Listeriosis other diagnostic studies
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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). Importantly, a negative culture does not rule out infection in the presence of strong clinical suspicion. Serological tests exist but they are unreliable and not recommended at the present time.
Other Laboratory Studies
CSF Analysis
CSF analysis may lead to the confirmation of listeriosis. Common findings include:
- Pleocytosis
- More than 25 lymphocytes in CSF differential count, without antibiotic therapy
- Moderately elevated CSF protein concentration with reduced CSF glucose concentration[1]
- Despite the name "monocytogenes", more that half the patients have increased levels of neutrophils in CSF.
- Gram stain of the CSF has very low sensitivity and even when organisms are seen, they may be misidentified. [2] Therefore, Listeria monocytogenes should always be considered when similar organisms are growing in blood or CSF cultures. The presumptive diagnosis of viral meningitis should also be carefully considered in immunocompromised, chronically ill, or elderly patients, presenting with acute meningitis and a negative Gram stain. In rhombencephalitis patients diagnosis is often delayed because CSF examination reveals only mild abnormalities.
- A polymerase chain reaction assay has been developed for the hly gene detection, which encodes for the listeriolysin O, in CSF cultures. However, despite a high specificity and more sensitivity, it is not commercially available yet.
Serodiagnosis
Diagnosis of listeriosis with antibodies for listeriolysin O can be useful among infected patients with noninvasive disease.[3]
References
- ↑ Mylonakis E, Hohmann EL, Calderwood SB (1998). "Central nervous system infection with Listeria monocytogenes. 33 years' experience at a general hospital and review of 776 episodes from the literature". Medicine (Baltimore). 77 (5): 313–36. PMID 9772921.
- ↑ Lavetter A, Leedom JM, Mathies AW, Ivler D, Wehrle PF (1971). "Meningitis due to Listeria monocytogenes. A review of 25 cases". N Engl J Med. 285 (11): 598–603. doi:10.1056/NEJM197109092851103. PMID 4998254.
- ↑ Mandell, Gerald L.; Bennett, John E. (John Eugene); Dolin, Raphael. (2010). Mandell, Douglas, and Bennett's principles and practice of infectious disease. Philadelphia, PA: Churchill Livingstone/Elsevier. ISBN 0-443-06839-9.