Open main menu

Lower respiratory tract infection

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.

Lower respiratory tract infection
Illu conducting passages.svg
Conducting passages
SpecialtyPulmonology Edit this on Wikidata
Frequency291 million (2015)[1]
Deaths2.74 million (2015)[2]

There are a number of symptoms that are characteristic of lower respiratory tract infections. The two most common are bronchitis and edema.[3] 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 2015 there were about 291 million cases.[1] These resulted in 2.74 million deaths down from 3.4 million deaths in 1990.[4][2] This was 4.8% of all deaths in 2013.[4]

Bronchitis describes the swelling or inflammation of the[5] 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.[3] It affects over 40 adults per 1000 each year and consists of transient inflammation of the major bronchi and trachea.[6] Most often it is caused by viral infection and hence antibiotic therapy is not indicated in immunocompetent individuals.[7][5] 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.[8][5] 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.[6][9] 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.[5]

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.[3] Antibiotics have only been shown to be effective if all three of the following symptoms are present: increased dyspnea, 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.[3]



Pneumonia occurs in a variety of situations and treatment must vary according to the situation.[8] 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.[10][11] The most common treatment is antibiotics and these vary in their adverse effects and their effectiveness.[10][12] Pneumonia is also the leading cause of death in children less than five years of age in low income countries.[12] The most common cause of pneumonia is pneumococcal bacteria, Streptococcus pneumoniae accounts for 2/3 of bacteremic pneumonias.[13] This is a dangerous type of lung infection with a mortality rate of around 25%.[11] 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.[14]

Other causesEdit

Deaths from lower respiratory infections per million persons in 2012
Disability-adjusted life year for lower respiratory infections per 100,000 inhabitants in 2004.[15]
  no data
  less than 100
  more than 7,000

Typical Bacterial Infections:

Atypical Bacterial Infections:

Parasitic infections:

Viral infections:

Aspiration pneumonia


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.[16] The indications for treatment are increased dyspnoea, and an increase in the volume or purulence of the sputum.[17] 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. Evidence shows that procalcitonin (a blood marker for bacterial infections) is a useful method in guiding the initiation and duration of antibiotic treatment.[18] Amoxicillin and doxycycline are suitable for many of the lower respiratory tract infections seen in general practice.[16]



Lower respiratory infectious disease is the fifth-leading cause of death and the combined leading infectious cause of death, being responsible for 2·74 million deaths worldwide.[20] This is generally similar to estimates in the 2010 Global Burden of Disease study.[21] This total only accounts for Streptococcus pneumoniae and Haemophilus Influenzae infections and does not account for atypical or nosocomial causes of lower respiratory disease, therefore underestimating total disease burden.

Society and cultureEdit

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

Workplace burdens arise from the acquisition of a lower respiratory tract infection, with factors such as total per person expenditures and total medical service utilisation demonstrated as greater among individuals experiencing a lower respiratory tract infection.[22]

Pan-national data collection indicates that childhood nutrition plays a significant role in determining the acquisition of a lower respiratory tract infection, with the promotion of the implementation of nutrition program, and policy guidelines in affected countries.[20]


  1. ^ a b GBD 2015 Disease Injury Incidence Prevalence Collaborators (October 2016). "Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015". Lancet. 388 (10053): 1545–1602. doi:10.1016/S0140-6736(16)31678-6. PMC 5055577. PMID 27733282.
  2. ^ a b GBD 2015 Mortality Causes of Death Collaborators (October 2016). "Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015". Lancet. 388 (10053): 1459–1544. doi:10.1016/s0140-6736(16)31012-1. PMC 5388903. PMID 27733281.
  3. ^ a b c d Antibiotic Expert Group. Therapeutic guidelines: Antibiotic. 13th ed. North Melbourne: Therapeutic Guidelines; 2006.
  4. ^ a b GBD 2013 Mortality Causes of Death Collaborators (January 2015). "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" (PDF). Lancet. 385 (9963): 117–71. doi:10.1016/S0140-6736(14)61682-2. PMC 4340604. PMID 25530442.
  5. ^ a b c d Becker LA, Hom J, Villasis-Keever M, van der Wouden JC (September 2015). "Beta2-agonists for acute cough or a clinical diagnosis of acute bronchitis". The Cochrane Database of Systematic Reviews (9): CD001726. doi:10.1002/14651858.CD001726.pub5. PMID 26333656.
  6. ^ a b Wark P (July 2015). "Bronchitis (acute)". BMJ Clinical Evidence. 2015. PMC 4505629. PMID 26186368.
  7. ^ Therapeutic guidelines : respiratory. 2nd ed: North Melbourne : Therapeutic Guidelines Limited, 2000.[page needed]
  8. ^ a b Integrated pharmacology / Clive Page ... [et al.]. 2nd ed: Edinburgh : Mosby, 2002.[page needed]
  9. ^ Smith, SM; Fahey, T; Smucny, J; Becker, LA (1 March 2014). "Antibiotics for acute bronchitis". The Cochrane Database of Systematic Reviews (3): CD000245. doi:10.1002/14651858.CD000245.pub3. PMID 24585130.
  10. ^ a b Pakhale S, Mulpuru S, Verheij TJ, Kochen MM, Rohde GG, Bjerre LM (October 2014). "Antibiotics for community-acquired pneumonia in adult outpatients". The Cochrane Database of Systematic Reviews (10): CD002109. doi:10.1002/14651858.CD002109.pub4. PMID 25300166.
  11. ^ a b Moberley S, Holden J, Tatham DP, Andrews RM (January 2013). "Vaccines for preventing pneumococcal infection in adults". The Cochrane Database of Systematic Reviews (1): CD000422. doi:10.1002/14651858.CD000422.pub3. PMID 23440780.
  12. ^ a b Lodha R, Kabra SK, Pandey RM (June 2013). "Antibiotics for community-acquired pneumonia in children". The Cochrane Database of Systematic Reviews (6): CD004874. doi:10.1002/14651858.CD004874.pub4. PMID 23733365.
  13. ^ The Merck manual of diagnosis and therapy. 17th ed / Mark H. Beers and Robert Berkow ed: Whitehouse Station, N.J. : Merck Research Laboratories, 1999.[page needed]
  14. ^ Kumar Pius, Prince Sree; Alexis, Anitha; P, Suresh Kumar; Ganesan, Manivel (2017). "Diagnosis of Sputum Culture Positive Organisms and Their Antimicrobial Sensitivity Profile in a Tertiary Care Centre- Kanyakumari". Journal of Evidence Based Medicine and Healthcare. 4 (4): 168–171. doi:10.18410/jebmh/2017/33.
  15. ^ "Mortality and Burden of Disease Estimates for WHO Member States in 2002" (xls). World Health Organization. 2002.
  16. ^ a b Ball P, Baquero F, Cars O, File T, Garau J, Klugman K, Low DE, Rubinstein E, Wise R (January 2002). "Antibiotic therapy of community respiratory tract infections: strategies for optimal outcomes and minimized resistance emergence". The Journal of Antimicrobial Chemotherapy. 49 (1): 31–40. doi:10.1093/jac/49.1.31. PMID 11751764.
  17. ^ Woodhead M, Blasi F, Ewig S, Huchon G, Ieven M, Leven M, Ortqvist A, Schaberg T, Torres A, van der Heijden G, Verheij TJ (December 2005). "Guidelines for the management of adult lower respiratory tract infections". The European Respiratory Journal. 26 (6): 1138–80. doi:10.1183/09031936.05.00055705. PMID 16319346.
  18. ^ Schuetz, Philipp; Wirz, Yannick; Sager, Ramon; Christ-Crain, Mirjam; Stolz, Daiana; Tamm, Michael; Bouadma, Lila; Luyt, Charles E.; Wolff, Michel (12 October 2017). "Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections". The Cochrane Database of Systematic Reviews. 10: CD007498. doi:10.1002/14651858.CD007498.pub3. ISSN 1469-493X. PMID 29025194.
  19. ^ Woodhead M, Blasi F, Ewig S, Garau J, Huchon G, Ieven M, Ortqvist A, Schaberg T, Torres A, van der Heijden G, Read R, Verheij TJ (November 2011). "Guidelines for the management of adult lower respiratory tract infections--full version". Clinical Microbiology and Infection. 17 Suppl 6: E1–59. doi:10.1111/j.1469-0691.2011.03672.x. PMID 21951385.
  20. ^ a b GBD 2015 LRI Collaborators (November 2017). "Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015". The Lancet. Infectious Diseases. 17 (11): 1133–1161. doi:10.1016/S1473-3099(17)30396-1. PMC 5666185. PMID 28843578.
  21. ^ 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. (December 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.
  22. ^ Chen Y, Shan X, Zhao J, Han X, Tian S, Chen F, Su X, Sun Y, Huang L, Grundmann H, Wang H, Han L (November 2017). "Predicting nosocomial lower respiratory tract infections by a risk index based system". Scientific Reports. 7 (1): 15933. doi:10.1038/s41598-017-15765-z. PMC 5698311. PMID 29162852.

External linksEdit