Listeriosis is a gram-positive bacterial infection that primarily affects neonates, pregnant women, adults over 45 to 50 years of age, and immunocompromised people.
It is mainly a food-borne disease. Prevention consists of hand hygiene, cooking food well, and avoiding unwashed and leftover food.
Outbreaks have been reported worldwide, with the reported source of contamination including cantaloupe melons, frozen vegetables, and chilled pork.
Bacteraemia, sepsis, meningitis, encephalitis, brain abscess, endocarditis, and gastroenteritis are the most common clinical manifestations.
Cultures from clinically sterile sites and serological tests are the keys for laboratory diagnosis.
Ampicillin is the preferred drug for initial treatment for systemic (non-gastroenteritic) manifestations. Gastroenteritis alone is usually self-limiting.
Listeriosis is a food-borne infection caused by a motile, non-spore-forming, gram-positive bacillus. Its incidence is relatively low in the general population.
History and exam
Key diagnostic factors
- presence of risk factors
- altered mental status
Other diagnostic factors
- diarrhoea and abdominal pain
- generalised malaise
- flu-like symptoms in pregnancy
- poor feeding (neonates)
- cranial nerve deficits
- cerebellar signs
- focal neurological signs
- intra-partum fever
- bleeding diathesis with haemorrhage
- cardiac murmur
- exposure to contaminated food
- age >45-50 years
- immunocompromised states
- impaired stomach acidification
1st investigations to order
- urine pregnancy test
- blood cultures
- brain MRI
- brain CT
- cerebrospinal fluid (CSF) analysis
Investigations to consider
- prothrombin time (PT) and PTT
- placenta and amniotic fluid culture
- cervical swab culture
- meconium Gram stain and culture
- Listeria serology
- food analysis
- stool culture
- polymerase chain reaction of blood
- other stool analyses
- meningitis/encephalitis panel
systemic infection: not gastroenteritis, not meningitis/meningoencephalitis
Petros M. Karsaliakos, MD, FRCP, MSc
Honorary Clinical Senior Lecturer
Consultant in General Medicine
Queen Elizabeth University Hospital
PMK declares that he has no competing interests.
Eleftherios Mylonakis, MD, PhD, FIDSA, FAAM
Charles C.J. Carpenter Professor of Infectious Disease
Chief, Infectious Diseases Division
Rhode Island Hospital and The Miriam Hospital
Alpert Medical School of Brown University
Assistant Dean for Outpatient Investigations
Professor of Molecular Microbiology and Immunology
EM is an author of several references cited in this topic.
Josiah D. Rich, MD, MPH
Professor of Medicine and Community Health
JDR declares that he has no competing interests.
Alistair Leonord, MBChB, BSc, MRCPath, MD, DTM&H
Infection and Immunity
Southern General Hospital
AL declares that he has no competing interests.
- Other bacterial meningitides
- Other brain abscesses
- Viral gastroenteritis
- Listeria (Listeriosis)
- ACOG Committee Opinion No. 614: Management of pregnant women with presumptive exposure to Listeria monocytogenes
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