Lower respiratory tract infection

Lower respiratory tract infection
Conducting passages.
Classification and external resources
Specialty pulmonology
ICD-10 J10-J22, J40-J47

Lower respiratory tract infection (LRTI), while often used as a synonym for pneumonia, can also be applied to other types of infection including lung abscess and acute bronchitis. Symptoms include shortness of breath, weakness, fever, coughing and fatigue.

There are a number of symptoms that are characteristic of lower respiratory tract infections. The two most common are bronchitis and pneumonia.[1] Influenza affects both the upper and lower respiratory tracts.

Antibiotics are the first line treatment for pneumonia; however, they are not effective or indicated for parasitic or viral infections. Acute bronchitis typically resolves on its own with time.

In 2013 there were about 150 million LRTIs.[2] These resulted in 2.7 million deaths down from 3.4 million deaths in 1990.[3] This was 4.8% of all deaths in 2013.[3]



Main article: Bronchitis

Bronchitis describes the swelling or inflammation of the bronchial tubes. Additionally, bronchitis is described as either acute or chronic depending on its presentation and is also further described by the causative agent. Acute bronchitis can be defined as acute bacterial or viral infection of the larger airways in healthy patients with no history of recurrent disease.[1] It affects over 40 adults per 1000 each year and consists of transient inflammation of the major bronchi and trachea.[4] Most often it is caused by viral infection and hence antibiotic therapy is not indicated in immunocompetent individuals.[5][6] Viral bronchitis can sometimes be treated using antiviral medications depending on the virus causing the infection, and medications such as anti-inflammatory drugs and expectorants can help mitigate the symptoms.[6][7] Treatment of acute bronchitis with antibiotics is common but controversial as their use has only moderate benefit weighted against potential side effects (nausea and vomiting), increased resistance, and cost of treatment in a self-limiting condition.[4][8] Beta2 agonists are sometimes used to relieve the cough associated with acute bronchitis. In a recent systematic review it was found there was no evidence to support their use.[6]

Acute Exacerbations of Chronic Bronchitis (AECB) are frequently due to non-infective causes along with viral ones. 50% of patients are colonised with Haemophilus influenzae, Streptococcus pneumoniae or Moraxella catarrhalis.[1] Antibiotics have only been shown to be effective if all three of the following symptoms are present: increased dyspnoea, increased sputum volume and purulence. In these cases 500 mg of Amoxycillin orally, every 8 hours for 5 days or 100 mg doxycycline orally for 5 days should be used.[1]


Main article: Pneumonia

Pneumonia occurs in a variety of situations and treatment must vary according to the situation.[7] It is classified as either community or hospital acquired depending on where the patient contracted the infection. It is life-threatening in the elderly or those who are immunocompromised.[9][10] The most common treatment is antibiotics and these vary in their adverse effects and their effectiveness.[9] Pneumonia is also the leading cause of death in children less than five years of age.[11] The most common cause of pneumonia is pneumococcal bacteria, Streptococcus pneumoniae accounts for 2/3 of bacteremic pneumonias.[12] This is a dangerous type of lung infection with a mortality rate of around 25%.[10] For optimal management of a pneumonia patient, the following must be assessed: pneumonia severity (including treatment location, e.g., home, hospital or intensive care), identification of causative organism, analgesia of chest pain, the need for supplemental oxygen, physiotherapy, hydration, bronchodilators and possible complications of emphysema or lung abscess.[13]

Other causes

This list is incomplete; you can help by expanding it.

Parasitic infections:

Viral infections:


Antibiotics do not help the many lower respiratory infections which are caused by parasites or viruses. While acute bronchitis often does not require antibiotic therapy, antibiotics can be given to patients with acute exacerbations of chronic bronchitis. The indications for treatment are increased dyspnoea, and an increase in the volume or purulence of the sputum. The treatment of bacterial pneumonia is selected by considering the age of the patient, the severity of the illness and the presence of underlying disease. Amoxycillin and doxycycline are suitable for many of the lower respiratory tract infections seen in general practice.


Vaccination helps prevent bronchopneumonia, mostly against influenza viruses, adenoviruses, measles, rubella, streptococcus pneumoniae, haemophilus influenzae, diphtheria, bacillus anthracis, chickenpox, and bordetella pertussis.


Deaths from lower respiratory infections per million persons in 2012
Disability-adjusted life year for lower respiratory infections per 100,000 inhabitants in 2004.[14]
  no data
  less than 100
  more than 7,000

In 2010, lower respiratory infections caused about 2.8 million deaths, down from 3.4 million in 1990.[15]

Society and culture

Lower respiratory tract infections place a considerable strain on the health budget and are generally more serious than upper respiratory infections.


  1. 1 2 3 4 Antibiotic Expert Group. Therapeutic guidelines: Antibiotic. 13th ed. North Melbourne: Therapeutic Guidelines; 2006.
  2. Global Burden of Disease Study 2013, Collaborators (22 August 2015). "Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.". Lancet (London, England). 386 (9995): 743–800. doi:10.1016/s0140-6736(15)60692-4. PMID 26063472.
  3. 1 2 GBD 2013 Mortality and Causes of Death, Collaborators (17 December 2014). "Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013.". Lancet. 385: 117–71. doi:10.1016/S0140-6736(14)61682-2. PMC 4340604Freely accessible. PMID 25530442.
  4. 1 2 BJM Clinical evidence: London, United Kingdom: BMJ, 1999-2007 : Accessed 29/3/7 at : http://0-www.clinicalevidence.com.library.newcastle.edu.au/ceweb/index.jsp.
  5. Therapeutic guidelines : respiratory. 2nd ed: North Melbourne : Therapeutic Guidelines Limited, 2000.
  6. 1 2 3 Becker LA, Hom J, Villasis-Keever M, van der Wouden JC (2011). Becker LA, ed. "Beta2-agonists for acute bronchitis". Cochrane Database Syst Rev (7): CD001726. doi:10.1002/14651858.CD001726.pub4. PMID 21735384.
  7. 1 2 Integrated pharmacology / Clive Page ... [et al.]. 2nd ed: Edinburgh : Mosby, 2002.
  8. Fahey T SJ, Becker L, Glazier R. . Antibiotics for acute bronchitis. Cochrane Database of Systematic Reviews 2004, Issue 4. Art. No.: CD000245. doi:10.1002/14651858.CD000245.pub2.
  9. 1 2 Bjerre LM, Verheij TJ, Kochen MM (2009). Bjerre LM, ed. "Antibiotics for community acquired pneumonia in adult outpatients". Cochrane Database Syst Rev (4): CD002109. doi:10.1002/14651858.CD002109.pub3. PMID 19821292.
  10. 1 2 Moberley S, Holden J, Tatham DP, Andrews RM (2013). Moberley S, ed. "Vaccines for preventing pneumococcal infection in adults". Cochrane Database Syst Rev. 1: CD000422. doi:10.1002/14651858.CD000422.pub3. PMID 23440780.
  11. Kabra SK, Lodha R, Pandey RM (2010). Kabra SK, ed. "Antibiotics for community-acquired pneumonia in children". Cochrane Database Syst Rev (3): CD004874. doi:10.1002/14651858.CD004874.pub3. PMID 20238334.
  12. The Merck manual of diagnosis and therapy. 17th ed / Mark H. Beers and Robert Berkow ed: Whitehouse Station, N.J. : Merck Research Laboratories, 1999.
  13. eTG complete [electronic resource] "?".
  14. "Mortality and Burden of Disease Estimates for WHO Member States in 2002" (xls). World Health Organization. 2002.
  15. Lozano, R; Naghavi, M; Foreman, K; Lim, S; Shibuya, K; Aboyans, V; Abraham, J; Adair, T; Aggarwal, R; Ahn, SY; Alvarado, M; Anderson, HR; Anderson, LM; Andrews, KG; Atkinson, C; Baddour, LM; Barker-Collo, S; Bartels, DH; Bell, ML; Benjamin, EJ; Bennett, D; Bhalla, K; Bikbov, B; Bin Abdulhak, A; Birbeck, G; Blyth, F; Bolliger, I; Boufous, S; Bucello, C; et al. (Dec 15, 2012). "Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010". Lancet. 380 (9859): 2095–128. doi:10.1016/S0140-6736(12)61728-0. PMID 23245604.
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