Understanding antibiotic resistance
Understanding antibiotic resistance

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Understanding antibiotic resistance

2.2 Introducing acquired resistance

As its name suggests, acquired resistance is not innate to a bacterial type. It occurs when a bacterium acquires the ability to resist the actions of a particular antibiotic.

Unlike intrinsic resistance, acquired resistance is only found in some populations of a bacterial type. This makes acquired resistance harder to track since each new outbreak or isolate may have acquired resistance to a different spectrum of antibiotics.

Acquired resistance is a very significant healthcare concern. Infections caused by bacteria that have acquired resistance to an antibiotic can no longer be treated with that antibiotic. Consequently, identifying the type of pathogenic bacteria causing an infection may not always be sufficient to determine which antibiotics will be effective treatments. Resistant isolates must be tested to determine which antibiotics are effective before treatment can be prescribed.

Activity 2 Acquiring multidrug resistance

Allow 15 minutes

The treatment options for infections caused by bacteria with acquired resistance can be further limited because bacteria can accumulate resistance to a variety of antibiotics over time. This is known as multidrug resistance (MDR).

Perhaps the most often cited example of intrinsic resistance is the multidrug resistance of Gram-negative bacteria.

Can you suggest why Gram-negative bacteria might be intrinsically resistant to many antibiotics?

Answer

Unlike Gram-positive bacteria, Gram-negative bacteria have an outer membrane which is impermeable to many antibiotics.

Now read the following BBC news article which highlights that, although multidrug resistance is rare, it can have a devastating impact.

Article 1 Bug resistant to all antibiotics kills woman [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]

While you read the article, note down the answers to the following questions.

1 Which bacterium caused the patient’s infection?

Answer

The patient’s infection was caused by the Gram-negative bacterium Klebsiella pneumoniae.

2 How many antibiotics was the infection resistant to?

Answer

It was resistant to 26 different antibiotics, including the ‘drug of last resort’ – colistin.

3 Is resistance to all antibiotics a common occurrence?

Answer

No, infections that are resistant to all antibiotics are uncommon.

Acquired resistance can occur as a result of genetic mutations or the transfer of resistance elements from other bacteria through a process called horizontal gene transfer. Don’t worry if you don’t understand these terms yet. You will return to these processes in Week 4.

Activity 3 Comparing intrinsic and acquired resistance

Allow 15 minutes

Look at the following statements in the table. Decide whether they are about intrinsic or acquired resistance or both and type your answer into the right-hand column.

Statement Intrinsic resistance, acquired resistance, or both?
Mechanism only present in a subpopulation of bacteria of a given type
You can type text here, but this facility requires a free OU account. Sign in or register.
Difficult to track
You can type text here, but this facility requires a free OU account. Sign in or register.
Can be identified if the bacterial type is known
You can type text here, but this facility requires a free OU account. Sign in or register.
Normal for bacteria of that type
You can type text here, but this facility requires a free OU account. Sign in or register.
Limits treatment options
You can type text here, but this facility requires a free OU account. Sign in or register.
Mechanism present in all bacteria of a given type
You can type text here, but this facility requires a free OU account. Sign in or register.
Occurs as a result of genetic mutation or horizontal gene transfer
You can type text here, but this facility requires a free OU account. Sign in or register.
Interactive feature not available in single page view (see it in standard view).

Answer

Statement Intrinsic resistance, acquired resistance, or both?
Mechanism only present in a subpopulation of bacteria of a given species Acquired resistance
Difficult to track Acquired resistance
Can be identified if the bacterial species is known Intrinsic resistance
Normal for bacteria of that species Intrinsic resistance
Limits treatment options Both
Mechanism present in all bacteria of a given species Intrinsic resistance
Occurs as a result of genetic mutation or horizontal gene transfer Acquired resistance

UAR_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has nearly 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus