Infections At Surfaces

Question 1

Why can surface infections originate from?

Answer 1

Natural surfaces

Prosthetic surfaces

Question 2

What types of natural surfaces are there?

Answer 2

Skin

Mucosa

Question 3

What type of natural surface infections are there?

Answer 3

External (cellulitis, UTI, Pneumoia)

Internal (endovascular, septic arthritis, Osteomyeitis)

Question 4

What type of prosthetic surfaces are there?

Answer 4

IV lines 
Catheters 
Joints 
Cardiac valaves 
Pacing wires

Question 5

Types of prosthetic infections

Answer 5

Prostheric valve/ pacing wire endocarditis
Joint infections
Infections of other prosthetics

Question 6

What is the importance of microbiotica in mucosal membranes?

Answer 6

Synthasise vitamins

Stop colanisation of harmful bacteria

Question 7

What is the main bacteria that causes prosthetic infections?

Answer 7

Coagulase negative staphylococci

Question 8

How does pathogenesis occour at surfaces?

Answer 8

Adherance to host cell/ prosthetic (eg use pili)
Biofilm formation (allows C neg staph stick)
Invasion and multiplication
Host response (Pyogenic and Granulomatous)

Question 9

What are some important microbiotica on mucosal surfaces?

Answer 9

Vagina- Lactobacilli (maintian low pH, kill invaiding bacteria)
Nasopharynx- steptococcus pneumonia (all carry, only issue when enter lungs)
Skin- Viruses, Bacteria, Fungi and Parasites

All are fine when in normal site

Question 10

What is a Biofilm?

Answer 10

Microbial communities that are attached to surfaces and encased in an extracellular matrix of microbial origin

Gel like substance

Question 11

How does Biofilm aid bacteria?

Answer 11

Prevents bacterial phagocytosis
Prevents antibodies binding
Prevents complement cascade
Prevent antimicrobial reaching the bacteria
Bacteria secreate b-lactamases/ increase ecpression of multi-drug resistance pumps

Question 12

How do Biofilms form?

Answer 12

Surface attatchment of bacteria

Micrococonies

Macrocolonies (cell detatchment)

Question 13

What is Quorum sensing?

Answer 13

Part of biofilm formation

1-Autoinducers (AI) signalling moleclues
2-AI bind to surface/ cytoplasm receptors
3-Gene expression, cooperative behaviours, more AI (can tell other bacteria around as all producing AI so know it is worth while producing biofilm)

Question 14

How do biofilm complicate imfections?

Answer 14

As make it so the infection is resistant to antibiotic treatments

Question 15

What is the managemnt of infected natural surfaces?

Answer 15

1- antibacterials

2-surgery to resect material

Question 16

What is the management of prosthetic surface infections?

Answer 16

remove prosthetic

Question 17

Complications of surface management?

Answer 17

Poor antibacterial penetration of the biofilm
Low metabolic activity of biofilm microbes
Dangers/ difficulties of surgery
Prosthetics avascular (difficult to deliver drugs)