Corynebacterium and Listeria and Erysipelothix pathogenicity

1. GRAM POSITIVE NON-SPORE
FORMING RODS
SAMIRA FATTAH HAMID
Ph.D. Medical Bacteriology
College of Health Sciences
Hawler Medical University

2. • GENUS :CORYNEBACTERIA
• GENUS: LISTERIA
• GENUS : ERYSIPELOTHRIX

3. GENUS CORYNEBACTERIA
Medically important species:
• Corynebacterium diphtheriae

4. Corynebacterium diphtheriae
Characteristics:
• Gram-positive rods
• non-spore forming
• non-capsulated
• non-motile
• aerobic or facultative anaerobic
• Possess metachromatic granules that stores inorganic phosphate, it looks
like irregular swelling at one end that give them the “club-shaped”
appearance

5. • The bacteria group together in characteristic way forming V,L , W
shapes, so called Chinese-character arrangement
Corynebacterium diphtheriae

6. It has three strains named as:
• gravis
• intermedius
• mitis
based on growth characteristics (such as colony morphology ,
biochemical reactions) and severity of disease produced by
infections.
All toxigenic strains produce exotoxin and are capable of colonizing
the throat.
Corynebacterium diphtheriae

7. Diphtheria toxin
• Extracellular toxin
Diphtheria toxin consists of two functionally distinct fragments:
A and B.
whereby B stands for binding to receptors of target cells and A stands for
toxic activity.
Fragment B facilitates movement of Fragment A into the host cell
cytoplasm
Fragment A inhibits polypeptide chain elongation factor EF-2 and protein
synthesis arrest.
Corynebacterium diphtheriae

9. Pathogenesis and clinical features:
• Infection of the mucosa of tonsils, pharynx and nose (wounds and skin
lesions can also be infected). The pathogens invade the host through these
portals, reproduce, and produce toxin, resulting in local cell damage.
• regional lymph nodes enlargement in the neck.
• spread by droplets or by contact.
The inflammatory reaction leads to collection of a grayish-white
exudate, the matrix of the “diphtherial pseudomembrane”
consisting of fibrin, dead granulocytes, and necrotic epithelial
cells.
Any attempt to remove the pseudomembrane
exposes and tears the capillaries and thus results in bleeding.
Corynebacterium diphtheriae

10. It clinically manifests with:
• low-grade fever
• sore throat
• suffocation (due to obstruction by upper respiratory
tract pseudomembrane formation)
• Arrhythmia
• difficulty of vision and swallowing
• Difficulty in upper and lower extremities movement.
Corynebacterium diphtheriae
Pathogenesis and clinical features:

11. Treatment
• Penicillin, Macrolides inhibit the growth of diphtheria bacilli
and arrest toxin production.
• administration of antitoxin.
Corynebacterium diphtheriae

12. GENUS: LISTERIA
Most important species:
• Listeria monocytogenes

13. General characteristics:
• Gram positive rods
• Non - sporulating
• Motile
• facultative anaerobe
• Catalase positive
• It can survive at refrigerator temperatures (4°C), under conditions of low
pH and high salt conditions. that make it an important foodborne
pathogen.
Listeria monocytogenes

14. Antigenic structure:
• Listreriolysin ( hemolysin) toxin.
• There are 13 known serovars based on O (somatic) and H (flagellar)
antigens.
• Serotype 4b causes most of the foodborne outbreaks
Listeria monocytogenes

15. Pathogenesis and clinical features:
• Transmitted to humans through ingestion of contaminated food.
• Bacteria inter epithelial cell with the help of cell wall surface protein called
internalins A and B. Organism start to proliferate, then listeria are released
and the cycle begins again.
Listeria monocytogenes
A person with listeriosis usually
experiences:
 Fever
 chills
 Headache
 myalgia
 Abdominal pain
 diarrhea.

16. Perinatal human listeriosis.
• Early onset syndrome (granulomatosis infantiseptica) is the result
of infection in utero when listeria crosses placenta. Death may
occur before or after delivery.
• The late-onset syndrome causes the development of meningitis
between birth and the third week of life; newborn may become
infected during or after delivery. It is often caused by serotype 4b.
Listeria monocytogenes
Pathogenesis and clinical features:

17. Treatment
• Ampicillin
• erythromycin
• intravenous trimethoprim–sulfamethoxazole.
Listeria monocytogenes

18. GENUS : ERYSIPELOTHRIX
Most important species:
Erysipelothrix rhusiopathiae

19. General characteristics:
• appear singly or in short chains.
• non-motile
• Non-sporulating
• facultative anaerobic rods
• causes disease in domestic swine,
turkeys, ducks, and sheep
• Swine is major reservoir
Erysipelothrix rhusiopathiae

20. Pathogenicity and clinical features:
• The most common E. rhusiopathiae infection in humans is called
erysipeloid. It usually occurs on the fingers (called seal finger and whale
finger).
• Persons at greatest risk are fishermen, fish handlers, abattoir workers,
butchers, and others who have contact with animal products.
• After 2–7 days incubation, pain, which can be severe, and swelling occur.
• The lesion is raised, well circumscribed, and violaceous in color. Pus is
usually not present at the infection site, which helps differentiate it from
Staphylococcal and Streptococcal skin infections.
Erysipelothrix rhusiopathiae

21. • it can resolve without treatment after 3–4
weeks or more rapidly with antibiotic
treatment.
• Additional clinical forms of infection is
bacteremia with or without endocarditis.
Erysipelothrix rhusiopathiae
Pathogenicity and clinical features:

22. Treatment
• Penicillin G - for severe infections.
Erysipelothrix rhusiopathiae