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Immunology > Pathogens- Bacteria > Flashcards

Pathogens- Bacteria Flashcards

1
Q

What are cocci?

A

Round cells

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2
Q

What are bacilli?

A

Rod-shaped cells

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3
Q

What are the different formations of bacterial cocci?

A

Monococcus- single cells
Diplococcus - paired cells
Staphylococcus- grouped cells
Streptococcus- chained cells

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4
Q

What are the different formations of bacterial bacilli?

A

Single rod- bacillus
As groups or clusters
Chains

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5
Q

What are fimbrilae/pilli?

A

They are thin protein tubule projections from the cytoplasmic membrane of many bacteria
-found in almost all gram-negative bacteria but not many found in gram-positive

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6
Q

What is an endospore?

A

An endospore is a resistant asxual spore that develops inside some bacterial cells

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7
Q

What are the 2 types of bacterial cell wall?

A

Gram-positive

Gram-negative

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8
Q

What are the properties of a gram-negative cell wall ?

A
  • Has 2 membranes, 1 inner and 1 outer
  • Smaller PG layer (peptidoglycan)
  • Has a peroplasmic space between PG layer and outer membrane
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9
Q

What are the properties of a gram-postive cell wall?

A
  • Only has an inner membrane

- Has a much thicker PG (peptidoglycan) layer than gram negative bacteria

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10
Q

How are some bacterial spores resistant?

A
  • Has a core of DNA that is resistant to heat and radiation
  • Has a coat that is resistant to chemical and enzymes such as lysozyme
  • Has an exosporium that provides adherence and biocide protection
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11
Q

What is the sequence of treatment of infectious diseases?

A 
Observation of patient-symptoms
Sampling
Lab observation and culture
Identifcation tests
Treatment- antibiotic therapy
Observation of population- epidemiology
Prevention of transmission
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12
Q

What are Koch’s postulates?

A

Four criteria designed to prove a causative relationship between a microbe and a disease

  1. The microorganism must be found in diseased but not healthy individuals
  2. The microorganism must be cultured from the diseased individual
  3. Inoculation of a healthy individual with the cultered microorganism, it must produce the same disease
  4. The microorganism must be re-isolated from the inoculated and match the orginal microorganism
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13
Q

What are the negatives to Koch’s postulates?

A

Less evident to prove conditions that are chronic, have multiple causes or when the pathogen cannot be grown in vitro

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14
Q

What is the iceberg concept of infection?

A

The iceberg concept decribes a situation in which a large percentage of the problem is subclinical, unreported or otherwise hidden from view. Thus, only the ‘tip of the iceberg’ is apparent to the epidemiologist

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15
Q

What is normal flora?

A

Normal flora are those organisms living in benign symbiosis with the host

  • they outcompete pathogens
  • some may be pathogenic but are unable to enter the disease process
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16
Q

What are the hazards with normal flora?

A
  • If conditions change microbes can grow more extensively and cause infections
  • a pathogen may blend in with normal flora
  • Normal flora is essential and treatment may target them
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17
Q

What factors influence the success of transmission in the disease process?

A

Number of microbes- more the better
Size, density, surface features, hydrophobicity
Spore formation, adhesion to surfaces
Distribution in the host

18
Q

What are the critical stages in disease success in the disease process?

A

Adhesion-depends on microbe and host features
Invasion- depends on breaks in the surafce layer or active procedures from microbe
Motility of the microbe- chemotaxis
Attachment to site- using pilli
Penetration of epithelium- using enzymes like proteases

19
Q

What are the consequences of disease success in the disease process?

A
  • Growth in tissues require cells to resist host responses
  • May have means to neutralise host cells
  • Growth takes away nutrients from host cells and tissues
  • Tissue damage results in host cell death- due to toxins and ezymes
20
Q

What does pathogenicity mean?

A

The ability of a pathogen to produce an infectious disease in an organism

21
Q

What does virulence mean?

A

The relative degree of damage done by a pathogen, or the degree of pathogenicity of a pathogen

22
Q

What is a pathogenicity/virulence factor?

A

A microbial product that contributes to virulence or pathogenicity

23
Q

How does a bacterial capsule help in penetration of host defenses?

A

Help in attachment of the microbe

Prevents phagocytosis of the microbe- may be resistant to lysozymes so can be broken down

24
Q

What are hemolysins and how to bacteria utilize them?

A

Hemolysins are enzymes that cause the complete or incomplete lysis of red blood cells
-bacterial can then utilize the nutrients (e.g iron) from the red blood cells to grow and replicate

25
Q

What is coagulase and how do bacteria utilize it?

A

Coagulase is an enzyme which causes the clotting of blood or plasma
- this protects the bacteria from white blood cells and other host defenses that are either in the blood or move via the bloodstream

26
Q

What is collagenase and how do bacteria utilize it?

A

Collagenase is an enzyme which breaks down collagen

-this increases the mobility of bacteria and allows them to spread through muscle tissue

27
Q

What are leukocidins and how do bacteria utilize them?

A

Leukocidins is a type of cytotoxin created by some types of bacteria
-Targets phagocytes, NK cells, dendritic cells and T cells which weakens both the innate and adaptive immunity for the microbe to survive

28
Q

What is a toxin?

A

A poisonous substance produced by a bacteria

- most work by damaging the eukaryotic cell membrane in some way

29
Q

What are the 2 main classes of toxins?

A

Exotoxins

Endotoxins- also known as LPS (lipopolysaccharides)

30
Q

What is difference between exotoxins and endotoxins?

A
  • Exotoxins are secreted outside of the bacterial cell by mostly gram-positive bacteria
  • Where as endotoxins are a part of the outer cell wall of gram negative bacteria. They are freed when the bacteria dies and the cell wall breaks.
31
Q

What are the 3 types of exotoxins?

A

Enterotoxin
Neurotoxin
Cytotoxin

32
Q

What are enterotoxins?

A

A toxin that is produced in or affects the intestines

33
Q

What are neurotoxins?

A

Toxins that are destructive to nervous tissue

34
Q

What are cytotoxins?

A

A cytotoxin is any substance that has a toxic effect on an important cellular function

35
Q

What is bacillus cereus?

A

A gram positive rod shaped bacteri commonly found in soil or food

36
Q

What toxins do bacillus cereus produce?

A
  • the 3 component enterotoxin haemolysin BL (HBL)
  • the 3 component non-haemolytic enterotoxin (NHE)
  • the 1 component enterotoxin cytotoxin K
  • Cereulide cytotoxin
37
Q

What are the symptoms of bacillus cereus?

A

Abdominal pain, watery diarrhoea for 12-24 hours

Nause, vomiting and malaise (discomfort) for 6-24 hours

38
Q

What happens to a patient if all 4 toxins are produced by the bacillus cereus?

A

If all 4 toxins are present, the patient will express all the symptoms

39
Q

What is a beta-lactam antibiotic?

A

A type of antibiotics that contain a beta-lactam ring in their molecular structure
e.g amoxicillin

40
Q

How do beta-lactams antibiotics kill bacteria?

A

They inhibit the synthesis of the peptidoglycan layer of bacterial cell walls, which is inportant for cell wall structural integrity (especially in gram-positive bacteria)

Immunology (10 decks)

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