Listeriosis
๐ Related Subjects:
| Listeriosis
๐ฆ About
- Listeria monocytogenes is a facultative intracellular, motile, Gram-positive bacillus.
- Primarily affects neonates ๐ถ and the immunocompromised ๐งโโ๏ธ.
- Notable for its ability to grow at low temperatures โ๏ธ (4โ8ยฐC).
- Infection can be associated with granuloma formation ๐งฉ.
๐ Source
- Spread via unpasteurised dairy ๐ง๐ฅ (e.g., soft cheeses).
- Also found in undercooked chicken ๐, pรขtรฉs, hot dogs ๐ญ, delicatessen meats, and fish ๐.
- Widely present in soil and water ๐ฑ๐ง.
โ ๏ธ Pathogenicity: Invasive Disease in the Immunocompromised
- At risk: pregnant ๐คฐ, HIV patients ๐งฌ, alcohol-dependent ๐ท, elderly ๐ต, neonates ๐ถ, and those with diabetes ๐ฌ.
- Patients on immunosuppressants ๐ (e.g., infliximab, renal transplant) are particularly vulnerable.
๐ค Clinical Features
- Gastroenteritis: Mild diarrhoea/vomiting in healthy hosts; some become asymptomatic carriers.
- Bacteraemia: Fever, malaise, myalgia.
- Pregnancy: Can cross the placenta โ miscarriage, stillbirth, or neonatal sepsis ๐จ.
- Neonates: Septicaemia or meningitis ๐ถ๐ง .
- Adults: Meningoencephalitis with ataxia; CSF glucose often normal.
๐งช Investigations
- Blood ๐ฉธ or CSF ๐ cultures โ organism isolation.
- CSF glucose: usually normal (key clue vs other bacterial meningitis).
- Blood agar โ beta-haemolysis ๐งซ.
- Catalase-positive โ
; hydrolyses aesculin.
- Characteristic tumbling motility ๐คน in broth at room temperature.
๐ Management
- First-line: Ampicillin + Gentamicin (synergistic therapy) ๐.
- Note: Intrinsically resistant to cephalosporins ๐ซ.
๐ซ Avoidance
- Pregnant and immunocompromised patients should avoid:
- Unpasteurised dairy ๐ง
- Undercooked meat ๐
- Pรขtรฉs and deli meats ๐ฅฉ
- Unwashed raw veg ๐ฅ