asepsis and infection control

• Pre-scientific era


  • Epidemics and plagues throughout history
  • Physicians fear of contagious disease
  • Hippocrates and others suspected an unseen invisible cause
  • Climate and environment blamed - not the ill, dying, or dead
• Microbiology - scientific era


  The study of microscopic organisms
• Anton van Leeuwenhoek


  • Dutch linen draper
  • Amateur scientist
  • Grinding lenses, magnifying glasses, hobby
  • First to see bacteria "little beasties"
  • No link between bacteria and disease
• Ignaz Semmelweiss


  • Obstetrician, practised in Vienna
  • Studied puerperal (childbed) fever
  • Established that high maternal mortality was due to failure of doctors to wash hands after post-mortems
  • Reduced maternal mortality by 90%
  • Ignored and ridiculed by colleagues
• Louis Pasteur


  • French professor of chemistry
  • Studied how yeasts (fungi) ferment wine and beer
  • Proved that heat destroys bacteria and fungi
  • Proved that bacteria can cause infection - the "germ theory" of disease
• Joseph Lister


  • Scottish surgeon
  • Recognized importance of Pasteur's work
  • Concerned about infection of compound fractures and post-operative wounds
  • Developed carbolic acid spray to disinfect instruments, patient's skin, surgeon's skin
  • Largely ignored by medical colleagues
• Robert Koch


  • German general practitioner
  • Grew bacteria in culture medium
  • Showed which bacteria caused particular diseases
• Antibiotic resistance is not a new problem - Penicillin in 1944
• Contemporary issues

  • Antibiotic resistance
• Antibiotic resistance


  • Hospital "superbugs"
  • Methicillin Resistant Staphylococcus Aureus [MRSA]
  • Vancomycin Intermediate Staphylococcus Aureus [VISA]
  • Tuberculosis - antibiotic resistant form
• 400 deaths per year in UK due to antibiotic resistant tuberculosis
• Up to £100,000 per patient to treat antibiotic resistant tuberculosis
• Annual NHS cost of antibiotic resistant tuberculosis - £5-million
• MRSA


  • Discovered in 1981
  • Found on skin and in the nose of 1 in 3 healthy people symptomless carriers
  • Widespread in hospitals and community
  • Resistant to most antibiotics
• Multiple Causation Theory or Ecologic Concept of Disease


  Health conditions result from a multitude of factors which must be analyzed and understood in terms of the relationship where a change in any of the three components will alter the internal and/or external equilibrium which eventually brings about diseases or illnesses
• Micro-organisms

  • Bacteria
  • Fungi
  • Viruses
  • Protozoa
  • Worms
• Pathogenic organisms


  Can cause infection
• Infection


  Exists when pathogenic organisms enter the body, reproduce, and cause disease
• Hospital Acquired Infection (HAI)


  • Infection which was neither present nor incubating at the time of admission
  • Includes infection which only becomes apparent after discharge from hospital, but which was acquired during hospitalization
• Incidence of hospital acquired infection is 10%
• 5,000 deaths per year are a direct result of hospital acquired infection
• 15,000 deaths per year are linked to hospital acquired infection
• Hospital acquired infection leads to delayed discharge from hospital
• Hospital acquired infection is expensive to treat, costing an extra £3,500 per case
• The cost of hospital acquired infection to the NHS is £1 billion per year
• Effective hand washing is the most effective preventative measure against hospital acquired infection
• Dirty wards and re-use of disposable equipment are also blamed for hospital acquired infection
• Prions


  • Proteinaceous infectious particles
  • Corrupted form of a normally harmless protein found in mammals and birds
  • Causes fatal neurodegenerative diseases of animals and humans
• Prion diseases

  • Scrapie - sheep
  • Bovine spongiform encephalopathy [BSE or Mad Cow Disease]
  • Creutzfeldt-Jakob disease [CJD]
• Endogenous or self-infection


  Organisms which are harmless in one site can be pathogenic when transferred to another site e.g. E. coli
• Exogenous or cross-infection


  Organisms transmitted from another source e.g. nurse, doctor, another patient, environment
• Modes of spread

  • Natural orifices - mouth, nose, ear, eye, urethra, vagina, rectum
  • Artificial orifices - such as tracheostomy, ileostomy, colostomy
  • Mucous membranes - which line most natural and artificial orifices
  • Skin breaks - either as a result of accidental damage or deliberate inoculation/incision
• Chain of infection

  • Source/reservoir of micro-organisms
  • Method of transmission
  • Point of entry
  • Susceptible host
• HAI - common bacteria


  • Staphylococci - wound, respiratory and gastro-intestinal infections
  • Escherichia coli - wound and urinary tract infections
  • Salmonella - food poisoning
  • Streptococci- wound, throat, and urinary tract infections
  • Proteus - wound and urinary tract infections
• Universal infection control precautions

  • Hand washing
  • Personal protective equipment [PPE]
  • Preventing/managing sharps injuries
  • Aseptic technique
  • Isolation
  • Staff health
  • Linen handling and disposal
  • Waste disposal
  • Spillages of body fluids
  • Environmental cleaning
  • Risk management/assessment
• Hand washing


  • Single most effective action to prevent HAI
  • Correct method - ensuring all surfaces are cleaned more important than agent used or length of time taken
  • Frequency should be determined by intended/completed actions
• Personal protective equipment (PPE)


  • Used when contamination or splashing with blood or body fluids is anticipated
  • Includes disposable gloves, plastic aprons, face masks, safety glasses, goggles, visors, head protection, foot protection, fluid repellent gowns
• Aseptic technique


  • Minimize risk of introducing pathogenic micro-organisms into susceptible sites
  • Prevent transfer of potential pathogens from contaminated site to other sites, patients or staff
  • Follow local policy
• Staff health


  • Risk of acquiring and transmitting infection
  • Acquiring infection - immunization, cover lesions, restrict non-immune/pregnant staff
  • Transmitting infection - advice when suffering infection, report accidents/untoward incidents
• Linen handling and disposal


  • Bedmaking and linen changing techniques
  • Gloves and apron when handling contaminated linen
  • Appropriate laundry bags
  • Avoid contamination of clean linen
  • Hazards of on-site ward-based laundering
  • Follow NHS Executive guidelines