W4: Health care associated infections Flashcards
How does WHO define a health care-associated infection?
An infection occurring in a patient during the process of hospital care or other health environment that was not present or incubating at the time of admission.
What are the consequences of health care associated infections?
Prolonged hospital stays
Long term disability
Increased resistance to antimicrobials
Additional costs for health systems
Financial and emotional costs for patients and their family
Avoidable deaths
How common are HCAIs?
Found in 7.1% of patients in acute care hospitals
30% of patients in ITU’s
What are the most common types of health care-associated infections?
Respiratory
Urinary Tract Infections
Surgical Site infections
Clinical sepsis
GIT e.g C.diff
Blood stream infections
What are the health care associated risk factors for health care associated infections?
Prolonged hospital admissions
Haemodialysis
Immunsuppression e.g in chemotherapy
Antibiotics within the last 90 days - risk of C.Diff and Candida. alibicans after penicillin causing thrush
Intensive Care Stay
Invasive Devices such as lines, catheter and ventilator
What patient factors increase the risk of health care associated infections?
Extremes of age
Immobility
Chronic illness e.g diabetes, COPD, obesity
Pre-existing colonisation with bacteria such as MRSA and C.Diff
How do gram negative bacteria tend to enter the body?
respiratory and urinary routes e.g intubation, poor vough responsice, catheters
Catheter - UTI and pneumonia.
How do gram positive bacteria tend to enter the body?
Tend to cause skin and soft tissue infections
Enter the body by cannulas, pressure sores and surgical sites.
What are the different routes by which pathogens can enter the body?
Intubation - often coupled with porr ventilation/cough response
Cannula/lines
Antibiotic associated infection
Catheter
Wound drains
Surgical incisions
Physical contact
What are the most common modes of transmission of HCAIs in the NHS?
Contact - from hands, equipment or other environment
Air-borne
Blood born is very very rare.
What is meant by an endogenous or an exogenous source of infection?
Endogenous - from patients own microflora - this is the most common type of HCAIs.
Exogenous - from external sources such as a contaminated surrounding environment or cross transmission
What is the difference between colonisation and infection?
How does this apply to HCAIs?
Colonisation - present on surface, no harmful effects, may even provide benefit. Most opportunistis infections are part of normal flora on skin or mucosa
Infection - causes disease - harmful tot he host
How can microbes change from colonisation to a biofilm (infection)?
Link to HCAIs
Planktonic pathogen (microbe on its own) adheres to a surface this is originally reversible.
Produces an extracellular matrix and proliferates to form a monolayer. ECM will contain polysaccharides, structural proteins and nucleic acid.
Process continues and a multi-layer microcolony forms, grows in three dimeinsation and cell to celll communication begins (adhesion is now irreversible)
A mature biofilm forms from a polysaccharide mesh, a characteristic mushroom-shape.
Some cells may detach and disperse into the environment as planktonic cells to potentially start a new cycle of biofilm formation.
Why is biofilm formation beneficial to bacteria?
More difficult to treat with antibiotics
Close proximity allows - metabolic substrate and products echange, this allows different species within the biofilm to support each other.
What are the most common gram postive bacteria causing hospital acquired infections?
Staphylococcus aureus (MRSA MSSA)
Enterococcus faecalis faecium
Coagulase negative Staphylococcus
C.diff
What are the most common gram negative pathogens causing HCAIs?
Escherichia coli
Klebsiella spp.
Pseudomonas aeruginoase
What are the most common viruses causing hospital acquired infections?
Influenza viruses
Norovirus
Blood born viruses such as Hepatitis,HIV (Not very common)