Cardiovascular Infections
Normal flora and defenses
• Sterile site
– Has NO normal flora. • Inaccessible ? (no – relatively easy and regular) • Unsuitable? (you have got to be kidding!) • PROTECTED? (Yes!)
• Defenses
– Mechanical (moving and “teflon” like endothelium) – Biological • Circulating immune cells and molecules • Reticulo-endothelial system
Bacteria in bloodstream
• Bacteraemia
» Transient presence. » Organisms not multiplying. » Patient asympotomatic. » Important means of spread for other diseases.
• Septicaemia
» Organisms actively multiplying. » Acutely symptomatic
Bacteraemia or Septicaemia
Bacteria enter the bloodstream bacteraemia HOST - susceptibility
Examples • Oral organisms and cardiac defects = endocarditis. •Meningococci and meningitis •Bowel organism and perforation. (Strongyloides bedtime
septicaemia MICROBE -virulence -number
Septicaemia
• Symptoms
– Fevers, chills, spiking temperature, rigors – Rash (petaechial)
• Mortality
– – – – Very high even with prompt therapy. Gram positive 10 – 20% Gram negatuve 25 – 40% Septic shock 40 – 90%
Septic shock
• Gram positive – some exotoxins. • Gram negative – all have endotoxin.
Endotoxin
Chemical mediators of HOST origin Endogenous pyrogen
FEVER
Vaso-actives
SHOCK
Clotting factors
DIC
MULTI ORGAN FAILURE
You don’t “catch” septicaemia
• Urinary tract infections
– Pyelonephritis, catheterisation.
• Respiratory tract
– Pneumonia (pneumococci) – Colonization (meningococci)
• Abscess
– Intermittent seeding.
• Surgical (and other) wounds
– Site is an important modifier – INDWELLING MEDICAL DEVICES
Venous catheter related BSI’s
• Commonest cause of BSI’s in Australia.
– 3500 cases annually (1.5 CR-BSI per 1000 admissions) – 25% case fatality (50% of which is directly attributable)
• Location of venous line
– Central line has 20X daily risk of peripheral line
• Access
– Down outside of catheter, in catheter, in infusate
• Prevention / treatment
– Minimize use and duration, optimize location. Collignon; Aus – Teams for insertion and care Prescriber – Antibiotics and REMOVAL
Blood cultures
Urine
Blood
Blood
days Broth
Blood cultures
• Need a “specimen collection” and culture strategy to deal with small numbers of organisms that may be present intermittently.
– Multiple collections (3 in 24 hours) – Maximum volume (do not overfill!)
– Aseptic collection / handling technique is CRITICAL – What if patient has venous catheter? • Do not take from catheter line!
Bacterial endocarditis
• Infection of endocardium • Portal of entry - primary focus / event Prior Bacteraemic injury - minor breach Sticky phase
endocardium transient Fibrin and platelets Bacteria adhere and multiply vegetation
Valve dysfunction and emboli
Bacterial endocarditis
• ACUTE versus SUB ACUTE
– Progression, virulence of organism, host factors
• Diagnosis
– Clinical (sounds), blood culture
• Treatment
– Prolonged aggressive combination therapy.
• Prevention
– Prophylactic antibiotics for those “AT RISK” • Previous endocardial damage or susceptibility • PLUS procedures producing bacteraemia