9 - Infections on Surfaces Flashcards
What are some surfaces in the body that can have their own flora?
What are some viruses that can be found on the skin?
- Papilloma: warts, verrucas
- Herpes Simplex: cold sores
What fungi can be found on the skin?
- Yeast
- Dermatophytes
What bacteria can be found on the skin?
What is coagulate positive staphylococci?
Staph aureus: more likely to cause disease
What gram bacteria are mainly found on the skin?
Mainly gram positive but as go below waist can find some gram negative
What are some parasites that can be found on the skin?
- Mites - Headlice - Scabies
What are some examples of external and internal natural surface infections?
What are some prosthetic surfaces susceptible to infections?
How can bacteria from surfaces cause infections?
- Invasion
- Migration
- Innoculation
- Haematogenous
What bacteria cause prosthetic valve endocarditis?
- >1 year post-operation: Viridans, Streptococci, Enterococcus faecalis, Staph aureus, HÁČEK group, Candida
- <1 year post operation: coagulase negative staphylococci
What bacteria causes native valve endocarditis?
Same as prosthetic >1 year post op
What bacteria cause prosthetic joint infections?
What bacteria causes cardiac pacing wire endocarditis?
What is the mechanism of infection at surfaces?
- Adherence to host or prosthetic surface
- Biofilm formation
- Invasion and multiplication
- Host response
What are the two responses to a surface infection?
- Pyogenic = pus (neutrophils)
- Graunomatous = fibroblasts, lymphocytes, macrophages, forming nodular inflammatory lesions
What is the three steps of management of surface infections?
- Diagnosis
- Treatment
- Prevention
How are surface infections diagnosed and what are some challenges with the identification?
Need to identify organism and it’s antimicrobial susceptibilities e.g blood cultures, tissue sonication and culture
Challenges: adherent organisms and low metabolic state/small colony variants
How are surface infections treated and what are the challenges with treatment?
- Aim: Reduce bioburden and sterilise tissue
- Treatment: antibacterials, remove prosthetic material, surgery to resect infected material
- Challenges: - Poor antibacterial penetration into biofilm, low metabolic activity of biofilm microorganisms, dangers of surgery
What are preventative measures for natural and prosthetic surfaces from surface infections?
What is the process of biofilm formation?
- Process where microorganisms irreversibly attach to and grow on a surface and produce extracellular polymers that facilitate attachment and matrix formation
How do different species form the same biofilm?
- Quorum sensing
- Autoinducers onto cell surface receptors stimulating gene expression so bacteria have coordianted behaviour to form biofilm
