Healthcare Acquired Infections Flashcards
What is a healthcare acquired infection?
- Infections that were not present or in the pre-symptomatic phase at the time of admission to hospital
- Which arise > 48 hrs after admission or within 48 hrs of discharge
What are the possible outcomes of HAI?
- Extended length of stay, pain, discomfort, permanent disability, death
- Increased Cost: 33% decrease in HAI in Scotland would lead to savings of £55 million (2007 National Prevalence Study)
- Litigation
- Loss of public confidence and decreased staff morale
What are the most common sites of HAI?
- UTI (related to catheterisation)
- Surgical site infection
- RTI (intubation)
- Bloodstream infections (central venous catheters)
- GI infection
- Skin and soft tissue infections
What is the relationship between humans and bacteria?
- Approx. 10^14 bacteria in adult human
- Approx 10 bacterial cells to every human cell
- Human beings carry >1kg of bacteria in their gut alone
- 500 different species of bacteria have been isolated from human stool
What are patients in hospital more vulnerable to?
Microbial colonisation and infection
What is the most common form of staph aureus to be colonised with?
Meticillin sensitive staphylococcus aureus (MSSA)
How can a colonising staph aureaus cause infection?
- Break in skin e.g. surgical site infection
- Vascular device e.g. PVC, CVC
- Catheter associated urinary tract infection (CAUTI)
- Ventilator associated pneumonia (VAP)
What process leads to most HAI?
A disturbance in the bacterial-host equilibrium
What microbial factors can tip the bacterial-host balance towards infection?
Increased
- Resistance
- Virulence
- Transmissability
- Increased survival ability
- Ability to evade host defences
What host factors can tip the bacterial-host balance towards infection?
- Devices: PVC, CVC, Urinary catheter, Ventilation
- Antibiotics
- Break in skin surface
- Foreign body
- Immunosuppression
- ?Gastric acid suppression
- Age extremes
- Overcrowding
- Increased opportunity for transmission e.g. Interventions, Hands!!!
What is required for chain of infection?
- Source of microbe (endogenous or exogenous)
- Transmission
- Host
What means of transmission are there for infection?
Direct contact
-e.g. Staphylococcus aureus, coliforms
Respiratory/Droplet
-e.g. Neisseria meningitidis, Mycobacteria tuberculosis
Faecal-Oral
-e.g. Clostridium difficile, Salmonella sp.
Penetrating Injury
-e.g. Group A streptococcus, Bloodborne viruses
How can the chain of infection be broken?
- Risk awareness
- Standard Infection Prevention and Control Precautions (SICPs)
- Hand Hygiene
- Appropriate PPE
- Vaccination
- Post Exposure Prophylaxis
- Environment
Cleaning
Physical removal of organic material and decrease in microbial load
Disinfection
Large reduction in microbe numbers-spores may remain
Sterilisation
Removal/destruction of ALL microbes and spores
How should spread of infection be prevented with low risk objects such as stethoscopes, cots and mattresses which have been in contact with intact skin?
Cleaning compatible with manufacturer’s instructions
How should spread of infection be prevented with medium risk objects such as bedpans, vaginal specula and endoscopes which have been in contact with mucous membranes?
Disinfection or sterilisation as appropriate
How should spread of infection be prevented with high risk objects such as surgical instruments?
Sterilisation
How should cleaning of equipment be carried out?
- Manufacturer’s instructions
- Detergent and water
- DRYING IS AN IMPORTANT PART OF THE PROCESS!
- Cleaning essential PRIOR to disinfection and Sterilisation if these are required
What methods of disinfection are there?
- Heat
- Chemical-Steam under pressure (autoclave)
- Gas (ethylene dioxide)
- Ionising radiation
How can heat be used as a method of disinfection?
- Pasteurisation (e.g. bedpans, linen, dishwashers)
- Boiling (vaginal specula, ear syringes)
How can chemical be used to disinfect items?
- Chemicals vary in their organism activity range
- Needs to be equipment compatible
- Examples: Alcohol, chlorhexidine, hypochlorites, hydrogen peroxide
How is local surveillance carried out for infection control?
- Lab based
- Ward/clinical area based
What types of surveillance are there for infection control?
- Local surveillance
- National surveillance
Give examples of national surveillance which has taken place in Scotland for infection control.
- MRSA bacteremia
- MSSA bacteremia
- Clostridium difficile
- Surgical Site Infections
- E coli bacteremia ?
Infection outbreak
An outbreak of an infection is defined as 2 or more cases of a infection linked in time and place.
What is the purpose of IPCT?
Prevent individual infections and surveillance
What is the purpose of surveillance?
Detect and identify a possible outbreak at the earliest opportunity
How are outbreaks identified?
- Have to act on suspicion
- Typing necessary to determine if the same strain present i.e. an outbreak
How can infections be typed?
- Antiobiogram (antibiotic sensitivity pattern)
- Phage typing (e.g. Staphylococcus aureus)
- Pyocin typing (Pseudomonas)
- Serotyping (Salmonella, Pseudomonas)
- Molecular typing (DNA typing)
What control measures are there for infection outbreaks?
- Single room isolation
- Cohorting of cases
- Clinical Area/Ward Closure
- Re-inforcement of IPC measures
- Staff exclusion (e.g. colonised staff in case of MRSA; non-immune staff in case of VZV, measles etc.)
- Staff decolonisation or other measures
What are the clinical characteristics of C diff. infection?
- Diarrhoea
- Faeces have a characteristic odour
- May have abdominal pain, pyrexia, raised white cell count
- Pseudomembranous colitis (PMC)=most serious form
Why is C.diff do prominent?
- Part of the normal gut flora in ~2% adults
- Carriage rate increases with age
- ~30% elderly are colonised
- Can survive in environment - importance of cleaning
What does C.diff produce?
- 2 toxins
- Toxin negative strains DO NOT cause disease
Who are more susceptible to C. diff?
Elderly men
What does C.diff cause?
Imbalance in gut flora
How is C.diff infection diagnose?
- Positive toxin test does not always mean disease
- Diarrhoeal symptoms NEED to be present for diagnosis of CDI
Why does C. diff. infection still occur?
- Not possible to prevent all cases
- All antibiotics can predispose to CDI although some are more predisposing than others
- New strains?
- Less handwashing because more handgelling?
- Environmental contamination may still be an issue?
- Increased no. of vulnerable patients close together?
- Increased throughput of patients?
- Other drugs having an effect e.g. PPIs?
What is the treatment for C.diff infection?
STOP THE ANTIBIOTICS PREDISPOSING TO C difficile IF POSSIBLE!
If symptomatic, treatment:
- Oral metronidazole
- Oral vancomycin if severe or failure to improve on metronidazole
- Oral fidaxomicin if 2nd episode
Use of what 4 antibiotics should be reduced to reduce C diff infections?
- Ceftriaxone (other cephalosporin’s)
- Co-amoxiclav
- Clindamycin
- Ciprofloxacin (Other quinolones)
