Pneumonia

Aspiration Pneumonia

Patient Population:
Adult

Patients with respiratory decompensation shortly after aspiration of gastric/oropharyngeal contents are considered to have aspiration pneumonitis (inflammation of the lung without true infection). Most of these patients will improve with supportive care alone over 24-48 hours (https://pubmed.ncbi.nlm.nih.gov/22392230/), though some can have a very severe course including ARDS.

Patients with aspiration pneumonitis can have a leukocytosis, fevers, opacity on chest X-ray, and worsening respiratory status, and these are not useful for distinguishing aspiration pneumonitis from a true bacterial pneumonia. The onset of symptoms is often very abrupt and, in conjunction with a known or strongly suspected aspiration event, can be suggestive of a chemical pneumonitis due to aspiration, rather than bacterial pneumonia.  Some scenarios where this can occur include a seizure event, code blue, intubation, etc.

A subset of patients with a macro-aspiration will go on to develop bacterial pneumonia during their recovery from their chemical pneumonitis. If a true bacterial pneumonia develops, it is typically 48-72 hours after the aspiration event. Note, however, most patients will recover spontaneously from aspiration pneumonitis with supportive care.

“Prophylactic” antibiotics after aspiration events do not seem to be effective in preventing the development of bacterial pneumonia. (https://pubmed.ncbi.nlm.nih.gov/29438467/). In inpatient scenarios, the entire clinical picture should be considered in deciding whether to pursue treatment for aspiration pneumonia or with broader coverage hospital acquired/ventilator associated pneumonia.  

Exclusion: Hematologic malignancy or bone marrow transplantation, cystic fibrosis, patients cared for under the Advanced Lung Diseases service, and other severe immunosuppression or immunocompromise

Diagnosis Common Pathogens Drug(s) of First Choice Alternative Drug(s) Comments Expected Duration

Acute Aspiration of Gastric Contents

"Aspiration Pneumonitis"

 Mixed enteric flora Antibiotics not indicated N/A

Patients who acutely aspirate gastric contents are considered to have aspiration pneumonitis. Many of these patients will have resolution of symptoms within 24-48 hours with only supportive care

Prophylactic antimicrobial therapy for acute aspiration pnuemonitis does not improve patient outcomes and may increase antimicrobial resistance

 Antibiotics not indicated
Bacterial Pneumonia after Community Aspiration Event Mixed enteric flora, oral flora, and CAP organisms Ceftriaxone Levofloxacin Anaerobes are not a common cause of bacterial pneumonia after aspiration. If present, ceftriaxone provides adequate coverage of oral anaerobes 5 days
Bacterial Pneumonia After In-Hospital Aspiration Refer to Hospital Acquired Pneumonia Guidelines Refer to Hospital Acquired Pneumonia Guidelines Refer to Hospital Acquired Pneumonia Guidelines Refer to Hospital Acquired Pneumonia Guidelines N/A
Lung Abscess or Empyema Oral anaerobes, Strep sp., Staph aureus

Ampicillin-sulbactam

Consider MRSA coverage in patients with history of MRSA infection or colonization

 Clindamycin Often characterized by insidious onset of cough/fever, purulent sputum, and evidence of cavitation/effusion in patients at risk for chronic aspiration

ID consult recommended

Asai N, Suematsu H, Ohashi W, Shibata Y, Sakanashi D, Kato H, Shiota A, Watanabe H, Hagihara M, Koizumi Y, Yamagishi Y, Mikamo H. Ceftriaxone versus tazobactam/piperacillin and carbapenems in the treatment of aspiration pneumonia: A propensity score matching analysis. J Infect Chemother. 2021 Oct;27(10):1465-1470. doi: 10.1016/j.jiac.2021.06.011. Epub 2021 Jun 20. PMID: 34158237

Bai, A. D., Srivastava, S., Digby, G. C., Girard, V., Razak, F., & Verma, A. A. (2024). Anaerobic Antibiotic Coverage in Aspiration Pneumonia and the Associated Benefits and Harms: A Retrospective Cohort Study. Chest, 166(1), 39–48. https://doi.org/10.1016/j.chest.2024.02.025

Dragan V, Wei Y, Elligsen M, Kiss A, Walker SAN, Leis JA. Prophylactic Antimicrobial Therapy for Acute Aspiration Pneumonitis. Clin Infect Dis. 2018 Aug 1;67(4):513-518. doi: 10.1093/cid/ciy120. PMID: 29438467.

Jaoude P, Badlam J, Anandam A, El-Solh AA. A comparison between time to clinical stability in community-acquired aspiration pneumonia and community-acquired pneumonia. Intern Emerg Med. 2014 Mar;9(2):143-50. doi: 10.1007/s11739-012-0764-2. Epub 2012 Mar 6. PMID: 22392230.

 

Pneumonia

Community-Acquired Pneumonia

Patient Population:
Adult
Diagnosis Common Pathogens Drug(s) of First Choice Alternative Drug(s) Comments Expected Duration

Admitted to the Medical Ward

Respiratory viruses

S.  pneumoniae

Mycoplasma pneumoniae

Chlamydia pneumoniae

H. influenzae

Legionella pneumophilia

Klebsiella pneumoniae

(alcoholics)

No Recent antibiotic therapy:*

Ceftriaxone

PLUS

Doxycycline

For severe beta-lactam allergy:

Levofloxacin

OR

Moxifloxacin

*If patient has had recent antibiotic therapy, antibiotics from a different class should be selected (i.e. recent use of a fluoroquinolone should dictate selection of a non-fluoroquinolone regimen, and vice versa).

Consider MRSA coverage (and collect a MRSA nares) if any of the following:

  • History of MRSA colonization or infection at any site within 1 year
  • MRSA nasal PCR positive
  • Other MRSA risk factors to consider: recent influenza, presence of cavitary disease, empyema

Consider Pseudomonas coverage if any of the following:

  • History of Pseudomonas colonization or infection at any site within 1 year
  • Advanced structural lung disease

If no microbiologic confirmation of MRSA then discontinue MRSA agent. If coverage for Pseudomonas is started, obtain blood and sputum cultures and de-escalate if this organism is not isolated.

Consider respiratory virus testing and treatment (if indicated)

 5 days

Admitted to the ICU for CAP

If indication for ICU admission is not CAP, follow "Admitted to the Medical Ward" section above

Respiratory viruses

S. pneumoniae

Mycoplasma pneumoniae

Chlamydia pneumoniae

H. influenzae

Legionella pneumophilia

Klebsiella pneumoniae

(alcoholics)

S. aureus

Ceftriaxone

PLUS

Azithromycin 500mg IV daily

WITH OR WITHOUT*:

Linezolid (preferred if no contraindications)

OR

Vancomycin

For severe beta-lactam allergy:

Vancomycin

PLUS one of EITHER:

Levofloxacin

OR

Moxifloxacin

ID consultation is recommended if ICU admission or high level PCN-resistant pneumococci documented

*Consider MRSA coverage (and collection of MRSA nares) if any of the following:

  • Receipt of parenteral antibiotics within 90 days
  • History of MRSA colonization or infection at any site within 1 year
  • MRSA nasal PCR positive
  • Other MRSA risk factors to consider: recent influenza, presence of cavitary disease, empyema

Consider Pseudomonas coverage if any of the following:

  • Receipt of parenteral antibiotics within 90 days
  • History of Pseudomonas colonization or infection at any site within 1 year
  • Advanced structural lung disease

If no microbiologic confirmation of MRSA then discontinue MRSA agent. If coverage for Pseudomonas is started, obtain blood and sputum cultures and de-escalate if this organism is not isolated.

Consider respiratory virus testing and treatment (if indicated)

 5-7 days
Outpatient, no comorbidities

Respiratory viruses

S.  pneumoniae

Mycoplasma pneumoniae

Chlamydia pneumoniae

H. influenza

Doxycycline

OR

Amoxicillin 1 g PO TID		  

Consider respiratory virus testing and treatment (if indicated)

Consider MRSA coverage if any of the following:

  • Receipt of parenteral antibiotics within 90 days
  • History of MRSA colonization or infection at any site within 1 year

Consider Pseudomonas coverage if any of the following:

  • Receipt of parenteral antibiotics within 90 days
  • History of Pseudomonas colonization or infection at any site within 1 year
  • Advanced structural lung disease
 5 days

Outpatient, with comorbidities

(e.g. chronic heart, lung, liver, kidney disease, diabetes, ethanol use disorder, malignancy, asplenia)

Respiratory viruses

S.  pneumoniae

Mycoplasma pneumoniae

Chlamydia pneumoniae

H. influenza

Amoxicillin 1 g PO TID

PLUS Doxycycline

OR

Levofloxacin as monotherapy

  

Consider respiratory virus testing and treatment (if indicated)

Consider MRSA coverage if any of the following:

  • Receipt of parenteral antibiotics within 90 days
  • History of MRSA colonization or infection at any site within 1 year

Consider Pseudomonas coverage if any of the following:

  • Receipt of parenteral antibiotics within 90 days
  • History of Pseudomonas colonization or infection at any site within 1 year
  • Advanced structural lung disease
 5 days

 

American Journal of Respiratory and Critical Care Medicine, Volume 200, Issue 7, 1 October 2019, Pages e45-e67, https://www.atsjournals.org/doi/full/10.1164/rccm.201908-1581ST

Linezolid in Methicillin-Resistant Staphylococcus aureus Nosocomial Pneumonia: A Randomized, Controlled Study, Clinical Infectious Diseases, Volume 54, Issue 5, 1 March 2012, Pages 621–629, https://doi.org/10.1093/cid/cir895

Pneumonia

Pneumonia, Hospital-acquired or Ventilator-associated

Patient Population:
Adult

Healthcare-associated pneumonia (HCAP), or pneumonia acquired outside the hospital in patients with healthcare-associated risk factors, is no longer distinguished in the guidelines. We recommended that most patients admitted for pneumonia who have had recent contact with the healthcare system (i.e., within 90 days, dialysis) be treated for CAP.

Institution-Specific Hospital-Acquired and Ventilator-Associated Pneumonia Guidelines
UCSF Medical Center UCSF Guidelines for Hospital-acquired/Ventilator-associated Pneumonia
Diagnosis Antibiotic Regimens Alternative Drug(s) Comments Expected Duration

UCSF Medical Center (including Parnassus, Mission Bay, and Mt. Zion)

Ventilator-associated pneumonia (VAP) AND Hospital-acquired pneumonia (HAP)

Guidelines available separately here: 

Hospital-acquired Pneumonia

Guidelines available separately here: 

Hospital-acquired Pneumonia

Guidelines available separately here: 

Hospital-acquired Pneumonia

 Generally 7 days, but see: 

Hospital-acquired Pneumonia

ZSFG & SFVA Hospitals

Ventilator-associated pneumonia (VAP) AND hospital-acquired pneumonia (HAP)

With gram stain available within 72 hours

What to start: cefepime OR ceftriaxone +/- vancomycin

Consider ceftriaxone: no risk factors for Pseudomonas, short duration of intubation (I.e., < 5 days), hemodynamically stable

Respiratory culture (tracheal aspirate) should be collected for ALL patients with suspected VAP (and intubated pts with suspected HAP) prior to starting antibiotics.

Antibiotics should be tailored based on tracheal aspirate gram stain findings:

ΔIf ceftriaxone was chosen based on considerations above, continue ceftriaxone. Broaden to cefepime if patient is hemodynamically unstable or clinically worsening.

Severe beta-lactam allergy precluding use of a cephalosporin:

What to start: Aztreonam* + vancomycin OR Levofloxacin +/- vancomycin

Antibiotics based on tracheal aspirate gram stain findings for patients with severe allergy precluding use of a cephalosporin:

*Aztreonam requires ID pharmacy/consult approval.

Consider withholding empiric vancomycin in patients with neg MRSA nares culture within prior 7 days.

Stop vancomycin at 48 hours if MRSA nares culture/PCR is negative and/or no MRSA isolated from clinical cultures.

A positive MRSA nares culture/PCR indicates that the patient is colonized with MRSA. Patients with a positive MRSA nares culture/PCR should be initiated on empiric anti-MRSA therapy (vancomycin). However, antibiotics should be tailored to respiratory gram stain & culture results. Stop vancomycin at 48 hours if no MRSA isolated from clinical cultures.

Antibiotic use at the time of respiratory culture collection may decrease gram stain yield. Contact ID pharmacy/ID consult with questions.

For patients with known respiratory colonization with multidrug resistant organisms (MDRO), consider empiric coverage of these organisms pending culture results

 7 days

ZSFG & SFVA Hospitals

Hospital Acquired Pneumonia (HAP) [ICU level of care / High-Flow Nasal Cannula] AND VAP)

With NO respiratory gram stain available

Cefepime +/- vancomycin

Consider ceftriaxone: no risk factors for Pseudomonas, short duration of hospitalization (I.e., < 5 days), hemodynamically stable

Severe beta-lactam allergy precluding use of a cephalosporin:

Aztreonam* + vancomycin OR levofloxacin +/- vancomycin

*Aztreonam requires ID pharmacy/consult approval.

Consider withholding empiric vancomycin in patients with neg MRSA nares culture within prior 7 days.

Consider coverage for MRSA and/or Pseudomonas aeruginosa in patients with respiratory isolation of these organisms or receipt of parenteral antibiotics within 90 days, admitted from skilled nursing or other long term care facility after at least one week stay. If these organisms are not isolated from clinical cultures (e.g., blood cultures), deescalate antibiotics.

Stop vancomycin at 48 hours if admission MRSA nares is negative and/or no MRSA isolated from clinical cultures

 7 days

ZSFG & SFVA Hospitals

Hospital Acquired Pneumonia (HAP)

Hemodynamically stable, floor patient NOT on high-flow nasal cannula

With NO respiratory gram stain available

Including patients with HAP due to aspiration

 

Ceftriaxone

Risk factors for Pseudomonas/resistant GNRs: Cefepime

Severe beta-lactam allergy precluding use of a cephalosporin:

Levofloxacin

Consider empiric vancomycin if clinical concern for MRSA pneumonia (e.g., necrotizing pneumonia on imaging). If starting vancomycin, collect MRSA nares culture/PCR.

Consider coverage for MRSA and/or Pseudomonas aeruginosa in patients with respiratory isolation of these organisms or receipt of parenteral antibiotics within 90 days, admitted from skilled nursing or other long term care facility after at least one week stay. If these organisms are not isolated from clinical cultures (e.g. blood cultures), deescalate antibiotics.

 7 days

Role and Interpretation of Methicillin-Resistant S. aureus (MRSA) Nares Results in Context of Hospital-Acquired and Ventilator-Associated Pneumonia (HAP/VAP)

Collecting a MRSA nares culture/PCR is recommended for all patients initiating anti-MRSA therapy (e.g. vancomycin) for suspected HAP or VAP.

How to interpret a negative MRSA nares result in patient with possible HAP/VAP:

A negative MRSA nares culture or PCR indicates the patient is less likely to be colonized with MRSA. Multiple studies indicate that a negative MRSA nares culture or PCR carries a high negative predictive value for MRSA pneumonia (> 95%),3-6 even when collected prior to onset of pneumonia.3,5 If a patient’s MRSA nares is negative, their likelihood of having MRSA pneumonia is exceedingly low and anti-MRSA therapy (e.g. vancomycin) can reasonably be discontinued or withheld.

How to interpret a positive MRSA nares result in patient with possible HAP/VAP:

A positive MRSA nares culture or PCR indicates that the patient is colonized with MRSA. Patients with a known positive MRSA nares culture/PCR who develop a HAP or VAP should be initiated on antibiotics including empiric anti-MRSA therapy (e.g. vancomycin). However, antibiotics should be tailored to respiratory gram stain & culture results. Stop vancomycin at 48 hours if no MRSA isolated from clinical cultures. If a patient's MRSA nares culture or PCR results positive after the patient has been started on antibiotics to treat HAP/VAP, no change in therapy is recommended (in other words – no need to add empiric anti-MRSA therapy) provided the patient is stable and clinically improving.

 

1.Clinical Infectious Diseases, Volume 63, Issue 5, 1 September 2016, Pages e61–e111, https://doi.org/10.1093/cid/ciw353

2.Yoshimura J, Yamakawa K, Ohta Y, et al. Effect of Gram Stain-Guided Initial Antibiotic Therapy on Clinical Response in Patients With VentilatorAssociated Pneumonia: The GRACE-VAP Randomized Clinical Trial. JAMA Netw Open. 2022;5(4):e226136. doi:10.1001/jamanetworkopen.2022.6136 

3. Parente DM, Cunha CB, Mylonakis E, Timbrook TT. The Clinical Utility of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screening to Rule Out MRSA Pneumonia: A Diagnostic Meta-analysis With Antimicrobial Stewardship Implications. Clin Infect Dis. 2018;67(1):1-7. doi:10.1093/cid/ciy024

4. Smith MN, Brotherton AL, Lusardi K, Tan CA, Hammond DA. Systematic Review of the Clinical Utility of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Screening for MRSA Pneumonia. Ann Pharmacother. 2019;53(6):627-638. doi:10.1177/1060028018823027

5. Mallidi MG, Slocum GW, Peksa GD, DeMott JM. Impact of Prior-to-Admission Methicillin-Resistant Staphylococcus aureus Nares Screening in Critically Ill Adults With Pneumonia. Ann Pharmacother. Published online June 6, 2021:10600280211023208. doi:10.1177/10600280211023209

6. Mergenhagen KA, Starr KE, Wattengel BA, Lesse AJ, Sumon Z, Sellick JA. Determining the Utility of Methicillin-Resistant Staphylococcus aureus Nares Screening in Antimicrobial Stewardship. Clinical Infectious Diseases. 2020;71(5):1142-1148. doi:10.1093/cid/ciz974

Pneumonia
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