Microbiology l

Question 1

What is a pathogen? What are some examples?

Answer 1

A disease causing microorganism. Examples include: bacteria, virus, fungi, yeast, protozoa

Question 2

What does the term ‘acellular’ mean? What does it mean in relation to the term ‘cellular’?

Answer 2

An acellular organism contains no cells - it has a single complex cell, whilst cellular organisms contain many cells

Question 3

Pathogenic microbial world - What type of pathogen is classified as an ‘acellular’ pathogen?

Answer 3

A virus

Question 4

What is a microbe?

Answer 4

A tiny living organism that is too small to be seen with the naked eye**

Question 5

Pathogenic microbial world - What type of pathogens are classified as ‘cellular’ pathogens that fit under prokaryotic cells?

Answer 5

Bacteria + Archea

Question 6

Pathogenic microbial world - What type of pathogens are classified as ‘cellular’ pathogens that fit under eukaryotic cells’ category?

Answer 6

Yeast + Protozoa

Question 7

Pathogenic microbial world (extra information) - What is a prion?

Answer 7

A specific type of protein that can trigger normal proteins to fold abnormally. for EXAMPLE:

• PrPc is a normal protein found in cell membranes (c = cellular)
• PrPsc infectious/atypical form of protein (sc = scrapie)
• PrPsc causes the PrPc to change its conformation to an abnormal form, they then convert more molecules, and a chain reaction occurs. They form an amyloid that accumulates and is deposited locally in the neural tissues.

Question 8

What are the most common prion related diseases?

Answer 8

• Creutzfeld-Jakob disease (CJD), variant CJD (Mad cow disease) are most common diseases associated with prions
• Prions = Still largely unknown pathogen

Question 9

Eukaryote Vs Prokaryote - What are the main differences between these two cell types?

Answer 9

EUKARYOTIC:

• Uni or multicellular
• Slow growth
• 5-20μm across (micrometres)
• Nucleus
• Nucleoli
• Histone associated DNA (*Histone= basic protein used in organising and packaging DNA)
• Membrane bound organelles
• Ribsomes 80s
• Cell membrane

PROKARYOTIC:

• Unicellular
• Rapid growth
• 0.5-3μm across (micrometres)
• Nuclear region
• NO nucleolus
• NO DNA associated protein
• No membrane bound organelles
• Ribosomes 70s
• Have a cell wall containing muramic acid
• Cell membrane

Question 10

Cellular - Prokaryotic

What is bacteria?

Answer 10

A unicellular organism that has some form of cellular respiration to produce energy

Question 11

Cellular - Prokaryotic

What different forms can bacteria come in?

Answer 11

A number of different shapes and anatomical variations, such as wall structures.

• Cocci/Coccus (spherical)
• Bacilli/Bacillus (Rod-shaped)
• Spirillum/Spirilla (spiral shaped)

Question 12

Cellular - Prokaryotic (Bacteria)

What is IMPORTANT to note about bacteria for paramedic students specifically - ***
?

Answer 12

That the identification of the nature of the pathogen links into the treatment required to overcome the infection

Question 13

Cellular - Prokaryotic (Bacteria)

What do the terms gram negative and gram positive refer to?***

Answer 13

This refers to two broad categories of bacteria, based on how they react to a special lab staining technique called the Gram stain. This reaction reflects differences in their cell wall structure, which affects how they interact with dyes, antibiotics, and the immune system.

Question 14

Cellular - Prokaryotic (Bacteria)

What colour does a gram negative bacteria stain?

Answer 14

Red

Question 15

Cellular - Prokaryotic (Bacteria)

What colour does a gram positive bacteria stain?

Answer 15

Blue

Question 16

What causes the differences in the results of the gram stain test? **

Answer 16

Gram-positive bacteria
Color after stain: Purple
Why: They retain the crystal violet dye even after the alcohol wash.
Cell wall structure: Thick peptidoglycan layer (a rigid mesh of sugars and amino acids)
- No outer membrane

Antibiotic sensitivity:

Often more sensitive to antibiotics like penicillin, which target the cell wall.

🔴 Gram-negative bacteria
Color after stain: Pink or red
Why: They lose the purple dye during the alcohol wash and take up the red counterstain.
Cell wall structure:
Thin peptidoglycan layer
Surrounded by an outer membrane with lipopolysaccharides (LPS) — toxic to humans
Antibiotic sensitivity: Often more resistant due to the outer membrane acting as a barrier.

Question 17

What is the basic structure of gram positive bacteria?

Answer 17

Gram-Positive Bacteria
- Thick peptidoglycan layer (outermost)
- No outer membrane
- No lipopolysaccharides (LPS)

• Stains purple in Gram stain

Both have inner cytoplasmic membrane

Question 18

What is the basic structure of gram negative bacteria?

Answer 18

Gram-Negative Bacteria
-Thin peptidoglycan layer (in the middle)
- Has an outer membrane
- Outer membrane contains lipopolysaccharides (LPS) (toxic to humans)

• Stains pink/red in Gram stain

Both have inner cytoplasmic membrane

Question 19

What does gram-negative bacteria release?

Answer 19

Endotoxins

Question 20

Gram negative bacteria: What are lipopolysaccharides (LPS)?

Answer 20

• A component of the outermost membrane layer in gram negative bacteria.

Question 21

Gram negative bacteria: When are Lipopolysaccharides/LPS (a type of endotoxin) released into the bloodstream?

Answer 21

When bacteria lyse/die (The breaking or bursting of the bacteria cell)

Question 22

Gram negative bacteria: What can antibiotics cause?

Answer 22

A large release of Endotoxins (*as they actively kill the cell wall of the bacteria)

Question 23

Gram negative bacteria: what are some characteristics of lipopolysaccharides/endotoxins?

Why are they crucial for the survival of gram negative bacteria?

Answer 23

• They are heat stable
• Not actively secreted
• Antiobiotics can cause a release of these endotoxins
• Contribute to the structural integrity of the bacteria
• Protect the bacteria from chemical attacks
• Can cause a toxic effect: fever, multi organ failure, sepsis, septic shock, blood clotting, vasodilation, inflammation etc

Question 24

Gram negative + positive bacteria:

both release endotoxins ADDITIONAL NOTES

Answer 24

• Exotoxins can cause damage to the host by destroying cells or disrupting normal cellular metabolism
• Exotoxins may be secreted or similar to endotoxins, released during lysis

Question 25

What are some types of endotoxins?

Answer 25

- Enterotoxins (found in the GI tract) - Neurotoxins (cause paralysis) - Pyrogenic (release cytokines) - Tissue invasive (skin IgA)

Question 26

Cellular Infections: What are some common examples of gram-positive bacteria?

Answer 26

- E-Coli - Staphylococcus aureus - Cellulitus

Question 27

Cellular Infections: What is Cellulitus? (and its different types)... - what do the toxins do?

Answer 27

- Cellulitus = Common bacterial infection of the dermal layers - Streptococcus or Staphylococcus are the two main types of Cellulitus - Toxins increase temp, blood flow, capillary permeability - Assist innate defence - If not overcome, (virulent) bacterial rate increases rapidly

Question 28

Cellulitus: Additional NOTES

Answer 28

- Tissue damage - Can enter the blood stream and cause systemic illness - Bacteraemia (also referred to as septicaemia) - Shock and multiple organ failure

Question 29

Cellular: Eukaryotic - NOTES (fungi + protozoa)

Answer 29

- Protozoa: - single cell, reside mostly in soil and water, two stage life span (mobile + cystic), some are parasitic (giardia lambia), others have a symbiotic relationship - Fungi: - Can be multicellular - Can be beneficial (e.g bread, cheese, alcohol, penicillin) - Generally cause a local infection, still possible to attain systemic infection - Common pathogenic fungi include: athletes foot (tinea pedis), thrush (albicans)

Question 30

Acellular viral infections: Acellular viruses - NOTES

Answer 30

- Are non-cellular and small - Non living - Consist of DNA or RNA core - Invade host cells and replicate inside the host cell only - Remain in the host and reproduce sporadically (Herpes simplex cold sores) - Incorporate viral DNA into host DNA

Question 31

Acellular: Pathogenesis NOTES

Answer 31

- Cell membranes have receptor sites - Can be recognised and bound to by other structures such as neurotransmitters and drugs - If receptor is activated it commences a cascade of activities that alter the cells activity - Speed up, slow down, increase cellular replication or lysis - Viruses can attach to cell membrane receptors - Viruses can be specific to certain cell types - Virus specificity to respiratory mucosa may result in upper airway infection but not affect GI mucosa

Question 32

Acellular: Pathogenesis What do the terms 'lytic' and 'lysogenic' refer to?

Answer 32

- Lytic: When a cell replicates the virus, causing them cell to die and release the newly replicated virus - Lysogenic: Cell integrates viral DNA into its own chromosome, will continue to replicate viral coding *Virus can remain latent until stimulus can can cause the infected cell to enter lytic process to release the virus (e.g cold sores)

Question 33

Bacteriophage: - Defintion? - Structure? - Function + result of this

Answer 33

- A bacteriophage is virus entity, a non-living vessel that contains either DNA or RNA - Bacteriophages are able to attach to membrane sites on the bacterial wall. The initiation of this bond results in nucleic acid structure being injected into the cell

Question 34

Acellular - Retrovirus: - What is a retrovirus? - What must it do? - Examples? -

Answer 34

- A retrovirus is a type of virus that uses RNA as its genetic material - Must produce DNA from RNA (reverse transcriptase) - HIV oncogenic (cancer causing)

Question 35

Viruses: What is the lytic cycle? How does it work?

Answer 35

- A type of viral replication pathway* - Attachment of a bacterial microphage (viral entity) to the cell - Injection of nucleic acid DNA or RNA - Synthesis of viral DNA and proteins - Assembly of the proteins into viral replicas (in eukaryotic cells this is the function of the ER) - Manufactured viral DNA starts a chemical cascade that results in the rupture of the cell membrane - cell death SO - attachment, injection, synthesis of proteins, Assembly of proteins into viral replicas, Manufactured viral DNA starts chemical cas, resulting in cell death

Question 36

Viruses: What is the lysogenic cycle? How does it work?

Answer 36

- In the lysogenic cycle, a bacteriophage (viral entity) attaches to the host cell... - Injection of nucleic acid DNA or RNA - Integration of viral DNA and proteins in the host cell - Prophage: bacteriophage genome integrated into the host genome - Cell replication re-engineering intact from generation to generation, laying dormat until cellular distress SO - attachment, injection, integration, prophage, cell replication -

Question 37

Infection to symptoms: What is an opportunistic infection?

Answer 37

- A result of bacteria flourishing in the warm/moist conditions created by the inflammatory response in the nasalpharynx - bacteria migrate to the lower reaches of the airway and result in bacterial pneumonia.

Question 38

Immunosuppression: NOTES

Answer 38

-Drugs can suppress the original protection, bacteria replicate more quickly, migrate and produce endotoxins resulting in illness - Ageing blunts immune responses - Comorbidity e.g. COPD reduces the amount of cilia of endothelial cells in lower airways - Symptoms of viral infections are caused by a combination of host cell death and the subsequent inflammatory response