Infections On Surfaces

Question 0

Describe the range and origins of surface infections on both natural and prosthetic surfaces

Answer 0

Natural:
External - conjunctivitis, pharyngitis, cellulitis, UTI, gastroenteritis, pneumonia
Internal - endovascular, septic arthritis, osteomyelitis
Prosthetic:
IV lines, peritoneal dialysis catheters, prosthetic joints, cardiac valves, pacing wires, ventriculoperitoneal shunts, urethral catheters

Question 1

Understand the concept of microbiota and appreciate the range of normal microbiota

Answer 1

Normal microorganisms present:
Eye - coagulase -ve staph, viridans strep, neisseria
Nares - staph aureus
Nasopharynx - neisseria meningitidis, strep. pneumonia, haemophilus influenzae
Mouth - viridans strep, neisseria, lactobacillus, candida
Stomach - helicobacter, strep, staph, lactobacillus
Intestine - lactobacillus, strep, clostridium
Urethra - enterobacteriaceae, lactobacillus, strep
Vagina - lactobacillus, coagulase -ve staph, strep, mycoplasma, yeast

Question 2

Describe the pathogenesis of infections at a surface

Answer 2

Invasion (e.g. pharyngitis)
Migration (e.g. UTI)
Inoculation (e.g. prosthetic joint)
Haematogenous (e.g. endocarditis)

Question 3

Describe the management, prevention and challenges of infected surfaces

Answer 3

Management:
Identify organisms and antimicrobial susceptibility
Sterilise tissue
Reduce bio burden
Prevention:
Natural - maintain surface integrity, prevent bacterial colonisation
Prosthetic - prevent contamination, inhibit/remove colonising bacteria
Challenges:
Poor antibacterial penetration into biofilm
Low metabolic activity of biofilm microorganisms
Dangers/difficulties of surgery