Infections on the surface Flashcards
viral skin microbiota
papilloma
herpes simplex
gram positive bacterial skin microbiota
- S.aureus
- Coagulase negative staphylococci
- Corynebacterium
gram negative bacterial skin microbiota
enterobacteriaecaea (E.coli)
fungi skin microbiota
yeasts
dermatophytes (multicellular)
parasitic skin microbiota
mites
mucosal flora in the eye
- Coagulase negative staphylococci,
- Diphtheroids
- saprophytic Neisseria species
- viridans group
- streptococci
mucosal flora of the nares (nose)
s.aureus
mucosal flora of the nasopharynx
mucosal flora of the mouth
- Viridans streptococci
- Neisseria
- Lacrobacillus
- Bacteroides
- Candida
mucosal flora of the stomach
- Helicobacter
- Streptocccus
- Staphylococci
- lactobacilli
mucosal flora of the intestine
- Bacteroides
- Lactobacillus
- Clostridium
- yeasts
mucosal flora of the urethra
mucosal flora of the vagina
- lactobacilli
- coagulase-negative staphylococci
- yeasts
- mycoplasmas
how do people get infections
When commensal (microbiota) carried on the skin and mucosal surfaces transfer to other sites.
ways commensal microorganisms are carried from the skin or muscosal sites to other sites
invasion- strep pyrogene pharyngitis
migration- e.g. E.coli UTI
inoculation - e.g. during surgery. Coagulase negative staphylococcus prosthetic joint infection
haemtogenous- virdans strep endocarditis. Bacteria from mouth eveolved to stick.
Natural surface infectionExternal
- Cellulitis
- Pharyngitis
- Conjunctivitis
- Gastroenteritis
- Urinary tract infection
- Pneumonia
Natural surface infection: Internal
- Endovascular
- Endocarditis
- Vasculitis
- Septic arthritis
- Osteomyelitis
- Empyema
prosthetic surface infections
- Intravascular lines
- Peritoneal dialysis catheters
- Prosthetic joints
- Cardiac valves
- Pacing wires
- Endovascular grafts
- Ventriculo-peritoneal shunts
cardiac pacing wire endocarditis
- Coagulase negative staphylococci
- S.aureus
- Hard to treat due to resistance
- Much more specific pathogens that cause this kind of infection compared to infection >1 post-operation
prosthetic valve endocarditis
1) Native valve endocarditis and prosthetic valve endocarditis >1 year post-operation
- Viridans
- Streptococci
- Enterococcus faecalis
- S.aureus
- Candida
2) Prosthetic valve endocarditis <1 year post-operation
- Coagulase negative staphylococci
prosthetic join infection
- Coagulase negative staphylococci
- S.aureus
processes in the pathogenesis of infection at surfaces
- Adherence to host cells or prosthetic surface
- Using Pili or fimbriae
- Biofilm formation
- Invasion and multiplication
- Host response
- Pyogenic (formation of pus- neutrophils)
- Granulomatous (fibroblasts, lymphocytes, macrophages –> nodular inflammatory lesions
How do microorganisms cause disease?
Virulence factors
virulence factors
exotoxins and endotoxins
exotoxins
- Cytolytic
- AB toxins
- Superantigenss
- Enzymes
endotoxins
- LPS
- Peptidoglycan
host cellular damage
- Direct
- Consequent to host immune response
management of surface infections: diagnosis
- Admin to identify infecting organism and its antimicrobial susceptibilities
-
Challenges
- Adherent organism
- Low metabolic state/small colony variants (harder to growth)
- Blood cultures
- Tissue/ prosthetic sonication and culture (ultrasound bath)
management of surfaces infections: managment
-
Aim:
- Sterilise tissue
- Reduce bioburden
- Antimicrobials
- Remove prosthetic material and resect infected material
-
Challenges
- Poor antimicrobial penetration into biofilm
- Low metabolic activity of biofilm micro-organisms
- Danger/ difficulties of surgery
prevention: natural surfaces
- maintain surface integrity (good quality skin care- moisturise)
- Prevent bacterial surface colonisation
- Remove colonising bacteria
prevention: prosthetic surfaces
- Prevent contamination
- Inhibit surface colonisation
- Remove closing bacteria
