Microbiology

Question 1

What is a microorganism?

Answer 1

They can be in any place on earth

Question 2

What are microorganisms that live under extreme conditions called?

Answer 2

extremophiles

Question 3

What is the environment of halophiles?

Answer 3

high salt conditions

Question 4

What is the environment of Thermophiles?

Answer 4

Temperatures between 60-120 degrees celsius

Question 5

What is the environment of Cryophiles

Answer 5

Temperatures below 15 degrees

Question 6

What is the environment of acidophiles?

Answer 6

ph below 3

Question 7

What is the environment of alkaliphiles?

Answer 7

ph above 9

Question 8

What is the environment of xerophiles?

Answer 8

extremely dry desiccating conditions

Question 9

Name the different bacterial morphology shapes?

Answer 9

coccus, bacillus, coccobacillus, fusiform bacillus, vibrio, spirillium, spirochete

Question 10

What are the different ways that microorganisms can be classified into?

Answer 10

Shapes, Kingdom, Phylum, class, order, family, genus, species, nucleus and other structures, gram negative or positive, size, type of chromosome, diversity, way they move and reproduction.

Question 11

Name and describe the different external structures of the bacteria.

Answer 11

Flagellum - via a motor (proton motive force), the flagella whips so that the cell can move.

Pili/sex pili/fimbriae - it has a protein at the tips so that it can attach to the host for the bacteria to colonize. It has a plasmid which can be passed on to another cell via replication (DNA double stranded).

Slime layers - excreted by cells is a gelatinous material that attaches loosely to surfaces and allows smooth movement. Formation of biofilms on teeth. Not highly organised.

Capsules - thick polysaccaride layer that strongly attaches to solid surfaces. Protects cell from desiccation and evades the immune system by preventing phagocytosis. Highly organised.

Question 12

Describe the gram negative bacteria and positive

Answer 12

The gram positive bacteria has peptidoglycan. The peptidoglycan chains are made up of 2 sugars that each have a peptide. The sugars link and the peptide link to make a long chain thus a strong membrane. The peptidoglycan makes up 90% of the cell wall. 1 membrane.

The negative bacteria has the same structure but thinner and is only 5-20% of the cell wall. This means that it can easily lyse but also it has good ability to transport material. 2 membrane (inner phospholipid and outer)

Question 13

Describe endospores

Answer 13

• resistant to heat, cold, drying, and many chemicals
• can survive for many years in soil or dust by being latent
• spores germinate after landing on moist, nutrient- rich surface and develop into vegetative cell.
Endospores can be latent until sufficient nutrient is provided and then it can turn into bacteria.
• important for survival, not reproduction (dormant)
• produced by Bacillus and Clostridium

Question 14

What are the 4 different ways that bacterial diversity can be classified?

Answer 14

Strain - genetic variation within subtypes
isolate - from which infected individual the bacteria was isolated from
serotype - what specified antibody attaches to it
Pathovar - from which tissue in the host it is found in

Question 15

What is the imune system?

Answer 15

It is everything that has access and in constant motion and change.

Question 16

What does the immune system do?

Answer 16

monitors molecular shapes of cells that is non self or self in wrong places (antigens), distinguishes between self and non self. Following this it removes, neutralises, alters or assimilate non self.
protects, assists in recofery from infection or tissue damage. Also maintains a relationship with the external environment

Question 17

What are the sources of antigens?

Answer 17

Viruses, Bacteria, Parasites, Dust particles or cells from other people (transfusion and transplants).

Question 18

What does the immune system do with the antigen?

Answer 18

Stores it to form a repertoire of different antigenic shapes for recognition. Anything can be an antigen as long as it is large enough to be recognized.

Question 19

What is innate immunity?

Answer 19

> First line barrier, not improved by repeated antigen exposure.
InvolvesLysozyme, complement, acute phase proteins, interferon
Cells=Phagocytes, Natural
Killer (NK) cells

Question 20

What is adaptive immunity?

Answer 20

> Comes after innate immunity fails. Improved by repeated exposure.
Involves Lysozyme, complement, acute phase proteins, interferon
Cells= lymphocytes, monocytes, antigen presenting cells

Question 21

What are the differences and similarities between innate and adaptive immunity?

Answer 21

Difference is adaptive immunity improves on repeated exposure while innate does not improve. innate is a physical barrier and a first line of defense. The are dependent on each other.

Innate immunity has physical, microbial, cellular and humoral factors. Adaptive immunity has cellular and humoral factors.

Question 22

How do neutrophils work and when do they work?

Answer 22

Work when surface barriers are breached. They phagocytose foreign material. (ingest and digest). The surface receptors on the phagocytes recognize the common features of the bacteria cell wall. The neutrophils then stick and get activated. At which point the phil folds its membrane around the bacteria ingesting it. Digestive enzymes in the phil digest the bacteria.

Question 23

what is the complement system?

Answer 23

The system is structured with 20 blood proteins that freely move to protect any surface breaches. They do this by

• changing vascular permeability for neutrophils to move- vasodialate
• attracting phagocytic neurtophils - chemotaxis
• coat the foreign material so that they can be easily phagocytosed - opsonisation
• breach the integrity of bacterial cell walls - lysis

Question 24

how the complement system work?

Answer 24

The system works to
amplify enzymatic cascade
1. One protein gets activated by adhering to the bacterial cell wall
2. That protein then activates other proteins
3. Those proteins activate other proteins which results in the amplification of enzymatic cascade

Question 25

How does the immune system recognize antigens?

Answer 25

Receptors. Two types of receptors = cell surface receptors and antibodies.

Question 26

What happens after antigen recognition?

Answer 26

When the first contact occurs an the immune system responds and builds up tolerance by creating self antigens. The response allows the foreign antigen to be stored up for memory for a future improved response. Secondary contact the immune systems recollects the antibodies it used from the primary contact and forms a better response against the antigen.

Question 27

What happens in the immune response?

Answer 27

The immune system neutralises, inactivates, destroys, disposes of and or assimilates the material recognized. It produces antibodies to recognize and cytotoxic lymphocytes to kill. The responses aren't immediate.

Question 28

What is the difference between self and non self?

Answer 28

The immune system learns not to respond to self but can also not respond to non self if the antigen is present before the system has matured. This is called acquired immunological tolerance.

Question 29

What is the Koch's postulate?

Answer 29

It is the proof of the germ theory. 1. the m.organism must be found in similarly diseased animals. (abandon because germs can be carried asymptomatically so you don't know if the animal has the disease) 2. The germ must be isolated and cultured purely (some organisms cannot be grown in culture) 3. the germ should be able to evoke the disease in another susceptible animal.(may not cause disease all the time) 4. The germ again should be able to be isolated and cultured

Question 30

What is symbiosis?

Answer 30

living together in close association

Question 31

Mutualism?

Answer 31

beneficial to both symbionts

Question 32

Neutralism:

Answer 32

neither symbiont is affected by relationship

Question 33

Commensalism:

Answer 33

beneficial to only one symbiont

Question 34

Parasitism

Answer 34

``` harmful to one symbiont (host), beneficial to other symbiont (parasite). ```

Question 35

Synergism:

Answer 35

two or more microorganisms “team up” to | cause disease. Synergistic or polymicrobial infection.

Question 36

Pathogen:

Answer 36

microorganism that cause disease (< 3%)

Question 37

Opportunistic pathogen:

Answer 37

has the potential to cause disease

Question 38

Ingestion

Answer 38

Salmonella

Question 39

•  Inhalation:

Answer 39

Legionella,

Question 40

Trauma:

Answer 40

Clostridium tetani

Question 41

Needlestick:

Answer 41

Pseudomonas

Question 42

Arthropod bite

Answer 42

Rickettsia,

Question 43

STD

Answer 43

Neisseria gonorrhoeae

Question 44

Why does exposure not always lead to disease?

Answer 44

O can't grow at site of contact, absence of host receptors, lysozyme in tears (antibacterial factors), microbial antagonism (indigenous flora are competitive or produce antibacterial factors), good health, immunity or elimination

Question 45

What are the four periods in the course of an infectious disease?

Answer 45

1.  Incubation period: time between infection and onset of symptoms 2. Prodromal period: patient feels “out of sorts” , but no disease symptoms 3. Illness: experience of symptoms associated with disease 4. Convalescent period: time during which the patient recovers

Question 46

What is a human carrier and name the 4 types?

Answer 46

A person infected with a particular pathogen without showing disease symptoms. 1.   Passive carrier: never had the disease 2.   Incubatory carrier: during incubation period 3.   Convalescent carrier: recovering from disease 4.   Active carrier: completely recovered

Question 47

Localised infection:

Answer 47

pathogens are contained at site of | infection (e.g. abscess).

Question 48

Systemic infection

Answer 48

pathogen spreads throughout the body

Question 49

Acute infection:

Answer 49

rapid onset and rapid recovery

Question 50

Chronic infection:

Answer 50

slow onset and slow recovery

Question 51

Latent infection

Answer 51

pathogen not completely eradicated after | recovery and can cause symptoms in future (herpes, TB)

Question 52

Secondary infection:

Answer 52

disease that follows primary infection | (ex. pneumonia after mild respiratory infection)

Question 53

What are the steps in pathogenesis of infectious diseases?

Answer 53

1.   Entry: see ‘portal of entry’ 2.   Attachment: binding to host tissue (colonisation) 3.   Multiplication: at infection site (localised infection) 4.   Invasion or spread (systemic disease) 5.   Evasion of host defenses (immune evasion) 6.   Damage to host tissue: symptoms, disability, death

Question 54

What is the difference between infectious disease and Microbial intoxication?

Answer 54

In infectious diseae the pathogen causes the disease in the body and can take a while to occur and the immune system responds. With microbial intoxication a pathogen in a cake will produce a toxin which will then be ingested. The toxin will cause the disease quickly causing vomiting or diarrhoea. The toxin can be removed by these methods as well.

Question 55

How does virulence factors change good bacteria into bad bacteria?

Answer 55

*   promote attachment to host cells (adhesins) *   help bacterium to enter host cell (invasins)! *   damage host cell or tissue (e.g. cytolysins)! *   help bacteria to spread from local infection (spreading factors)! *   over-stimulate immune response (immunopathogenic factors)! *   mediate immune evasion !

Question 56

What do invasins do?

Answer 56

get into cells that don't have protective measures

Question 57

What do cytolysins do?

Answer 57

bacteria for example lyse the RBC to take iron thereby destroying the tissue cells for bacteria to spread. destroy erys, leukocytes and tissue cells - access to nutrients - immune evasion - bacterial spreading

Question 58

What do biofilms do?

Answer 58

The bacteria create a sticky web of secreted polysaccharides that don't allow the body's cells to reach and fix the damaged site.

Question 59

What do bacteria do the cytokines?

Answer 59

cytokines release signals to attract WBC (chemotaxis) but bacteria destroy these interlukins.

Question 60

How do bacteria evade the immune system?

Answer 60

-   capsules (prevent opsonisation and phagocytosis) -   destruction of phagocytes -   inhibition of phagocyte chemotaxis -   inhibition of phagocytosis -   destruction of complement factors -   destruction of immunoglobulins -   intracellular replication

Question 61

Why is recognition of self/ immune tolerance not genetic?

Answer 61

In the child genes for Mum’s receptors against Dad’s antigens, and Dad’s receptors against Mum’s antigens. Therefore, self tolerance is learned.

Question 62

Explain the mechanism and give an example of exotoxins.

Answer 62

Clostridium inhibits the release of neurotransmitters across synapses causing tetanus and botulism. Vibrio cholera secrets electrolytes causing diarrhea. Staphylococcus aureus releases toxin to cause: necrosis around them. cytokine causing toxic shock syndrome using syperantigens - bridge things E.coli produces Shiga toxins which cause apoptosis. Remember clown wears silly coloured eyeglasses

Question 63

Explain the mechanism and give an example of endotoxin.

Answer 63

Gram negative bacteria have lipopolysaccharide in cell wall which causes an inflammatory cascade.

Question 64

Explain and give an example of cell wall fragment in gram positive that illicit an inflammatory cascade

Answer 64

Gram positive bacteria has lipotechoic acid in its walls causing an inflammatory cascade.

Question 65

Explain and give an example of hydrolytic enzymes that are produced by S.aureus.

Answer 65

S. aureus enable bacteria to spread through tissues by producing hyaluronidase and protease which digest tissue.

Question 66

Explain and give examples of a bacteria that inhibit the release of products in the stomach and intestine respectively.

Answer 66

Helicobactor pylori inhibit stomach acid secretion allowing itself to survive in an acidic environment. Giardia lamblia inhibits and degrades digestive enzyme.

Question 67

Explain and give an example of bacteria that causes the invasion and intracellular multiplication in the body.

Answer 67

Myobacterium tubercolosis takes our body cell shape but still has some bacterial characteristics causing our body to attack to our own body cells.

Question 68

Explain and give an example of a bacteria that causes the induction of autoantibodies

Answer 68

Streptococcus pyogenes are microbial antigens similar to host antigens evoking an autoantibody response causing rheumatic fever.

Question 69

Explain and give an example of a bacteria that causes mutation

Answer 69

HTLV-1 carry oncogenes that cause our cells to tumours.

Question 70

Explain and give an example of a bacteria that causes obstructions in the body

Answer 70

Echinococcusform hydatid cysts that obstructs vessels and other areas.

Question 71

What are the two ways that the hosts respond to microbes?

Answer 71

Inflammation(non specific) and immune response (antigen specific).

Question 72

What are the five causes of inflammation?

Answer 72

ischaemic, physical, chemical, infectious or immunological

Question 73

What are the cardinal signs of inflammation?

Answer 73

``` Redness Swelling Heat Pain Loss of function pyrexia ```

Question 74

Why is the anatomical location of the inflammation important?

Answer 74

The type of tissue injured affects the course of events and structural changes which occur

Question 75

Describe what Suppuration is

Answer 75

Pus forming organism/pyogenic organism that occurs on solid tissue i.e. an organ

Question 76

Decribe Abscess

Answer 76

Localised fibroblast boundary | Necrotic, pus-filled centre

Question 77

Ulcer description

Answer 77

Lesions in epithelial surfaces

Question 78

Decribe Cellulitis

Answer 78

Inflammatory reaction spreading through connective tissue planes.

Question 79

What are the primary and secondary responses of inflammation?

Answer 79

The release of mediators both from activated cells and plasma is the primary response. The secondary response is the vasodialation i.e hyperaemia causing redness and heat at the injury area. Increase oressure in capillaries and veinules resulting lymphatic vessels taking out the fluid.

Question 80

What are the systemics of inflammation

Answer 80

Monocytes and macrophages release cytokine interlukin or IL-1 which mediate pyrexia. increased temperature means increased kinetic energy and so increased metabolism. Also increased temperature decreases the optimal environment of the bacteria. But, pyrexia must be regulated. Increased neutrophils (polymorphonuclear leukocytes) and monocytes being made from the bone marrow = leukocytosis increased number of liver proteins which limit tissue damage, resolve infection and inflammation. Increased clotting factor = Acute Phase proteins Increased glucocorticoid steroid hormones because of stress. Other organs could be affected when stress is severe or sustained. The hormones try to balance process that are going on.

Question 81

What are the two groups of lymphoid organs?

Answer 81

Primary and secondary

Question 82

What are the function of primary lymphoid organs?

Answer 82

Bone marrow = produces B lymphocytes | Thymus = T lymphocytes

Question 83

What are the function of secondary lymphoid organs?

Answer 83

The mature lymphocytes from the primary lymphoid organs go to the secondary lymphoid organs. filter foreign matter out of body fluids when immune responses occur. 10% of total lymphocytes circulate at any given time. Lymph node, Spleen, Peyer’s patches, skin, Tonsils, Adenoids

Question 84

What is the structure of lymphatic vessels?

Answer 84

Lymphatic vessels have entrances at the ends of the vessels taking interstitial fluid and other inflammatory components. The vessels also have valves which allow fluid flow in one direction which is towards the thoracic duct.

Question 85

Why do we need to return fluid?

Answer 85

Increased fluid to damaged cells causes swelling of cells in the area. So, the fluid is collected slowly from the cells into the thoracic duct and back to the heart and blood vessels. The vessels do this by muscle movement when you relax and contract. Lymphatic vessels also allow constant communication and thus status reports.

Question 86

What do microfilaria parasitic worms do?

Answer 86

Attaches to walls of lymph vessels drinking the fluid and blocking vessels and lymphatic drainage. This causes swelling of the area because it can't return fluid from cells. The vessels collapse. No drainage means massive swelling.

Question 87

What are the two ways that the body knows about infection?

Answer 87

One = bacteria get into lymphatic vessels and to the secondary lymphoid organs. Two= Langerhans' cells ingest the bacteria which then get into the lymphatic vessels and thus into the secondary lymphoid organs. The cells become dendritic cells presenting the antigens. T Lymphocytes cluster around them in nodes test with their receptors if they should respond. Specific T lymphocytes respond.