Nosocomial infection Flashcards
Define nosocomial infection.
Infection that is diagnosed 48-72 hours after hospital admission (not evident on presentation).
Why is nosocomial infection particularly problematic in ICU patients?
EPIC and EPIC II trials identified around 1 in 5 ICU patients will develop nosocomial infection. Most common sites include: - Respiratory - Abdominal - Bacteraemia - Urinary tract
Particularly problematic in ICU due to patient factors and treatment/environmental factors.
Patient factors:
- vulnerable patients
- multiple co-morbidities
- often immunosuppressed or immunodeficient from critical illness
- malnutrition
- unable to tell us of symptoms
Treatment factors:
- invasive devices breach normal barriers to infection
- broad-spectrum antibiotics can damage normal microbiome
- antibiotic resistance organisms and risk of transmission to/contamination of other patients
- loss of cough reflex or clearance of respiratory secretions
- recent abdominal contamination or surgery
When would you treat bacteriuria in ICU patients?
Commensal bacteriuria in catheterised patients is common as is asymptomatic bacteriuria in elderly patients.
Asymptomatic bacteriuria should not be treated.
Treatment should be initiated when:
- the patient is symptomatic (LUTS)
- evidence of same organism cultured in blood
- unexplained pyrexia with no other source identified
What is CRBSI?
Catheter-related bloodstream infection is a nosocomial infection related to an indwelling vascular device.
They account for 10-20% of nosocomial infections in the UK.
For diagnosis:
- peripheral blood culture positive
- no other source of bacteraemia identified
- clinical manifestations of infection
PLUS:
- Quantitative parameter: culture ratio 5:1 (line to peripheral)
AND/OR - Non-quantitative parameter: Time to positivity of catheter sample >2hrs earlier for simultaneous samples.
AND/OR - catheter tip sample positive for same organism as peripheral sample
What are the risk factors for CRBSI?
Insertion factors:
- ANTT
- 2% chlorhexadine and 70% alcohol prep
Care/Use factors:
- Frequency of access
- TPN
Site factors:
- Subclavian < jugular < femoral
- contiguous infection
What is a CLABSI?
Central line associated blood stream infection is a bacteraemia with features of infection that develops with 48 hours of central line insertion that isn’t related to infection at another site.
How can we prevent catheter related blood stream infections.
Reduction in risk factors.
The Matching Michigan initiative developed a set of evidence based measures to reduce risk, which have largely become standard practice.
Five elements:
- Aseptic hand washing
- Strict ANTT with full barrier precautions
- Use of 2% chlorhexadine and 70% alcohol skin prep
- Avoidance of femoral route
- Daily line review and removal if not needed.
What is ventilator associated pneumonia?
VAP is the development of pneumonia in a ventilated patient after 48hrs after starting ventilation.
It can be classified as early onset (within first 4 days) or late onset (after 4 days).
Associated organisms vary;
Early:
- Staph
- haemophilus
- MSSA
- ABx sensitive gram -ve
Late:
- MRSA
- ESBL
- pseudomonas
What are the risk factors for ventilator associated pneumonia?
- Duration of mechanical ventilation
- Muscle paralysis/deep sedation
- Burns
- Trauma
- Supine body position
- Enteral nutrition
- Pulmonary pathology
What can be done to prevent VAP?
3 main approaches:
- Reduce colonisation of gastrointestinal tract and oropharynx
- Prevent aspiration
- Limit duration of mechanical ventilation
Care bundles:
- daily sedation holds
- spontaneous ventilation
- selective decontamination of digestive tract
- Head of bed at 30-45 degrees
- regular and frequent physio
- chlorhexadine mouth care
- subglottic suction
How is VAP diagnosed?
Clinical pulmonary infection score (CPIS): TWOCCC - temperature - white cell count elevated - oxygen requirements increased/ P/F ratio decreased - CXR changes - chest secretions - culture of aspirate
What is the management of VAP?
Patient should be managed in an ABCDE approach, correcting abnormalities as you find them.
Specific interventions include:
- Antimicrobials based on timing of VAP, previous cultures and known colonisation, then based on positive cultures and sensitivities.
- BAL
- Lung protective ventilation
What is the definition of diarrhoea?
WHO definition is of 3 or more loose or liquid stools per day.
What is the incidence of diarrhoea on ICU?
25-50%
What is the pathophysiology of diarrhoea?
Imbalance between water and solute transport in the GI tract.
4 main causes:
- Osmotic (osmotically active substances in GI which are struggled to absorb e.g enteral feed-associated diarrhoea)
- Inflammatory (inflammed GI mucosa impairs absorption e.g. IBD)
- Secretory (increased secretion or reduced absorption across gut mucosa e.g. enterotoxin production or laxative use).
- Dysmotility (rapid transit time through small bowel which overwhelms the colon e.g. recovery from ileus).
