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Microbiology > Infectious Disease and Pathogenicity > Flashcards

Infectious Disease and Pathogenicity Flashcards

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Biology 101 flashcards
1
Q

Cocci bacteria

A

Round and spherical

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2
Q

Bacilli

A

Rod shaped

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3
Q

Monococcus

A

Single round cell

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4
Q

Diplococcus

A

Paired cells

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5
Q

Staphylococcus

A

Grouped cells

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6
Q

Streptococcus

A

Chained cells

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7
Q

Bacteria cell components

A 
Cell Wall
Flagella
Pilli/fimbriae
Nucleoid
Plasmids
Cytoplasm 
Ribosomes
Endospore 
Capsule
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8
Q

What is an endopsore?

A

Small, highly resistant, thick-walled, “resting” cells
Produced in response to environmental stressors
Formed when bacteria stops growing as environment cant support its growth

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9
Q

What are inclusion bodies?

A

Form in cytoplasm
Can be fat/iron/proteins
Protein aggregates
Site of viral multiplication

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10
Q

Gram negative bacteria

A

Outer and inner membrane

Thin layer of peptidoglycan

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11
Q

Gram positive bacteria

A

No outer membrane

Thick layer of peptidoglycan

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12
Q

What separates the outer and inner membrane in gram negative bacteria?

A

Periplasm

Smaller one in gram positive

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13
Q

Function of periplasmic space

A 
Protein oxidation
Folding 
Thin layer of peptidoglycan
Quality control
Contains enzymes involved in cell's metabolism
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14
Q

When are resistant spores formed?

A

In adverse conditions

Environmental stress e.g lack of nutrients, bad pH

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15
Q

Why do bacteria produce spores?

A

To produce a dormant and highly resistant cell to preserve the cell’s genetic material in times of extreme stress
The spores are resistant to UV/radiation/Biocides/ Gamma radiation

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16
Q

Layers of spore (innermost to outermost)

A 
Core
Inner membrane 
Germ cell wall
Cortex
Outer membrane 
Coat 
Exosporum
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17
Q

Function of exosporum?

A

adherence and biocide protection

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18
Q

Sequence of treatment

A
  1. Observance of patient- symptoms
  2. Sampling
  3. Laboratory observation and culture
  4. Identification tests
  5. Treatment e.g antibiotics
  6. Observation of population
  7. Preventing transmission
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19
Q

Definition of disease

A

A disturbance in the state of health wherin the body cannot carry out all its normal functions

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20
Q

Infectious disease definition

A

Infection caused by pathogenic micro-organisms

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21
Q

Infection definition

A

Invasion and multiplication of a pathogenic microbe within or on a host

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22
Q

Contamination

A

Presence of microbes in a location/environment

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23
Q

What is koch’s postulates?

A

4 criteria to establish a causative relationship between a microbe and disease

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24
Q

What are the 4 criterias of koch’s postulates?

A
  1. The specific causing agent must be seen in every disease
  2. The agent must be isolated from a diseased host and grown in pure culture
  3. The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host
  4. The agent must be re-isolated from the diseased host and identified as identical to the specific disease causing agent
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25
Q

What diseases does koch’s postulates work for?

A

Plague
Anthrax
Cholera
Typhoid

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26
Q

When is koch’s postulates less evident in?

A

Condition is chronic
Condition has multiple causes
Conditions where pathogen can’t be grown outside of body (in-vitro)
No suitable animal model of infection

27
Q

What conditions would koch’s postulates be less evident for?

A

Pneumonia
Wound infections
Septicaemia
Urinary Tract infections

28
Q

What is normal flora?

A

Micro-organisms present on body surfaces covered by epithelial cells and are exposed to the external environment

29
Q

Where in the body is normal flora found?

A

Gastrointestinal tract
Respiratory Tract
Genitourinary tract

30
Q

Normal flora and host cell

A

They live in benign symbiosis with one another

31
Q

Examples of normal flora

A

E.coli found in the intestines

Staphylococcus aureus in nostrils

32
Q

Why can’t normal flora cause disease even if they are pathogenic?

A

They lack attachment to a suitable surface

33
Q

When does normal flora become pathogenic?

A

When environment changes e.g environmental stress, hormonal levels, stress, climatic
e.g MRSA

34
Q

6 stages of disease progression

A

1 and 2- transmission and exposure to disease
3 and 4- Adherence and invasion
5 and 6- Colonisation and Tissue Damage

35
Q

What does successful exposure and transmission depend on?

A

Number of microbes- the more the better
Airborne- size, density, surface features
Waterborne- density, surface features, hydrophobicity
Contact- resistance to dessication, spore formation, adhesion
Vectors
Fomites
Distribution on host: into cuts , digestive system, genitourinary system, lungs

36
Q

What does adherence and invasion depend on?

A

Adherence depends on host’s and microbe’s features
Invasion depends on breaking i surface layers or acitve procedures from microbe
Chemotaxis and motility Attachment via pilli/non-fimbrial adhesions
Penetrations of epithelia/cells via proteases
Anti-phagocytic capsules may allow survival stopping phagocyte entering microbe
Virulent bacteria can inject epithelium cells with molecules to change features of surface

37
Q

What does colonisation and tissue damage depend on?

A

Growth of bacteria in host means host’s responses are avoided
Growth of microbe in host requires nutrients
There is limited nutrient availability in the host cell
Tissue damage caused by accumulation of toxins released by microbe

38
Q

What defences does the host cell have?

A
  1. Physical barriers (e.g sebum on skin)
  2. Cellular defences (phagocytes, killer cells)
  3. Inflammation
  4. Complement System
  5. Immunity
39
Q

What is the result of bacteria prolonging an immune response?

A

Chronic infection

40
Q

3 characteristics of a pathogen

A
  1. Virulence
  2. Pathogenicity
  3. Virulence/Pathogenicity factor
41
Q

Pathogenicity

A

Ability of a pathogen to produce an infectious disease in an organism

42
Q

Virulence

A

Relative degree of damage caused by pathogen/ degree of pathogenicity of a pathogen

43
Q

Virulence/Pathogenicity Factor

A

Microbial product/strategy that causes virulence/pathogenicity

44
Q

Molecular determinants of pathogenicity

A
  1. Attachment to host tissues
  2. Production and delivery of various factors
  3. Replication and evasion of immunity
  4. Damage to host tissues
45
Q

How do bacteria adhere to host?

A

Bacteria employ proteins such as adhesins which are normally found on ends of fimbriae/pilli
Adhesins can consist of glycocalyx

46
Q

What do bacteria use to penetrate host?

A

Enzymes (proteases)
Capsules
Cell wall components

47
Q

How do bacteria damage host cells?

A 
Direct damage 
Endotoxins
Exotoxins
Toxins
Hypersensitivity reactions (allergies)
48
Q

What do pilli/fimbriae attach to on host cell?

A

Host cell glycoprotein receptors

49
Q

Role of capsules in bacteria?

A

Prevent phagocytes attaching
Preventing phagocytosis
e.g streptococcus pneumoniae

50
Q

What enzyme is released by bacteria to get into host cell?

A

Proteases

51
Q

A few enzymes released by bacteria that harm eukaryotic cells

A

Coagulase
Collagenase
Haemolysins
Leukocydins

52
Q

Which bacteria releases haemolysins?

A

Alpha haemolytic streptococci

Beta haemolytic streptococci

53
Q

Difference between alpha and beta haemolytic streptococci?

A

Alpha- haemolysins released cause incomplete lysis of RBCs

Beta- haemolysins released cause complete lysis of RBCs

54
Q

Which bacteria produces coagulase?

A

Staphylococcus aureus

55
Q

Action of coagulase?

A

Causes blood to coagulate (clot)
Blood clot prevents phagocytes phagocytosing bacteria
Fibrinogen converted to fibrin= clot

56
Q

What bacteria produces collagenase?

A

Clostridium perfringens

57
Q

Action of collagenase?

A

Breaks down collagen in muscle tissue

Allowing bacteria to spread through muscle tissue

58
Q

Action of leukocidins?

A

Pore forming exotoxins that kill leukocytes
Cause degranulation of lysosomes within leukocytes
Decreases host resistance

59
Q

2 types of toxins released by bacteria

A

Endotoxins

Exotoxins

60
Q

What bacteria are exotoxins mainly produced in?

A

Gram positive bacteria

61
Q

How do exotoxins work?

A

Secreted by bacteria cell into surrounding medium

Mainly by gram positive bacteria

62
Q

What are endotoxins part of?

A

Part of outer portion of cell wall in gram negative bacteria

63
Q

How do endotoxins work?

A

Once bacteria dies and cell wall is broken down endotoxins are released

Microbiology (5 decks)

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