Infection Control Prelims

• Semmelweis


  Doctor undertaking obstetrics in a hospital in Vienna in 1847 who did an audit on postdelivery mortality rates
• If a doctor or medical student delivered a baby, the chance of the mother dying was as high as 18%, but if a midwife or midwifery student delivered the baby, the death rate dropped to 2%
• Semmelweis' intervention


  1. Rigorously assessed factors

  2. Concluded doctors were becoming contaminated by cadavers

  3. Got doctors to wash their hands

  4. Redid audit and found death rate dropped to 2%
• Semmelweis demonstrated


  • Healthcare has the potential to make people sick (nosocomial infection)
  • Interventions can be undertaken to reduce this risk (infection control)
• Semmelweis was ahead of his time, his superiors did not attribute the handwashing to the improved survival rates, instead crediting the hospital's newly installed ventilation system
• Germ theory of disease


  Microorganisms are responsible for infections
• Joseph Lister


  • Became aware of Pasteur's research
  • Formulated methods of delivering antiseptic surgery, publishing his initial findings in 1867
• There were still many in the medical establishment that were resistant to Lister's methods, but by the end of the nineteenth century, the success of those that did adopt his techniques became too many to ignore
• Lister's research


  1. Sought to find chemicals that would disinfect wounds (antisepsis)

  2. Sought to disinfect hands of operators and instruments (asepsis)
• William Halsted commissioned the Goodyear Rubber Company to make rubber gloves, which were then worn by theatre nurses
• Joseph Bloodgood started using rubber gloves to undertake surgery
• Willoughby Miller (1891)


  Wrote about disinfection of dental instruments in reducing the risk of patient-to-patient transmission of infection, citing examples of spread of syphilis due to dental care
• Miller's recommendations


  • Boiling of linen
  • Single use of rubber dam
  • Scrubbing instruments first to remove bioburden before sterilisation
• Boiling water was cited as the preferred method of instrument reprocessing during this period
• Fossume (1905) argued that the implementation of infection control is a moral and intellectual obligation of the modern dentist, calling upon the values of professionalism
• In 1915 in the USA, there were guidelines on infection control in dentistry issued by the Public Health Service under the auspices of the Hygienic Laboratory, which would later become part of the National Institutes of Health
• Hasseltine's 1915 guidance


  • Encompassed asepsis, validation, cross infection, instrument reprocessing including the role of cleaning prior to sterilisation and methods of sterilisation
  • Favoured moist heat sterilisation over chemical disinfectants
  • Detailed single-use instruments and equipment
  • Encompassed the surgery and dental chair, the maintenance of the cuspidor and the role of protective barriers
• Hepatitis


  Infectious jaundice due to a virus, classified as hepatitis A (infectious) or B (serum)
• In 1952 an expert panel came together as part of the World Health Organization to address the problems posed by hepatitis, and recommended that chemical disinfectants should not be used as they could not be relied upon to be effective
• In 1963 the discovery of the Australia antigen (hepatitis B surface antigen) by Baruch Blumberg and Harvey Alter led to increased progress in the understanding of the virus
• The first commercial vaccination against hepatitis B, developed by Maurice Hilleman, was released in 1981
• Uptake of the hepatitis B vaccine by the dental profession remains low in many countries due to a range of factors
• Autoclave


  Invented by Charles Chamberland and Pasteur in 1879, an effective method of destroying microorganisms
• By the 1890s steam sterilisers were in use in some American hospitals
• In 1933 the American Sterilizer Company introduced the first machine that used temperature indicators, improving the control and accuracy of the sterilisation process
• From the mid-1950s onwards, the cost of automatic autoclaves that were quick to run had started to come down in price, making them more affordable and practical for general dental practice
• Spaulding's system


  Classifies surgical and medical instruments based on the risk of associated infection: critical, semi-critical, non-critical
• In the 1950s, UK hospitals began centralising their sterilisation services to achieve a uniform standard of reprocessing, better maintenance of equipment and well-trained staff
• AIDS


  Acquired immune deficiency syndrome, caused by the human immunodeficiency virus (HIV)
• In 1983, the CDC issued guidance on the management of patients' blood and body fluids, highlighting the use of personal protective equipment including gloves and masks as important in protecting healthcare workers
• The 1985 universal precautions guidance recognised the deficiency of the 1983 guidance, and advised that all blood and some body fluids should be considered infected
• In 1990, an American dentist, David Acer, died of AIDS-related illness, and it would emerge that in all likelihood six of his patients had contracted HIV from him
• The CDC replaced universal precautions in 1996 with standard precautions, prompted by the need to unify the CDC-issued guidance on moist body substances and universal precautions
• In 2003 the CDC issued its guidelines for dentistry which were a more tailored version of the standard precautions, applicable to the dental setting
• Prions


  Proteinaceous infectious particles described by Stanley Prusiner in 1982, responsible for diseases like bovine spongiform encephalitis (BSE)
• In an enquiry led by Lord Phillips, it was revealed that parts of the British government were seemingly more concerned about the impact BSE would have on the beef industry than any possibility that it could be a risk to humans
• Prions


  Proteinaceous infectious particles described by Stanley Prusiner in 1982
• First case of bovine spongiform encephalitis (BSE) noted in the UK


  1984
• By 1988 the number of BSE cases in the UK had risen to approximately 600
• The spread of BSE amongst cows was likely due to the use of recycled animal protein in ruminant feed, following an initial sporadic case