1. Healthcare Acquired Infections - HAI’s
Antibiotic resistance
Why infections in hospitals are so prevalent and the codes of practice developed to limit them.
Key Terms: Natural Selection, Evolutionary Arms Race, C. Difficile, MRSA, Superbugs, Resistance.

2. Antibiotic resistance
Boardworks AS Biology
Infectious Diseases
In the presence of an antibiotic, bacteria with resistance to that antibiotic (due to genetic mutation) have an advantage.
They are able to survive and reproduce, giving rise to a population of antibiotic-resistant bacteria. In some cases this resistance is evolving faster than the development of new antibiotics.
Photo credit: Wellcome Library, London
An assortment of antibiotics in tablet and capsule form.
M. tuberculosis has evolved resistance to streptomycin and other antibiotics.
Multi-drug resistant TB is still relatively rare, but there is growing concern about its spread.

3. How does Resistance develop?

4. How does Resistance develop?
‘Evolutionary Arms Race’ between Pathogens and their Hosts
Colony of bacteria susceptible to antibiotic
Most bacteria in colony killed
If mutation occurs in a bacterium that confers resistance, that bacterium will survive.
These can then reproduce into a colony which is resistant.

5. Mechanisms of Resistance

6. Mechanisms of Transfer

7. Superbugs ‘Healthcare-acquired Infections’ Main two are:
Methicillin Resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C. difficile)
Why are they more prevalent in hospitals?
Why are they such a big problem? (Patients/NHS)

8. Invasive MRSA infections can lead to the following conditions:
blood poisoning (sepsis) - which could lead to septic shock, where your blood pressure drops to a dangerously low level.
urinary tract infection - infection of the parts of the body used to take urine out of the body, such as the bladder.
endocarditis - infection of the lining of the heart.
pneumonia - a lung infection.
septic bursitis - inflammation of bursa (small fluid-filled sacs under the skin) caused by a bacterial infection.
septic arthritis - inflammation of a joint caused by a bacterial infection.
osteomyelitis - a bone infection caused by bacteria.

9. The most common symptoms of a mild to moderate C. difficile are:
regular bouts of usually foul-smelling, watery diarrhoea; which can sometimes be blood stained; most people have around 3-5 bouts of diarrhoea a day.
abdominal cramping and pain.
In more severe cases of C. difficile your colon (large bowel) can become inflamed, which is known as colitis.
Symptoms of colitis include:
more frequent bouts of diarrhoea; between a day
a high temperature (fever) of or above 38C (100.4F)
more severe abdominal cramping
dehydration (not having enough fluid in your body)
feeling sick
loss of appetite
weight loss

10. Antibiotic resistance: MRSA
Boardworks AS Biology
Infectious Diseases
Antibiotic resistance: MRSA
The bacteria Staphylococcus aureus has become resistant to most antibiotics, including methicillin. This methicillin- resistant S. aureus (MRSA), which is becoming common in hospitals, can cause a life-threatening infection.
Due to the emergence of antibiotic resistance, several methods of prevention and control have been adopted:
Photo credit: Janice Haney Carr / CDC
This 2005 scanning electron micrograph (SEM) depicted numerous clumps of methicillin-resistant Staphylococcus aureus bacteria, commonly referred to by the acronym, MRSA (magnified x 9560). Recently recognized outbreaks, or clusters of MRSA in community settings have been associated with strains that have some unique microbiologic and genetic properties, compared with the traditional hospital-based MRSA strains, which suggests some biologic properties, e.g, virulence factors like toxins, may allow the community strains to spread more easily, or cause more skin disease. A common strain named USA has caused many such outbreaks in the United States.
Teacher notes
Students could be asked to explain the reasoning behind the three methods of prevention and control listed.
antibiotics should only be prescribed when needed
patients should finish the complete course of antibiotics
introduction of infection control in hospitals.

11. Antibiotic resistance worldwide
Boardworks AS Biology
Infectious Diseases
Antibiotic resistance worldwide
pathogen
% of drug- resistant infections
drug
country/region
Staphylococcus aureus
methicillin multidrug
US Japan
32 60
any drug any drug multidrug
Mycobacterium tuberculosis
US New York City Eastern Europe
Kenya Ghana Zimbabwe Thailand
Plasmodium falciparum
chloroquine
Teacher notes
The table shows the percentage of antibiotic resistance infections in different parts of the world for different pathogens.
Data from the Office of the Director of National Intelligence (
US, Asia, Chile Spain Hungary
10–
Streptococcus pneumoniae
penicillin

12. Activities
Read pages carefully, along with the articles ‘MRSA: a hospital superbug’, ‘Antibiotics’ revision guide sheet and the newspaper headlines sheet.
Use all the information to create and complete a table with the following headings outlining the preventative measures used in hospitals to limit the spread of infection:
Describe 3 reasons why a person is more likely to pick up an infection in a hospital than in the outside world?
Type of Preventative Measure
Explanation of how preventative measure tackles problem
Potential problems and limitations of measure

13. Homework
Read and highlight all the pages of the ‘Resistance in Pathogens’ booklet.
Use all the information you have gained over the last couple of lessons to complete all the questions.