expansion devices that deliver positive pressure to the airway (for example, CPAP,
BiPAP, Bi-level, IPPB, and PEEP) via non-invasive means (for example, nasal prongs, nasal mask, full face
mask, total mask, etc.) are not considered ventilators unless positive pressure is delivered via an
artificial airway (oral/nasal endotracheal or tracheostomy tube).
Ventilator-associated pneumonia (VAP): A pneumonia where the patient is on mechanical ventilation for
> 2 consecutive calendar days on the date of event, with day of ventilator placement being Day 1*
AND
the ventilator was in place on the date of event or the day before.
*If the ventilator was in place prior to inpatient admission, the ventilator day count begins with the
admission date to the first inpatient location.
If a break in mechanical ventilation occurs for at least one full calendar day, ventilator day count for
ventilator association starts anew upon reintubation and/or re-initiation of mechanical ventilation.
Guidance for Determination of Eligible Imaging Test Evidence
• If only one imaging test is available, it is acceptable for this to satisfy the imaging requirement
for PNEU/VAP POA determinations regardless of whether the patient has underlying pulmonary
or cardiac disease.
• When multiple imaging test results are available, persistence of imaging test evidence of
pneumonia is a requirement for all patients, not just those with underlying cardiac or pulmonary
disease.
• All elements of PNEU/VAP definition must be present within the Infection Window Period (IWP).
The exception may occur when identifying persistence of imaging test evidence of pneumonia,
as the second imaging test must occur within seven days of the first but is not required to occur
within the IWP. The date of the first eligible imaging test will be utilized when determining if the
PNEU/VAP criteria are met within the IWP.
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General Comments Applicable to All Pneumonia Specific Site Criteria
1. Physician’s diagnosis of pneumonia alone is not an acceptable criterion for present on admission
(POA) or healthcare-associated (HAI) pneumonia.
2. Although specific criteria are included for infants and children and immunocompromised
patients, all patients may meet any of the other pneumonia site-specific criteria.
3. Pneumonia due to gross aspiration (for example, in the setting of intubation in the field,
emergency department, or operating room) that meets the PNEU/VAP definition with a date of
event during the HAI timeframe is considered healthcare-associated.
4. Multiple episodes of healthcare-associated pneumonia may occur in critically ill patients with
lengthy hospital stays. When determining whether to report multiple episodes of healthcare-
associated pneumonia in a single patient, follow the Repeat Infection Timeframe (RIT) guidance
found in Chapter 2.
5. Excluded organisms that cannot be used to meet the PNEU/VAP definition are as follows:
a. “Normal respiratory flora,” “normal oral flora,” “mixed respiratory flora,” “mixed oral
flora,” “altered oral flora,” or other similar results indicating isolation of commensal
flora of the oral cavity or upper respiratory tract. NOTE: A report of “flora” does not
exclude the use of an eligible organism isolated or identified from the specimen. Only
the “flora” is excluded from use.
b. The following organisms, unless identified from lung tissue or pleural fluid (where
specimen was obtained during thoracentesis or within 24 hours of chest tube
placement; pleural fluid specimens collected after a chest tube is repositioned or from a
chest tube in place > 24 hours are not eligible):
i. Any Candida species as well as a report of “yeast” that is not otherwise specified
ii. Any coagulase-negative Staphylococcus species
iii. Any Enterococcus species
6. If the excluded pathogens, any Candida species* or yeast not otherwise specified, any
coagulase-negative Staphylococcus species, and any Enterococcus species, are identified from
blood they can only be attributed as a secondary BSI to PNEU if PNU2 or PNU3 is met with a
matching organism identified from lung tissue or pleural fluid (where specimen was obtained
during thoracentesis or within 24 hours of chest tube placement; pleural fluid specimens
collected after a chest tube is repositioned or from a chest tube in place > 24 hours are not
eligible) and the blood specimen collection date is within the Secondary BSI Attribution Period
(SBAP).
*The exception to this is any Candida species or yeast not otherwise specified identified
from blood can be attributed as a secondary BSI to PNEU if PNU3 is met using the blood
specimen and a sputum, endotracheal aspirate, bronchoalveolar lavage (BAL), or
protected specimen brushing with matching Candida species, and both specimens have
a collection date in the IWP.
7. Additionally, because organisms belonging to the following genera are typically causes of
community-associated infections and are rarely or are not known to be causes of healthcare-
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associated infections, they are also excluded and cannot be used to meet any NHSN definition:
Blastomyces, Histoplasma, Coccidioides, Paracoccidioides, Cryptococcus, and Pneumocystis.
8. Abbreviations used in the PNEU laboratory criteria:
BAL – bronchoalveolar lavage
EIA – enzyme immunoassay
IFA – immunofluorescent antibody
LRT – lower respiratory tract
PMN – polymorphonuclear leukocyte
RIA – radioimmunoassay
Reporting Instructions
• There is a hierarchy of specific categories within the major type pneumonia (PNEU). If the patient
meets criteria for more than one specific type during the IWP or the RIT, report only one:
o If a patient meets criteria for both PNU1 and PNU2, report PNU2.
o If a patient meets criteria for both PNU2 and PNU3, report PNU3.
o If a patient meets criteria for both PNU1 and PNU3, report PNU3.
• Pathogens and secondary bloodstream infections can only be reported for PNU2 and PNU3 specific
events.
• Report concurrent LUNG and PNEU with at least one matching organism(s) as PNEU.
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Table 1: Specific Site Algorithms for Clinically Defined Pneumonia (PNU1)
Imaging Test
Evidence
Signs/Symptoms
Two or more serial
chest imaging test
results with at least one
of the following
(1,2,14):
New and persistent
or
Progressive and
persistent
• Infiltrate
• Consolidation
• Cavitation
• Pneumatoceles, in
infants ≤1 year old
Note: In patients
without underlying
pulmonary or cardiac
disease (such as
respiratory distress
syndrome,
bronchopulmonary
dysplasia, pulmonary
edema, or chronic
obstructive pulmonary
disease), one definitive
imaging test result is
acceptable. (1)
For ANY PATIENT, at least one of the following:
• Fever (> 38.0°C or > 100.4°F)
• Leukopenia (≤ 4000 WBC/mm
3
) or leukocytosis (≥ 12,000 WBC/mm
3
)
• For adults ≥ 70 years old, altered mental status with no other recognized cause
And at least two of the following (from separate bullets):
• New onset of purulent sputum (3) or change in character of sputum (4), or increased
respiratory secretions, or increased suctioning requirements
• Dyspnea, or tachypnea (5), or new onset or worsening cough
• Rales (6) or bronchial breath sounds
• Worsening gas exchange (for example, O
2
desaturations [for example, PaO
2
/FiO
2
≤ 240] (7), increased oxygen requirements, or increased ventilator demand)
ALTERNATE CRITERIA, for infants ≤ 1 year old:
Worsening gas exchange (for example, O
2
desaturations [for example, pulse oximetry
< 94%], increased oxygen requirements, or increased ventilator demand)
And at least three of the following (from separate bullets):
• Temperature instability
• Leukopenia (≤ 4000 WBC/mm
3
) or leukocytosis (≥ 15,000 WBC/mm
3
) and left shift
(≥ 10% band forms)
• New onset of purulent sputum (3) or change in character of sputum (4), or increased
respiratory secretions, or increased suctioning requirements
• Apnea, tachypnea (5), nasal flaring with retraction of chest wall, or nasal flaring with
grunting
• Wheezing, rales (6), or rhonchi
• Cough
• Bradycardia (< 100 beats/min) or tachycardia (> 170 beats/min)
ALTERNATE CRITERIA, for child > 1 year old or ≤ 12 years old, at least three of the
following (from separate bullets):
• Fever (> 38. 0°C or > 100. 4°F) or hypothermia (< 36. 0°C or < 96.8°F)
• Leukopenia (≤ 4000 WBC/mm
3
) or leukocytosis (≥ 15,000 WBC/mm
3
)
• New onset of purulent sputum (3) or change in character of sputum (4), or increased
respiratory secretions, or increased suctioning requirements
• Dyspnea, or apnea, or tachypnea (5), or new onset or worsening cough
• Rales (6) or bronchial breath sounds
• Worsening gas exchange (for example, O
2
desaturations [for example, pulse oximetry
< 94%], increased oxygen requirements, or increased ventilator demand)
NOTE: The PNEU Algorithms (PNU1,2,3) and Flowcharts include FOOTNOTE references. The interpretation and
guidance provided in the FOOTNOTES are an important part of the algorithms and must be incorporated into the
decision-making process when determining if a PNEU definition is met.
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Table 2: Specific Site Algorithm for Pneumonia with Common Bacterial or
Filamentous Fungal Pathogens and Specific Laboratory Findings (PNU2)
Imaging Test Evidence
Signs/Symptoms
Laboratory
Two or more serial chest
imaging test results with at
least one of the following
(1,2,14):
New and persistent
or
Progressive and persistent
• Infiltrate
• Consolidation
• Cavitation
• Pneumatoceles, in
infants ≤1 year old
Note: In patients without
underlying pulmonary or
cardiac disease (such as
respiratory distress
syndrome,
bronchopulmonary
dysplasia, pulmonary
edema, or chronic
obstructive pulmonary
disease), one definitive
chest imaging test result is
acceptable. (1)
At least one of the following:
• Fever (> 38.0°C or > 100.4°F)
• Leukopenia (≤ 4000 WBC/mm
3
)
or leukocytosis (≥ 12,000
WBC/mm
3
)
• For adults ≥ 70 years old,
altered mental status with no
other recognized cause
And at least one of the following:
• New onset of purulent sputum (3)
or change in character of sputum
(4), or increased respiratory
secretions, or increased
suctioning requirements
• Dyspnea, or tachypnea (5), or
new onset or worsening cough
• Rales (6) or bronchial breath
sounds
• Worsening gas exchange (for
example, O
2
desaturations [for
example, PaO
2
/FiO
2
≤ 240] (7),
increased oxygen requirements,
or increased ventilator demand)
At least one of the following:
• Organism identified from blood (8,13)
• Organism identified from pleural fluid
(9,13)
• Positive quantitative culture or
corresponding semi-quantitative culture
result (9) from minimally-contaminated
LRT specimen (specifically, BAL,
protected specimen brushing, or
endotracheal aspirate)
• ≥ 5% BAL-obtained cells contain
intracellular bacteria on direct
microscopic exam (for example, Gram’s
stain)
• Positive quantitative culture or
corresponding semi-quantitative culture
result (9) of lung tissue
• Histopathologic exam shows at least
one of the following evidences of
pneumonia:
o Abscess formation or foci of
consolidation with intense PMN
accumulation in bronchioles and
alveoli
o Evidence of lung parenchyma
invasion by fungal hyphae or
pseudohyphae
NOTE: The PNEU Algorithms (PNU1,2,3) and Flowcharts include FOOTNOTE references. The interpretation and
guidance provided in the FOOTNOTES are an important part of the algorithms and must be incorporated into the
decision-making process when determining if a PNEU definition is met.
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Table 3: Specific Site Algorithm for Viral, Legionella, and other Bacterial
Pneumonias with Definitive Laboratory Findings (PNU2)
Imaging Test Evidence Signs/Symptoms Laboratory
Two or more serial chest
imaging test results with
at least one of the
following (1,2,14):
New and persistent
or
Progressive and
persistent
• Infiltrate
• Consolidation
• Cavitation
• Pneumatoceles, in
infants ≤1 year old
Note: In patients without
underlying pulmonary or
cardiac disease (such as
respiratory distress
syndrome,
bronchopulmonary
dysplasia, pulmonary
edema, or chronic
obstructive pulmonary
disease), one definitive
chest imaging test result
is acceptable. (1)
At least one of the following:
• Fever (> 38.0°C or > 100.4°F)
• Leukopenia (≤ 4000 WBC/mm
3
)
or leukocytosis (≥ 12,000
WBC/mm
3
)
• For adults ≥ 70 years old, altered
mental status with no other
recognized cause
And at least one of the following:
• New onset of purulent sputum (3)
or change in character of sputum
(4), or increased respiratory
secretions, or increased suctioning
requirements
• Dyspnea, or tachypnea (5), or new
onset or worsening cough
• Rales (6) or bronchial breath
sounds
• Worsening gas exchange (for
example, O2 desaturations [for
example, PaO2/FiO2 ≤ 240] (7),
increased oxygen requirements, or
increased ventilator demand)
At least one of the following:
• Virus, Bordetella, Legionella,
Chlamydia, or Mycoplasma
identified from respiratory
secretions or tissue by a culture
or non-culture based
microbiologic testing method
which is performed for purposes
of clinical diagnosis or treatment
(for example, not Active
Surveillance Culture/Testing
(ASC/AST)
• Fourfold rise in paired sera (IgG)
for pathogen (for example,
influenza viruses, Chlamydia)
• Fourfold rise in Legionella
pneumophila serogroup 1
antibody titer to ≥ 1:128 in
paired acute and convalescent
sera by indirect IFA
• Detection of L. pneumophila
serogroup 1 antigens in urine by
RIA or EIA
NOTE: The PNEU Algorithms (PNU1,2,3) and Flowcharts include FOOTNOTE references. The interpretation and
guidance provided in the FOOTNOTES are an important part of the algorithms and must be incorporated into
the decision-making process when determining if a PNEU definition is met.
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Table 4: Specific Site Algorithm for Pneumonia in Immunocompromised
Patients (PNU3)
Imaging Test Evidence Signs/Symptoms Laboratory
Two or more serial chest
imaging test results with
at least one of the
following (1,2,14):
New and persistent
or
Progressive and persistent
• Infiltrate
• Consolidation
• Cavitation
• Pneumatoceles, in
infants ≤1 year old
Note: In patients without
underlying pulmonary or
cardiac disease (such as
respiratory distress
syndrome,
bronchopulmonary
dysplasia, pulmonary
edema, or chronic
obstructive pulmonary
disease), one definitive
chest imaging test result
is acceptable. (1)
Patient who is
immunocompromised (see
definition in footnote
10) has at
least one of the following:
• Fever (> 38.0°C or > 100.4°F)
• For adults ≥ 70 years old, altered
mental status with no other
recognized cause
• New onset of purulent sputum
(3), or change in character of
sputum (4), or increased
respiratory secretions, or
increased suctioning
requirements
• Dyspnea, or tachypnea (5), or
new onset or worsening cough
• Rales (6) or bronchial breath
sounds
• Worsening gas exchange (for
example, O
2
desaturations [for
example, PaO
2
/FiO
2
≤ 240] (7),
increased oxygen requirements,
or increased ventilator demand)
• Hemoptysis
• Pleuritic chest pain
At least one of the following:
• Identification of matching Candida spp.
from blood and one of the following:
sputum, endotracheal aspirate, BAL or
protected specimen brushing (11,12,13)
• Evidence of fungi (excluding any Candida
and yeast not otherwise specified) from
minimally-contaminated LRT specimen
(specifically BAL, protected specimen
brushing or endotracheal aspirate) from
one of the following:
− Direct microscopic exam
− Positive culture of fungi
− Non-culture diagnostic laboratory test
OR
Any of the following from:
LABORATORY CRITERIA DEFINED UNDER
PNU2
NOTE: The PNEU Algorithms (PNU1,2,3) and Flowcharts include FOOTNOTE references. The interpretation and
guidance provided in the FOOTNOTES are an important part of the algorithms and must be incorporated into
the decision-making process when determining if a PNEU definition is met.
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Figure 1: Pneumonia Flow Diagram for Patients of Any Age
P atient with unde rlying dise ases
1 ,2
has 2 or more
imagi ng tes t re sul ts wit h one of the following:
New & persistent OR
Progressive & persistent
Inf iltrate
Consoli dation
Cavitation
Pneumatoceles , in ≤ 1 y.o
PNU1 / PNU2
At least o ne of the following:
Fever ( > 3 8.0° C or > 100.4°F)
Le uko pe ni a (≤ 4,000 WBC/mm
3
) or le ukocytos is (≥ 12,000 WBC /mm
3
)
Al tered mental stat us w it h no othe r cause, i n ≥ 70 y.o.
PNU1
And at le ast two of the following (from
separate bullets):
New onset of purulent
sputum
3
, o r chan ge i n ch aracter
of sputum
4
, or increa sed
respiratory secretions, or
in cre ased suc ti oni ng
requi re me nt s
Dyspnea, or tachypnea
5
, or ne w
onset or worsening cough
Rales
6
or br onchial brea th
sounds
Worsening ga s exc hange (for
example, O
2
desat urat ions [f or
example, PaO
2
/FiO
2
≤ 240]
7
,
increased oxygen
requi re me nt s, or in cr eas ed
venti lat or demand)
PNU2
And at le ast one
of the following:
New onset of purulent sputum
3
,
or change in charact er of
sputum
4
, or increa sed
respiratory secretions, or
increased suctioning
requi re me nt s
Dyspnea, or tachypnea
5
, or ne w
onset or worsening cough
Rales
6
or br onchial brea th
sounds
Worsening ga s exchange (for
example, O
2
desat urat ions [f or
example, PaO
2
/FiO
2
< 240]
7
,
increased oxygenation
requi re me nt s, o r in cr eas ed
venti lat or demand)
PNU3
At least one of the following:
Identification of matching Candida
spp. from blood and one of the
following: sputum, endotracheal
aspirate, BAL or protected specimen
brushing
1 1,12 ,13
Evidence of fungi (e xcluding any
Can did a spp. a nd yeas t no t
otherwise specified) from minimal ly
contaminated LRT specimen
(specif ica lly BAL, protected s peci men
brushing or endotracheal aspirate)
fr om one
of the following:
• Direc t micros copic exam
• Positive culture of fungi
• Non
-culture diagnostic
la boratory test
PNU2 / PNU3
At least o ne of the following:
Virus, Borde tella, Legionella,
Chl amydia, or Mycoplasma identified
from respi ratory secretions or tissue
by a culture or non-culture based
microbiologic test ing method which
is performed for purposes of clinical
diagn os is or treatmen t (f or e xam pl e,
not Active Surveillance Culture/
Testing (ASC/AST))
4-fold rise in paired sera (IgG) for
path ogen (for exam pl e, infl uenz a
viruses, Chlamydia)
4-fold rise in Le gi one lla pneu mophil a
an ti bod y tite r to ≥ 1:128 in paired
acute and c onvale sce nt se ra by
indirect IFA
Detection of Le gione lla p neumoph il a
serogroup 1 antigens in urine by RIA
or EI A
PNU3
PNU2
PNU1
PNU2 / PNU3
At least o ne of the following:
Organism identified from blood
8,13
Organism identified from pleural
fluid
9,13
Positive quantitative culture or
corresponding semi-quantit ati ve
result
9
fr om mini mal ly-contaminated
LRT specimen (specifically, BAL,
protected specimen brushing, or
endotracheal aspirate)
≥ 5% BAL-obtained cel ls contain
intracellular bacteria on direct
microscopic exam
Positive quantitative culture or
corresponding semi-quantit ati ve
result
9
of l un g t is sue
Histopathologic exam shows at least
one of the following:
• Abscess formation or foci of
consolidation with intense
PMN accumulation in
bronchioles and alveoli
• Evidence of lung
pare nchym a i nvasi on by
fungal hyphae or
pseudohyphae
LABORATORY
SIGNS & SYMPTOMS IMAGING
PNU3
At least one of the following in an immunocompromised
pat ie nt
10 :
Fever ( > 3 8.0°C or > 100.4°F)
Al tered men tal stat us w it h no othe r cause, i n ≥ 70 y.o.
New onset of purulent sputum
3
, o r chan ge i n ch aracter o f
sputum
4
, or increased respiratory secretions, or increased
suctioning requirements
Dyspnea, or tachypnea
5
, or ne w onset or worse ning co ug h
Rales
6
or br onchial brea th so unds
Worsening ga s exchange (for example, O
2
desaturat ions
[for example, PaO
2
/FiO
2
≤ 240]
7
, increased oxygen
requi re me nt s, o r in cr eas ed v en ti lator deman d)
Hemoptysi s
Pleuritic ches t pai n
Pati en t without underlying diseases
1 ,2
has 1 or more
imagi ng tes t resul ts with one of the following:
New & persistent OR
Progressive & persistent
Inf iltrate
Consoli dation
Cavitation
Pneumatoceles , in ≤ 1 y.o.
OR
PNU 1
PNU 2
PNU 3
NOTE: The PNEU Algorithms (PNU1,2,3) and Flowcharts include FOOTNOTE references. The interpretation and
guidance provided in the FOOTNOTES are an important part of the algorithms and must be incorporated into
the decision-making process when determining if a PNEU definition is met.
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Figure 2: Pneumonia Flow Diagram, Alternative Criteria for Infants and
Children
SIGNS & SYMPTOMS IMAGING
ALTERNATE CRITERIA for infants
≤ 1 year old
Worsening gas exchange (for example, O
2
desaturations [for example, pulse
oximetry < 94%], increased oxygen
requirements, or increased ventilator
demand)
AND at least THREE of the following (from
separate bullets):
Temperature instability
Leukopen ia (≤ 400 0 WBC/mm
3
) or
leukocytosis (≥ 15,000 WBC /m m
3
) and
left shift (≥ 10% band forms)
New onset of pur ulent sputum
3
, or
change in character of sputum
4
, or
increased respiratory secretions, or
increased suctioning requirements
Apnea, tachypnea
5
, nasal flaring with
retraction of chest wall, or nasal flaring
with grunting
Wheezing, rales
6
, or rhonchi
Cough
Bradycardia (< 100 beats/min) or
tachy car dia (> 1 70 b eats/min)
ALTERNATE CRITERIA for
children
> 1 year old or ≤ 12 years old
At least THR EE of the fo ll o wi ng (f rom sep ar ate
bu llets):
F ev er (> 38.0°C or > 100.4°F) or
hypothermia (< 36.0°C or < 96.8°F)
Leukopen ia (≤ 400 0 WBC/mm
3
) or
leukocytosis (≥ 15,000 WBC/mm
3
)
New onset of pur ulent sputum
3
, or
change in character of sputum
4
, or
increased respiratory secretions, or
increased suctioning requirements
Dyspnea, or apnea, or tachypnea
5
, or new
onset or worsening cough
R al es
6
or bronchial breath sounds
Worsening gas exchange (for example, O
2
desaturations [for example, pulse
oximetry < 94%], increased oxygen
requirements, or increased ventilator
demand)
PNU1
Patient w ith underlying diseases
1,2
has 2 or more
imaging test results
with one of the follo wing:
New & persistent
OR
Progressive & persistent
Infiltrate
Consolidation
Cavitation
Pn eu matoc eles , in ≤ 1 y.o
Patient without un derlying diseases
1,2
has 1 or more
imaging test results with one of the following:
New & persistent
OR
Progressive & persistent
Infiltrate
Consolidation
Cavitation
Pneumatoceles, in ≤ 1 y.o.
NOTE: The PNEU Algorithms (PNU1,2,3) and Flowcharts include FOOTNOTE references. The interpretation and
guidance provided in the FOOTNOTES are an important part of the algorithms and must be incorporated into
the decision-making process when determining if a PNEU definition is met.
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Footnotes to Algorithms and Flow Diagrams
1. To help confirm difficult cases, multiple imaging test results spanning over several calendar days
must be considered when determining if there is imaging test evidence of pneumonia.
Pneumonia may have rapid onset and progression but does not resolve quickly. Imaging test
evidence of pneumonia will persist. Rapid imaging resolution suggests that the patient does not
have pneumonia, but rather a non-infectious process such as atelectasis or congestive heart
failure.
• The diagnosis of healthcare-associated pneumonia may be quite clear on the basis of
signs, symptoms, and a single definitive chest imaging test result. Therefore, in a patient
without underlying pulmonary or cardiac disease and when there is only one imaging
test available, if the imaging finding is an eligible and definitive finding, the imaging test
evidence requirement can be met.
• In patients without underlying disease, if more than one imaging test is available the
serial imaging test results (typically, within a 7-day timeframe) must also be evaluated
and must demonstrate persistence of eligible and definitive findings.
• In patients with underlying pulmonary or cardiac disease (such as interstitial lung
disease, congestive heart failure, etc.), the diagnosis of pneumonia may be particularly
difficult. For example, imaging findings of pulmonary edema from decompensated
congestive heart failure may simulate the presentation of pneumonia. Therefore, in
patients with underlying disease, serial chest imaging test results (typically, within a 7-
day timeframe) must be examined and must demonstrate persistence of eligible and
definitive findings to help separate infectious from non-infectious pulmonary processes.
2. Note that there are many ways of describing the imaging appearance of pneumonia. Examples
include, but are not limited to, “air-space disease,” “focal opacification,” “patchy areas of
increased density.” Although perhaps not specifically delineated as pneumonia by the
radiologist, in the appropriate clinical setting these alternative descriptive wordings should be
seriously considered as potentially positive findings. If provided and the findings are not
documented as attributed to another issue (for example, pulmonary edema, chronic lung
disease), they are eligible for meeting imaging test evidence of pneumonia.
3. Purulent sputum is defined as secretions from the lungs, bronchi, or trachea that contain ≥ 25
neutrophils and ≤ 10 squamous epithelial cells per low power field (x100). Refer to the table
below if your laboratory reports these data semi-quantitatively or uses a different format for
reporting Gram stain or direct examination results (for example, “many WBCs” or “few
squamous epithelial cells”). This laboratory confirmation is required since written clinical
descriptions of purulence are highly variable.
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4. Change in character of sputum refers to the color, consistency, odor, and quantity.
5. In adults, tachypnea is defined as respiration rate > 25 breaths per minute. Tachypnea is defined
as > 75 breaths per minute in premature infants born at < 37 weeks gestation and until the 40
th
week; > 60 breaths per minute in patients < 2 months old; > 50 breaths per minute in patients 2-
12 months old; and > 30 breaths per minute in children > 1 year old.
6. Rales may be described as “crackles”.
How do I use the purulent respiratory
secretions criterion if …
Instruction
My laboratory reports counts of “white blood
cells” or “polymorphonuclear leukocytes” or
“leukocytes” rather than counts of
“neutrophils”?
Assume that counts of cells identified by these other
descriptors (for example, “white blood cells”) are
equivalent to counts of neutrophils, unless the
laboratory tells you this is not the case.
My laboratory reports semi-quantitative
results (not quantitative results) for numbers
of neutrophils and squamous epithelial cells?
Check with the laboratory to get information about
what quantitative ranges the semi-quantitative reports
correspond to.
My laboratory cannot provide additional
information on how its semi-quantitative
reporting corresponds to quantitative
reporting ranges for neutrophils and
squamous epithelial cells?
Use the following direct examination results to meet
the purulent respiratory secretions criterion: many,
heavy, numerous 4+, or ≥ 25 neutrophils per low
power field (lpf) [x100], AND no, rare, occasional, few,
1+ or 2+, or ≤ 10 squamous epithelial cells per lpf
[x100].
My laboratory reports only the numbers of
neutrophils present, without reporting the
number of squamous epithelial cells?
In this situation, the purulent secretions criterion may
be met using the specified quantitative and semi-
quantitative thresholds for neutrophils alone
(specifically many, heavy, numerous, 4+, or ≥ 25
neutrophils per lpf [x100]).
My laboratory uses different reporting
thresholds for neutrophils and squamous
epithelial cells (for example, maximum report
of ≥ 20 neutrophils per low power field
[x100], or minimum report of ≤ 15 squamous
epithelial cells per low power field [x100])?
In this situation, the purulent secretions criterion may
be met using the laboratory’s specified maximum
quantitative threshold for neutrophils, and/or
minimum quantitative threshold for squamous
epithelial cells.
My laboratory processes respiratory
specimens such as bronchoalveolar lavage
fluid using a centrifugation procedure (for
example, “cytospin”), and there is no
quantitation or semi-quantitation of
neutrophils or white blood cells in the direct
examination report?
In this situation, a report indicating the presence of
white blood cells, without quantitation, is sufficient to
meet the purulent secretions criterion.
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7. This measure of arterial oxygenation is defined as the ratio of the arterial tension (PaO
2
) to the
inspiratory fraction of oxygen (FiO
2
).
8. Any coagulase-negative Staphylococcus species, any Enterococcus species, and any Candida
species or yeast not otherwise specified that are identified from blood cannot be deemed
secondary to a PNEU event unless the organism was also identified from lung tissue or pleural
fluid (where specimen was obtained during thoracentesis or within 24 hours of chest tube
placement; a pleural fluid specimen collected after a chest tube is repositioned or from a chest
tube in place > 24 hours is not eligible). This applies when meeting PNU2 or when meeting PNU3
(for patients meeting the immunocompromised definition) with the laboratory findings found in
PNU2. Identification of matching Candida spp. from blood and sputum, endotracheal aspirate,
BAL or protected specimen brushing with specimen collection dates in the same IWP (see
footnote 11) can be used to satisfy PNU3 definition for patients meeting the
immunocompromised definition (see footnote 10).
9. Refer to threshold values for cultured specimens (lung tissue, BAL, protected specimen
brushing, or endotracheal aspirate) with growth of eligible pathogens (Table 5).
Notes:
• A specimen that is not obtained through an artificial airway (specifically an endotracheal
tube or a tracheostomy) from a ventilated patient is not considered minimally
contaminated and is not eligible for use in meeting the laboratory criteria for PNEU
(PNU2 or PNU3 when using the laboratory findings found in PNU2). Sputum or tracheal
secretions collected from a non-ventilated patient are not minimally-contaminated
specimens.
• The following organisms can only be used to meet PNEU definitions when identified
from lung tissue or pleural fluid obtained during thoracentesis or within 24 hours of
chest tube placement (not from a chest tube that has been repositioned or from a chest
tube that has been in place > 24 hours):
o Any coagulase-negative Staphylococcus species
o Any Enterococcus species
o Any Candida species or yeast not otherwise specified.
• Exception: identification of matching Candida spp. from blood and
sputum, endotracheal aspirate, BAL, or protected specimen brushing
with specimen collection dates in the same IWP can be used to satisfy
PNU3 definition for immunocompromised patients (see footnote 10).
10. Immunocompromised patients include only
• those with neutropenia defined as absolute neutrophil count or total white blood cell count
(WBC) < 500/mm
3
• those with leukemia, lymphoma, or who are HIV positive with CD4 count < 200
• those who have undergone splenectomy
• those who have a history of solid organ or hematopoietic stem cell transplant
• those on cytotoxic chemotherapy
• those on enteral or parenteral administered steroids (excludes inhaled and topical steroids)
daily for > 14 consecutive days on the date of event
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11. Blood specimen and respiratory specimen (sputum, endotracheal aspirate, BAL, or protected
specimen brushing) must have a collection date that occurs within the IWP.
12. Semi-quantitative or non-quantitative cultures of sputum obtained by deep cough, induction,
aspiration, or lavage are acceptable.
13. Identification of organism by a culture or non-culture based microbiologic testing method which
is performed for purposes of clinical diagnosis or treatment (for example, not Active Surveillance
Culture/Testing (ASC/AST)).
14. If the imaging test result is equivocal for pneumonia, check to see if subsequent imaging tests
are definitive. For example, if a chest imaging test result states infiltrate vs. atelectasis and a
subsequent imaging test result is definitive for infiltrate, the initial imaging test would be eligible
for use. In the absence of finding a subsequent imaging result that clarifies the equivocal finding,
if there is clinical correlation (see Chapter 16) then the equivocal imaging test is eligible for use.
Table 5: Threshold values for cultured specimens used in the diagnosis of
pneumonia
Specimen collection/technique
Values*
Lung tissue†
≥ 10
4
CFU/g tissue
Bronchoscopically (B) obtained specimens
Bronchoalveolar lavage (B-BAL)
≥ 10
4
CFU/ml
Protected BAL (B-PBAL)
≥ 10
4
CFU/ml
Protected specimen brushing (B-PSB)
≥ 10
3
CFU/ml
Nonbronchoscopically (NB) obtained (blind) specimens
NB-BAL
≥ 10
4
CFU/ml
NB-PSB
≥ 10
3
CFU/ml
Endotracheal aspirate (ETA)
≥ 10
5
CFU/ml
CFU = colony forming units, g = gram, ml = milliliter
*Consult with your laboratory to determine if reported semi-quantitative results match the quantitative
thresholds. In the absence of additional information available from your laboratory, a semi-quantitative
result of “moderate” or “heavy” or “many” or “numerous” growth, or 2+, 3+, or 4+ growth is considered
to correspond.
†Lung tissue specimens obtained by either open or closed lung biopsy methods. For post-mortem
specimens, only lung tissue specimens obtained by transthoracic or transbronchial biopsy that are
collected immediately post-mortem are eligible for use.
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Numerator Data
The Pneumonia (PNEU) form (CDC 57.111) is used to collect and report each VAP that is identified during
the month selected for surveillance. The Instructions for Completion of Pneumonia (PNEU) form contains
brief instructions for collection and entry of each data element on the form. The pneumonia form
includes patient demographic information and information on whether or not mechanically-assisted
ventilation was present. Additional data include the specific criteria met for identifying pneumonia,
whether the patient developed a secondary bloodstream infection, whether the patient died, the
organisms identified from culture or non-culture based microbiologic testing methods, and the
organisms’ antimicrobial susceptibilities.
Reporting Instruction: If no VAPs are identified during the month of surveillance, the “Report No Events”
box must be checked on the appropriate denominator summary screen, for example, Denominators for
Intensive Care Unit (ICU)/Other Locations (Not NICU or SCA/ONC), etc.
Denominator Data
Device days and patient days are used for denominators (see Chapter 16). Ventilator days, which are the
number of patients managed with a ventilatory device, are collected daily, at the same time each day,
according to the chosen location using the appropriate form (CDC 57.116 [NICU], 57.117 [Specialty Care
Areas], and 57.118 [ICU/Other Locations]). These daily counts are summed and only the total for the
month is entered into NHSN. Ventilator days and patient days are collected for each of the locations
where VAP is monitored. When denominator data are available from electronic sources, these sources
may be used as long as the counts are within +/- 5% of manually-collected counts, validated for a
minimum of three consecutive months. Validation of electronic counts should be performed separately
for each location conducting VAP surveillance.
When converting from one electronic counting system to another electronic counting system, the new
electronic system should be validated against manual counts as above. If electronic counts for the new
electronic system are not within 5% of manual counts, resume manual counting and continue working
with IT staff to improve design of electronic denominator data extraction (while reporting manual
counts) until concurrent counts are within 5% for 3 consecutive months.
Note: This guideline is important because validating a new electronic counting system against an
existing electronic system can magnify errors and result in inaccurate denominator counts.
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Data Analyses
All data that is entered into NHSN can be analyzed at event or summary level. The data in NHSN can be
visualized and analyzed in various ways, specifically, descriptive analysis reports for both the
denominator and numerator data.
Types of VAP Analysis Reports
VAP Rate
The VAP rate per 1000 ventilator days is calculated by dividing the number of VAPs by the number of
ventilator days and multiplying the result by 1000 (ventilator days).
VAP Rate per 1000 ventilator days =
.
.
* 1000
Device Utilization Ratio
The Ventilator Utilization Ratio is calculated by dividing the number of ventilator days by the number of
patient days. These calculations will be performed separately for the different types of ICUs, SCAs, and
other locations in the institution.
DUR =
.
.
Descriptive Analysis Output Options
Descriptive analysis output options of numerator and denominator data, such as line listings, frequency
tables, and bar and pie charts are also available in the NHSN application.
Line List: Creating a Line List
Frequency Tables: Creating a Frequency Table
Bar Chart: Creating a Bar Chart
Pie Chart: Creating a Pie Chart
Rate Table: Creating a Rate Table
Analysis Resources Links
Analysis Resources Website
Analysis Quick Reference Guides
Data Quality Resources Links
Data Quality Website
Data Quality Manual
Data Quality Training
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Table 6: VAP Measures Available in NHSN
Measure Calculation Application
VAP Rates
The number of VAPs for a location
The number of Ventilator Days for that location
X 1000
Location specific
measure only
DUR
The number of Ventilator Days for a location
The number of Patient Days for that location
Location specific
measure only
NHSN Group Analysis
NHSN Group Users can perform the same analysis as facility level users in NHSN. A few helpful tools in
NHSN for groups are listed in the resources below. These tools are guides on how to start and join a
Group; how to create a template to request data from facilities; how to determine the level of access
granted by the facility following the previous steps, and how to analyze the facilities data.
Group Analysis Resources
NHSN Group Users Page:
https://www.cdc.gov/nhsn/group-users/index.html
Group User’s Guide to the Membership Rights Report:
https://www.cdc.gov/nhsn/pdfs/ps-analysis-resources/GroupAnalysisWebinar.pdf
Group User’s Guide to the Line Listing - Participation Alerts:
https://www.cdc.gov/nhsn/pdfs/ps-analysis-resources/group-alerts.pdf
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References
1
Magill SS, O’Leary E, Janelle SJ, et al. Changes in Prevalence of Health Care–Associated Infections in U.S.
Hospitals. N Engl J Med. 2018;379(18):1732-1744.
2
Magill SS, Klompas M, Balk R, et al. Developing a new, national approach to surveillance for ventilator-
associated events. Crit Care Med. 2013;41(11):2467-2475.
