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PCS Unit 2 > Applied Immunology and Microbiology > Flashcards

Applied Immunology and Microbiology Flashcards

1
Q

What are the five main categories of pathogen-organisms capable of causing disease in man

A

Bacteria, viruses, fungi, protozoa and helminths

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2
Q

What are the two main forms of fungi

A

Yeast and mycelia

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3
Q

What are the 3 groups fungi are divided into depending on where infection occurs

A

Superficial (skin or hair), infection of the nails or subcutaneous layer of the skin, systemic (often seen as opportunistic infections in immune-compromised patients)

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4
Q

How are protozoa classified

A

According to their intracellular or extracellular locations

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5
Q

What are the main sites of protozoa infection in man

A

CNS, skin, urogenital tract, blood, liver and intestines

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6
Q

What are the 3 main groups of helminths relevant in man

A

Tapeworms, flukes and roundworms

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7
Q

What does transmission of helminths mainly occur through

A

Faecal-oral route (ingesting infective eggs or larvae from an infected human host), intermediate (ingesting infective larvae from another infected host), active (larval stage directly penetrates skin) or bit (when insect sucks blood)

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8
Q

What are agents that can penetrate intact skin

A

Biting arthropods, needles, abrasions, surgical wounds

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9
Q

Why is the respiratory tract particularly vulnerable to infection

A

Due to a large moist surface area and limited anatomical barrier between air and blood circulation

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10
Q

What environmental factor may contribute to defense penetration in the respiratory tract

A

Smoking and foreign bodies including food inhalation

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11
Q

Why is the gastrointestinal tract particularly vulnerable to infection

A

Due to large moist surface area that is exposed to the environment

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12
Q

How do most urogenital tract infections occur

A

Via the urethra

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13
Q

Why are the eyes vulnerable to infection during childbirth

A

During childbirth the conjunctivae of the neonate are vulnerable to infections of the mother’s cervix or vagina e.g. Chlamydia trachomatis

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14
Q

What is transmission of a pathogen dependent on

A

The number of organisms and route of shedding, the stability of the pathogen outside of the host, number of organisms required to infect a fresh host

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15
Q

What are the two types of transmission

A

Vertical and horizontal

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16
Q

Describe vertical transmission

A

Mother -> foetus/ neonate. Placental transfer, during deliver, breastfeeding

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17
Q

Describe horizontal transfer

A

Between individuals. Direct or indirect (possibly involving a vector)

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18
Q

Which parts of the body have commensal flora

A

Mouth, gut, skin, upper airways etc.

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19
Q

Describe commensal flora

A

Symbiotic relationship

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20
Q

What is the source of infections that cause meningitis

A

Commonly commensal organisms in the nasopharynx that gain access via bloodstream and hone in on the CNS

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21
Q

How can bacteria be classified

A

By shapes, cultural characteristics, how they reproduce, how they stain and genomic sequencing

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22
Q

Describe the shapes of bacteria

A

Spherical (coccus), long chains (streptococci)m in pairs (diplococci), clusters (staphylcocci), rod shaped (bacillus) comma shaped (vibrio), spiral (spirochaetes)

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23
Q

Describe cultural characteristics of bacteria

A

Whether they need oxygen

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24
Q

Describe how bacteria reproduce

A

Sporing/ non=sporing

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25
Q

Describe a gram positive bacteria

A

Thick later of peptidoglycan

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26
Q

Describe a gram negative bacteria

A

Has a thin peptidoglycan layer and an outer membrane

27
Q

Describe a gram positive result

A

The crystal violet of gram stain is precipitated by gram iodine and is trapped in the thick peptidoglycan layer in gram positive bacteria

28
Q

How are gram negative bacteria visualised

A

By the red counter stain

29
Q

What does the outer membrane in gram-negative bacteria possess

A

Lipopolysaccharides

30
Q

When do anaerobic bacteria cause disease

A

Killed by oxygen. Cause infection in dead devitalised tissue (gas gangrene) or in mixed infections where other organism use available oxygen and allow anaerobes to thrive

31
Q

What are bacterial virulence factors

A

Adherence, invasion, byproducts of growth (gas, acid), toxins, degradative enzymes, cytotoxic proteins, endotoxin, superantigen, induction of excess inflammation, evasion of phagocytic and immune clearance, capsule, resistance to antibiotics, untracellular growth

32
Q

How are capsules a bacterial virulence factor

A

Pathogens are able to evade antibiotics by existing in different genetic strains, which differ in their capsular polysaccharides. Each strain are termed serotypes because antibody-based serological assays are often used to define the differences between them. generation of a protective antibody response to one serotype may not protect you against another serotype

33
Q

What are the main cause of bacterial meningitis

A

Encapsulated bacteria

34
Q

What is a healthcare associated infection

A

Any infection that relates to interaction with healthcare services resulting from surgical site, catheter UTI, central line infection or feeding tube

35
Q

What are the general features of a virus

A

Contain genetic material but are metabolically inert and require replication machinery of the host cell to complete their life cycle. Virsuses consist of a DNA or RNA genome surronded by a shell of protein (capsid)

36
Q

What are the six common steps in a virus cycle

A
  1. Virus entry (specific host and specific cell, mostly receptor-mediated). 2. Uncoating (genome unpacked). 3. Replication (of the genome). 4. Protein synthesis. 5. Assembly. 6. Virus-egress (budding or lysis)
37
Q

What are targets for antiviral drugs

A

All steps of the virus life cycle

38
Q

What is the Baltimore classification scheme of viruses

A

Different nucleic acid genomes in virsuses. Sense (+)- used directly as mRNA to translate viral proteins. Antisense (-)- complementary RNA strand must first be produced within the host cell to be used as mRNA

39
Q

What is class I in the Baltimore classification scheme

A

dsDNA

40
Q

What is class II in the Baltimore classification scheme

A

ssDNA

41
Q

What is class III in the Baltimore classification scheme

A

dsRNA

42
Q

What is class IV in the Baltimore classification scheme

A

(+) ssRNA

43
Q

What is class V in the Baltimore classification scheme

A

(-)ssRNA

44
Q

What is class VI in the Baltimore classification scheme

A

(reverse) RNA

45
Q

What is class VII in the Baltimore classification scheme

A

(reverse) DNA

46
Q

How do viruses gain entry to the body

A

Inhalation (infected droplets), ingestion (contaminated food, drink, saliva), inoculation (injection, trauma, body fluids or insect bite), transplacentally, sexual intercourse

47
Q

What types of viral infection can occur at the cellular level

A

Acute or lytic, persistent or chronic, latent or proviral, transforming

48
Q

Describe and give an example of acute or lytic viral infection at a cellular level

A

Rapid host cell killing and production of progeny virus e.g. Influenza A

49
Q

Describe and give an example of persistent or chronic viral infection at a cellular level

A

Long term infections with low levels of progeny virus e.g. Hepatitis B Virus

50
Q

Describe and give an example of latent or proviral viral infection at a cellular level

A

Viral genome is maintained in an inert state within the host cell e.g. Herpes simplex virus

51
Q

Describe and give an example of transforming viral infection at a cellular level

A

Virus produced altered cell growth e.g. Human Papilloma Virus

52
Q

Which viruses have been associated with human cancer

A

Hepatitis B and C, Human Papilloma Virus, Epstein Barr Virus

53
Q

What are the cellular components of innate immunity

A

Macrophages, dendritic cells, mast cells, neutrophils, basophils, eosinophils and natural killer cells

54
Q

Describe the role of macrophages in innate immunity

A

Located in all peripheral tissue. Able to sense the pathogen through a number of cell surface, cytosolic and endosomal ‘pattern recognition receptors’ (PRRs) that permit recognition of microbe derived components. Macrophages acr as the first innate cell to detect the presence of the pathogen and communicate the detection to other cells through the secretion of inflammatory cytokines (IL-1, IL-6, IL-12, TNF alpha and interferons)

55
Q

What are some of the key effects of IL-1 and TNF alpha

A

Exerted on local blood vessels causing vasodilation of capillaries and making the endothelial wall of vessels more permeable

56
Q

What are macrophages particularly well equipped for carrying out

A

Phagocytosis

57
Q

Describe the role of dendritic cells in innate immunity

A

Located in peripheral tissue, possess PRRs, secrete inflammatory cytokines and can perform efficient phagocytosis. Can also migrate from site of infection via lymphatic vessels to the nearest draining lymph node where they can present MHC/peptide complexes to the TRCs on T naive T cells

58
Q

Describe the role of mast cells in innate immunity

A

Resident cells of myeloid lineage found in all connective tissues. Rich in granules containing histamine and prostaglandins. Activating mast cells (degranulation)= trigger release of histamines/ prostaglandins.

59
Q

What do histamine/ prostaglandins released from mast cells do

A

Act on endothelium of blood vessels at site of infection to both dilate vessels and make vessels more permeable. The released histamines act in concert with IL-1 and TNF alpha

60
Q

Describe the role of neutrophils in innate immunity

A

Machismo cell of innate immunity. Found in blood prior to infection only able to exit if the local endothelium at the site of infection becomes leaky. Enter site of infection in huge number, extremely efficient at carrying out phagocytosis. Most important granulocyte, characterised by irregular shaped nucleus

61
Q

Describe the role of basophils and eosinophils in innate immunity

A

Much rarer granulocytes and are implicated in defense from helminths and protozoa

62
Q

Describe the role of natural killer (NK) cells in innate immunity

A

Primarily found in blood some are located in peripheral tissues. Very important in context of viral infections and can bring about direct lysis of virally infected cells

63
Q

Up to

A

Page 11 components microbes distinguish

PCS Unit 2 (1 decks)

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