Microorganisms and the chain of infection

Question 1

What is a healthcare associated infection? ( HCAI)

Answer 1

A problem which develops as a direct result of healthcare interventions.

Question 2

How are HCAI’s transmitted?

Answer 2

Any from:
- transmitted via blood, body fluids, secretions
- Inhalation of droplets or airborne infections
-inoculation incidents
- contact with non-intact skin or membranes
- any equipment that has been contaminated

Question 3

What are the risks of developing a HCAI

Answer 3

• increased length of stay
• mortality and morbidity
• drain on financial resources

Question 4

Where are the most common sites of HCAIs?

Answer 4

-Respiratory infections
- surgical site infections ]
- UTI’s

Question 5

General factors affecting the risk of a HCAI

Answer 5

• Age : weaker immune system in elderly and young children
• Mental state: unable to reach self actualisation
• Nutrition: poor diet = susceptible host

Question 6

What are the local factors of HCAIs

Answer 6

• Oedema ( build up of fluid in the body; makes tissues swollen)
• Skin lesions
• Foreign Body
• Ischaemia ( lack of blood flow)

Question 7

What are invasive procedures?

Answer 7

Surgery, Catheterisation, cannulation, intubation.

Question 8

What are the main classification of microorganisms?

Answer 8

-> fungi
-> viruses
-> bacteria
-> protoza

Question 9

Infection vs Colonisation

Answer 9

Colonisation presence of bacteria on a body surface without causing disease in the person i.e response to the presence of a microbe is absent / slight.

Infection: when pathogens / disease causing micro-organisms gain access to host tissue and elicit an immune response.

Question 10

What is commensal?

Answer 10

microbes that live in close association with their host & in the correct environment do not harm it and can positively benefit it e.g skin flora

Question 11

Pathogen

Answer 11

a microorganism that is able to cause disease

Question 12

Pathogenicity

Answer 12

ability to cause disease in a host organism

Question 13

Pathogenesis

Answer 13

process of how a microorganism produces disease

Question 14

Virulence

Answer 14

The degree of pathogenicity e.g. genetic,structural or biochemical features

Question 15

What is microbial flora?

Answer 15

Microbial flora refers to the microorganisms that live on or inside the body, such as bacteria and fungi

Question 16

What is resident flora

Answer 16

less likely to be associated with infections, but may cause infections in sterile body cavities, the eyes, or on non-intact skin.

Question 17

Transient flora

Answer 17

colonises the superficial layers of the skin, is more amenable to removal by routine hand hygiene.

Question 18

How does a microbe establish an infection in a host?

Answer 18

Gain access to a host cell
Adhere to, enter and move to a favourable site
Penetrate or evade host defences in order to multiply
Dissemination of new pathogens within or outside of the host ( exocytosis)

Question 19

What is the chain of infection

Answer 19

Infectious agent: bacteria etc
Reservoirs: people, food etc
Portal of exit: blood, excretions
Modes of transmission: physical
Portals of entry: broken skin
Susceptible host: age

Question 20

What makes microorganisms good pathogens

Answer 20

• Flagella for movement
• Multiple bacteria grouped together
• Spores – enhance ability to survive in unfavourable conditions
• Fimbria – enhance adhesion to surfaces

Question 21

Components of a virus

Answer 21

Nucleic acid- dna or rna
Capsid- protective protein coat composed of capsomers
Envelope: lipidprotein membrane
Glycoprotein spikes: attachment and recognition

Question 22

Viral replication

Answer 22

1)virion attaches to host cell
2) Virion penetrated cell and its dna is uncoated
3)early transcription and translation
4) Late transcription, DNA is replicated
5) Late translation: capsid proteins and synthesized
6) Virions mature
7) Virions are released