pathogenic micro study guide II final finished

1. What are the virulence factors of Staphylococcus aureus

- Capsule

- Toxin production

- Invasins

- Protein A

What is the difference between generalized and localized Staphylococcal scalded skin syndrome (SSSS)?

Generalized SSSS

• Toxin produced by local infections spreads throughout the body causing generalized scalding (blistering).

• No bacteria or pus present in blisters

• Disease is self-limited

Localized SSSS (Bullous impetigo)

• Localized spread of toxin around a colonized wound

• Individual usually has some immunity

o (prevents the widespread dissemination of the

toxin)

• Blistering is localized and may contain bacteria

2. What are the virulence factors of Streptococcus pyogenes

- M - Protein

- Tissue invasion

- Capsule

- Toxin production

Identify the pathogen most known to cause "Necrotizing Fasciitis" emphasizing the mechanisms by which this bacterial pathogen evades their host immune system?

- Group A Streptococcus

- Streptococcus pyogenes is a major cause of necrotizing fasciitis (flesh-eating disease)

-Host cell invasion: invade respiratory epithelial cells

- Tissue invasion

- Streptokinase (blood clot lysis)

3. What are the virulence factors of Streptococcus pneumoniae, and what are the factors by which this pathogen prevent its killing by phagocytes?

Capsule: prevents phagocyte uptake in the absence of

antibodies

Pneumococcal surface protein A (PspA) : prevents

complement opsonization

Pneumolysin: a toxin that kills phagocytes. It also kills

ciliated cells, which facilitates spread (i.e. invasion)

4. What are the virulence factors of Bacillus anthracis

- capsule,

- lethal toxin (LT),

- edema toxin (ET)

PA binds to a host anthrax toxin receptor (ATR)

LF or EF enter the cell through the PA.

Once internalized, the toxins are released

o LF causes cell death

o EF causes edema (swelling)

pX01 and pX02, respectively, are the only known virulence factors of Bacillus anthracis and are considered essential for full virulence.

What are the roles of plasmid px-01 ( Bacillus anthracis)

- regulation of protein functions in B. anthracis.

Protective antigen (PA)

Lethal factor (LF)

Edema factor (EF)

plasmid px-02 in the pathogenecity of this pathogen(Bacillus anthracis)?

- pXO2 plasmid encodes a polypeptide capsule

5. What are the virulence factors of Bacillus cereus,

- tripartite toxins hemolysin BL (HBL)

- nonhemolytic enterotoxin (NHE)

- cytotoxin K

what are the differences between the two clinical diseases this pathogen (Bacillus cereus,) causes?

Causes disease by toxin production

o Emetic toxin

- Heat stable

- Acid stable

- Causes emetic disease

Clinical diseases

• Emetic disease

o Vomiting

o 6 h incubation

o Associated with rice

o Enterotoxin

- Heat sensitive

- Acid sensitive

- Causes diarrheal disease

Diarrheal disease

o Diarrhea

o 12 h incubation

o Associated with meat and vegetables

6. What are the virulence factors of Listeria monocytogenes?

- Internalins enable L. monocytogenes to invade cells

- Listeriolysin O and Phospholipase C enable escape from the phagosome

- Act A

Listeriosis - fever, muscle aches, headache, stiff neck, confusion, loss of balance, and convulsions

what is the special characteristic of this bacterium (Listeria monocytogenes) when it comes to growth temperature?

- Can grow happily in refrigeration temperatures

- Ex. 4 degrees celsius

what unique way of movement this bacterium (Listeria monocytogenes) uses to move in and in between cells?

- ActA to polymerize host cell actin and enable it to move within and between cells

7. What are the virulence factors of Corynbacterium diphtheriae?

Diphtherial cord factor

- allows the bacteria to grow in rope-like lateral aggregates to colonize in the upper respiratory tract.

Diphtheria toxin

- Toxin expression is regulated by iron concentration. high concentration = toxin is not expressed

low concentration = toxin is expressed

Diphtheria - Serious infection of nose and throat (grey mattter in back)

And what is the structure and function of its exotoxin. (Corynbacterium diphtheria)

A-B subunit exotoxin.

The toxin functions by inhibiting protein synthesis.

B subunit enables the Active subunit to translocated the phagosome membrane and enter the cytoplasm.

Once inside the cytoplasm, the active subunit inhibits protein synthesis

What is the nature of the vaccine used to prevent the disease? (diphtheria)

Active immunization (vaccination)

- vaccine contains inactivated toxin

- immunogenic

- (Diphteria Pertussis Tetanus) given to children at same time

8. What are the virulence factors of Mycobacterium tuberculosis?

- Cells are engulfed by macrophages in the lung

- They avoid macrophage killing by preventing phagolysosome fusion

- TB cells replicate inside the phagosome

Describe in details "Granuloma" formation in the development of tuberculosis.

• Activated macrophages are unable to eliminate the infection

• A granuloma forms with a caseous center surrounded by macrophages and T-cells

• The caseous center has a cheesy consistency and there is no oxygen present.

The TB cells survive at the caseous center of the granuloma.

What stage of the disease that the microbe can be transmitted to other hosts?

It is only during this stage of active pulmonary

disease that TB is transmitted to other hosts

9. What are the virulence factors that Neisseria gonorrhoeae?

Pili - help N. gonorrhoeae attach to a host's mucosa surface. (Attachment and evasion)

Antigenic variation and phase variation enables evasion of antibody inactivation

Porin (Por) proteins

• Invasion

o Facilitate host cell entry

• Evasion

o Prevent phagolysosome fusion in neutrophil

IgA protease, a toxic protein that this bacterium uses to destroy Immunoglobulin A - IgA.

IgA is an immune system protein that's normally found in the mucosa secretions

- Lga helps with bacteria opsonization - meaning it tags the bacteria so that neutrophils can recognize and destroy them.

How they attach, invade and evade? (n. gonorrhoeae)

N. gonorrhoeae attaches to non-ciliated epithelial cells

• Pili and Opa proteins mediate attachment

• Porin proteins mediate invasion

• Cells multiply inside the phagosome

Releasing N. gonorrhoeae into the subepithelial tissues

• LOS initiates inflammation; attracting neutrophils to the site

• The neutrophils engulf the bacteria and survive

10. What are the general virulence factors of Enterobacteriaceae?

- Endotoxin

o Lipid A component of the LPS

• Capsule

o Protects against phagocytosis

• Phase variation

o Remember what phase variation is?

Type III secretion system (TTSS)

o A molecular syringe that allows virulence factors to be secreted from the bacterial cell to the host cell

What are the various types of pathogenic E. coli intestinal

Intestinal E. coli

- Gastroenteritis

Enteropathogenic (EPEC)

{Cause of infant diarrhea in developing countries

Enterohemorrhagic (EHEC)

• Most common gastrointestinal E. coli in developed countries

- Shiga toxin causes bloody diarrhea due to undercooked/raw/unpasteurized product.

Enterotoxigenic (ETEC)

• Leading cause of traveler's diarrhea

Enteroinvasive (EIEC)

- EIEC invade colonic epithelial cells

• Enteroaggregative (EAEC)

o Causes foodborne outbreaks in developing countries

What are the detailed steps by which Enteropathogenic E. coli (EPEC) forms attaching and effacing lesions in the host?

- Bundle forming pili initiate a lose attachment to the microvilli of the host cell

- Destruction of microvilli occurs (Effacement)

- TTSS injects (Tir) into the host cell

- Pedestal forms at the attachment

site

produce attaching and effacing lesions

11. What are the virulence factors of Yersinia pestis?

o The plague, The Black Death

o Systemic disease

• Usually enter following a flea bite

• Initially phagocytized by macrophages

• Replicate in macrophages and are eventually released

• Released cells are resistant to further phagocytosis

• Resistance to phagocytosis is mediated by:

o TTSS

inject cytotoxic proteins into host phagocyte cells

o An antiphagocytic protein capsule

Plasmid mediated

What are the virulence factors of Shigella?

Shigella is intracellular

• Attaches

o To intestinal epithelial cells

• Invades

o Initiates phagocytosis using TTSS

• Evades

o Escape the phagosome and replicate in the cytoplasm

• Toxin production

o S. dysenteriae produce an exotoxin called a Shiga toxin

• Transmitted between people by the fecal oral route

non-typhoidal Salmonella?

Non-Typhoidal Salmonella

• Cause Salmonellosis

- gastroenteritis

• Can infect a variety of animals and humans

- Can be shed for weeks after symptoms

resolve

12. What are the virulence factor of Vibrio cholerae?

o Causes cholera - an acute epidemic infectious disease

cholera toxin (CT) is encoded by:

- lysogenic bacteriophage (CTXΦ),

- (TCP), an essential colonization factor

What is the epidemiology of Cholera?

Waterborne - present in marine waters

o Numbers increase in warmer months

- Causes epidemics and pandemics

• Transmission is associated with

contaminated food and water

• Cholera is a problem in countries with

poor sanitation

What is the disease caused by V. parahaemolyticus?

V. parahaemolyticus disease

• Gastroenteritis

o Explosive watery diarrhea

And how one can get such an infection? (V. parahaemolyticus disease )

Disease associated with

o Seafood consumption (e.g. oysters

) o Exposure to contaminated seawater

Microaerophilic

- require oxygen at a level lower than that found of

the atmosphere

Name two bacterial pathogens that are both capnophilic and microaerophilic.

C. jejuni

o Causes intestinal disease

C. fetus

o Causes bacteremia

Which one of the two pathogens can survive well in the stomach? and why? (between c. jejuni and c. fetus)

C. jejuni seems to be well adapted to survive the acidic milieu of the human stomach during the passage to the lower intestinal tract, where infection is established.

C. fetus is associated with septicemia

Most camplyobacter cannot handle the acidity of the stomach however C.Jejuni can since causes infection in the intestines.

capnophilic

require high levels of carbon dioxide

typhoidal salmonella

Typhoidal

- enteric fever, a syndrome associated with fever and abdominal pain

- Only found in humans

- Salmonella can be shed for up to a year after symptoms resolve

What are the various types of pathogenic E. coli extra-intestinal?

Extraintestinal E. coli

- Neonatal meningitis

E. coli with the K-1 capsular antigen is associated with neonatal meningitis

- UTI

Siderophores also play an important role in UTIs

P pili enable uropathogenic E. coli to attach to the specific receptors in the urinary tract of susceptible individuals

Describe in details "Granuloma" formation and breakage in the development of tuberculosis.

The granuloma breaks down and the caseous center liquefies

o Bacteria begin to grow

• The liquefied caseous material is necrotic and

causes cavities to form in the lungs. These

cavities further support bacterial replication.

Corynbacterium diphtheriae? What disease does it cause?

Diphtheria - Serious infection of nose and throat (grey mattter in back)

generalized Staphylococcal scalded skin syndrome (SSSS)?

Generalized SSSS

• Toxin produced by local infections spreads throughout the body causing generalized scalding (blistering).

• No bacteria or pus present in blisters

• Disease is self-limited

localized Staphylococcal scalded skin syndrome (SSSS)?

Localized SSSS (Bullous impetigo)

• Localized spread of toxin around a colonized wound

• Individual usually has some immunity

o (prevents the widespread dissemination of the

toxin)

• Blistering is localized and may contain bacteria