Session 6-Infections On Surfaces

Question 1

What is a surface?

Answer 1

Interface between solid and either liquid or gas

Question 2

Which skin surfaces can infection arise from?

Answer 2

Epithelium
Hair
Nails

Question 3

Which mucosal surfaces can infection arise from?

Answer 3

Conjunctival
Gastrointestinal
Respiratory
Genitourinary

Question 4

Which viruses are skin microorganisms?

Answer 4

Papilloma

Herpes simplex

Question 5

Which gram positive bacteria are present on skin?

Answer 5

• Staphylococcus aureus
• Coagulase negative staphylococci
• Corynebacterium

Question 6

Which gram negative bacteria are present on skin?

Answer 6

Enterobacteriaceae

Question 7

Which fungi are present on skin?

Answer 7

• yeasts

- dermatophytes

Question 8

Give an example of flora in the eye

Answer 8

Coagulase negative staphylococci

Question 9

Give an example of flora in the nasopharynx

Answer 9

Neisseria meningitidis

Streptococcus pneumoniae

Question 10

Give an example of flora in the mouth

Answer 10

Viridans streptococci

Question 11

Give an example of flora in the stomach

Answer 11

Helicobacter

Question 12

How do people get infections and give an example of an infection for each method?

Answer 12

• invasion: strep pyogenes pharyngitis
• migration: E. coli UTI
• inoculation: coagulase negative staph prosthetic joint infection
• haematogenous: viridans Strep endocarditis

Question 13

Give examples of external surface infections

Answer 13

Cellulitis
Pharyngitis 
Conjunctivitis 
Gastroenteritis 
UTI
Pneumonia

Question 14

Give examples of internal surface infections

Answer 14

Endocarditis 
Vasculitis 
Septic arthritis 
Osteomyelitis 
Empyema

Question 15

Which organisms cause prosthetic joint infections?

Answer 15

• Coagulase negative staphylococci

- Staphylococcus aureus

Question 16

Which organisms cause cardiac pacing wire endocarditis?

Answer 16

• coagulase negative staphylococci

- staphylococcus aureus

Question 17

What are the processes in the pathogenesis of infection at surfaces?

Answer 17

• adherence to host cells or prosthetic surface
• biofilm formation
• invasion and multiplication
• host response (pyogenic or granulomatous)

Question 18

What is biofilm?

Answer 18

Slime layer which protects bacteria against host defences and antimicrobial agents

Question 19

What are the three principles of quorum sensing?

Answer 19

1) signalling molecules - autoinducers (AI)
2) Cell surface or cytoplasmic receptors
3) gene expression -> co-operative behaviours and more AI production

Question 20

How can natural surface infections be prevented?

Answer 20

• maintain surface integrity
• prevent bacterial surface colonisation
• remove colonising bacteria

Question 21

How can prosthetic surface infections be prevented?

Answer 21

• prevent contamination
• inhibit surface colonisation
• remove colonising bacteria