Microbio: Infective endocarditis + Wound, bone & joint Flashcards
What is infective endocarditis?
Infection of the innermost layer of the heart, usually the valves
Endocardium = innermost layer of the heart Endocarditis = infection of innermost layer of the heart – especially the valves
Where does infective endocarditis usually affect in the heart?
Usually mitral and aortic valves; R sided (tricuspid) in IVDU
What are the different types of infective endocarditis infection?
Acute: fulminant illness, patient is very unwell
Subacute: over weeks – months, patient is less unwell, more signs O/E
RFs for infective endocarditis?
Bacteraemia (long-term lines, IVDU, poor dentition)
Abnormal valves (prosthetic valves, rheumatic heart disease)
What pathogens cause infective endocarditis?
Acute (high-virulence): Strep pyogenes, Staph aureus (IVDU), CoNS (prosthetic valves)
Subacute (low virulence):
Staph epidermidis, Strep viridans
HACEK: uncommon causes, do not grow on culture
Haemophilus, Acinetobacter, Cardiobacterium, Eikinella, Kingella
What is the presentation of infective endocarditis
Fever
New heart murmur, often changes day to day, regurgitant
In subacute:
- Embolic phenomena: Janeway lesions, splinter haemorrhages, splenomegaly, septic abscesses, microemboli
- Immune phenomena: Roth spots, Osler’s nodes, haematuria
Ix and Rx of infective endocarditis?
Blood cultures (x3, before starting Abx)
Echo
IV Abx for 6wks
E.g. flucloxacillin (if less severe and less RFs), vancomycin, gentamycin (more RFs and more complex disease)
What criteria is used for dx of infective endocarditis?
Duke’s Criteria
2 major, or 1 major + 3 minor, or 5 minor for Dx
Major:
- Positive blood cultures growing typical organisms
- New regurgitant murmur / vegetation on echo
Minor:
- Risk factor
- Fever
- Embolic phenomena
- Immune phenomena
- Positive blood cultures growing other organism
What are some different wound, bone and joint infections and their aetiologies?
Surgical site infection - Direct from skin
Osteomyelitis - local / haem spread
Septic Arthritis - local / haem spread
Prosthetic joint infection - local / haem spread
What are organisms are wound, bone and joint infections caused by?
S. aureus (MAIN)
Other Staphs and Streps
E. coli
What is the presentation of surgical site infection?
Pain, swelling, not healing
How is surgical site infection diagnosed?
Clinical +
Wound swabs
How is surgical site infection managed?
Abx (fluclox) - generally use oral fluclox if they are well and IV if it is deeper infection / v. unwell
What is the presentation of osteomyelitis?
Pain, swelling, fevers, unwell
How is osteomyelitis diagnosed?
MRI
Blood culture
Bone biopsy (v rarely)
