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Test 2: Micro-organisms of relevance to infection prevention and control

  1. Micro-organisms are:
    • Visible to the naked eye
    • All harmful to human health
    • Only found on humans and family
    • Very small, single or multi-celled life forms.
  2. Pathogens are:
    • Micro-organisms that can cause disease in humans
    • Not able to overcome the body’s immune defences
    • Not transferrable from one person to another
    • Not harmful to human health.
  3. Bacteria are easily recognisable under the microscope because they:
    • Move about slowly
    • Stain yellow or green with Gram stain
    • Form into long string-like filaments
    • Follow particular grouping or clustering patterns.
  4. The most common method used to stain bacteria for identification under the microscope is:
    • The Ziehl-Neelsen (ZN) stain
    • The methylene blue stain
    • The Gram stain
    • The carbol fuchsin stain.
  5. The Gram stain can assist with bacterial identification by:
    • Identifying the growth requirements of the bacteria
    • Differentiating Gram-positive from Gram-negative organisms by colour
    • Identifying which bacteria are antibiotic-resistant
    • Identifying whether bacteria are pathogens or not.
  6. Regarding growth of bacteria:
    • Bacteria need the right nutrients, humidity and temperature to multiply
    • Bacteria can replicate as fast as every two minutes
    • Bacteria can only grow if oxygen is available
    • The phase of rapid bacterial growth is called the ‘lag phase’.
  7. Regarding viruses:
    • Most viruses infect cells of the endocrine system
    • Viruses with an envelope are more difficult to kill
    • Viruses can only survive inside of the host’s cells (intracellularly)
    • Most viruses are not easily transmissible.
  8. What is the main route of infection transmission in healthcare facilities?
    • Respiratory transmission
    • Contact transmission
    • Inoculation
    • Ingestion.
  9. Which of the following are required for an infection to be transmitted?
    • A host with a good immune system
    • The bacteria must be Gram positive
    • The bacteria must be Gram negative
    • An infectious agent or pathogen.
  10. What is the chain of infection?
    • The sequence in which an infection is transmitted from its reservoir to its host
    • The list of people who have been linked to an outbreak of infectious disease
    • The route by which a particular infection is spread
    • A theory about how infectious disease outbreaks are started.
  11. With regard to colonisation:
    • The host’s normal flora provide no protection against colonisation
    • Colonising micro-organisms can be potentially transmitted to others
    • Colonisation always results in development of infection
    • Carriage of colonising micro-organisms is lifelong.
  12. Micro-organisms cause disease in the host by:
    • Causing local inflammation
    • Using up nutrients needed by the normal flora
    • Using their virulence factors to overcome the host’s defences
    • Multiplying until their growth is out of control.
  13. With regard to host invasion by micro-organisms:
    • Endogenous micro-organisms cannot invade the host and cause infection
    • Colonising micro-organisms cannot invade the host and cause infection
    • The host has no way to prevent infection after microbial invasion has occurred
    • A weakened immune system puts the host at higher risk of microbial invasion.
  14. Normal flora:
    • Are micro-organisms that live in and on the human body without causing infection
    • Only live on the body for short periods of time (hours)
    • Are not affected by antibiotic use in the host
    • Cannot be transferred from person-to-person by close contact.
  15. Factors that increase the likelihood of healthcare-associated infection are:
    • Many empty hospital beds
    • A very tight control of antibiotic use
    • Handrubs rather than hand sprays
    • The presence of indwelling devices, e.g. drips, urinary catheters.
  16. Healthcare-associated infections:
    • Occur less than 48 hours after admission to hospital
    • Include site-specific and device-associated infections
    • Do not include gastrointestinal tract infections that develop in hospital
    • Do not include respiratory tract infections that develop in hospital.
  17. Standard precautions:
    • Reduce the chance of infection transmission from known sources of infection only
    • Are the specific precautions taken to prevent droplet transmission of infection
    • Should be applied to all patients, by all healthcare workers, at all times
    • Should only be applied when there is an obvious infection risk, e.g. a blood spill.
  18. The laboratory has an important role to play in infection control by:
    • Informing IPC and healthcare staff of patients with transmissible pathogens
    • Assisting clinicians with rational selection of antibiotics/antibiotic stewardship
    • Assisting IPC practitioners with outbreak investigation
    • All of the above.
  19. Meaningful microbiology laboratory results can be obtained when:
    • The sample is kept on ice while in transit.
    • Appropriate aseptic technique is used during specimen collection
    • The specimen is delayed in transit to the laboratory
    • The attending doctor asks a student to obtain the specimen.
  20. When interpreting microbiology culture results:
    • All cultured pathogens should be treated with appropriate antibiotics
    • The possibility of culture contamination is very small
    • The pathogen cultured should be interpreted in the context of the patient’s clinical picture
    • The possibility of colonisation rather than infection is not worth considering.