FAQs: Pneumonia (PNEU) Events

Lower Respiratory Tract Events

We know this can be an area of confusion. We need to consider events occurring in patients on mechanical ventilation and events occurring in patients NOT on mechanical ventilation, and we have to consider events that occur in adults and events that occur in neonates and in children. Let’s review what is available for in-plan or off-plan surveillance of lower respiratory tract events in NHSN. Keep in mind that “in-plan” surveillance means that you/your facility have committed to following the NHSN surveillance protocol for that particular event in your NHSN monthly reporting plan. “Off-plan” surveillance is surveillance that is done because you/your facility have decided to track a particular event for internal use. Data that are entered into NHSN “off-plan” are not used or reported in NSHN annual reports or other NHSN publications. A facility makes no commitment to follow the protocol for “off-plan” events.

What lower respiratory tract event surveillance can be done “in-plan”?

  1. VAE: This event is available for in-plan surveillance of mechanically ventilated inpatients in adult locations only (regardless of the age of the patient). Pediatric and neonatal locations are excluded from VAE surveillance (even in circumstances where a pediatric unit may occasionally care for adult patients).
  2. PedVAP: This event uses the PNEU protocol and is available for in-plan surveillance of mechanically ventilated inpatients in pediatric locations only (regardless of the age of the patient). In-plan surveillance for ventilator-associated PNEU (VAP) is not available for inpatients in adult or neonatal locations.
  3. PedVAE: This event is available for in-plan surveillance of mechanically ventilated inpatients in pediatric and neonatal locations only. Adult locations are excluded from PedVAE surveillance (even in circumstances where an adult unit may occasionally care for pediatric patients).

NOTE: When conducting CLABSI surveillance, the PNEU definition is available for use as a site-specific infection to which a bloodstream infection can be attributed as a secondary BSI for all patients, all locations, regardless of use of mechanical ventilation. This includes ventilated or non-ventilated adults, children, or neonates in any patient location.

What lower respiratory tract event surveillance can be done “off-plan”?

  1. VAE: VAE surveillance can be done “off-plan” in mechanically-ventilated inpatients in adult locations only.
  2. PedVAP or PNEU/VAP: Surveillance using the PNEU protocol is available for “off-plan” surveillance in all mechanically-ventilated inpatients (adults, children, or neonates) in any inpatient location.
  3. PedVAE: PedVAE surveillance can be done “off-plan” in mechanically-ventilated inpatients in neonatal and pediatric locations only.
  4. PNEU: PNEU surveillance is available for “off-plan” surveillance in non-mechanically-ventilated adults, children, and neonates in any inpatient location.
  5. LRI: Surveillance for non-pneumonia lower respiratory infections (using LUNG definition) is available for “off-plan” surveillance in mechanically-ventilated or non-mechanically-ventilated adults, children, and neonates.

VAE and PNEU/VAP surveillance; PedVAE and PedVAP surveillance

Yes. An adult location can conduct simultaneous in-plan VAE surveillance and off-plan PNEU/VAP surveillance. Likewise, a pediatric location can conduct simultaneous in-plan PedVAE and in-plan PedVAP surveillance, or a neonatal location can conduct simultaneous in-plan PedVAE and off-plan PedVAP surveillance. VAE is a separate event from PNEU/VAP, and PedVAE is a separate event from PedVAP. In other words, detection of one type of event (such as a VAE) in a particular patient would have no bearing on the conduct of surveillance for the other event type (PNEU/VAP) in the same patient. Patients who meet a VAE definition and a PNEU/VAP definition, or a PedVAE definition and a PedVAP definition, would have two events identified in units where surveillance for multiple respiratory events is occurring.

PedVAP surveillance and weaning

Yes. As long as the patient is receiving support from a mechanical ventilator for some portion of each calendar day, they are eligible for PedVAP surveillance. Keep in mind, it is important to conduct your device day count at the same time every day and only include those patients on ventilator support at the time of the count. Therefore, we recommend ventilator day counts perhaps be conducted at night, so as to capture all eligible patients (to include those who are undergoing weaning) in the denominator for the location where surveillance is being conducted.

Submitting a PNEU case review to NHSN

For NHSN to assist with a PNEU case determination, please send the following information to nhsn@cdc.gov:

  • Date of admission
  • Age of patient
  • Underlying pulmonary and cardiac diseases
  • Dates and results (findings and impressions) of ALL temporally related imaging tests, including imaging tests before, during, and after the IWP
  • Collection dates and organisms identified for site-specific cultures, including quantitative/semi-quantitative results
  • Collections dates and organisms identified for positive blood cultures
  • All eligible signs/symptoms available for use in meeting PNEU, including corresponding dates for all

New and Persistent or Progressive and Persistent

The findings must provide evidence of pneumonia. This includes but is not limited to new or worsening infiltrate, consolidation, opacity, or air space disease that is not attributed to something other than pneumonia


Evidence of persistence. There should not be rapid resolution of the finding or contradictory information in a subsequent imaging test which suggests the finding is attributable to another condition (for example, 2 days later the opacity is now attributed to pulmonary edema). Pneumonia may have rapid onset and progression but does not resolve quickly. Rapid imaging resolution suggests that the patient does not have pneumonia, but rather a non-infectious process.

One chest imaging test in some instances can be utilized to satisfy the imaging element of the pneumonia definitions; however, if subsequent imaging tests are available, the subsequent imaging tests must be assessed to make sure the requirement of persistence is satisfied. So, for any patient, regardless of underlying cardiac or pulmonary disease, all temporally related subsequent imaging tests must be taken into consideration and must show persistence of eligible findings for the imaging requirement to be met. Subsequent imaging findings noting rapid clearing or attribution of imaging test findings to something other than pneumonia precludes the use of a prior finding. Point being, for all patients, you must look at the complete imaging picture, not just a select one or two imaging tests, when making a determination if the imaging requirement is met.


Imaging Test Results

When imaging test findings are equivocal for pneumonia (for example, a report of infiltrate vs. atelectasis, or a report stating opacity may be pneumonia or may represent congestive heart failure), the first step is to look for subsequent imaging test results that provide a definitive result. If subsequent imaging findings are definitive for pneumonia and these findings are persistent, the equivocal imaging is eligible for use. If subsequent imaging tests show rapid clearing or show findings that are definitive for something other than pneumonia, the equivocal imaging is not eligible for use. Note: The subsequent imaging tests do not have to occur in the IWP but must be temporally related to the equivocal imaging findings.

In the event subsequent imaging test results are not available or do not provide further delineation one way or another, then clinical correlation can be used to clarify the equivocal imaging. Clinical correlation requires that there is documentation in the medical record that the physician has prescribed antimicrobial treatment for pneumonia. Note: The purpose of clinical correlation is to clarify that equivocal imaging findings are representative of pneumonia. Clinical correlation does not have to be documented within the IWP, but it must be documented around the time of the equivocal imaging. If subsequent imaging results indicate the finding is definitively attributed to something other than pneumonia, clinical correlation cannot be used.

Serial Imaging

NHSN does not offer an all-inclusive list of pulmonary and cardiac conditions that require serial imaging. Certain underlying diseases or conditions may make interpretation of the imaging test findings difficult, and the purpose of serial imaging is to ensure the imaging findings for these patients are due to pneumonia and not a reflection of the underlying disease/condition. This would include conditions such as COPD, CHF, bronchopulmonary dysplasia (BPD), respiratory distress syndrome (ARDS/RDS), etc. Conditions that do not typically present with imaging findings that could make evaluation of imaging for pneumonia difficult (such as hypertension, asthma, etc.) would not be included as underlying pulmonary or cardiac disease that require serial imaging.

Excluded Pathogens

This means the following are excluded:

All Candida species – those that have been identified to the species level such as Candida albicans, those that are reported as Candida species, and also to include culture reports that may simply say, for example, “many yeast isolated”

All coagulase-negative Staphylococcus species – for example, coagulase-negative Staphylococci, Staphylococcus epidermidis, Staphylococcus species

All Enterococcus species – for example, Enterococcus species, Enterococcus faecalis, VRE

Use of sputum and endotracheal aspirate specimen results

Please note that the respiratory tract specimens eligible for satisfying the PNU2 laboratory findings specify that the specimen be a minimally contaminated lower respiratory tract specimen. This includes only bronchial alveolar lavage (BAL), bronchial wash, protected specimen brushing, and endotracheal aspirate. Note that endotracheal aspirate indicates the specimen is collected via an artificial airway. A sputum specimen that is not obtained through an artificial airway (specifically, endotracheal tube or tracheostomy) from a ventilated patient is not considered minimally contaminated and is not eligible for use in meeting the laboratory criteria. Specimens labelled sputum or tracheal secretions collected from a non-ventilated patient are not minimally-contaminated specimens and therefore are only available for use when meeting PNU3 laboratory finding of a matching Candida species identified in both sputum and blood with both specimen collection dates found in the same infection window period.

Secondary BSI assignment to a PNEU event

Yes, it is possible.

A secondary BSI cannot be attributed to PNU1. However, in this instance if a BSI is thought to be secondary to pneumonia but the blood culture collection date did not occur within the infection window period such that it could be used as an element to meet the PNU2 definition, reassess to determine if the PNU2 definition can be met within the PNEU RIT. Similarly, if PNU2 is met and there is a subsequent blood specimen with an eligible pathogen, however it does not match the specimen used to originally meet PNU2, then reassess to determine if PNU2 can be met using the blood culture such that the date of event falls within the originally established PNEU RIT.

NOTE: When re-meeting PNEU within the RIT, provided that definitive imaging findings are persistent, a single definitive imaging finding with a test date that occurs in a new IWP and demonstrates evidence of persistence of prior eligible findings will satisfy the imaging requirement for all patients. New or progressive or serial imaging (for patients with underlying cardiac or pulmonary disease) does not have to be re-demonstrated. Evidence of persistence of eligible findings alone will meet the imaging requirement in the RIT. See the example and the table below.

All elements necessary to satisfy the PNU1 definition occur within the infection window period. The date of event is 2/14. This establishes a PNEU (PNU1) RIT 2/14- 2/27 and a BSI secondary attribution period (SBAP) 2/11 – 2/27. Subsequently a blood specimen with a collection date 2/20 identifies Pseudomonas aeruginosa. The collection date is within the secondary BSI attribution period for the PNEU event; however, a secondary BSI cannot be reported for PNU1 since the blood culture is not used to satisfy the PNU1 definition and there is no site-specific culture to which the blood culture pathogen can match. If during the PNEU RIT and within a new IWP, all elements needed to meet the PNU2 definition are present to include the blood specimen and this results in a date of event within the RIT, then the BSI can be attributed as secondary to the PNEU event. The PNEU date of event remains (2/14), as does the originally determined RIT, secondary BSI attribution period, device association, and location of attribution. If the PNU2 definition is not met as described above and if additionally, another site-specific infection for which the BSI can be attributed as a secondary BSI is not identified, then the BSI is a primary BSI/CLABSI.


VAP Table which lists the date, repeat infection timeframe, infection window period and secondary BSI attributable period.

No. In order to cite the BSI as secondary to PNEU at least one organism from the blood specimen that was collected during the secondary BSI attribution period (SBAP) must match an organism identified from the site-specific specimen that was used to meet the infection criterion (Scenario 1 of the Secondary BSI Guide, Appendix B of the BSI protocol). In this case, PNU2 was met with the E. coli from the endotracheal aspirate so the BSI cannot be automatically attributed as secondary to the PNEU event by matching pathogens. Instead, you will want to reassess to determine if the PNU2 definition can be re-met using the blood specimen, as explained in Q6 above.

Any BSI with an eligible organism that is captured in the IWP and is eligible for use in meeting the site-specific criterion can be attributed to the site-specific infection as a secondary BSI (as per Secondary BSI Scenario 2, BSI Chapter, Appendix), whether or not the BSI pathogen matches the pathogens from other specimens in the IWP that are also eligible for use in meeting the site-specific definition. If the PNU2 definition can be met with an eligible respiratory specimen (such that all of the required elements – eligible imaging, temperature/WBC count, sign/symptom – are present in the same IWP with the respiratory specimen) and the PNU2 definition can also be met with an eligible blood specimen (such that all of the required elements are present in the same IWP with the blood specimen), the BSI can be considered a secondary BSI to PNEU, even if the organisms in the respiratory specimen and the blood specimen do not match, and both organisms would be listed as pathogens for the PNEU event.

Breath Sounds

Bronchial breath sounds are generally documented as such when heard upon auscultation. Documentation in the medical record of “bronchial breath sounds heard” will satisfy this requirement. If a physician/provider documents “bronchial breath sounds” the finding is considered abnormal as he/she is indicating he/she is hearing bronchial breath sounds in a place they should not be heard. If no documentation similar to this is found in the medical record for purposes of NHSN surveillance “bronchial breath sounds” were not heard and that element of the definition is not available for use in meeting a PNEU definition.

Bronchial breath sounds are a distinctive finding. Rhonchi are not bronchial breath sounds. Also, a descriptor preceding “breath sounds” (for example, coarse breath sounds, diminished breath sounds, etc.) is not bronchial breath sounds.

Descriptors such as “coarse” breath sounds and “diminished” breath sounds, are not eligible findings for meeting PNEU for any patient. For all patients, documentation of rales/crackles or bronchial breath sounds are eligible findings for use in meeting PNU1, PNU2, and PNU3. When applying the alternate criteria for meeting PNU1 for infants ≤ 1 year old, documentation of wheezing, rales/crackles, or rhonchi are eligible findings.