Corynebacteria, Listeria, Lactobacillus, Propionibacteria

C. diphtheriae oxygen use

Aerobic, facultative anaerobic

C. diptheriae characteristics

• Gram-positive bacilli - “Chinese letters”

• Growth on blood agar with tellurite

• Non-motile

• B-phage toxin producer

What is the natural reservoir for C. diptheriae?

Humans ONLY

How is C. diptheriae spread?

It is spread by droplets

Is C. diptheriae invasive?

No, it is non-invasive

C. diptheriae exotoxin

• B-segment binds to cell receptors

• A-segment is active, stops protein synthesis leading to cell death

What iron concentration induces C. diptheriae toxin?

Low iron concentration

What organs does C. diptheriae target?

Heart, nerves, and kidneys (myocarditis, demyelination, tubular necrosis)

Are large amounts of C. diptheriae requires for infection?

No, C. diptheriae is very potent

Diphtheria Symptoms

Pharyngeal necrosis, forming of pseudomembrane, aspiration leading to suffocations, Bull Neck

Diphtheria Prevention

Toxoid vaccination (inactivated toxin)

Diphtheria Treatment

Penicillin, erythromycin; antitoxin that deactivated unbound, circulating toxin

What species causes anthrax?

Bacillus anthracis

Who is the first anthrax disease attributed to?

Robert Koch

Who developed an attenuated, animal vaccine to anthrax?

Pasteur

Is Bacillus anthracis catalase positive or negative?

Bacillus anthracis is catalase positive

Air requirement of Bacillus anthracis

Bacillus anthracis is aerobic, or facultative anaerobic

Characteristics of Bacillus anthracis

• Gram-positive

• Non-motile

• Non-hemolytic

• Oval spores

Bacillus anthracis Endospores

• Allow survival and high resistance

• Germinate if inhaled/ingested to cause infection

Anthrax Virulence Factors

• pX02 encodes PGA capsule, inhibiting phagocytosis

• pX02 encodes EF, LF, PA

Edema Toxin

Combination of PA and EF, causing edema

Lethal Toxin

Combination of PA and LF, highly lethal

Most lethal pX01 combination of anthrax

PA + EF + LF

Protective Antigen (PA)

Binds to host cells, producing a protective antibody that allows EF and LF to bind

Which Anthrax factor is used in vaccines?

Protective Antigen

Edema Toxin Mechanism

Increase cAMP, interfering with cellular function

Lethal Toxin Mechanism

Cleaves MAP Kinase, interfering with signal transduction

Cutaneous Anthrax

Local inoculation, no pus just black scabs, swelling, erythema

Inhalational Anthrax

• “Woolsorter’s Disease”

• Rapid progession

• Pleural fluid, widened mediastinum

GI Anthrax

Ingestion of contaminated food, rare

CNS Anthrax

Meningitis, rapid, bioterrorism

Treatment of Anthrax

Antibiotics (cipro and doxy), antitoxins

Anthrax Vaccines

• BioThrax prevents and treats the infected

• Cyfendus prevents post-exposure, second adjuvant

Inhalational Anthrax Treatment

60 days of antimicrobials

Anthrax meningitis Treatment

3 antimicrobial combinationq

Systemic Anthrax Treatment

Antibiotics and antitoxin

Cutaneuous Anthrax Treatment

Antibiotic 3-7 days

Listeria monocytogenes Characteristics

• Gram-positive bacilli

• Catalase positive

• B-hemolytic

• Obligate intracellular

Who is at highest risk for listeria?

Pregnancy, high frequency and dangerous to neonate

What system does Listeria primarily affect?

CNS and placenta

Motility of Listeria

• Tumbling motility to escape

• Jet (actin-tail) to leave macrophage

Listeria pathogenesis

• Intracellular replication in macrophages

• Listeriolysin secretion to escape phagosome

• ActA protein to surf on Actin tail

Listeria Prevention

• Pasteurization - can survive in freezers and multiply in fridge

• Washing raw veggies

• Separate uncooked meats

How do humans acquire Listeria?

Animal (Zoonotic)

Food Products associated with Listeria

Milk, soft cheese, milk products

Listeria Syndromes

• Meningitis Encephalitis

• Bacteremia

• Placental/fetal disease

Lactobacillus oxygen requirement

Lactobacillus if facultative anaerobic (microaerophilic)

Lactobacillus Characteristics

• Gram-positive bacilli

• Lactose → Lactic Acid converters

• Dental Caries

L. kimchii

Associated with kimchii

L. acidophilus

Found in yogurt and cheese

L. brevis, L. lindneri, L. casei

Beer spoilage species

L. crispatus, L. gasseri, L. jensenii, L. iners

Vaginal flora species, keep pH low to prevent yeast

Unique Function of Lactobacilli

Sourdough starter (symbiosis between yeast and Lactobacilli)

Propionibacteria Metabolism

Synthesis of propionic acid

What condition is caused by Propionibacteria?

Acne: keratinization, sebum, proliferation, inflammation

Treatment of Propionibacterial Acne

Topicals, oral antibiotics (iso

Propionibacterium freudenreichii

Produce CO2 from fermentation to make swiss cheese, along with L. helveticus (amino acid)