Bloodstream Infections

Question 1

Why should blood normally be sterile?

Answer 1

Lysozyme
Leucocytes
Immunoglobuline (sIgA)
Complement

Question 2

What is a transient bloodstream infection?

Answer 2

This is wherby bacteria can enter the bloodsteam but only for a few minutes
They are quickly moped up by the leucocytes etc

Question 3

What causes a transient blood infection to become a bloodstream infection?

Answer 3

If host defences are overwhelmed or evaded

Question 4

What is the mortality associated with bloodstream infections?

Answer 4

Between 10 and 40%

Question 5

Other than the high mortality rate associated with BSI, what is the main major concern with BSI?

Answer 5

Patients who survive sepsis have a x2 times risk of dying in the next 5 years

Patiens usually suffer physical and cognitive impairment after survival

Question 6

What is the mortality of BSI based on?

Answer 6

It is based on what organism you are infected with vs host immune system

Question 7

What are the four ways that a bloodstream infection can occur, give examples of each?

Answer 7

A focal point of infection within the body outside of the blood (most common) -> e.g. a UTI (urosepsis) or S. pneumonia pneumonia spread to blood

Normal flora of the skin/mucous membrane such as S. aureus enter through cuts or wounds/burns etc

Gut flora enter through GIT perforation, infection or diverticulitis e.g. E. Coli

Direct introduction e.g. IV drug users, intravenous catheters or contaminated medical equipment

Question 8

What are the different names for BSIs, what do they mean, what one should you use?

Answer 8

Bacteraemia - just means bacteria present in the blood

Septicaemia - focuses on clinical symptoms

BSI should be used

Question 9

What are the different names for BSIs, what do they mean, what one should you use?

Answer 9

Bacteraemia - just means bacteria present in the blood

Septicaemia - focuses on clinical symptoms

BSI should be used

Question 10

What are the four steps to a bloodstream infection?

Answer 10

Systemic Inflammatory Response Syndrome (SIRS)

Sepsis

Sever Sepsis

Septic Shock

Question 11

What is SIRS?

Answer 11

Systemic Inflammatory Response Syndrome

The initiation of clinical symptoms due to immune response to toxic bacteria or to their products

Question 12

What is sepsis?

Answer 12

This is where there is clinical evidence of infection along with a systemic response

Two of the following:
- Fever
- Tachycardia
- Tachypnoea
- White cell count >12,000

Question 13

What is sever sepsis?

Answer 13

Sepsis plus evidence of abnormal perfusion of any organ, indicating more sever organ dysfunction

i.e. sepsis + spread to one other organ

This is where we see te 5 year mortality

Question 14

What is septic shock?

Answer 14

This is where patients with septic syndrome develop hypotension

This represents a critical stage that requires immediate intervention or the patient will die

This is one of the biggest hospital emergencies

Question 15

What causes septic shock, what organisms, how does it happen?

Answer 15

It is most frequently seen with gram negative BSIs but less commonly can be seen in gram-positives

Gram negatives:
- Lipid A portion of endotoxin triggers a series of reactions including production of TNF, IL-1 and complement which contribute to shock response

Gram positives:
- Associated with pneumococal infections (GAS) or staphylococcal BSIs

Question 16

What are the three types of BSIs?

Answer 16

Transient Bloodstream Infections

Intermittent Bloodstream infections

Continuous Bloodstream Infections

Question 17

Define a transient bloodstream infection, when would you see it

Answer 17

The temporary presence of bacteria in the bloodstream lasting less than 20 minutes

Self limiting - may not cause symptoms

Often seen after dental work e.g. S. viridans, localised infections such as pneumococcal pneumonia, dental extraction or chewin with poor dental hygiene, or intravenous drug abuse

Question 18

Define an intermittent BSI

Answer 18

Bacteria present in the bloodstream at irregular intervals

Lasts for hours or longer, occuring at specific times

Symptoms may recur with each episode of bacteraemia

E.g. undrained intra-abdominal abscesses, earlly in the course of a variety of systemic and localised infections such as pneumococcal pneumonia

Question 19

Define continuous BSI, give some examples

Answer 19

The persistant presence of bacteria in the bloodstream, suggesting a severe infection that has overwhelmed host defences

Its ongoing and wont go away without treatment

Symptoms are persistant and can lead to sever illness

Infections related to catheters, S. aureus, HIV or cancer showing ongoing bacteraemia

Question 20

What are the four most common causes of sepsis in adults?

Answer 20

36% of patients had a lung infection
25% had a UTI
11% had a gut infection
11% had a skin infection

Question 21

What sepsis is associated with oropharynx carriage?

Answer 21

N. meningitidis colonises the oropharynx
This can spread to blood = sepsis
This can then invade meninges to cause meningitis

Question 22

What sepsis is associated with oral carriage?

Answer 22

Dentistry manipulation of teeth can lead to oral streptococci entering the blood

Occult bacteraemia -> can set up infection in damaged heart valves

results in endocarditis

Question 23

What sepsis is associated with long-term central line catheters?

Answer 23

Coagulase-negative staphylococci
These can form biofilms and give rise to a continuous bacteraemia
-> line needs to be removed

Question 24

What sepsis can be associated with bacterial pneumonia?

Answer 24

S. pnemonia caused pneumonia
Results in a transient bacteraemia

Question 25

What sepsis is associated with cellulitis

Answer 25

Staphylococcus aureus

Question 26

What sepsis is associated with liver abscesses

Answer 26

Liver abscesses tend to be polymicrobial -> usually sourced from appendix
Can cause a ‘dirty’ poymicrobial bacteraeia -> coliforms and such

Question 27

What sepsis is associated with pyelonephritis

Answer 27

Urosepsis

E. Coli

Can cause septic shock (think Gram neg)

Question 28

What kind of sepsis is associated with necrotisin fasciitis?

Answer 28

Group A streptococcus