healthcare acquired infections

• Colonisation is when microorganisms (pathogenic/not) are present but no harm or symptoms of infection. The person colonised is called a 'carrier’. For example, the skin is normally colonised by coagulase negative Staphylococci and can also be colonised by pathogenic Staphylococcus aureus. If transferred to another site e.g. a wound, or another person it can cause an infection.    
• Infection is the process where an infectious agent (microorganism) invades and multiplies in the body tissues of the host resulting in the person developing clinical signs and symptoms of infection (E.g. Increased temperature, rigors, rash).   
• Healthcare associated infections (HCAI’s) are infections that develop in a patient, as a direct result of receiving healthcare, either in hospital or in a community setting, that was not present or incubating at admission. The most commonly reported HCAI’s are urinary tract infections, wound infections and infections that cause vomiting and/or diarrhoea.
• Why are they important?•prolonged hospital stays•long-term disability•increased resistance to antimicrobials•additional costs for health systems•high costs for patients and their family•avoidable deaths
• negative effects of HCAI:

  •prolonged hospital stays

  •long-term disability

  •increased resistance to antimicrobials

  •additional costs for health systems

  •high costs for patients and their family

  •avoidable deaths
• factors increasing the risk of HCAI:

  Patient factors: Extremes of age (neonates and the elderly), Immobility, Chronic illness (diabetes, COPD, obesity), Pre-existing colonisation with bacteria (e.g. MRSA, C. difficile)

  Health-care associated factors: Prolonged hospital admission, Haemodialysis (invasive), Immunosuppression, Antibiotics within last 90 days, Intensive care stay, Prosthetic devices e.g. lines, catheter, ventilator
• common routes of entry in HCAI:

  Respiratory and urinary routes: Main route for Gram negative bacteria. Catheter associated UTI, hospital acquired pneumonia

  Skin and soft tissue infections: Gram positive bacteria. Cannulas, pressure sores, surgical site infection
• source of pathogens:

  Endogenous: From patient’s own micro-flora, Commonest

  Exogenous: Contaminated environment, Cross-transmission from staff or Other patients
• Colonisation

  •opportunistic bacteria part of normal human flora

  •Exist on skin or mucosa without causing harm

  •May provide benefit to host

  •Biofilm formation on plastics
• examples of common bacteria, viruses and fungi

  bacteria: staphylococcus aureus (MRSA and MSSA), Enterococcus faecelis faecium, coagulase negative staphylococci (CONS), Clostridium difficile. G negative- E.coli, keibsiella spp

  viruses: influenza viruses, norovirus, BBVs (hepatitis, HIV),

  fungi: candida spp, aspergillus spp,
• fungi have two form:

  yeast form: small and free-floating

  mould form: big, branched, hard to treat, produces spores that turn into yeast form
• types of viruses structurally:

  • RT RNA
  • dsDNA
  • ssDNA
  • dsRNA
  • +ve ssRNA
  • -ve ssRNA
• Importance of Microbiological confirmation:

  •Confirms infection

  •Identifies cause

  •Guides appropriate treatment based on the sensitivity of cultures

  done timely for better outcomes
• what sampling would you think about for:

  skin (MRSA screen)

  surgical incision (wound swab)

  wound drain (drain fluids)

  catheters (urine samples)

  intubation (sputum sample)

  cannulas/lines (swabs)

  antibiotic associated infxn (stool sample)
• Catheter associated UTIs

  •Bacteria colonise the plastic

  •Bypass the body’s defence mechanisms (can get directly into the urinary system)

  •The longer a catheter is in place, the more likely bacteria are found in the urine

  
  

  Treatment

  •Remove the source of infection

  •Antibiotics based on culture results

  •Require longer abx course than simple UTIs
• hospital acquired pneumonia:

  •Risk Factors- ventilation, immobility, reduced cough, aspiration, age

  •Can be hard to distinguish from other conditions e.g. heart failure

  •Causes- more likely to be Gram negative and antibiotic resistant bacteria than CAP (e.g. Pseudomonas, E.coli, Klebsiella)

  •Watch out for viral causes e.g. Influenza, Covid
• impact of antibiotics:

  Exert strong selective pressure on normal microbial flora:

  •Select out more resistant bacteria

  •Risk of C. difficile

  •Can lead to outbreaks

  Impacts of antimicrobial resistance

  •Delays in effective treatment

  •More toxic antibiotics required

  •Longer hospital stays

  •Increased mortality
• E.Coli resistant to third generation cephalosporins is increasing over the years, particularyl high in italy and malta
• preventing HCAI:
• preventing HCAI

  • screen patients: MRSA for all admitted, COVID for elective surgical and anyone who develops sx in hospital, high risk patients
  • hygiene to break chain of transmission
  • hydrogen peroxide decontamination machines- put in room after an infected patient, seal the room and fumes of hydrogen peroxide kill microbials
  • UV light machine for decontamination but only kills where light reaches
  • PPE
  • isolation of very infected patients
  • monitoring and surveillance: make sure outbreaks are noted and acted on
• Outbreak

  Normally characterised by two or more cases of the same infection related in time and place with evidence of transmission

  In exceptional circumstances, a single case for certain rare diseases would be managed as an outbreak e.g. hospital acquired legionella
• impacts of infection outbreaks:

  •Bed closures

  •Increased hospital stays

  •Increased morbidity and mortality

  •Healthcare costs
• new challenges with HCAI:

  • respiratory infections: mortality rates have more than doubled
  • high risk infections: MERS, monkey pox
• prevent spread of high risk infections:

  • identify those at risk
  • Ask (Have you travelled abroad in the last 21 days?Do you have a fever or other symptoms of infection?)
  • Isolate individual for further assessment
  • Staff to wear enhanced PPE
• why reporting infections is important:

  •Monitor rates against baseline

  •Compare to other organisms

  •Government targets

  •Penalties for excessive numbers
• answer these questions after all the cards:

  
• 1. attachment to surface ( reversible ) - initial contact of the moving planktonic bacteria with the surface is the starting point
  2. irreversible attachment - bacteria form a monolayer and produce  extracellular matrix or “slime” for protection consisting of polysaccharides, structural proteins, cell debris and nucleic acids; referred to as extracellular polymeric substances (EPS). Initially matrix formation dominated by extracellular DNA (eDNA),  polysaccharides and structural proteins take over later
  3. microcolony formation - significant growth and cell-cell communication like quorum sensing


  here

  
• 4. The biofilm grows in a three-dimensional manner and the attachment is now irreversible, it has the characteristic "mushroom" shape

  5. In the last stage, some cells of the mature biofilm start to detach and disperse into the environment as planktonic cells again to potentially start a new cycle of biofilm formation.

  here