10. Sepsis Flashcards
What is sepsis?
- consequence of septicaemia or blood poisoning caused by bacteraemia
- overreaction of immune system in response to septicaemia
What are the symptoms of sepsis?
- 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
What is sepsis incidence and mortality?
- 11m deaths globally and annually
- 48k deaths annually in UK
- 25k child cases every year
Where does sepsis come from?
bacterial infection leads to bacteraemia (disseminated infection), causing sepsis (septicaemic shock)
What pathogens can blood cultures be used for?
S. aureus
E.coli
S. pneumoniae
Enterococcus spp.
Pseudonomas aueruginosa
Candida albicans
When should a blood culture be taken?
post fever spike but before antibiotics administered
- taken every 24hrs until clear
Which blood culture bottles are used?
Adults
- FN blood culture (anaerobic)
- FA blood culture (aerobic)
Paediatric
- PF Plus blood culture
*never refrigerated
What happens once blood cultures arrive in the lab?
- details entered into LIMS
- bottles scanned into BacTec; uses fluorescence to monitor bacterial growth
What happens when the BacTec flags positive?
- immediately alert ward to a positive culture
- BMS visually checks graph and bottles to confirm
- BMS must process positive in 2 hours
What are the immediate tests for all blood cultures?
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
What happens when a gram positive result is given?
- 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
What happens if you get a gram negative result?
3 plates set up for 24 hrs
- Chocolate agar (HPV, meningitis)
- MacConkey Agar (E.coli, salmonella)
- Neomycin FAA plate with metronidazole disc
What is S.aureus bacteremia?
- 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
What is streptococcal bacteraemia?
- 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
What are beta-haemolytic streptococci?
They are encountered in blood from skin or soft tissue infection
- Lancefield groups A, C and G can be found
What is alpha-haemolytic streptococci?
-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)
What is Escherichia coli bacteraemia?
- 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.
What is enterococci bacteraemia?
- frequently encountered as blood pathogens
- enterococcal septicaemia can be problematic to treat due to limited therapeutics
What is Neisseria bacteraemia?
- 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
What is fungal bacteraemia?
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
What is fungal bacteraemia?
- 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
