Lecture 8 Enterococci (Streptococci) and Bacillus

Question 1

1. Where are Enterococci sp. (alpha hemolytic Streptococci) typically found?
2. What is their pathogenic involvement? (i.e what diseases do they cause and where)

Answer 1

1. Intestinal tract, and mammary glands mainly
2. They are common causes of:
   
   1. Valvular endocarditis
   2. Mastitis
   3. Dental plaque

Question 2

Streptococcus pneumoniae is such a frequent cause of mortality in humans that it was given the title “Captain of the men death”. What type of infections does this bacteria cause to be so mortiferous?

Answer 2

Respiratory infections

Even with the advent of antimicrobial therapy, it still remains a leading cause of death in humans (40,000 per year). Age also is a factor for the cause of death as, people over 40 years of age have a 4 to 5 times greater incidence of clinical disease.

Question 3

List the common morphological features of bacteria which belong to the genus bacillus.

Answer 3

Gram positive

Large rods (1-2 X 3-8um)

Spore forming

Motile via flagella (except for B. anthracis)

Grow in chains

Question 4

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1. List the morphological features one would expect when culturing Bacillus anthracis.
2. Would the colonies be hemolytic or non-hemolytic?

Answer 4

1. Forms long chains in situ; are non-motile; capsule forming​
2. Colonies are non-hemolytic

Capsules will only be evident when the culture is grown in CO2 on bicarb. (or 50% serum) plates

Question 5

T or F

Bacillus anthracis spores are killed by phenol disinfectants and boiling for 20 min

Answer 5

False

Bacillus anthracis spores are resistant to phenol disinfectants and boiling for 20 min.

These spores can only be killed by formalin, autoclaving

Question 6

List the three types of toxins which are produced by Bacillus anthracis

Answer 6

Protective Antigen (PA)

Edema Factor (EF)

Lethal Factor (LF)

Question 7

How does the Bacillus anthracis toxin Protective Antigen (PA) work?

Answer 7

Protective Antigen(PA) acts as a binding unit for edema factor and lethal factor.

• MOA:
  
  • PA will attach to a host cell it will then undergo proteolytic seperation from B. anthracis
  • Once this occurs a portion of the PA remains bound to the cell and serves as a docking station for binding of either EF or LF.

Question 8

How does the Bacillus anthracis toxin Edema Factor (EF) work?

Answer 8

Edema Factor(EF) binding activates adenylate cyclase and dramatically interferes with cell function by halting cAMP conversion from ATP

Question 9

How does the Bacillus anthracis toxin Lethal Factor (LF) work?

Answer 9

• Lethal Factor (LF) will cleave the kinase (MAPK/ERK kinase) involved w/ signal transduction in CD4+ T-Lymphocytes & Fibroblasts.
  
  • In T-Cells this inhibits the IL-2 production and proliferative response.
    
    • Blocking critical functions in the regulation of immune reponses.
  • The cleavage of MAPK directly leads to the death of fibroblasts

Question 10

1. Bacillus anthracis is the only organism which we will talk about that contains what type of capsule?
2. Where are the genes located to create this type (the capsule) of virulence factor?

Answer 10

1. The poly-D-glutamic acid capsule
2. On the plasmid

The uniqueness of this capsule is a strong virulence factor because the immune system has not been exposed to this type of virulence factor and is not primed to handle.

Question 11

Describe the worldwide distribution of Bacillus anthracis.

(ie common geographical location and soil type)

Answer 11

• In tropics or subtropics
• Found in alkaline soils with high N content with alternating flooding and drying periods.

Question 12

Bacillus anthracis is common in discussions of bioterriorism. What are some of the ways people can get this disease?

Answer 12

Through inhalation (woolsorter’s disease; leads to fever, malaise, myalgia, & nonproductive cough)(Possible death if acute respiratory distress in 24 hrs)

Introduction into wounds (malignant carbuncle; most common)

Ingestion of infected carcasses

Question 13

If you come upon a case which you believe is possibly death from Ba**cillus anthracis what should you NOT do.

Answer 13

You should NOT preform a necropsy

Opening the carcass will aerosolize th organism and allow it to persist in the environment as well as possibly infect you.

Question 14

In vaccinating against Bacillus anthracis what toxin is needed to produce proper immunization?

Answer 14

The Protective Antigen (PA)

An avirulent nonencapsulated strain; used successfully

Question 15

How does one properly dispose of an animal carcass which is infected with Bacillus anthracis?

Answer 15

Burning or Deep burial in quick lime

Question 16

1. What antibiotics would one use in treating an animal with Bacillus anthracis?
2. What antibiotics for a human?

Answer 16

1. Penicillin, Tetracycline
2. Penicillin, Tetracycline, and ciprofloxacin

Detection early with aggressive treatment is vital

Question 17

1. Bacillus cereus has seven different toxins only three where covered in class name one?
2. What disease is common in humans which B. cereus causes?

Answer 17

1. Seven different toxins (only three where covered in class
   
   1. Emetic toxin
   2. Lethal toxin
   3. Cereolysin
2. Food poisoning
   
   1. also can cause Abscesses, bacteremia, cellulitis, osteomyelitis, and urinary tract infections in immunocompromised individuals

Question 18

What bacteria is a common insect pathogen. Forms parasporal crystals that are toxic to insects; which is used by some gardeners as a natural method to kill certain garden pests in lieu of using insecticides?

Answer 18

Bacillus thuringiensis