This document discusses infective endocarditis, which is an infection of the inner lining of the heart. It outlines predisposing factors like congenital heart defects, risk factors like intravenous drug use, and the typical causative organisms. Staphylococcus and streptococcal species are common causes. Vegetations form on the heart valves as platelets and fibrin deposit, allowing bacteria to adhere and grow. The document details the pathogenesis and characteristics of different organisms that can cause this infection.

1. ENDOCARDITIS
By : Mahalatchmy Tamil Selvan
012012100321

2. OUTLINES
 PREDISPOSING FACTORS
 PATHOGENESIS
 GENESIS OF VEGETATION
 CAUSATIVE ORGANISMS
 RISK FACTORS
 REFERENCES

3. PREDISPOSING FACTORS
a) Congenital valve disease.
b) Septal defects (usually ventricular).
c) Degenerative valve disease.
d) Rheumatic heart disease.
e) Intravenous drug abuse (right-sided IE,
common in young males).

4. CONT..
f) HIV infection.
g) Calcified aortic valve (usually in elderly patients).
h) Cardiac surgery, including artificial or biological
valve implants.
i) Bacteremia of oral or dental origin (Prophylaxis is
directed mainly against streptococcus sp.).
j) GIT: Colonic carcinoma and Colonoscopy (usually
associated with Streptococcus bovis)

6. PATHOGENESIS
a) Surface Alteration
b) Non-Bacterial Thrombotic Embolism
i. Fibrin/Platelet deposition
c) Bacterial attachment
i. Transient bacteremia
d) Sheath covering
i. Fibrin/Platelets
ii. Protective environment
iii. Vegetation growth
 109-1010 org per gram of tissue
 Valvular tissue destruction

7. VEGETATION (abnormal growth)
a) Damaged vascular endothelium promotes
platelet and fibrin deposition. (sterile)
b) These small thrombi allow organisms to
adhere and grow. (protective environment)
c) More fibrin and platelets are deposited
leading on to a infected vegetation.
(bacterial)
BACTEREMIA
a) Presence of bacteria in blood
CONT..

8. Endothelium resistant to bacteria and thrombus formation
Endothelial injury and hypercoagulable state- high velocity jets, obstructive
lesions, aberrant flows, direct invasion by virulent pathogens can lead to
non-bacterial thrombotic embolism(NBTE).
Mitral regurgitation, Aortic stenosis, Aortic regurgitation, Ventricular
Septal Defect, complex congenital heart disease can create NBTE.
Most bacteria find NBTE a convenient site or nidus for adherence.
Virulent organisms- Staph. aureus, Strep. pyogenes, Strep. pneumoniae
have surface molecules which allow them to adhere to intact endothelium
and to exposed sub-endothelial tissues.
If the adhering bacteria are able to survive serum cidal activity, peptides,
complement , antibody etc., they multiply – infective vegetation.

9. CONT..
PATHOGENESIS :
a) Caused by turbulent flow
b) Caused by Intravenous drug user
c) Caused by prosthetic heart valve

10. CONT..

12. The aortic valve with a large,
irregular, reddish tan vegetation
Here, infective endocarditis on the
mitral valve has spread into the septum
all the way to the tricuspid valve,
producing a fistula.

13. Rheumatic
heart disease
IVDUEarly Prosthetic
valves (60 Days)
Late Prosthetic
valves
High-pressure
gradients and
turbulent flow
Direct
intraoperative
contamination
Endothelialization
of the sutures
(attachment sites
for bacteria)
Staphylococcus epidermidis
Staphylococcus aureus
Drug particles
bombardment
Platelets + Fibrin = Primary sterile
Vegetation
Bacterial vegetation

14. CAUSATIVE ORGANISM

15. CHARACTERISTICS OF CAUSATIVE
ORGANISM
a) Adherence factors critical for growth in the vegetation
i. Can adhere to damaged valves (Staph, Strep and
Enterococci have adhesins that mediate
attachment)
ii. Staph adhesin binds fibrinogen and fibronectin
iii. Bacteria trigger tissue-factor production from
local monocytes and induce platelet aggregation
so the organisms become enveloped in the
vegetation
iv. Protection from immune clearance leads to large
numbers of bacteria (109-1010 per g of tissue)

16. CAUSATIVE ORGANISMS
IN NON-DRUG USER
a) Among non–drug users with native valve endocarditis,
Staphylococcus is responsible for >30% of cases,
followed by streptococci and enterococci.

17. CAUSATIVE ORGANISMS
IN DRUG USER
a) Skin flora and contaminated injection devices are the
most frequent sources of microorganisms.
b) S. aureus accounts for >50% of cases, followed by
streptococcal species, and coagulase-negative
staphylococci.
c) Streptococci and enterococci infect previously abnormal
mitral or aortic valves in addicts.

18. CAUSATIVE ORGANISMS
IN –VE BLOOD CULTURES
a) Blood cultures are negative in about 5% of patients
with IE, and half of those are due to prior antibiotic
administration.
b) For those cases associated with negative blood
cultures and without prior antibiotic
administration, infection is due to fastidious
organisms, such as:
i. Bartonella species, or Coxiella burnetii.
ii. The HACEK group

19. HACEK GROUP
a) Haemophilis parainfluenzae
b) Actinobacillus
c) Cardiobacterium
d) Eikenella
e) Kingella

20. CAUSATIVE ORGANISMS
IN PROSTHETIC VALVE IE
a) Early prosthetic IE: Often reflect contamination
during the perioperative period, with S.
epidermidis being a commonly isolated organism.
b) Late prosthetic IE: usually cuased by Staph. aureus.
c) Aspergillus and Candida albicans account for the
majority of cases of mycotic prosthetic valve
endocarditis, and are associated with large
vegetations and emboli.

21. NOSOCOMIAL INFECTIVE
ENDOCARDITIS
a) Staphylococcus aureus
b) Enterococci.

22. RISK FACTORS
a) Structural heart disease
i. Rheumatic, congenital, aging
ii. Prosthetic heart valves (highest risk)
b) Intravenous drug abuse (IVDA)
c) Invasive procedures (surgical)
d) Artificial heart valves and pacemakers
e) Cardiac lesion
f) Nosocomial bacteremia

23. CONT..
e) Acquired heart defects
i. Calcific aortic stenosis
ii. Mitral valve prolapse with regurgitation
f) Congenital heart defects
g) Intravascular devices (pul.art.catheters)
h) History of Infective Endocarditis
i) Other infection with bacteremia (pneumonia,
meningitis)

24. Q & A
1. Which of the following organisms is not commonly implicated in
infective endocarditis?
A. Streptococcus species
B. Staphylococcus species
C. Enterococcus species
D. Candida species
2. A condition associated with the highest risk of developing infective
endocarditis (IE) is :
A. mitral valve prolapse with regurgitation
B. the presence of a prosthetic heart valve
C. rheumatic fever without valvular defects
D. intravenous drug abuse

25. REFERENCES
a) Mims Microbiology
b) Microbiology lecture notes
c) www.medscape.com
d) Slideshare

26. THANK YOU