Community-acquired pneumonia: Difference between revisions
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=== Microbiology === |
=== Microbiology === |
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* Bacteria (15-30%)[[CiteRef::gadsby2022th]] |
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* Bacteria (15-30%)<ref>Gadsby NJ, Musher DM. The Microbial Etiology of Community-Acquired Pneumonia in Adults: from Classical Bacteriology to Host Transcriptional Signatures. ''Clin Microbiol Rev''. 2022 Sep 27:e0001522. doi: [https://doi.org/10.1128/cmr.00015-22 10.1128/cmr.00015-22]. Epub ahead of print. PMID: [https://pubmed.ncbi.nlm.nih.gov/36165783/ 36165783].</ref> |
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** Typical organisms |
** Typical organisms |
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*** [[Streptococcus pneumoniae]] (5-15%) |
*** [[Streptococcus pneumoniae]] (5-15%) |
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Latest revision as of 17:30, 19 September 2024
Background
- See also Respiratory infection in an immunocompromised person and Respiratory infection in unimmunized hosts
Microbiology
- Bacteria (15-30%)1
- Typical organisms
- Streptococcus pneumoniae (5-15%)
- Haemophilus influenzae (1-7%)
- Staphylococcus aureus (2-5%)
- Group A streptococcus
- Moraxella catarrhalis
- Anaerobes and aerobic gram-negative bacteria
- Atypical organisms
- Legionella species (1-6%)
- Mycoplasma pneumoniae (1-10%)
- Chlamydia pneumoniae (1-3%)
- Chlamydia psittaci
- Others
- Typical organisms
- Viruses (25-60%)
- Rhinovirus (8-17%)
- Coronavirus (3-13%)
- Influenza virus (1-6%)
- Human metapneumovirus (1-8%)
- Parainfluenza virus (1-8%)
- RSV (1-8%)
- Adenovirus (1-8%)
- Fungi (1-3%)
- No cause identified (46-66%)
- Clinically-important but uncommon organisms
- Legionella species
- Influenza A and B, including avian influenza A H5N1 and avian influenza A H7N9
- MERS-CoV and severe acute respiratory syndrome coronavirus (SARS-CoV)
- Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA)
Clinical Manifestations
- Acute onset cough, dyspnea, and fever
- If effusion, consider Legionella
Severity
- Per IDSA guidelines2, severe CAP includes either one major criterion or three or more minor criteria
- Minor criteria
- Respiratory rate ≥ 30 breaths/min
- PaO2/FiO2 ratio ≤ 250
- Multilobar infiltrates
- Confusion/disorientation
- Uremia (blood urea nitrogen level ≥ 20 mg/dl)
- Leukopenia not due to chemotherapy (white blood cell count < 4,000 cells/μl)
- Thrombocytopenia (platelet count < 100,000/μl)
- Hypothermia (core temperature < 36°C)
- Hypotension requiring aggressive fluid resuscitation
- Major criteria
- Septic shock with need for vasopressors
- Respiratory failure requiring mechanical ventilation
Investigations
- Always add Legionella testing in immunocompromised, critical illness, recent travel, significant alcohol, and consider when pleural effusion is present
