Listeriosis laboratory tests: Difference between revisions
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{{CMG}}; {{AE}} {{JS}} | {{CMG}}; {{AE}} {{JS}} | ||
==Overview== | ==Overview== | ||
For symptomatic patients, diagnosis is confirmed only after isolation of ''Listeria monocytogenes'' from a normally sterile site, such as [[blood]], [[spinal fluid]] (in the setting of [[nervous system]] involvement), or [[amniotic fluid]]/[[placenta]] (in the setting of [[pregnancy]]). | For symptomatic patients, diagnosis is confirmed only after isolation of ''Listeria monocytogenes'' from a normally sterile site, such as [[blood]], [[spinal fluid]] (in the setting of [[nervous system]] involvement), or [[amniotic fluid]]/[[placenta]] (in the setting of [[pregnancy]]). Cultures from non-sterile sites, such as stool samples, are not recommended (1-15% carriage rate) but may still be useful in gastroenteritis with high suspicion of listeriosis. ''Listeria monocytogenes'' may be isolated readily on routine media. Since ''Listeria'' is an intracellular organism, only 1/3 of cultures yield positive Gram-stains. Selective enrichment media improve rates of isolation from contaminated specimens. The cultures typically require 1-2 days for growth. A negative culture does not rule out infection in the presence of strong clinical suspicion. Serological tests are unreliable and currently not recommended. Laboratory testing on asymptomatic patients (including high-risk asymptomatic patients) is not recommended.<ref name=CDC>{{cite web | title = Listeria | url = http://www.cdc.gov/listeria/diagnosis.html }}</ref> | ||
==Laboratory Tests== | ==Laboratory Tests== | ||
=== | ''The gold standard for the diagnosis of listeriosis is culture from sterile sites.'' | ||
* [[ | |||
* Identification is enhanced if the primary cultures are | ===Culture=== | ||
*Diagnosis of listeriosis is made by culturing ''Listeria'' from sterile sites (e.g. blood, spinal fluid). | |||
*Cultures from non-sterile sites, such as stool culture or vaginal culture, are not helpful for the diagnosis of listeriosis (approximately 5% to 15% fecal carriage, especially among patients who receive [[PPI]] therapy).<ref name="pmid6701102">{{cite journal| author=Lennon D, Lewis B, Mantell C, Becroft D, Dove B, Farmer K et al.| title=Epidemic perinatal listeriosis. | journal=Pediatr Infect Dis | year= 1984 | volume= 3 | issue= 1 | pages= 30-4 | pmid=6701102 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6701102 }} </ref> | |||
*Gram-stain may yield positive results in approximately 1/3 of infected patients (''Listeria'' is an intracellular organism). | |||
* ''Listeria'' grows on media such as Mueller-Hinton agar. | |||
* Identification is enhanced if the primary cultures are performed on agar containing sheep blood given the characteristic small zone of [[hemolysis]] that can be observed around, and under the colonies. | |||
* Isolation can be enhanced if the tissue is kept at 4°C for some days before inoculation into bacteriologic media. | * Isolation can be enhanced if the tissue is kept at 4°C for some days before inoculation into bacteriologic media. | ||
* The [[motility]] at room temperature and [[hemolysin]] production are primary findings that help differentiate | * The [[motility]] at room temperature and [[hemolysin]] production are primary findings that help differentiate listeria from other organisms (e.g. coryneform bacteria). | ||
===Stool Cultures=== | ===Stool Cultures=== | ||
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*In cases of outbreaks of [[listeriosis]] or individual patients with suspected ''listerial'' [[gastroenteritis]], special selected media can be used. | *In cases of outbreaks of [[listeriosis]] or individual patients with suspected ''listerial'' [[gastroenteritis]], special selected media can be used. | ||
=== | ===Listeriolysin O Titers=== | ||
* | *Elevated titers of listeriolysin O titers may distinguish patients with active ''Listeria'' infections from those who are carriers of the organism. | ||
*The use of listeriolysin O for the diagnosis of listeriosis is still controversial.<ref name="pmid8972666">{{cite journal| author=Salamina G, Dalle Donne E, Niccolini A, Poda G, Cesaroni D, Bucci M et al.| title=A foodborne outbreak of gastroenteritis involving Listeria monocytogenes. | journal=Epidemiol Infect | year= 1996 | volume= 117 | issue= 3 | pages= 429-36 | pmid=8972666 | doi= | pmc=PMC2271639 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8972666 }} </ref><ref name="pmid8988887">{{cite journal| author=Dalton CB, Austin CC, Sobel J, Hayes PS, Bibb WF, Graves LM et al.| title=An outbreak of gastroenteritis and fever due to Listeria monocytogenes in milk. | journal=N Engl J Med | year= 1997 | volume= 336 | issue= 2 | pages= 100-5 | pmid=8988887 | doi=10.1056/NEJM199701093360204 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8988887 }} </ref> | |||
==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}} | ||
[[Category:Bacterial diseases]] | [[Category:Bacterial diseases]] | ||
[[Category:Disease]] | [[Category:Disease]] | ||
[[Category:Infectious disease]] | [[Category:Infectious disease]] | ||
Revision as of 15:26, 26 January 2016
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
For symptomatic patients, diagnosis is confirmed only after isolation of Listeria monocytogenes from a normally sterile site, such as blood, spinal fluid (in the setting of nervous system involvement), or amniotic fluid/placenta (in the setting of pregnancy). Cultures from non-sterile sites, such as stool samples, are not recommended (1-15% carriage rate) but may still be useful in gastroenteritis with high suspicion of listeriosis. Listeria monocytogenes may be isolated readily on routine media. Since Listeria is an intracellular organism, only 1/3 of cultures yield positive Gram-stains. Selective enrichment media improve rates of isolation from contaminated specimens. The cultures typically require 1-2 days for growth. A negative culture does not rule out infection in the presence of strong clinical suspicion. Serological tests are unreliable and currently not recommended. Laboratory testing on asymptomatic patients (including high-risk asymptomatic patients) is not recommended.[1]
Laboratory Tests
The gold standard for the diagnosis of listeriosis is culture from sterile sites.
Culture
- Diagnosis of listeriosis is made by culturing Listeria from sterile sites (e.g. blood, spinal fluid).
- Cultures from non-sterile sites, such as stool culture or vaginal culture, are not helpful for the diagnosis of listeriosis (approximately 5% to 15% fecal carriage, especially among patients who receive PPI therapy).[2]
- Gram-stain may yield positive results in approximately 1/3 of infected patients (Listeria is an intracellular organism).
- Listeria grows on media such as Mueller-Hinton agar.
- Identification is enhanced if the primary cultures are performed on agar containing sheep blood given the characteristic small zone of hemolysis that can be observed around, and under the colonies.
- Isolation can be enhanced if the tissue is kept at 4°C for some days before inoculation into bacteriologic media.
- The motility at room temperature and hemolysin production are primary findings that help differentiate listeria from other organisms (e.g. coryneform bacteria).
Stool Cultures
- Stool cultures are not indicated in systemic listeriosis patients because routine culture media for enteric pathogens are not appropriate for the growth of Listeria.
- In cases of outbreaks of listeriosis or individual patients with suspected listerial gastroenteritis, special selected media can be used.
Listeriolysin O Titers
- Elevated titers of listeriolysin O titers may distinguish patients with active Listeria infections from those who are carriers of the organism.
- The use of listeriolysin O for the diagnosis of listeriosis is still controversial.[3][4]
References
- ↑ "Listeria".
- ↑ Lennon D, Lewis B, Mantell C, Becroft D, Dove B, Farmer K; et al. (1984). "Epidemic perinatal listeriosis". Pediatr Infect Dis. 3 (1): 30–4. PMID 6701102.
- ↑ Salamina G, Dalle Donne E, Niccolini A, Poda G, Cesaroni D, Bucci M; et al. (1996). "A foodborne outbreak of gastroenteritis involving Listeria monocytogenes". Epidemiol Infect. 117 (3): 429–36. PMC 2271639. PMID 8972666.
- ↑ Dalton CB, Austin CC, Sobel J, Hayes PS, Bibb WF, Graves LM; et al. (1997). "An outbreak of gastroenteritis and fever due to Listeria monocytogenes in milk". N Engl J Med. 336 (2): 100–5. doi:10.1056/NEJM199701093360204. PMID 8988887.