General Principles of Microbiology

Question 1

What is the composition of viruses and how do the replicate and how do the affect host cell?

Answer 1

nucleic acids and sometimes proteins shells (capsid)
- enter cells and divert the synthetic processes of those cells for replication
- can kill or not kill host cell

Question 2

How does the bacteria ,Chlamydia, differ/ similar from viruses?

Answer 2

differ
- more complex

similar
- can only multiple in living cells
- recognizable morphology and life cycle

Question 3

What are the characteristics of prokaryotic bacteria?

Answer 3

• rigid cell wall with cytoplasm
• genetic material is organized in circular chromosomes

Question 4

How do mycoplasmas differ from other bacteria?

Answer 4

• similar but don’t have rigid cell wall
• lack of rigid cell wall makes them more delicate than other bacteria

Question 4

What are eukaryotes and how do they differ from prokaryotes?

Answer 4

• include all unicellular and multicellular animals and plants
• have their genetic material organized into a nucleus

Question 5

What is the difference between resident and transient bacterial flora?

Answer 5

RF - permanent microbial populations that live in specific areas of the body
TF - temporary population that often appear due to injury, trauma, or behavior

Question 5

How does infection occur with bacteria and what determines the outcome?

Answer 5

• infection happens when a single bacterial species becomes dominant or invades a normally sterile site
• the outcome is determined by both the pathogenicity of the and the host’s immune response

Question 6

Why is normal bacterial flora important for health?

Answer 6

1. protection: against infection by invasive organisms
2. metabolism: help synthesize vitamins (e.g., K)
3. antibiotic disturbance: antibiotics disturb balance causing issues like antibiotic-induced diarrhea
4. host defense: helps immune system; deficiencies may lead to infections
5. lab confusion: can interfere with the interpretation of lab results

Question 7

What are the key defense mechanisms when it comes the interactions between pathogenicity mechanisms and host defenses?

Answer 7

• normal flora control: host defenses prevent invasive disease and keep normal flora in check
• Invasive infection: the outcome of an infection depends on the interaction between host defenses and bacterial pathogenicity mechanisms

Question 7

What are the key physical factors that bacteria must overcome to become infectious?

Answer 7

Mechanical Barriers: Skin acts as a physical barrier to prevent bacterial entry.
Adherence: Bacteria attach to host tissues using specific ligands and receptors.

Question 7

What causes patients to become compromised?

Answer 7

Deficiencies in defenses: conditions or treatments can impair antimicrobial defenses
Examples:
- Phagocytosis (e.g., leukopenia): increases risk for Staph and Strep due to them producing protective polysaccharide capsule
- Antibody-mediated immunity: increases susceptibility to Strep and viral infections
- Cell-mediated immunity (e.g., AIDS): increases risk for infection like Tuberculosis

Question 8

What are the key defense mechanisms the body uses against bacterial infection when is comes to macrophages?

Answer 8

Cell-Mediated Immunity: Activated macrophages and immune system cells (ex. T-cells) target and kill specific bacteria like Mycobacterium tuberculosis and Legionella.

Phagocytosis: Macrophages and neutrophils ingest and destroy bacteria, though some bacteria protect themselves with capsules.

Antibodies: Bind to bacteria to enhance phagocytosis or directly kill the bacteria.

Question 9

What is the spread of bacterial infections called and how does it happen?

Answer 9

Metastatic spread
- Bacteremia/ Septicemia: bacteria spread through the bloodstream from the primary site of infection
- Dissemination: Bacteria can cause symptoms in distant sites from the original infection focus

Question 9

What are the key defense mechanisms the of body, when it comes to plasma and exotoxins, that protects against bacterial infection?

Answer 9

Complement System: Plasma proteins work together to help resist bacterial infections.
Exotoxin Production: Some bacteria release exotoxins that damage tissue; antibodies help neutralize these toxins.

Question 10

What are the main defense mechanisms of the body against bacterial infections?

Answer 10

• mechanical barrier
• phagocytosis
• antibodies to bacteria
• complement
• cell mediated immunity
• exotoxins (host produces antibodies in the process)

Question 11

If the host defense is missing (or deficient in) phagocytic cells, antibody mediated immunity, and cell mediated immunity?

Answer 11

• Staph and Strep
• Strep and viral infection
• TB, legionella and AIDS related infections

Question 11

What are microbial diseases?

Answer 11

interaction between microorganisms and the host organism, including processes like adhering, penetrating, and multiplying

Question 12

What are microorganisms and what are their characteristics?

Answer 12

Organism that is invisible to the naked eye
- majority are harmless or beneficial; only a small amount causes harm to animals and plants

Question 12

What is an infection and what are the different 3 types?

Answer 12

penetration of a microorganism into a host organism which multiplies and causes disease (apparent) or no disease (inapparent)
1. colonization: microorganism establish themselves and multiply without causing disease
2. contamination: microorganism deposit without multiplication (e.g., water contaminated with sewage)
3. clinical infections

Question 13

What are the 3 types of clinical infections?

Answer 13

Clinical infection: functional damage to the host (disease)
factors:
- large vs. small # or microbes
- high virulence vs. attenuated virulence
- susceptible vs. resistant host
Subclinical infection: without apparent symptoms (asymptomatic)
No infection: host remain unaffected

Question 14

What is the difference between pathogenicity and virulence?

Answer 14

P - the ability of a microorganism to produce disease
V - microorganisms relative capacity to cause damage (i.e., degree of pathogenicity)

Question 15

What is opportunistic pathogens?

Answer 15

microorganisms that do not usually cause disease but can do so when defense mechanisms are breached or compromised

Question 16

What are the opposing force operate in infection?

Answer 16

Microorganism: strives to multiply and invade tissues
Host: strives to block invasion and destroy microorganism

Question 17

What is transmissibility and what are the different ways of entry?

Answer 17

the ability of a microorganism to transfer an effective amount from a source to a host
- inhalation
- ingestion
- break in protective barrier
- direct deposit

Question 18

What is pathogenicity and what are the 3 kinds?

Answer 18

the ability of a microorganism to cause disease
- invasiveness: overcoming host defenses to multiply
- toxigenicity: production of toxins
- combination of the both: both

Question 19

What are some mechanisms microorganisms use for adherence and evading host defense?

Answer 19

• Surface structures adhere to specific receptors on host cell surface
• Capsules: polysaccharides that protect microorganisms from immune cells like leukocytes

Question 20

What role do enzymes play in the virulence of microorganisms?

Answer 20

• Coagulase: accelerates clotting of plasma, forming a barrier around the infection site
• Hyaluronidase: breaks down hyaluronic acid, allowing bacterial spread through tissues

Question 21

What is toxigenicity?

Answer 21

is the production of toxins by microorganisms that damage host tissues or disrupt vital systems

Question 22

What are the two types of toxins produced by bacteria?

Answer 22

1. exotoxins
2. endotoxins

Question 23

What are 4 characteristics of exotoxins?

Answer 23

• proteins secreted by living bacteria
• have specific attraction for host systems (e.g., botulinum toxin affects nervous tissue)
• active in very small concentrations and highly toxic
• often thermolabile (sensitive to heat)

Question 24

What are 3 characteristics of endotoxins?

Answer 24

• associated with the bacterial cell structure and released when the cell die
• less specific and potent than exotoxins, but can cause fever, malaise, and shock (septic)
• Thermostable (resistant to heat)