Lecture 15: Endocarditis and Meningitis

Question 1

What is infective endocarditis

Answer 1

An infection of the encardial surface of the heart

Question 2

What part of the heart is infective endocarditis most involved in

Answer 2

mostly involved in the heart valves, but the wall of the heart may be involved or infected ion may occur at the site of structural defects

It I’d also very common for patients with prosthetic valves and other foreign materials in their valves

Question 3

Explain how the heart works

Answer 3

The blood comes up the great veins and gets into the right side of the heart and then down into the right ventricle and is pumped out into the pulmonary truck and goes out to the lungs, comes back through the left atrium into the left ventricle and shut out through the aorta

Question 4

What are considered acute infections in infective endocarditis

Answer 4

Presenting within 6 weeks, often caused by more virulent organisms that cause more damage more quickly

Ex. S. Aureus, S. pneumoniae

Question 5

What are considered Subacute infections in infective endocarditis

Answer 5

Presenting from 6 weeks to 3 months

Often caused by organisms of low virulence with gradual destruction of valves

Ex. Viridans (alpha haemolytic) Streptococci

Question 6

What are considered chronic infections in infective endocarditis

Answer 6

Presenting after more then 3 months

Often caused by organisms of low virulence wirh gradual destruction of the valves

Ex. Viridans (alpha hemolytic) Streptococci

Question 7

How do Viridans work in infective endocarditis

Answer 7

They are found in the mouth, they produce these sticky substances that enable them to stick onto the side of the teeth, they can also use this sticky substance to hang on in the heart valves

Question 8

What is the epidemiology of endocarditis

Answer 8

Infective endocarditis is very rare; approximately 20 cases per year might be seen at the QEII

Question 9

What type of hearts does endocarditis take place on

Answer 9

Normal and abnormal heart valves and on congenital abnormal hearts

Question 10

What bacteria typically infects normal hearts with endocarditis

Answer 10

S. Aureus (a highly virulent bacterial)

Question 11

What is most likely to cause endocarditis on abnormal valves and where are these organisms most common

Answer 11

Low virulence, oral and skin microorganisms are more likely to cause infection on abnormal valves (e.g. alpha hemolytic streptococci, enterococci, and coagulase negative staphylococci).

Most common in the oral and gastric flora and produce capsular materials to aid in sticking to teeth (and heart valves)

Question 12

What is the most common organism to cause native valve IE

Answer 12

Alpha haemolytic (“Viridans”) Streptococci

Question 13

What are the risks of infection in prosthetic valves

Answer 13

They are most susceptible and may be infected by all of the above in addition to bacteria contaminating the valve at the time of its insertion

Ex. Coagulate negative staphylococci are commonest in PV IE

Question 14

What is bacteremia

Answer 14

Bacteria circulating in the blood

Question 15

Describe the steps in the pathogenesis of Endocarditis

Answer 15

1. Mucous membranes and skin are colonized
2. Trauma results in bacteremia
3. Organisms adhere to roughed endocardial surfaces
4. Adherence is promoted by fibrin, platelet aggregation, and endothelial damage
5. Further platelet fibrin depositions takes place
6. Bacteria divided begins and vegetations (looks like warts) develop
7. Vegetations develop with dormant organisms at the centre
8. As vegetation fragment, parts break off into the blood stream and embolism other organs (ex., brain or kidney)

Question 16

What are the consequences of infection of the heart valves

Answer 16

Cauliflower vegetations may develop on the valves, and impair normal valve function or mat break off into the systemic circulation

Ongoing inflammation may destroy the valve and produce valvular insufficiency

Small emboli may enter the coronary arteries and cause myocardial infarction

Abscesses may develop in the heart muscle which impair electrical conduction

Question 17

What are the consequences in the brain of endocarditis

Answer 17

The cortex may be showered with multiple micro-emboli (block vessels in the brain from blood clots) regulating in the development of confusion or coma

Large emboli may produce a stroke

Large emboli may occasionally result in one or more brain abscesses

Meningitis may occur from ongoing bacteraemia or emboli

Question 18

What are the consequences in the kidney of endocarditis

Answer 18

Large emboli may break off and obstruct renal arteries

Immune complexes (bacterial antigens, complement and immunoglobulin) may cause renal kidney inflammation and damage

Question 19

Can endocarditis affect the spleen

Answer 19

yes, emboli from large vegetations may go to the spleen, extremities, eye, or other organs

Question 20

In endocarditis occasionally involved blood vessels will ____ and result in ___

Answer 20

weaken

stretching and bursting

Question 21

What are janeway lesions

Answer 21

They are peripheral emboli that look like black dots on the skin or under nails

Question 22

What increases the risk of developing endocarditis

Answer 22

previously recognized valvular heart disease

Preceding dental or other surgical procedures

Intravenous drug use (Encouraging bacteria to get into the blood)

Recent heart surgery

Long standing indwelling lines

Question 23

How is endocarditis diagnosed

Answer 23

Blood cultures: they are positive in approximately 90% of cases
Negative cultures may occur with prior treatment or with organisms that do not grow in blood cultures

Echocardiogrpahy (looking at the action of heart in real time) it recognizes vegetations, if valves are moving abnormally

Question 24

What is the treatment for endocarditis

Answer 24

The treatment is customized for every patient and depends on;

• They type of organism and its susceptibility pattern
• The presence or absence of foreign material (harder to treat)
• The feasibility of surgery
• Allergies, toleration of the therapy and convince

Question 25

How long are cases of endocarditis created for

Answer 25

almost all cases are treated for at least 4 weeks

Question 26

What type of combination treatments are common for endocarditis

Answer 26

penicillin and aminoglycoside combinations which act more effectively when combined for some organisms

Question 27

Who has published guidelines for prophylactic antibiotics for at risk dental and surgical procedures

Answer 27

The American Heart Association

Question 28

What prevention is there for endocarditis

Answer 28

Prophylactic antibiotics are normally given immediately before and for several hours after the procedure when a bacteremia is considered likely

Antibiotics likely interfere to decrease bacterial adherence so infection does not become established

Question 29

What is meningitis

Answer 29

Inflammation of the membranes covering the brain and spinal cord (meninges)

This inflammation of the brain tissue is encephalitis (usually viral)

Question 30

What symptoms are associated with acute meningitis

Answer 30

sudden onset
headaches that can lead to comotose
neck stiffness
Confusion (as the infection progresses)

Question 31

What are the causes of acute bacterial meningitis

Answer 31

Streptococcus pneumonia

Neisseria meningitides (cousin of Neisseria gonerria): common in young adults

Haemopilus influenzae: less common because of immunization

Listeria monocytogenes: common in babies, older, and immuno suppressed

Question 32

What are causes of acute viral meningitis

Answer 32

Enteroviruses (esp late summer and fall)
Arboviurses (transmitted by vectors)
Herpesviruses

Question 33

Is bacterial or viral causes of meningitis more severe

Answer 33

Bacterial is more severe

Question 34

what are the causes of chronic meningitis

Answer 34

Other diseases may be complicated by meningitis such as;

syphilis and Lyme disease
Tuberculosis
Cryptococcus ( a fungus) infection

Question 35

What is the epidemiology of Streptococcus pneumoniae

Answer 35

Streptococcus pneumoniae occurs in both young children and adults and does not cause outbreaks

Question 36

What is the epidemiology of Neisseria meningitides

Answer 36

Neisseria meningitides occurs primarily in infants, younger children, and teenagers/young adults; both sporadic and outbreak cases occur. Immunization may reduce future rates

Question 37

What is the epidemiology of Haemophilus influenza

Answer 37

Haemophilus influenza affects children between 3 months and 5 years. Now virtually eliminated where HI vaccine is used

Question 38

What is the epidemiology of Listeria monocytogenes

Answer 38

May affect the very young and the older (<50); most cases are likely food related and outbreaks occur

Question 39

What is the epidemiology of enteroviruses

Answer 39

Usually responsible for mild cases during summer may occur in clusters

Question 40

What is the epidemiology of arboviruses

Answer 40

these are misquotes seen primarily in localized areas of the work where the virus, mosquitos and other hosts encounter optimal conditions

Question 41

Describe the initial invasion of the pathogenesis of bacterial meningitis

Answer 41

1. Nasopharyngeal colonization (common esp in young adults crowed together)
2. Local invasion
3. Bacteremia
4. Meningeal invasion (headaches, bacteria is starting to multiply under the membranes causing inflammation and puss)
5. Bacterial replication in the subarachnoid space
6. Release of bacterial cell wall components, endotoxins are very toxic and cause inflammation

Question 42

Describe the development of the disease in the pathogenesis of bacterial meningitis

Answer 42

1. Release of bacterial cell components
2. Activation of macrophages to release cytokines
3. Subarachnoid space inflammation
4. Increased CSF (very delicate and clear gets cloudy with this) outflow resistance
5. Cerebral vasculitis (swelling of brain)
6. Increased blood brain barrier permeability
7. Increased brain edema
8. Confusion and coma

Question 43

How is meningitis diagnosed

Answer 43

clinical features: headaches, stiff neck, fever, confusion (can progress over hours)

CT scan showing no evidence of a mass in the brain

Cloudy cerebral spinal fluid with increased numbers of white cells, high protein and low glucose

Organisms seen on gram stain (not always seen though) may be negative when antibiotics have been administered, or in early infection

CSF culture for bacteria, culture of blood also useful, PCR for bacteria in CSF may be used if cultures are negative

Question 44

How is viral meningitis diagnosed

Answer 44

viral meningitis may be diagnosed using PCR

Question 45

How is chronic meningitis diagnosed

Answer 45

test for specific agents

Question 46

What is the treatment for meningitis

Answer 46

usually given empirically (right away) before the organism has been identified

Cerftriazone/vancomycin + ampicillin for a risk groups

Question 47

What treatment is given for S. pneumonia meningitis

Answer 47

third-generation cephalosporin (such as cerftriaxone), vancomycin if resistant

penicillin treated for a week

Question 48

What is the treatment for neisseria meningitis

Answer 48

ceftriaxone: penicillin for a week

Question 49

What treatment is used for haemophilia influenzae

Answer 49

cerftriaxone

Question 50

What treatment is used for Listeria

Answer 50

ampicillin because its resistant to all cephalosporins

treated for 3 weeks or so, hard to get rid of

Question 51

What is meant by definitive treatment

Answer 51

once the cause is known