Listeria Monocytogenes Flashcards
What Foods are associated with Listeria Monocytogenes?
•Foods associated with this bacteria: *
–Soft cheeses
–Deli meats
–Cabbages (coleslaw)
–Unpasteurized milk products
The Largest Listeriosis outbreak (US) occured in 2011. The consumption of what fruit is associated with this outbreak?
canteloupe
Who are at high risk for serious infection?
•Those at high risk for severe infection→ weakened or immature immune system: *
–Developing fetus, newborn infants (via infected mother) *
–Older adults (65 yrs or older)
–Immunocompromised:
- Those with underlying medical conditions - cancer *
- pts on immunosuppressive therapy * (steroids, chemotherapy, radiation)
- Renal transplant recipients *
- HIV/AIDS, diabetes, alcoholism, liver or kidney disease
Facts about Listeria Monocytogenes:
- Small Gram positive rod
- Facultative Intracellular parasite
- Tumbling motility *
- Cold growth
–Grows at refrigeration temps *
What is the Reservoir of Listeria Monocytogenes?
•Reservoir:
–Animals (GI and genital tracts)
–Unpasteurized milk products
–Plants, soil
–Cold growth: soft cheeses, deli meats, cabbages (coleslaw), _hot dogs *_
How is Listeria Monocytogenes transmitted?
•Transmission:
–Foodborne *
_–Across the placenta (mother to fetus) *_
Pathogenesis of Listeria
- Intracellular pathogen (facultative)
- Attaches to intestinal epithelial cells and macrophages
→Secretes Listeriolysin-O*(hemolysin) allows escape from phagosome
→ replicates within cytoplasm
→ assembles actin-jet filament → jet motility *
–allows Listeria to spread from cytoplasm of one host cell to another host cell
- Predilection for placenta and central nervous system
- Antibodies to Listeria are ineffective
–since the bacterium is intracellular and moves from cell to cell while protected
–Cellular immunity imp. for clearance of Listeria *
•Individuals with impaired cellular immunity are at risk for severe infections *
Pathogenesis of Listeria Monocytogenes
Pathogenesis of Listeria (2)
Clinical Diseases of Listeria Monocytogenes
•Immunocompetent individuals
–May present with febrile gastroenteritis
–Some with no symptoms
•Pregnant women (immunocompetent) *
–Fever, fatigue, aches
–Fetal loss (miscarriage)
•Newborns *
–Septicemia and meningitis
•Immuno_compromised_ * individuals & Older adults (>65yrs)
–Septicemia and meningitis
•Immunocompetent individuals
–May present with febrile gastroenteritis
–Some with no symptoms
•Pregnant women (immunocompetent) *
–Fever, fatigue, aches
–Fetal loss (miscarriage)
•Newborns *
–Septicemia and meningitis
•Immunocompromised * individuals & Older adults (>65yrs)
–Septicemia and meningitis
Neonatal Listeriosis:
•Granulomatosis infantiseptica *
–Early - onset disease acquired transplacentally (in utero)
–Disseminated abscesses and granulomas *
–Baby will die unless treated quickly
–Also causes spontaneous abortion
•Meningitis * (or meningoencephalitis)
–Late - onset disease → occurs at 2-3 weeks
•Transmission during delivery
–Usually accompanied by septicemia
–Cannot be differentiated clinically from other neonatal meningitides
Lab Diagnosis of Listeriosis:
•Specimens: blood, CSF, amniotic fluid
•Gram stain of CSF *
–often negative, OR
–Intracellular & extracellular short GPRs (coccobacilli)
•Culture
–Cold enrichment *
•put specimen in nutrient broth in refrigerator
–Narrow zone of hemolysis
What characterstic motility does Listeria have at room temperature?
Tumbling Motility
Is Serology useful with this organism (Listeriosis)?
No.
Study of plasma serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies.
Treatment of Listeriosis:
•Treatment of Listeriosis * *
–Penicillin / ampicillin + gentamycin
–Cannot use cephalosporins (Listeria are naturally resistant)
Case Presentation of Listeria Monocytogenes
- A 2-week-old female is brought to the emergency room because of high fever and convulsions. She also has an extensive skin rash on her legs and trunk.
- PE: generalized hypotonia; extensive maculopapular skin rash; nuchal rigidity; involuntary flexion of hips when flexing neck (Brudzinski’s sign)
- Labs:
–CBC: neutrophilic leukocytosis
–LP: elevated CSF cell count, mostly neutrophils; elevated CSF protein; low CSF sugar
–Gram stain & culture
–Gram-positive, faculatative, intracellular, non-sporulating motile bacilli
- Purulent meningitis
- Bacterium provokes both acute suppurative reaction with neutrophilic infiltration and chronic granuloma formation with focal necrosis
treatment of listeria Monocytogenes (continued)
- Treatment: IV antibiotics – High dose Ampicillin *
- Discussion:
–Listeriosis is caused by Listeria monocytogenes. Bacteria infection in newborns may occur early (in utero) or later (drinking contaminated milk).
–May be rapidly fatal if disseminated. Also occurs in adults immunocpmpromised by disease (eg. Renal disease or HIV)
–Group B Streptococcus and E.coli are the other common causes of meningitis
