GRAM POSITIVE RODS. PART 1

Question 1

Mention 4 medically important gram positive rods

Answer 1

1. Bacillus
2. Clostridium
3. Corynebacterium
4. Listeria

Question 2

which medically important gram positive rods forms spores

Answer 2

1. Bacillus
2. Clostridium

Question 3

which medically important gram positive rods are non spore forming

Answer 3

1. Corynebacterium
2. Listeria

Question 4

Mention two (2) medically important bacillus species

Answer 4

1. Bacillus anthracis
2. Bacillus cereus

Question 5

What disease is caused by bacillus anthracis

Answer 5

Anthrax

Question 6

Mention the main forms in which human anthrax manifests

Answer 6

1. Cutaneous
2. Pulmonary (inhalation)
3. Gastrointestinal

Question 7

explain the morphology of bacillus anthracis

Answer 7

B. anthracis is a large gram-positive rod with square ends frequently found in chains

Question 8

what are the 2 characteristics of bacillus anthracis

Answer 8

1. • Its antiphagocytic capsule is composed of D-glutamate (capsules of other bacteria are polysaccharides)
2. It is nonmotile

Question 9

How do spores of the anthrax organism persist in the environment?

Answer 9

Anthrax spores can persist in soil for years

Question 10

What causes cutaneous anthrax infections?

Answer 10

Cutaneous anthrax infections occur when there is trauma to the skin (e.g., cuts, abrasions)

This allows the spores present on animal products (such as hides, bristles, and wool) to enter the body

Question 11

What is pulmonary (inhalation) anthrax?

Answer 11

1. Pulmonary anthrax occurs when anthrax spores are inhaled into the lungs.
2. It is not communicable from person to person (i.e., it does not spread directly between individuals).

Question 12

How does gastrointestinal anthrax occur?

Answer 12

ingesting contaminated meat.

Question 13

What is the basis of anthrax pathogenesis?

Answer 13

involves the production of two exotoxins: edema factor and lethal factor.

Question 14

What are the components of the anthrax exotoxins

Answer 14

Each anthrax exotoxin consists of two proteins arranged in an A–B subunit configuration.
The B subunit (binding subunit) in both exotoxins is called “protective antigen.”
The A subunit (active subunit) has enzymatic activity.

Question 15

What does edema factor do

Answer 15

Edema factor is an adenylate cyclase.
It causes an increase in the intracellular concentration of cyclic adenosine monophosphate (cAMP).
This leads to an outpouring of fluid from the cell into the extracellular space, resulting in edema.
Edema toxin may also increase host susceptibility to infection by disrupting the cytokine response of monocytes and suppressing neutrophil functions.

Question 16

What is the role of lethal factor?

Answer 16

~Lethal factor is a protease.
~It cleaves the phosphokinase that activates the mitogen-activated protein kinase (MAPK) signal transduction pathway.
~By inhibiting this pathway, lethal factor affects cell growth.

Question 17

How does protective antigen contribute to anthrax pathogenesis?

Answer 17

Protective antigen forms pores in the human cell membrane.
These pores allow edema factor and lethal factor to enter the cell.
The name “protective antigen” refers to the fact that antibodies against this protein can protect against disease.

Question 18

Clinical manifestations of anthrax

Answer 18

1. A skin lesion
2. A respiratory illness
3. Abdominal distress
   (90% are cutaneous anthrax)

Question 19

What is Cutaneous Anthrax?

Answer 19

Cutaneous anthrax is a type of anthrax infection that affects the skin.
It occurs when spores of the bacterium Bacillus anthracis infect the skin.

Question 20

What are the stages of Cutaneous Anthrax?

Answer 20

Papule: Initially, a small, raised bump (papule) forms at the site of infection

Vesicle: The papule develops into a fluid-filled blister (vesicle).

Malignant Pustule: The vesicle becomes a painful, pus-filled sore (malignant pustule).

Necrotic Ulcer: Eventually, the pustule ulcerates, forming a necrotic (dead tissue) ulcer

Question 21

How do most cases of Cutaneous Anthrax resolve

Answer 21

Approximately 80-90% of cutaneous anthrax cases heal spontaneously within 2-6 weeks

Question 22

What percentage of cases progress to a more severe form of the disease?

Answer 22

0-20% of cutaneous anthrax cases progress to a more severe form

Question 23

What happens if cutaneous anthrax is left untreated?

Answer 23

Untreated cases of cutaneous anthrax can lead to death.

Question 24

What proportion of all human anthrax cases are cutaneous anthrax?

Answer 24

95-99% of all human anthrax cases occur as cutaneous anthrax.

Question 25

What are the general symptoms of cutaneous anthrax?

Answer 25

Fever
Chills
Weakness
Hypotension (low blood pressure)

Question 26

What is pulmonary anthrax

Answer 26

Pulmonary anthrax, also known as “wool-sorter’s disease,” is an infection caused by the bacterium Bacillus anthracis.

Question 27

How is pulmonary anthrax acquired?

Answer 27

inhalation of spores

Question 28

What are the initial symptoms of pulmonary anthrax?

Answer 28

1. Dry cough
2. Substernal pressure (pressure or discomfort behind the breastbone)

Question 29

How does pulmonary anthrax progress

Answer 29

Hemorrhagic mediastinitis: Inflammation and bleeding in the area between the lungs (mediastinum).
Bloody pleural effusions: Accumulation of blood in the pleural cavity (around the lungs).
Septic shock: A life-threatening condition caused by bacterial toxins.
Ultimately, it can lead to death if left untreated

Question 30

What causes Intestinal Anthrax

Answer 30

Intestinal Anthrax is caused by the ingestion of infected carcasses.

Question 31

What part of the body does Intestinal Anthrax affect?

Answer 31

It affects the mucosal lining of the lymphatic system

Question 32

What are the symptoms of gastrointestinal anthrax?

Answer 32

The symptoms include vomiting, abdominal pain, and bloody diarrhea.

Question 33

How soon after symptom onset does death occur in Intestinal Anthrax cases?

Answer 33

Death typically occurs 2 to 5 days after the onset of symptoms.

Question 34

Why is diagnosing Intestinal Anthrax challenging?

Answer 34

Non-Specific Symptoms: The symptoms of gastrointestinal anthrax (vomiting, abdominal pain, and bloody diarrhea) are not unique to this disease. They can resemble other common gastrointestinal infections, making it difficult to differentiate

Question 35

What do smears show in cases of Intestinal Anthrax

Answer 35

Smears show large, gram-positive rods in chains.

Question 36

What type of colonies form on blood agar aerobically in Intestinal Anthrax?

Answer 36

Nonhemolytic colonies form on blood agar aerobically.

Question 37

How can rapid diagnosis be performed in case of a bioterror attack involving Intestinal Anthrax?

Answer 37

In such cases, rapid diagnosis can be achieved using polymerase chain reaction (PCR)–based assays in specialized laboratories.

Question 38

What is another rapid diagnostic procedure for Intestinal Anthrax?

Answer 38

The direct fluorescent antibody test detects antigens of the organism in the lesion.

Question 39

What are serologic tests used for in Intestinal Anthrax diagnosis?

Answer 39

Serologic tests, such as the enzyme-linked immunosorbent assay (ELISA) test, are used to detect antibodies. However, they require acute and convalescent serum samples and can only be used for retrospective diagnosis.

Question 40

Treatment of anthrax

Answer 40

Penicillin is the drug of choice for cutaneous anthrax and is given for
5–7 days.
* Tetracyclines, erythromycin and chloramphenicol are also effective.
* Parenteral ciprofloxacin or doxycycline for inhalation anthrax

Question 41

prevention of anthrax

Answer 41

• Immunize high-risk persons
• Incinerating animals that die of anthrax, rather than burying them,
  will prevent the soil from becoming contaminated with spores