Bacterial pneumonia causes
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Arooj Naz, M.B.B.S
Overview
Bacterial pneumonia may be due to a variety of underlying causes. The microorganisms responsible are divided into typical and atypical. Typical bacteria often result in a classic pneumonia whereas atypical bacteria lead to a much milder presentation often referred to as “walking pneumonia“. These patients appear near normal but have extensive findings on chest x-ray. Apart from typical and atypical classifications, bacterial pneumonia can be categorized based on demographics by differentiating into neonates (<4 weeks old), toddlers (2 – 4 years), children (4 weeks – 18 years), adults (18 – 65 years), and the elderly (>65 years). Underlying characteristics may also help determine the specific cause. These include alcoholics, those at risk of aspiration, cystic fibrosis, intravenous drug users, and those that are immunocompromised or at risk of nosocomial pneumonia.
Causes
According to Microorganisms
| Typical Pneumonia[1] | Atypical Pneumonia |
|---|---|
| Streptococcus pneumoniae | Legionella |
| Staphylococcus aureus | Mycoplasma pneumoniae |
| Haemophilus influenzae | Chlamydia pneumoniae |
| Listeria monocytogenes | Chlamydia psittaci |
| Group A streptococci | Chlamydia Trachomatis |
| Moraxella catarrhalis | |
| Anaerobes and aerobic gram-negative bacteria |
According to Demographics
| Age Group | Most common organism |
|---|---|
| Neonates (<4 weeks old) [2][3] | Group B streptococci, Escherichia coli, Listeria monocytogenes |
| Toddlers (2 – 4 years) [3] | Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis |
| Children (4 weeks – 18 years) [3] | Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae |
| Adults (18 – 65 years) [4] | Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Klebsiella, Pseudomonas aeruginosa, Legionella, Mycoplasma pneumoniae, Chlamydia pneumoniae |
| Elderly (>65 years) [5] | Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, Legionella, Gram Negative Rods (Escherichia coli, Klebsiella, Enterobacter species, Pseudomonas aeruginosa) |
According to Specific Groups
| Group Description | Most common organism |
|---|---|
| Alcoholics [6][7] | Streptococcus Pneumoniae, Oral anaerobes, Klebsiella Pneumoniae, Acinetobacter |
| Aspiration [6][7] | Oral anaerobes, Pseudomonas aeruginosa, Gram-Negative Rods (Escherichia coli, Klebsiella, Enterobacter species) |
| Cystic fibrosis [6][7] | Pseudomonas Aeruginosa, Burkholderia Cepacia, Staphylococcus Aureus |
| Immunocompromised [6][7] | Streptococcus Pneumoniae, Haemophilus Influenzae |
| Intravenous drug users [6][7] | Staphylococcus Aureus, Oral anaerobes, Streptococcus Pneumoniae |
| Nosocomial (hospital acquired) [8] | Staphylococcus aureus (MRSA), Streptococcus species, Pseudomonas aeruginosa, Gram-Negative Rods (Escherichia coli, Klebsiella, Enterobacter species), Acinetobacter species |
| Postviral [9] | Staphylococcus aureus, Streptococcus Pneumoniae
Less likely to be Haemophilus influenzae |
References
- ↑ “StatPearls”. 2021. PMID 30020693.
- ↑ Webber S, Wilkinson AR, Lindsell D, Hope PL, Dobson SR, Isaacs D (1990). “Neonatal pneumonia”. Arch Dis Child. 65 (2): 207–11. doi:10.1136/adc.65.2.207. PMC 1792235. PMID 2107797.
- ↑ 3.0 3.1 3.2 Nguyen TK, Tran TH, Roberts CL, Graham SM, Marais BJ (2017). “Child pneumonia – focus on the Western Pacific Region”. Paediatr Respir Rev. 21: 102–110. doi:10.1016/j.prrv.2016.07.004. PMC 7106312 Check
|pmc=value (help). PMID 27569107. - ↑ Eshwara VK, Mukhopadhyay C, Rello J (2020). “Community-acquired bacterial pneumonia in adults: An update”. Indian J Med Res. 151 (4): 287–302. doi:10.4103/ijmr.IJMR_1678_19. PMC 7371062 Check
|pmc=value (help). PMID 32461392 Check|pmid=value (help). - ↑ Henig O, Kaye KS (2017). “Bacterial Pneumonia in Older Adults”. Infect Dis Clin North Am. 31 (4): 689–713. doi:10.1016/j.idc.2017.07.015. PMC 7127502 Check
|pmc=value (help). PMID 28916385. - ↑ 6.0 6.1 6.2 6.3 6.4 {{https://www.wikidoc.org/index.php/Pneumonia_risk_factors}}
- ↑ 7.0 7.1 7.2 7.3 7.4 {{https://academic.oup.com/cid/article/44/Supplement_2/S27/372079}}
- ↑ “StatPearls”. 2021. PMID 30571062.
- ↑ Prasso JE, Deng JC (2017). “Postviral Complications: Bacterial Pneumonia”. Clin Chest Med. 38 (1): 127–138. doi:10.1016/j.ccm.2016.11.006. PMC 5324726. PMID 28159155.
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