Bacteriology - Corynebacteriaceae, Listeria, Erysipelothrix, Bacillus

Corynebacteriaceae?

Gram-positive, club-shaped rod

- Non-spore forming

Cytoplasm: metachromatic granules -> seen w/ anylin blue

Most clinically relevant Corynebacteriaceae?

- C. diphtheriae (human is the only reservoir)

- C. ulcerans

- C. pseudotuberculosis (zoonotic infection)

- C. jeikeium

C. diphtheriae?

Main virulence factor: Exotoxin (diphtheriae toxin)

- Can inhibit protein synthesis

- Causes cell death

- Contributes to pseudomembrane formation

Transmission C. diphtheriae?

Respiratory droplets

Toxin effect - C. diphtheriae?

Pseudomembranous pharyngitis

- Can dislodge and suffocate patient

Systemic effect - C. diphtheriae?

Diphtheric polyneuropathy

- paresis of soft palate, and other cranial nerves - damage myelin fibres

Cardiomyopathy

- myocarditis, arrhythmias, block

Diagnosis - C. diphtheriae?

Swab sample

Tellur agar

. Black colonies

Loeffler medium

Elek test (detects exotoxin)

Prevention C. diphtheriae?

DPT vaccine

Treatment C. diphtheriae?

ANTITOXIN

Listeria?

Gram-postive, rod shaped

L. monocytogenes

Causes beta-hemolysis on blood agar

Catalase positive

Highly motile

Outside: flagella for motility

Inside cells: propelled around

Where can listeria be found?

It can grow between 1-45 degrees

Therefore: can be found in refrigerated food

(Soft cheeses)

Who is highly at risk of being infected by listeria?

Pregnant women (x20 higher risk)

- Advised to stay away from soft cheeses

Early trimester - infection:

- Early termination

Late trimester - infection:

- Diseases of the newborn

Neonatal meningitis? Listeria

Can be infected via pregnant mother

- Is the 3rd most common cause of meningitis in newborns (after group B streptococci and E.coli)

- Can also cause meningitis in adults over 60

Listeria infection in young, non-pregnant and immunocompetent person?

May be basically asymptomatic

- Mild flu-like symptoms

Treatment Listeria?

Standard emperic treatment of meningitis in adults:

- Vancomycin

- Ceftriaxone

Both Gr+ and Gr- bacteria are covered.

Treatment in elderly - listeria?

Ampicillin (to cover listeria infection)

What is Listeria resistant to?

3rd generation cephalosporins, like ceftriaxone

(går igjen i pastpapers)

Erysipelothrix?

Gram positive rod

- Microaerophilic

Clinical picture:

- Localized cutaneous infection

Transmission Erysipelothrix?

Turkey, pigs and other domestic animals

= Zoonotic infection

Transmitted through skin bites

Bacillus?

Gram-positive, rod-shaped bacteria

- They are lined in shapes - VERY uncharacteristic for rods

Important human pathogens of bacillus?

B. anthracis -> causes anthrax

B. cereus -> food poisoning

B. subtilis

B. anthracis - transmission?

Zoonotic infection

- Can also spread from human-to-human

Are bacillus encapsulated?

Yes

- They have unique capsule

They er built up of proteins, "poly-D-glutamate"

(not the regular polysaccharide)

What type of aerob is bacillus?

Obligate aerob

- Only survive in the presence of oxygen

Why is B anthracis able to survive in the mail?

Because it is a spore-forming bacteria

- Endospore formation

Hibernate in a state of minimal metabolic activity

- Highly resistant to temperature and chemicals

- Regarded as a biological warfare

Toxins of B. anthracis?

Edema factors

- Function as an adenylate cyclase

- Prevents phagocytosis

Lethal factor

- Exotoxin

- Tissue necrosis

Features of anthrax?

Cutaneous anthrax

- Redness and blisters

- Later: black, necrotic core

"Ring of fire"

Pulmonary anthrax

- "Wool sorter's disease"

- Spore get into wool of animal -> hide -> people handle wool and inhale it

- Can lead to hemorrhagic mediastinitis

Intestinal anthrax

- Extremely rare

Injections anthrax

- Infection deep in skin where needle was given

Treatment B. anthracis?

Fluoroquinolones