CSI 3 hospital acquired infections

Question 1

What is meant by a reservoir

Answer 1

A reservoir of an infectious agent is the habitat where it normally grows e.g humans

Question 2

Give some examples of diseases without intermediaries

Answer 2

STDs, measles, mumps

Question 3

Why was smallpox eradicated after the last human case was identified and isolated

Answer 3

Humans are the only reservoir for the smallpox virus

Question 4

What is a carrier when referring to a human

Answer 4

Someone who has no symptoms but can still capable of transmitting the disease to others

Question 5

What is the difference between a carrier and a vector

Answer 5

A carrier is infected with the pathogen (even if they are asymptomatic) but a vector is not infected with it

Question 6

What are 3 different types of carriers

Answer 6

Incubatory, convalescent and chronic

Question 7

What is a incubatory carrier

Answer 7

Someone that can transmit the agent during the incubation period before chronic illness begins

Question 8

What is a convalescent carrier

Answer 8

Those who have recovered from illness but remain capable of transmitting it to others

Question 9

What is a chronic carrier

Answer 9

Someone that continues to harbour the causative agent for weeks or months after infection

Question 10

What is zoonosis

Answer 10

Infectious disease that is transmissible under natural conditions from vertebrae animals to humans

Question 11

Give 5 ways in which a pathogen can leave a host

Answer 11

Respiratory tract, urine, feces, crossing placenta from mother to foetus, cuts or needles in skin

Question 12

Describe and explain the two modes of direct transmission

Answer 12

Direct contact - skin to skin and sexual intercourse
Droplet spread - coughing, sneezing in short range

Question 13

Describe 3 ways of indirect transmission

Answer 13

Airborne transmission - when infectious agent is carried by dust or droplet suspended in air
Vehicles - food, water, blood or formites (inanimate objects)
Vectors - Mosquitoes, fleas and ticks

Question 14

Give 3 examples of non specific factors that defend against infection

Answer 14

Skin, mucous membranes and gastric activity

Question 15

How can vehiclebourne transmissions be reduced

Answer 15

Elimination or decontamination of vehicle

Question 16

How can airborne transmission be reduced

Answer 16

Modify ventilation or air pressure, filtering or treating air

Question 17

How can vectorbourne transmission be reduced

Answer 17

Controlling vector population e.g bug spray

Question 18

Give 2 examples of interventions that aim to increase a Hosts defence

Answer 18

Vaccination, prophylactic use of antimalarial drugs

Question 19

What type of intervention might prevent a pathogen from encountering a susceptible host

Answer 19

Herd immunity

Question 20

What is a hospital acquired infection

Answer 20

An infection a patient gets whilst receiving treatment for medical or surgical conditions

Question 21

What are the 4 main risks factors of HAIs

Answer 21

Medical procedures and antibiotic use, organisational factors, patient characteristics, behaviour of healthcare staff

Question 22

How can HAIs be prevented

Answer 22

Increased compliance with and adoption of best practices of healthcare workers

Question 23

What is a bacterial cell wall made of

Answer 23

Lipid bilayer and peptidoglycin matrix

Question 24

What are the differences in cell walls between gram positive and negative bacteria

Answer 24

Gram positive - builds thick peptidoglycan sheath around a single membrane whereas gram negative builds a thin layer between two lipopolysaccharide membranes

Question 25

What colour are gram positive and negative bacteria

Answer 25

Positive is purple Negative is red/pink

Question 26

When someone has an infection what are their WBC count, CRP levels and Respiratory rate like

Answer 26

All high

Question 27

How does penicillin obstruct bacteria

Answer 27

It prevents peptidoglycan production so cell bursts due to osmotic pressure

Question 28

How does penicillin prevent peptidoglycan production

Answer 28

It binds to serine on the penicillin binding proteins active site which inactivates the enzyme preventing it from forming a peptidoglycan matrix

Question 29

How does MRSA evade certain antibiotics

Answer 29

It expresses penicillin binding protein 2a which has an altered active site which penicillin and other similar antibiotics cannot bind to

Question 30

How can an antibiotic be inactivated

Answer 30

Enzyme degradation or alteration making it useless

Question 31

How can bacteria evade beta lactam containing antibiotics

Answer 31

It can express a beta lactamase enzyme that breaks the beta lactam of the antibiotic making it useless

Question 32

How can antibiotics overcome bacteria that produces beta lactamase

Answer 32

They contain beta lactamase inhibitors, allowing the beta lactam in the antibiotic to work normally

Question 33

What is horizontal gene transfer

Answer 33

Where genetic material (plasmids) are transferred to another organism that isn’t its offspring

Question 34

What is vertical gene transfer

Answer 34

Transfer of genetic information including mutations from parent to offspring

Question 35

How can antibiotic resistance within one population of bacteria spread to another population

Answer 35

Horizontal gene transfer of antibiotic resistance or by vertical gene transfer from one generation to the next

Question 36

What are antimicrobials

Answer 36

Drugs used to treat infections and disease caused by microbes

Question 37

What are the two types of microbes treated by

Answer 37

Bacteria by antibiotics Fungi by antifunguls

Question 38

Where do you typically find antibiotic resistant DNA in bacteria

Answer 38

Plasmids

Question 39

What gram of bacteria has an outer layer that protects it from their antibiotics Drugs

Answer 39

Gram negative

Question 40

How do germs get rid of antibiotics

Answer 40

Use pumps in their cell walls to remove antibiotic drugs that enter the cell wall

Question 41

What other methods do bacteria use to get rid of antibiotics

Answer 41

Change or destroy antibiotics using an enzyme Develop new processes that avoid the antibiotics target Change the antibiotics target so it no longer does it’s job

Question 42

What is sepsis

Answer 42

Body’s extreme reaction to an infection which can lead to tissue damage, organ failure and death

Question 43

What is meant by shock

Answer 43

Inbalance in supply and demand

Question 44

What is the sequence of septic shock

Answer 44

Hypotension > tachycardia > tachypnoea (high respiratory rate)

Question 45

How are antibiotics delivered during sepsis

Answer 45

Intravenously as they have a faster delivery than oral antibiotics