Healthcare Associated Infections Flashcards
What are healthcare associated infections (HAI)?
Infections which were not present, or were in the pre symptomatic phase at the time of admission to hospital, but which arise 48 hours or more after admission or within 48 hours of discharge
What percentage of patients in Scotland develop HAI?
4.9%
Possible outcomes of HAI
Extended length of stay, pain, discomfort, permanent disability, death
Financial implications
Loss of public confidence and decreased staff morale
Litigation
Common HAIs
UTI Surgical site infection Pneumonia Blood stream infection Eye/ear/nose/throat/mouth infection GI infection Skin and soft tissue Systemic LRTI CVC/PVC related Neonatal CNS Bone/joint Reproductive tract CVS
How many bacteria are there in the adult human body?
10^14
10 bacterial cells to every human cell
1kg bacteria in the human gut alone
500 different species of bacteria have been isolated from human stool
First line of defence against infection
Intact skin Normal bacterial flora Body secretions Coughing Gastric acid Flushing
Why do ventilation and catheterisation increase the risk of HAI?
They bypass the body’s natural protective mechanisms (coughing and urination)
Second line defence against infection
Immune system
Why are patients in hospital more vulnerable to microbial colonisation and infection?
People and inanimate objects all harbour microbes that may pose a risk to others, other patients are more likely to carry more microbes
What percentage of the population are colonised with staph aureus?
Approximately 30%, most with methicillin sensitive staph aureus (MSSA)
How can the same strain of staph aureus that colonises the population cause infection?
Break in skin
Vascular device
Catheter associated UTI
Ventilator associated pneumonia
What causes most HAI?
Disturbance in the bacterial-host equilibrium
What is colonisation?
When bacteria are in or on the body but do not cause illness
What is infection?
Where bacteria are in or on the body and cause illness, resulting in signs and symptoms
Microbial factors leading to increased risk of infection
Resistance Virulence Transmissibility Increased survival ability Ability to evade host defences
Host factors leading to increased risk of infection
Devices e.g. PVC, CVC, urinary catheter, ventilation Antibiotics Break in skin surface Foreign bodies Immunosuppression Gastric acid suppression Age extremes Proximity to others Increased opportunity for infection e.g. poor hand washing Overcrowding
Modes of transmission of microbes
Direct contact
Respiratory/droplet
Faecal-oral
Penetrating injury
Chain of infection
Source of microbe
Transmission vector
Host
Ways to break the chain of infection
Risk awareness Standard IPC precautions Hand hygiene Personal protective equipment Vaccination Post exposure prophylaxis Environment
What is cleaning?
Physical removal of organic material and microbial load reduction
When can cleaning be used?
For low risk e.g. intact skin contact - stethoscopes, cots, mattresses
When is cleaning essential?
Prior to disinfection/sterilisation
What is disinfection?
Large reduction in microbial numbers, spores may remain
When can disinfection be used?
For medium risk e.g. mucous membrane contact - bedpans, endoscopes
Method of cleaning
Detergent and water
Drying
Method of disinfection
Heat - pasteurisation, boiling
Chemical e.g. alcohol, chlorhexidine, hypochlorites, hydrogen peroxide
What is sterilisation?
Removal/destruction of all microbes and spores
When can sterilisation be used?
High risk e.g. penetration through the skin/sterile body cavities - surgical instruments
Methods of sterilisation
Steam under pressure - autoclave
Hot air oven
Gas
Ionising radiation
Infection prevention and control surveillance methods
Local surveillance
National surveillance
Features of local surveillance - lab based
Lab detects microbe and notifies IPCT and clinicians
Identify microbe and recommendations can be specific
Depends on samples being sent, takes time to grow and identify microbe
Features of ward/clinical area based surveillance
Ward/clinical staff notify IPCT or microbiology
Detects potential problem sooner and can ensure correct samples are sent
Potential causative microbe is not always clear initially, IPC measures more general
Mandatory surveillance reporting for Scotland
MRSA bacteraemia MSSA bacteraemia C. diff E. coli bacteraemia Surgical sites
What is an outbreak?
2 or more defined cases of an infection linked in time and place
What is the purpose of the IPCT?
To prevent individual infections and outbreaks
What is the purpose of surveillance?
To detect and identify a possible outbreak at the earliest opportunity
Typing methods, to determine strain responsible
Antibiogram Phage typing Pyocin typing Serotyping Molecular typing
Control measures for outbreaks
Reinforcements of IPC measures Single room in isolation Cohorting of cases Ward/clinical area closure Staff/patient decolonisation Staff exclusion
Features of C. diff infection
Diarrhoea
Abdominal pain, pyrexia, raised WCC
Pseudomembranous colitis
In what percentage of adults is C. diff part of the normal gut flora?
Around 2%
Pattern of carriage rate of C. diff with age
C. diff carriage rate increases with age
What percentage of the elderly are colonised with C. diff?
Around 30%
When does C. diff infection occur?
When there is an imbalance in the gut flora due to an endogenous or exogenous source
Variable in severity
Elderly more at risk
What must be present for a diagnosis of C. diff infection to be made?
Diarrhoeal symptoms - positive toxin test does not always indicate disease
Possible reasons for increasing incidence
More antibiotics More of a particular type of antibiotic New strains Less hand washing due to more hand-gelling Increasing environmental contamination Increased number of vulnerable patients close together Increased throughput of patients Other drugs having effect
Treatment of C. diff
Stop predisposing antibiotic is possible
Oral metronidazole if symptomatic
Oral vancomycin if severe or failure of metronidazole
Oral fidaxomicin
