Overview #
Definitions
Pneumonia is an infection of the lung parenchyma (1). It can be classified by source of acquisitionas:
- Community Acquired Pneumonia (CAP) = pneumonia that develops in the community or in a patient hospitalised for <48 hours (2)
- Hospital Acquired Pneumonia (HAP) = pneumonia that develops in a patient hospitalised for >48 hours (3)
- Aspiration Pneumonia = pneumonia that develops from the aspiration of pathogens (4)
- Ventilator Associated Pneumonia (VAP) = pneumonia that develops in a patient mechanically ventilated for >48 hours (5)
Pneumonia can also be classified by causative pathogen or pattern of lung involvement (see below for more details)
Prioritisation
- If there are signs of respiratory insufficiency or organ dysfunction, management must be made an urgent priority
Key points
- Antibiotic therapy is based on classification of pneumonia
- It is important to monitor response to therapy. If there is no clinical improvement with current therapy, re-evaluation is required
- Antibiotic therapy must not be delayed for severe pneumonia
Triage #
- Emergency requiring immediate attention: signs of respiratory insufficiency or organ dysfunction
- Attend within 30 min – 1 hour: mild/moderate pneumonia
Causes #
Pneumonia is most commonly caused by bacterial infections including typical and atypical pathogens. Causative bacterial and viral pathogens are summarised in the following table (1):
[TABLE TO BE DISPLAYED IN CALLOUT BOX]
| Bacterial pathogens | Viral Pathogens |
| Typical:Streptococcus pneumoniae (most common cause of CAP)Haemophilus influenzae Klebsiella pneumoniaePseudomonas aeruginosaStaphylococcus aureusAtypical:Mycoplasma pneumoniaeLegionella speciesChlamydophila pneumoniae | Influenza virusSARS-CoV-2RhinovirusRespiratory syncytial virusParainfluenza virusHuman MetapneumovirusAdenovirus |
Clinical features #
Patients with red flags should be escalated to senior clinicians and treated as a priority. Red flags include signs of respiratory insufficiency and/or organ dysfunction (1, 6, 7):
- Abnormal vital signs (tachypnoea, tachycardia, hypotension, oxygen desaturation)
- Altered conscious state/confusion
- Lactate >2 mmol/L
- Multilobar involvement on CXR
- Poor peripheral perfusion
- Oliguria
Other signs/symptoms include:
- Cough (productive or non-productive)
- Fever
- Dyspnoea
- Chills, fatigue, malaise
- Pleuritic chest pain
- Signs of consolidation on auscultation (crackles, dull percussion, tactile fremitus)
- Non-respiratory symptoms including confusion and diarrhoea (particularly in atypical pneumonia) (1, 6, 7)
Diagnosis #
Diagnosis of pneumonia can be made based on history and examination in conjunction with a CXR (1)
Investigations #
Initial investigations (1, 6, 7)
| Investigation | Significance |
| Sputum culture and gram stain | Guides antibiotic therapy. Note that patient may not have a productive cough |
| Nasopharyngeal swab | Exclude COVID-19 and other viral infections |
| VBG | Lactate >2 mmol/L is a sign of organ dysfunction (red flag) |
| FBE | Leukocytosis and neutrophilia support infective process |
| UEC | Raised creatinine and urea associated with poorer prognosis |
| CRP | Supports bacterial infection |
| Blood cultures | Preferably collect prior to antibiotic therapy, but should not delay treatment. if bacteraemia present, guides antibiotic therapy |
| CXR | Consolidation |
Further investigations
Consider these if there is suspicion of an atypical pathogen.
- Nucleic acid amplification testing (to confirm/exclude viral infection)
- Pneumococcal urinary antigen assay
- Legionella urinary antigen assay
- Serological testing (e.g. serology for M. pneumonia, Legionella species, C.pneumoniae, etc.) (1, 6, 7)
Classification #
The severity of pneumonia can be classified as mild, moderate or severe using the following tools.
CURB-65 (8) [TO BE DISPLAYED IN CALLOUT BOX]
Identifies the severity of CAP and guides the necessity of admission to hospital.
| C | Confusion (acute onset) | 1 point |
| U | Uraemia | 1 point |
| R | Respiratory Rate ≥30 breaths/min | 1 point |
| B | Systolic Blood Pressure ≤90 mmHg or Diastolic Blood Pressure ≤60 mmHg | 1 point |
| 65 | ≥65 years of age | 1 point |
Score 0-1: <3% 30-day mortality; manage at home if safe to do so
Score 2: 9% 30-day mortality; manage as an inpatient
Score 3-5: 5-40% 30-day mortality; manage as an inpatient and consider ICU
SMART COP (9) [TO BE DISPLAYED IN CALLOUT BOX]
Identifies likelihood of a patient requiring Intensive Respiratory or Vasopressor Support (IVRS)
| S | Systolic Blood Pressure ≤90 mmHg | 2 points |
| M | Multilobar CXR involvement | 1 point |
| A | Albumin <35 g/L | 1 point |
| R | Respiratory Rate ≥25 breaths/min (≤50 years) or ≥ 30 breaths/min (<50 years) | 1 point |
| T | Tachycardia ≥125 beats/min | 1 point |
| C | Confusion (acute onset) | 1 point |
| O | Oxygen desaturation ≤50 years: PaO₂ <70 mmHg or O₂ saturation ≤93%>50 years: PaO₂ <60 mmHg or O₂ saturation ≤90% | 2 points |
| P | Arterial pH <7.35 | 2 points |
Score 0-2: ≤2% 30-day mortality; low risk of needing IVRS
Score 3-4: 5-13% 30-day mortality; moderate risk of needing IVRS (1 in 8)
Score 5-6: 11-18% 30-day mortality; high risk of needing IVRS (1 in 3)
Score ≥7: 33% 30-day mortality; very high risk of needing IVRS (2 in 3)
Management #
Immediate management:
- DRSABCD
- MET Call/Code blue as appropriate
Non-antibiotic management (8):
- Oxygen therapy as appropriate to maintain SpO₂ >94%
- Oral or intravenous fluids to maintain euvolaemia
- Analgesia if required
- Antipyrexials if febrile
Antibiotic management:
- The below recommendations are empirical antibiotic regimes
- If a causative pathogen is identified, use directed antibiotic therapy
Management – Community Acquired Pneumonia #
Mild CAP
Can usually be managed in the community
| Amoxicillin 1 g oral, 8-hourly |
If atypical pathogens suspected, add:
| Doxycycline 100 mg oral, 12-hourly OR Clarithromycin 500 mg oral, 12-hourly |
If allergic to penicillins, use doxycycline
Duration of therapy: 5 – 7 days based on clinical improvement (2, 6)
Moderate CAP
| Benzylpenicillin 1.2 g IV, 6-hourlyPLUS Doxycycline 100 mg oral, 12-hourly OR Clarithromycin 500 mg oral, 12-hourly |
If non-severe allergy to penicillins:
| Ceftriaxone 1 g IV, 24-hourlyPLUS Doxycycline 100 mg oral, 12-hourly OR Clarithromycin 500 mg oral, 12-hourly |
If severe allergy to penicillins:
| Moxifloxacin 400 mg oral, 24-hourlyPLUS Doxycycline 100 mg oral 12-hourly OR Clarithromycin 500 mg oral, 12-hourly |
Once the patient is clinically stable, can switch from IV to oral therapy. Use:
| Amoxicillin 1 g oral, 8-hourlyPLUSDoxycycline 100 mg oral, 12-hourly OR Clarithromycin 500 mg oral 12-hourly |
Duration of therapy: 5 – 7 days (IV + oral) based on clinical improvement (2, 6)
Severe CAP
Do not delay antibiotics for severe pneumonia. Ensure to escalate to seniors and call MET/Code Blue if required. Depending on severity, may also require discussion with ICU and/or Infectious Diseases team.
| Ceftriaxone 2 g IV, 24-hourlyPLUS Azithromycin 500 mg IV, 24-hourly |
Patients may require additional therapy based on causative organism and clinical response. These cases should be escalated to seniors.
For example:
- Staphylococcus aureus: add vancomycin IV (dose based on clinical guidelines)
- Pseudomonas: piperacillin+tazobactam 4+0.5g IV, 6 hourly + gentamicin IV (dose based on clinical guidelines)
Once the patient is clinically stable, can switch from IV to oral therapy. Use:
| Amoxicillin 1 g oral, 8-hourlyPLUSDoxycycline 100 mg oral, 12-hourly OR Clarithromycin 500 mg oral, 12-hourly |
Duration of therapy: 5 – 7 days (IV + oral) based on clinical improvement (2, 6)
Management – Hospital Acquired Pneumonia #
Mild/Moderate HAP
If oral therapy is tolerated:
| Amoxicillin + clavulanate 875 + 125 mg oral, 12-hourly |
If non-severe allergy to penicillins:
| Cefuroxime 500 mg oral, 12-hourly |
If severe allergy to penicillins:
| Moxifloxacin 400 mg oral, 24-hourly |
Duration of therapy: 7 days (IV + oral) based on clinical improvement
If oral therapy is not tolerated:
| Ceftriaxone 1 g IV, 24-hourlyORAmoxicillin + clavulanate 1 + 0.2 g IV, 8-hourly |
If severe allergy to penicillin:
| Moxifloxacin 400 mg IV, 24-hourly |
Once the patient is clinically stable, can switch from IV to oral therapy as outlined above
Duration of therapy: 7 days (IV + oral) based on clinical improvement (3, 7)
Severe HAP
| Piperacillin + tazobactam 4 + 0.5 g IV, 6-hourly |
If severe allergy to penicillin:
| Ciprofloxacin 400 mg IV, 8-hourlyANDVancomycin IV (dose based on clinical guidelines) OR Meropenem 1 g IV, 8-hourly |
Once the patient is clinically stable, can switch from IV to oral therapy as outlined above
Duration of therapy: 7 days (IV + oral) based on clinical improvement
Patients may require additional therapy based on causative organism and clinical response. These cases should be escalated to seniors.
For example:
- Staphylococcus aureus: add vancomycin IV (dose based on clinical guidelines)
- Pseudomonas: piperacillin+tazobactam 4+0.5g IV, 6 hourly + gentamicin IV (dose based on clinical guidelines) (3, 7)
Management – Aspiration Pneumonia #
It is important to exclude aspiration pneumonitis which does not require antibiotic therapy.
Initial management
Treat as per CAP or HAP based on duration of hospitalisation (i.e. treat as CAP if hospitalised for <48 hours or as HAP if hospitalised for >48 hours)
If there is no clinical improvement after 48 hours of initial therapy, consider the following.
If oral therapy is tolerated:
| Single drug regime:Amoxicillin + clavulanate 875 + 125 mg oral, 12-hourly OR Clindamycin 450 mg oral, 8-hourly OR Moxifloxacin 400 mg oral, 24-hourly Dual drug regime:Amoxicillin 1 g oral, 8-hourly PLUS Metronidazole 400 mg oral, 12-hourly |
If allergic to penicillin, use clindamycin or moxifloxacin.
If oral therapy is not tolerated:
| Benzylpenicillin 1.2 g IV, 6-hourly PLUS Metronidazole 500 mg IV, 12-hourlyOR Amoxicillin + clavulanate 1 + 0.2 g IV, 8-hourly |
If non-severe allergy to penicillin:
| Ceftriaxone 1 g IV, 24-hourly PLUS Metronidazole 500 mg IV, 12-hourly |
If severe allergy to penicillin
| Clindamycin 600mg IV 8-hourly OR Moxifloxacin 400 mg IV, 24-hourly |
Once the patient is clinically stable, can switch from IV to oral therapy as outlined above
Duration of therapy: 5 – 7 days (IV + oral) based on clinical improvement (4, 10)
Complications of pneumonia #
Complications of pneumonia include:
- Parapneumonic effusion
- Empyema
- Lung abscess
If any complications arise, treat as appropriate with the assistance of senior clinicians. (8(
References #
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2019. Pneumonia diagnosis and follow-up; [updated 2019 April; cited 2021 Sep 21]. Available from: https://tgldcdp.tg.org.au.acs.hcn.com.au/viewTopic?topicfile=pneumonia-diagnosis-follow-up&guidelineName=Antibiotic&topicNavigation=navigateTopic#toc_d1e47
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2019. Community-acquired pneumonia in adults; [updated 2019 April; cited 2021 Sep 21]. Available from: https://tgldcdp.tg.org.au.acs.hcn.com.au/viewTopic?topicfile=community-acquired-pneumonia-adults&guidelineName=Antibiotic&topicNavigation=navigateTopic#MPS_d1e2786
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2019. Hospital-acquired pneumonia in adults; [updated 2019 April; cited 2021 Sep 21]. Available from: https://tgldcdp.tg.org.au.acs.hcn.com.au/viewTopic?topicfile=hospital-acquired-pneumonia&guidelineName=Antibiotic&topicNavigation=navigateTopic#MPS_d1e1063
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2019. Aspiration pneumonia; [updated 2019 April; cited 2021 Sep 21]. Available from: https://tgldcdp.tg.org.au.acs.hcn.com.au/viewTopic?topicfile=aspiration-pneumonia&guidelineName=Antibiotic&topicNavigation=navigateTopic
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2019. Ventilator-associated pneumonia; [updated 2019 April; cited 2021 Sep 21]. Available from: https://tgldcdp.tg.org.au.acs.hcn.com.au/viewTopic?topicfile=ventilator-associated-pneumonia&guidelineName=Antibiotic&topicNavigation=navigateTopic#toc_d1e865
- Ramirez JA. Overview of community-acquired pneumonia in adults. In File TM, Bond S, editors.; UpToDate. [Internet]. UpToDate Inc; 2021. [updated 2021 Sep 07, cited 2021 Sep 21]. Available from: https://www.uptodate.com/contents/overview-of-community-acquired-pneumonia-in-adults?search=community%20acquired%20pneumonia&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2
- Klompas M. Treatment of hospital-acquired and ventilator-associated pneumonia in adults. In File TM, Bond S, editors.; UpToDate. [Internet]. UpToDate Inc; 2021. [updated 2021 Sep 02, cited 2021 Sep 21]. Available from: https://www.uptodate.com/contents/treatment-of-hospital-acquired-and-ventilator-associated-pneumonia-in-adults?search=hospital%20acquired%20pneumonia&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
- Lim WS, Baudouin SV, George RC, et al. British Thoracic Society guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009 Sep 24;64(Suppl III):iii1–iii55.
- Charles PGP, Wolfe R, Whitby M, et al. Clin Infect Dis. 2008 Aug 1;47(3):375-384.
- Klompas M. Aspiration pneumonia in adults. In Sexton DJ, Hollingsworth H, editors.; UpToDate. [Internet]. UpToDate Inc; 2021. [updated 2021 Jul 26, cited 2021 Sep 21]. Available from: https://www.uptodate.com/contents/aspiration-pneumonia-in-adults?search=aspiration%20pneumonia&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
Contributors
Reviewing Consultant/Senior Registrar
Dr Caitlin Falloon
Dr Alice Liu
