Suspected HAP or VAP in an adult
HAP: pneumonia 48 h or more after admission, not on a ventilator. VAP: pneumonia more than 48 h after intubation. New lung infiltrate plus new fever, purulent sputum, leukocytosis or falling oxygenation.
All Pathways
Infectious DiseaseManagement
Hospital-Acquired and Ventilator-Associated Pneumonia (ATS/IDSA 2016)
Hospital-Acquired and Ventilator-Associated Pneumonia (ATS/IDSA 2016): Suspected HAP or VAP in an adult → Immunocompromised or child: this pathway does ...
Pathway Overview
16 steps
Algorithm Steps
16 total
01Start 02Warning Immunocompromised or child: this pathway does not apply
The source guideline covers adults who are not immunocompromised.
- Neutropenia: use the febrile neutropenia pathway
- Transplant, chemotherapy, advanced HIV or high-dose immunosuppression: opportunistic pathogens are possible; get ID advice
- Children: use paediatric guidance
03Action Take cultures, then start antibiotics without delay
Septic shock: give antibiotics within 1 h. Do not delay them to get cultures.
- Blood cultures x2
- HAP: sputum (spontaneous or induced) for culture
- VAP: endotracheal aspirate, semiquantitative culture (preferred to invasive sampling)
- Check previous cultures and MRSA screens
- Check allergies, kidney function and the local antibiogram
04Warning Before you choose: penicillin allergy, kidney function, pregnancy
Adjust the regimen in the next steps for these patients.
- Severe penicillin allergy: use aztreonam 2 g IV 8-hourly instead of a beta-lactam, and add S. aureus cover (vancomycin or linezolid)
- Kidney impairment: adjust beta-lactam, aminoglycoside and vancomycin doses; high cefepime levels can cause neurotoxicity
- Pregnancy: aminoglycosides can cause fetal harm; avoid if an alternative exists; get ID and obstetric advice
05Decision Does the patient need 2 antipseudomonal agents?
Yes if any: IV antibiotics in the last 90 days; septic shock; HAP that needs ventilation; bronchiectasis or cystic fibrosis; Pseudomonas or MDR gram-negative in previous cultures. VAP also: ARDS or acute dialysis before VAP, 5 or more days in hospital, or unit gram-negative resistance over 10% or unknown.
- If Yes
06Action High Pseudomonas or MDR risk: 2 antipseudomonal agents from different classes
One beta-lactam plus one non-beta-lactam agent. Do not use 2 beta-lactams. Adult doses, normal kidney function. On valproate: avoid meropenem and imipenem (valproate levels fall; seizures). Myasthenia gravis: avoid fluoroquinolones.
- Beta-lactam: piperacillin-tazobactam 4.5 g IV 6-hourly, OR cefepime 2 g IV 8-hourly, OR ceftazidime 2 g IV 8-hourly, OR meropenem 1 g IV 8-hourly
- PLUS ciprofloxacin 400 mg IV 8-hourly, OR levofloxacin 750 mg IV daily (not on the ARTG in Australia). Fluoroquinolones: avoid in myasthenia gravis; caution with long QT
- OR PLUS an aminoglycoside (gentamicin, tobramycin or amikacin). Dose: see eTG Antibiotic or local protocol; monitor levels
- Never use an aminoglycoside as the only antipseudomonal agent. In VAP, avoid aminoglycosides if another active agent is available
- Base the choice on the local antibiogram
07Decision Does the patient need MRSA cover?
Yes if any: IV antibiotics in the last 90 days; MRSA in a previous culture or screen; septic shock; HAP that needs ventilation; VAP with ARDS or acute dialysis before VAP, or 5 or more days in hospital; unit MRSA rate among S. aureus over 20% for HAP (over 10-20% for VAP) or not known.
- If Yes
08Action MRSA risk: add vancomycin or linezolid
Linezolid: do not give with an MAOI or within 2 weeks of one. With SSRIs, SNRIs or other serotonergic drugs, prefer vancomycin or monitor for serotonin syndrome.
- Vancomycin (adult): loading dose 25-30 mg/kg IV (severe illness), actual body weight, max 3000 mg; then AUC-guided dosing (AUC24 400-600 mg.h/L) per local protocol, with pharmacy
- OR linezolid (adult) 600 mg IV 12-hourly
- Linezolid: check full blood count weekly (thrombocytopenia, more likely in kidney or liver impairment)
- Choose by kidney function, blood counts, interacting drugs and local guidance
09Decision At 48-72 h: is the patient improving?
Review cultures, clinical signs and oxygenation. If there is no strong evidence of pneumonia, reconsider the diagnosis and stop antibiotics.
- If Yes
10Action Improving: de-escalate to targeted therapy
Narrow the regimen to the culture results.
- Stop MRSA cover if MRSA is not found
- Pseudomonas with known susceptibility: 1 active agent, unless still in septic shock or at high risk of death
- ESBL organism: choose by susceptibility. Acinetobacter or carbapenem-resistant organism: get ID advice
- Change from combination to one agent when possible; switch to oral when stable (eTG criteria)
- Dose by kidney function and drug levels
11Action Improving: give 7 days of antibiotics in total
7 days for most HAP and VAP. The course can be shorter or longer, based on clinical, radiological and laboratory response.
- Procalcitonin plus clinical criteria can help decide when to stop
- Empyema, lung abscess or S. aureus bacteraemia need longer, source-directed treatment: get ID advice
12Outcome Course complete: stop antibiotics
If No13Action Not improving at 48-72 h: find the cause
Do not only add more antibiotics.
- Repeat cultures; check drug choice, doses and levels against culture results
- Image for empyema, lung abscess or other complications
- Consider other diagnoses: PE, heart failure, atelectasis, ARDS, drug fever, other infection source
- Consider resistant, viral or fungal pathogens
- Get ID advice; broaden only for deterioration or new culture results
14Outcome Not improving: treat the cause with ID input; review ICU need and reassess daily
If No15Action No MRSA risk: no MRSA agent
The regimen must still cover MSSA. Piperacillin-tazobactam, cefepime, meropenem, imipenem and levofloxacin do. Ceftazidime, aztreonam, ciprofloxacin and aminoglycosides do not reliably do so: if the regimen has only these, add MSSA cover.
- Path rejoins step 09Shared downstream outcome
If No16Action Lower Pseudomonas and MDR risk: give 1 agent active against Pseudomonas and MSSA
Adult doses, normal kidney function. Choose by the local antibiogram. On valproate: avoid meropenem and imipenem (valproate levels fall; seizures). Myasthenia gravis: avoid fluoroquinolones.
- Piperacillin-tazobactam 4.5 g IV 6-hourly, OR
- Cefepime 2 g IV 8-hourly, OR
- Meropenem 1 g IV 8-hourly or imipenem 500 mg IV 6-hourly, OR
- Levofloxacin 750 mg IV daily (not on the ARTG in Australia; avoid in myasthenia gravis)
- Australia: eTG Antibiotic (2025) can use narrower regimens by severity and Pseudomonas risk; follow eTG and local guidance
- Path rejoins step 07Shared downstream outcome
Guideline Source
Kalil AC et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the IDSA and ATS. Clin Infect Dis 2016;63(5):e61-e111
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults who are not immunocompromised only (neutropenia, transplant, chemotherapy, advanced HIV excluded by the source).
- Regimens follow the US ATS/IDSA 2016 tables. In Australia use eTG Antibiotic (2025 revision) and the local antibiogram; levofloxacin is not on the ARTG.
- Aminoglycoside doses are not given; use eTG or the local aminoglycoside protocol.
- Doses are for adults with normal kidney function; adjust for kidney or liver impairment.
- Quantitative cultures and procalcitonin are not available everywhere.
Contraindicated Populations
Immunocompromised patients (neutropenia, solid organ or stem cell transplant, chemotherapy, advanced HIV)Children
Applicable Regions
USEUAUGlobal
AU: Therapeutic Guidelines: Antibiotic (2025 revision) defines HAP to include discharge within 7 days after an admission of more than 48 h, treats sepsis as high-severity HAP, and gives VAP regimens by Pseudomonas risk (ceftriaxone monotherapy when risk is low). Levofloxacin is not on the ARTG. Use lean body weight for aminoglycoside doses.
EU: ERS/ESICM/ESCMID/ALAT 2017 HAP/VAP guideline is the European equivalent; local antibiograms apply.
US: ATS/IDSA 2016 HAP/VAP guideline (still the current ATS/IDSA version).
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Hospital-Acquired and Ventilator-Associated Pneumonia (ATS/IDSA 2016)?
The Hospital-Acquired and Ventilator-Associated Pneumonia (ATS/IDSA 2016) is a management clinical algorithm for Infectious Disease. It provides a structured decision tree to guide clinical decision-making, based on Kalil AC et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the IDSA and ATS. Clin Infect Dis 2016;63(5):e61-e111.
What guideline is the Hospital-Acquired and Ventilator-Associated Pneumonia (ATS/IDSA 2016) based on?
This algorithm is based on Kalil AC et al. Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the IDSA and ATS. Clin Infect Dis 2016;63(5):e61-e111 (DOI: 10.1093/cid/ciw353).
What are the limitations of the Hospital-Acquired and Ventilator-Associated Pneumonia (ATS/IDSA 2016)?
Known limitations include: Adults who are not immunocompromised only (neutropenia, transplant, chemotherapy, advanced HIV excluded by the source).; Regimens follow the US ATS/IDSA 2016 tables. In Australia use eTG Antibiotic (2025 revision) and the local antibiogram; levofloxacin is not on the ARTG.; Aminoglycoside doses are not given; use eTG or the local aminoglycoside protocol.; Doses are for adults with normal kidney function; adjust for kidney or liver impairment.; Quantitative cultures and procalcitonin are not available everywhere.. Individual patient factors may require deviation from these recommendations.
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