10. Sepsis

Question 1

What is sepsis?

Answer 1

• consequence of septicaemia or blood poisoning caused by bacteraemia
• overreaction of immune system in response to septicaemia

Question 2

What are the symptoms of sepsis?

Answer 2

• Slurred speech or confusion
• Extreme shivering or muscle pain
• Passing no urine all day
• It feels like death
• Skin mottles or discoloured
• patchy, blue skin, lips, tongue
• rash that doesn’t blanche
• difficulty/rapid breathing
• high pitched crying in infants
• confusion
• feeling lethargic
• fever, loss of appetite, vomiting, septic abrasion

Question 3

What is sepsis incidence and mortality?

Answer 3

• 11m deaths globally and annually
• 48k deaths annually in UK
• 25k child cases every year

Question 4

Where does sepsis come from?

Answer 4

bacterial infection leads to bacteraemia (disseminated infection), causing sepsis (septicaemic shock)

Question 5

What pathogens can blood cultures be used for?

Answer 5

S. aureus
E.coli
S. pneumoniae
Enterococcus spp.
Pseudonomas aueruginosa
Candida albicans

Question 6

When should a blood culture be taken?

Answer 6

post fever spike but before antibiotics administered
- taken every 24hrs until clear

Question 7

Which blood culture bottles are used?

Answer 7

Adults
- FN blood culture (anaerobic)
- FA blood culture (aerobic)

Paediatric
- PF Plus blood culture

*never refrigerated

Question 8

What happens once blood cultures arrive in the lab?

Answer 8

• details entered into LIMS
• bottles scanned into BacTec; uses fluorescence to monitor bacterial growth

Question 9

What happens when the BacTec flags positive?

Answer 9

• immediately alert ward to a positive culture
• BMS visually checks graph and bottles to confirm
• BMS must process positive in 2 hours

Question 10

What are the immediate tests for all blood cultures?

Answer 10

blood cultures are ventilated with a needle to perform initial testing
- add a few drops to a slide and leave to air dry
- add a drop to blood agar plate and quadrant streak with a loop
- adda drop to fastidious anaerobe agar and quadrant streak
- place labelled plate into an incubator and 37 degrees for 24hrs
- heat fix dry slide and gram stain

Question 11

What happens when a gram positive result is given?

Answer 11

• two additional plates are set up for 24hours culture:
  1. second BA with optochin disc (if zone of inhibition, can be S. pneum)
  2. S.aureus selective agar
• Tube coagulase test (Stap test) immediately performed, fibrin clot = S.aureus

Question 12

What happens if you get a gram negative result?

Answer 12

3 plates set up for 24 hrs

• Chocolate agar (HPV, meningitis)
• MacConkey Agar (E.coli, salmonella)
• Neomycin FAA plate with metronidazole disc

Question 13

What is S.aureus bacteremia?

Answer 13

• most frequent
• enters blood from an infected site:
  abscesses in tissues or organs, infected lesions in skin,
  infected joints,
  pneumonia with S.aures leads to septicaemia
• coagulase-negative staphylococci are frequently found in blood cultures

Question 14

What is streptococcal bacteraemia?

Answer 14

• S. pneumoniae is often isolated from patients with chest infections or occasionally meningitis
• blood cultures can be used for diagnosis; if sputum production is poor
• S. agalactiae is commonly encountered in neonatal sepsis

Question 15

What are beta-haemolytic streptococci?

Answer 15

They are encountered in blood from skin or soft tissue infection
- Lancefield groups A, C and G can be found

Question 16

What is alpha-haemolytic streptococci?

Answer 16

-They are found in blood form patients with endocarditis

• organisms are derived from oropharynx
• can occur as contaminants in blood cultures (oral contaminants from venepuncture)

Question 17

What is Escherichia coli bacteraemia?

Answer 17

• frequent and associated with UTI
• in elderly or immunocompromised
• can be caused by intestinal lesions and infections in biliary tracts
• salmonella spp. can cause billiary sepsis; enteric fever, necessitating rapid diagnosis and treatment
• all non-lactose fermenting, oxidase negative, gram negative bacilli isolated from blood culture need to be checked to exclude Salmonella spp.

Question 18

What is enterococci bacteraemia?

Answer 18

• frequently encountered as blood pathogens
• enterococcal septicaemia can be problematic to treat due to limited therapeutics

Question 19

What is Neisseria bacteraemia?

Answer 19

• N.meningitidis extremely rare but important pathogen
• indicated septicaemia with possibility of meningitis
• should be bought to attention immediately
• very severe and rapid clinical progression, requiring aggressive antibiotic therapy
• biochemical tests needed to differentiate between N. meningitidis and N. gonorrhoeae

Question 20

What is fungal bacteraemia?

Answer 20

Candida albicans is 4/5 most common blood culture
- common in immunocompromised, patients with central venous catheters and premature infants

• use of broad spectrum antibiotics; remove flora and increase yeast colonisation
• cytotoxic therapy for cancer may damage gut mucosa; Candida moves from gut to stream
• high mortality; rapid diagnosis and speciation required
• some species of candida are resistant to antifungals
• Additional Sabourand agar SAB set up

Question 21

What is fungal bacteraemia?

Answer 21

• where 2+ microorganisms are isolated
• associated with serious underlying conditions
• frequently arise from bowels
• include: enterobacteria, enterococci and anaerobes
• death rate is higher than monomicrobial bacteraemia
• requires aggressive therapy for 2 diff organisms