From Citizendium
Jump to navigation Jump to search
This article is a stub and thus not approved.
Main Article
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
This editable Main Article is under development and subject to a disclaimer.

Infection happens when one organism invades (infects) the body of another, unwitting and usually much larger organism, and this results in harm to the "host" organism. Organisms that can cause infection include bacteria, fungi, viruses and parasites. The type and severity of infections range greatly, from a mere annoyance or embarrassing condition, such as a fungus under the nail, which one can live with for years, to a severe condition or life-threatening disease. Some infections are of short duration and go away of their own accord or with simple remedies, such as the common cold or thrush on the tongue or vaginal yeast infections.

Human beings often speak of being "attacked" by an invading organism, because that is how we perceive the infection, especially when it causes us illness or pain. In reality, such organisms are simply seeking hosts on which to feed or in which to complete their own life cycles.


Triggering receptor expressed on myeloid cells-1 (TREM-1) may be the most accurate serum biomarker for diagnosing infection.[1][2]

Procalcitonin has been use in various diagnostic roles: Prediction of mortality in community-acquired pneumonia:[3]

  • Sensitivity 35%
  • Specificity 92%

Diagnosis of bacteremia (according to a systematic review)[4]

  • Sensitivity 76%
  • Specificity 70%

Diagnosis of bacteremia in the elderly:[5]

  • Sensitivity 96%
  • Specificity 68%


  1. Su L, Han B, Liu C, Liang L, Jiang Z, Deng J et al. (2012). "Value of soluble TREM-1, procalcitonin, and C-reactive protein serum levels as biomarkers for detecting bacteremia among sepsis patients with new fever in intensive care units: a prospective cohort study.". BMC Infect Dis 12: 157. DOI:10.1186/1471-2334-12-157. PMID 22809118. PMC PMC3426475. Research Blogging.
  2. Gibot S, Kolopp-Sarda MN, Béné MC, Cravoisy A, Levy B, Faure GC et al. (2004). "Plasma level of a triggering receptor expressed on myeloid cells-1: its diagnostic accuracy in patients with suspected sepsis.". Ann Intern Med 141 (1): 9-15. PMID 15238365. [e]
  3. Huang DT, Weissfeld LA, Kellum JA, Yealy DM, Kong L, Martino M et al. (2008). "Risk prediction with procalcitonin and clinical rules in community-acquired pneumonia.". Ann Emerg Med 52 (1): 48-58.e2. DOI:10.1016/j.annemergmed.2008.01.003. PMID 18342993. PMC PMC2775454. Research Blogging.
  4. Jones AE, Fiechtl JF, Brown MD, Ballew JJ, Kline JA (2007). "Procalcitonin test in the diagnosis of bacteremia: a meta-analysis.". Ann Emerg Med 50 (1): 34-41. DOI:10.1016/j.annemergmed.2006.10.020. PMID 17161501. Research Blogging.
  5. Lai CC, Chen SY, Wang CY, Wang JY, Su CP, Liao CH et al. (2010). "Diagnostic value of procalcitonin for bacterial infection in elderly patients in the emergency department.". J Am Geriatr Soc 58 (3): 518-22. DOI:10.1111/j.1532-5415.2010.02730.x. PMID 20163483. Research Blogging.