Bloodstream Infections

Question 1

What is sepsis (definition in man)

Answer 1

Life threatening organ dysfunction caused by a dysregulated host response to infection. body’s extreme response to an infection

Question 2

Difference between bacteraemia and septicaemia (now sepsis)

Answer 2

Bac: Presence of bacteria in the blood- may have no disease implications/ asymptomatic & transient
Sept: presence of bacteria in blood with clinical symptoms (e.g temp high/ hear. Rate/ respiratory rate ^of septicaemia)

Question 3

3 types of bacteremia patterns

Answer 3

Transient- cleared rapidly by macrophages- no clinical consequence - dental extraction
Intermittent- in clinical conditions, whether there’s bacteria in blood depends on timing of when blood culture has been taken or whether it has had antibiotics- pneumococcal pneumonia, gram negative sepsis, intra-abdominal abscess
Continuous- continuously in blood; infective endocarditis, catheter bacteria

Question 4

Is Systemic inflammatory response syndrome (SIRS) specific for infection?

Answer 4

NO

Question 5

What are SIRS
Where do we get SIRS (Systemic inflammatory response syndrome)

Answer 5

Systemic signs of inflammation
Infection, trauma, burns, surgery, thrombo-embolism, autoimmune disease, chemical poisoning, vasculitis

Question 6

Sepsis is over or underdiagnosed?

Answer 6

Under-diagnosed

Question 7

Sepsis real definition

Answer 7

SIRS (systemic inflammatory response) plus infection (documented or clinical suspicion of infection)

Question 8

What does uncomplicated infection mean

Answer 8

Infection that isn’t sepsis; no systemic features/physiological derangement,localised; confined to the skin or lungs or bladder etc

Question 9

What is severe sepsis

Answer 9

sepsis induced organ dysfunction or tissue hypo-perfusion- organism are starting to fail due to not enough o2 delivery to tissues

Question 10

What is septic shock and what’s the major problem with it

Answer 10

Sepsis induced hypotension (fall in blood pressure) not responding to fluid resuscitation- sepsis caused by infection causing low blood pressure, to treat this need to give fluids however with septic shock it doesn’t work because vessels are vasodilated and vasculature is leaky therefore fluid being lost

Question 11

Causes of sepsis

Answer 11

-Bacteria;gram positive and gram negative and their secreted products e.g toxins they produce
-Fungi- mainly yeasts
-Some systemic & localised viral infections e.g canine parvovirus,influenza,Ebola
-Malaria

Question 12

Sepsis is a systemic infection. What does it release into blood stream and describe the cycle that this causes

Answer 12

Releases cytokines TNF-a and IL-1 into blood stream which causes loss of blood volume; dilation of veins, blood lost from veins and fluid. In tissues; this leads to physiological derangement i.e coaggulation; leads to clotting factors being used up; leads to bleeding; failure of organs; death.

Question 13

What is the diamond skin disease

Answer 13

Bleeding/clotting of blood into the skin from the bloodstream infection

Question 14

Can sepsis occur even when blood bacteria cultures are negative? (No live bacteria in blood). If yes, how?

Answer 14

Yes, it is a severe localised infection of the e.g lung, urinary tract, soft tissue and bacterial components (peptidoglycan, LPS) are released into blood causing clinical symptoms

Question 15

Difficult or easy to distinguish G-positive from G-neg?

Answer 15

Difficult

Question 16

Certain bacterial toxins called ________ cause systemic symptoms of shock
Which types of bacteria relaease these toxins?

Answer 16

-superanttigens
-bacteria involved in skin or soft tissues- usually gram positive

Question 17

The sepsis cascade

Answer 17

Look over this

Question 18

How does the superantigen (SA) work

Answer 18

Cross links the MHC and T cell receptor; causes massive release of pro-inflammatory cytokines leading to septic shock/toxic shock syndrome

Question 19

What are host cell pattern recognition receptors (PRRs)

Answer 19

Recognition molecules that are the link between organism and activation of sepsis response in host- toll-like receptors
Recognise structures of pathogen

Question 20

What bacterial component do each of these toll like receptors recognise?
-TLR-2
-TLR-4
-TLR-5
-TLR-9

Answer 20

1. Peptidoglycan,lipoproteins
   2.LPS, lipid A
2. Flagellin
3. Bacterial DNA

Question 21

Viral infections and intracellular bacteria recognised by what kind of receptors?

Answer 21

Intracellular pattern-recognition receptors- not surface receptors

Question 22

How do the toll-like receptors work (fungi do this as well)

Answer 22

-bind their specific component
-induces a signal transduction cascade which activates transcription factor
-factor induces pro inflammatory cytokines which have the systemic effects of sepsis and septic chock

Question 23

Which molecule links local/systemic inflammation with acquired immune response?

Answer 23

Macrophages

Question 24

What do citrates macrophages release?

Answer 24

Cytokine

Question 25

Severe sepsis & septic shock causes release of physical derangements such as;

Answer 25

Shock Impaired O2 delivery exchange Lung damage- lung filled with fluid and starts drowning and leaking resulted by complement activated Activation of clotting factors; once used up haemorrhage occurs

Question 26

Where should complement not be active and why?

Answer 26

In tissue as it binds to surfaces, produces membrane attack complex and cells are destroyed

Question 27

Severe sepsis/septic shock clinical implications

Answer 27

Acute Respiratory Distress Syndrome (ARDS) Cardiac output initially rises then falls Hypotension often leads to renal failure Haematology: ^ white cells, ^ platelets -Disseminated Intravascular Coagulation (DIC) -Widespread tissue ischemia & organ failure -Increased bleeding

Question 28

What is Sepsis “therapy” and what does it consist of

Answer 28

Maintenance of physiological parameters as close to normal as possible -Fluid management – maintain arterial and venous pressures -Respiratory support – oxygen or ventilator -Renal support

Question 29

Sepsis is bacterial or viral?

Answer 29

Mostly bacterial but sometimes viral

Question 30

What is primary viraemia and how does it work What is secondary viraemia and how does it work

Answer 30

spread of the virus into the blood from the initial site of infection -clinically silent. Virus acquired that gets into bloodstream and goes to target organ; grown in organ during incubation period Secondary viraemia is when symptoms of infection start appearing; virus multiplied sufficiently and now gets back into blood stream. Once back causes the physiological consequences of sepsis