Listeria monocytogenes
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Bacteria - Gram Positive
- Staph aureus: Overview
- Staph aureus: Presentation
- Methicillin-Resistant Staph aureus (MRSA)
- Staph saprophyticus
- Strep pneumoniae: Overview
- Strep pneumoniae: Presentation
- Strep viridans
- Strep pyogenes: Overview
- Strep pyogenes: Presentation
- Strep agalactiae
- Strep bovis
- Enterococcus
- Bacillus anthracis
- Bacillus cereus
- Clostridium tetani
- Clostridium perfringens
- Clostridium botulinum
- Clostridium difficile
- Corynebacterium diphtheriae
- Listeria monocytogenes
- Nocardia
- Actinomyces
Listeria monocytogenes
- Characteristics
- Gram + rod
- Facultative intracellular
- Grows well in cold temperatures (“cold-enrichment”)
- Can grow at refrigeration temperatures (4-10 degrees C)
- Tumbling motility under light microscopy
- Forms “rocket tails” via actin polymerization, which enhance intracellular movement and cell-to-cell spread
- Transmission
- Acquired by ingestion of unpasteurized dairy products and cold deli meats
- Listeria is found in GI tract and milk of cows
- Acquired by ingestion of unpasteurized dairy products and cold deli meats
- Presentation
- Infections occur in individuals with weak cellular immunity
- Neonates < 3 months old
- May be transmitted transplacentally or by vaginal transmission during birth
- Immunocompromised individuals
- e.g. HIV patients, organ transplant recipients, and individuals with certain malignancies.
- Elderly
- Pregnant women
- Neonates < 3 months old
- Meningitis
- CSF obtained via LP will demonstrate WBCs and gram-positive bacilli.
- Contrast w Neisseria meningitidis: gram stain would show gram-negative diplococci
- Febrile gastroenteritis
- Most often seen in healthy individuals
- Sepsis
- May present as spontaneous abortion in pregnant women
- Infections occur in individuals with weak cellular immunity
- Treatment
- Ampicillin
- Ampicillin is first-line for treatment of Listeria, which is resistant to cephalosporins.
- TMP-SMX (second line)
- Ampicillin