All courses › Microbiology and Infection Control
Microbiology and Infection Control: free practice, theory and problems
Microorganisms are bacteria, viruses, fungi and parasites. Most are harmless and many are useful (the normal flora), but some cause disease.
Contents
1. Microorganisms
What is it about?
Microorganisms are bacteria, viruses, fungi and parasites. Most are harmless and many are useful (the normal flora), but some cause disease.
Concepts
- Bacteria are single-celled organisms without a nucleus. They can be treated with antibiotics.
- Viruses are not cells and can only multiply inside living cells. Antibiotics do not work on viruses.
- Fungi (for example Candida) often cause infections in people with weakened immunity or after antibiotic use.
- Gram staining divides bacteria into gram-positive and gram-negative according to the cell wall.
- Some bacteria form spores that survive drying and alcohol, for example Clostridioides difficile. Then hands must be washed with soap and water.
- The normal flora on the skin and in the gut protects against disease-causing microbes.
2. The chain of infection and standard precautions
What is it about?
Infection happens when all the links in the chain of infection are connected. Break one link and the infection stops. Standard precautions apply to all patients, all the time.
The chain of infection
- Infectious agent (the microbe).
- Reservoir (a person, animal or object where the microbe lives).
- Portal of exit (for example the airways, wounds or stool).
- Mode of transmission: contact (the most common in hospitals), droplet or airborne.
- Portal of entry (mucous membranes, wounds, catheters and insertion sites).
- Susceptible host (for example older people, newborns and people with weakened immunity).
Standard precautions
- Hand hygiene is the most important measure: hand rub before and after patient contact, before clean procedures, after contact with body fluids and after contact with the patient's surroundings.
- No rings, watches or bracelets, and short nails.
- Gloves when there is a risk of contact with blood and body fluids. Gloves do not replace hand hygiene.
- Cough hygiene, correct handling of waste and linen, and cleaning of equipment.
Practise the chain of infection and standard precautions in the app →
3. Antibiotics and resistance
What is it about?
Antibiotic resistance means that bacteria are no longer killed by antibiotics that used to work. Every unnecessary course of antibiotics increases the risk. Norway has low levels of resistance, partly because narrow-spectrum antibiotics such as penicillin are used whenever possible.
Concepts
- Narrow-spectrum antibiotics hit few types of bacteria. Broad-spectrum ones hit many and disturb the normal flora more.
- Resistant bacteria you should know: MRSA (methicillin-resistant Staphylococcus aureus), ESBL-producing gut bacteria and VRE (vancomycin-resistant enterococci).
- Resistance spreads when bacteria share genes, and through transmission between people. Good infection control slows the spread.
- Antibiotics must be taken as prescribed by the doctor, and leftovers returned to the pharmacy, not saved.
Example problems with solutions
Here are some of the problems in microbiology and Infection Control. In the app, calculation problems get new numbers every time, so you can practise until it sticks – and take a graded practice exam before the real one.
Microorganisms: Why do antibiotics not work against viruses?
Answer: Viruses are not cells and lack what antibiotics attack
Antibiotics attack structures in bacteria, such as the cell wall. Viruses do not have these.
The chain of infection and standard precautions: What is the single most important measure to prevent infection in hospitals?
Answer: Hand hygiene
Contact transmission via hands is the most common route of infection in healthcare.
Antibiotics and resistance: Why are narrow-spectrum antibiotics preferred when possible?
Answer: They cause less resistance and disturb the normal flora less
Broad-spectrum antibiotics drive resistance in many types of bacteria.
Microorganisms: Which hand hygiene is right for Clostridioides difficile?
Answer: Wash with soap and water
The spores survive alcohol, so they must be removed mechanically with soap and water.