Infection

Question 1

What categories of organism cause infection

Answer 1

Largest to smallest:
Helminths
Insects
Protozoa
Fungi
Bacteria
Viruses
Prions

Question 2

What is a parasite

Answer 2

An organism which depends on another for its survival to the detriment of its host

Question 3

What categories of organism are referred to as parasites

Answer 3

Helminths
Insects
Protozoa

Question 4

What are the characteristics of endoparasites and ectoparasites

Answer 4

Endo: live inside of body, major cause of illness, examples are helminths and protozoa

Ect: live outside the body, minor symptoms but can transmit other infections, examples are fleas, lice, bed bugs and ticks

Question 5

What are protozoa and what are the types

Answer 5

Unicellular organisms
Too small to see by eye
Some have complex lifecycles involving more than 1 host

Amoeba
Sporozoa (malaria)

Question 6

What are helminths and what are the characteristics of the different types

Answer 6

Complex organisms
Some have complex lifecycles involving more than 1 host

Cestodes: (tapeworms) segmented, flat
Trematodes: (flukes) unsegmented, flat
Nematodes: (round worms) cylindrical, have digestive tract with lips, teeth and anus

Question 7

What are the two types of fungal infection and their characteristics

Answer 7

Yeats: single cells which bud
Moulds: filamentous strands
Some can switch between yeast and mould

Question 8

What are bacteria

Answer 8

unicellular organisms
Prokaryotes
Cell membrane
Cell wall
No nucleus
Reproduce asexually

Question 9

What is a gram stain

Answer 9

Looks at cell wall because bacteria cell walls vary in composition with some retaining crystal violet stain and others not
Gram-positive: purple
Gram-negative: pink

Question 10

What are viruses

Answer 10

Dependent on infection of host cell for metabolism and replication
Contain protein core, surrounding genetic material, protein coat and outer membrane
Very small
Can only be seen with powerful microscopes

Question 11

What are the three categories of viral infection

Answer 11

Acute
Chronic
Latent

Question 12

What are prions

Answer 12

Smallest infective agents
Not a living organism
Proteins are abnormal and accumulate, mainly in neural tissue
Very difficult to destroy

Question 13

What is an endogenous infection and what is an example

Answer 13

Infection comes from normal flora; usually starts in normal place and moves to the wrong place resulting in an infection
Cystitis (UTI): caused by gut flora moving into urinary tract, most commonly E.coli (gram negative bacteria)

Question 14

What is exogenous infection

Answer 14

Comes from another organism or something in the outside environment

Question 15

How can endogenous infection happen

Answer 15

Migration
Perforation
Blood spread

Question 16

How can exogenous infection happen and what are examples of each route

Answer 16

Contact: direct (Impetigo); indirect (MRSA)
Injury: trauma (Tetanus); bites (malaria)
Airborne (influenza virus)
Oral: food (food poisoning); water
Blood-borne (hepatitis)
Sex (chlamydia)
Mother-to-baby /vertical (Herpes, rubella)

Question 17

What pathogen factors affect response to infection

Answer 17

Infectious dose
Direct infection cells/tissues
Virulence factors and toxins
Resistance to antibiotics

Question 18

What patient factors affect response to infection

Answer 18

Environment
Barriers to infection
Genetics

Question 19

What are examples of bacteria

Answer 19

Staphylococcus aureus
Streptococci
Escherichia coli
Tuberculosis

Question 20

What are examples of Viruses

Answer 20

Rhinovirus (common cold)
Influenza
Hepatitis B/C
HIV

Question 21

What are examples of Fungi

Answer 21

Candida

Tinea

Question 22

What are examples of parasites

Answer 22

Malaria

Hookworm

Question 23

What do each white blood cell type suggest if elevated

Answer 23

Neutrophil: bacterial infection
Lymphocyte: viral infection
Eosinophil: parasitic infection

Question 24

What is the CRP test

Answer 24

C-reactive protein is a marker of inflammation, can show if someone is improving or deteriorating

Question 25

What are UandEs

Answer 25

Urea and electrolyte levels (kidney function)

Question 26

What are LFTs

Answer 26

Liver function tests

Question 27

What tests do microbiologists do with the samples sent to the lab

Answer 27

Antibody detection
Microscopy
Culture
Antibiotic sensitivity testing
PCR
Antigen detection

Question 28

What is the IgM antibody

Answer 28

Initial antibody response

Appears within a week and usually disappears after a few months

Question 29

What is the IgG antibody

Answer 29

Later antibody response
Appears 10-14 days
Persists throughout life as part go immunological memory
Useful to test whether you are immune to an infection

Question 30

What are antimicrobials

Answer 30

Any drug that kills microorganism

Question 31

What are antibiotics

Answer 31

A chemical substance derived from a mould or bacterium that can kill microorganisms and cure bacterial infections

Question 32

What is desired of an antimicrobial

Answer 32

Selective toxicity
Bacteriocidal (kills bacteria) rather than bacteriostatic (inhibits its growth)
No resistance
Good pharmacokinetics
No side effects
Not inactivated by enzymes secreted by microbes or by the host

Question 33

What are the categories of antibiotic action

Answer 33

Cell wall synthesis (---illin, ceph---, ---penem)
DNA replication (quinolone)
Folic acid (trimethoprim)
Protein synthesis (cindamycin)

Question 34

What are broad spectrum vs narrow spectrum antimicrobials

Answer 34

Broad: kill lots of different organisms, may also kill out natural flora
Narrow: kills few specific organisms

Question 35

What is antibiotic stewardship

Answer 35

Using antibiotics wisely to make sure we aren’t overprescribing antibiotics and thereby increasing resistance