Listeria Monocytogenes Flashcards
Characteristic Listeria
Gram +ve rod,
arranged in V- or L-shaped
motile and tumbling movement
Classification Listeria
Aerobe and facultative anaerobes
Obligatory intracellular ✍️
β-hemolytic
Catalase +ve
Transmission Listeria
unpasteurized milk unpasteurized cheese, undercooked meat, and raw vegetables. animals and their feces
Virulence factors Listeria
- Internalin:
interact with E-cadherin, a receptor on epithelial cells, promoting phagocytosis into the epithelial cells.
- Listeriolysin O
lyses the membrane of the phagolysosome
Pathogenesis Listeria
فهمت الtoxin فهمت الpatho
بس
Listeria monocytogenes can move from cell to cell by means of actin rockets—filaments of actin polymerize and propel the bacteria through the membrane of one human cell
طالما انها داخل الخلية فما حتتقل الا بالد cell-mediated immunit
predisposes to Listeria افهمي افهمي
impaired cell-mediated immunity such as pregnancy, advanced age, AIDS, lymphoma, and organ transplantation
Disease Listeria
[1] Gastroenteritis
fever, headache, watery diarrhea
[2] Neonatal meningitis 3#
[3] Adult meningitis
Diagnosis of listeria
▪ Specimen collection: In gastroenteritis: stool In meningitis: CSF
▪ Microscopic examination: Gram +ve bacilli
▪ Culture: blood agar: colonies are small, gray with a narrow zone of β-hemolysis
▪ Biochemical test
- Catalase test: +ve
- Motility test:
differentiates Listeria (motile) from diphtheria (non-motile)
Treatment listeria
بصورة عامة ampicillin
➖➖➖➖➖
In gastroenteritis:
Self-limited rehydration. e.g., fluids, electrolytes no antimicrobial drugs are administered.
In neonatal meningitis: Ampicillin
In adult meningitis:
Combinations of ampicillin and gentamicin or ampicillin and trimethoprimsulfamethoxazole,
Prevention listeria
1.Limited unpasteurized milk products, and raw vegetables
- Trimethoprim-sulfamethoxazole
