Antibiotic Resistence

Resistance to antibiotics

Alexander Fleming discovered penicillin in 1921 and in 1941 its use on people began. Many bacterial infections previously associated with a fatal outcome could then be treated. Ever since, antibiotics have been in common use. Over time, many bacteria have developed resistance to antibiotics. Antibiotic resistance is a growing threat since it jeopardizes treatment of infections where antibiotics are necessary. Medical care depends on effective antibiotics in situations such as surgery, transplants and cancer treatment that may involve an increased risk of infection. 


Antibiotics are drugs used to kill or inhibit bacterial growth. Antibiotics have no effect on infections caused by viruses or fungi. Consequently, use of antibiotics to treat influenza is completely ineffective. 

Penicillin is the most common type of antibiotic. Antibiotics destroy bacteria-specific structures which are not found in human cells. For example, penicillin acts by degrading the bacterial cell wall, which means the bacteria cannot survive. 

Resistance to antibiotics

Bacteria continually undergo mutations in their genetic code. Mutations can sometimes lead to a new bacterial property. If that changed property provides the bacterium with an advantage it will be able to reproduce more effectively than bacteria without the mutation. If a mutation causes the bacterium to become less sensitive to antibiotics, it may lead to development of an antibiotic-resistant strain of bacteria. Antibiotic resistance to one or more antibiotics is then established.

What bacterial changes can make antibiotics ineffective?

  • –  Bacteria block the transport of antibiotics into the cell.
  • –  Bacteria produce substances that break down the antibiotic.
  • –  Bacteria pump the antibiotic out of the cell.
  • –  Bacteria change so the antibiotic can no longer become attached onto or inside them.

The mutated bacterium is often found in human or animal bodies without causing problems. The mutated bacterium first begins to multiply when the environment changes so that it derives an advantage from its new property. In the case of antibiotic resistance, antibiotics select for resistance since the mutated bacterium survives and can multiply, while the non-mutated bacteria are killed. 

Antibiotic use is linked to both the development and spread of resistance. The risk of spreading in hospitals is high since antibiotics are often used. Antibiotic-resistant bacteria can also be transmitted between people, animals and the environment. Bacteria may also share their resistance genes with each other. Antibiotic resistance is also found in foods. 

Antibiotics have been widely used since the 1940s, which has led to an increase in antibiotic resistance over time. Antibiotic resistance has become such a large problem in many countries that a significant number of antibiotics lack effectiveness which has resulted in deaths. In addition, development of new antibiotics is not keeping pace with the development of antibiotic resistance. This is obviously a major problem since it complicates treatment of serious infections in the medical setting. 

Both the World Health Organization (WHO) and the Swedish Institute for Communicable Disease Control rank the rapid development of antibiotic resistance as one of the greatest threats to human health. 

How does antibiotic resistance develop and spread today?

Resistance may arise during antibiotic treatment. Antibiotic-resistant bacteria spread in our hospitals, but can also be found in both animals and food. In a global world, resistant bacteria spread rapidly, both with people who travel and with food transported within and between countries.

When should antibiotics be used?

Doctors often ask themselves two questions when considering antibiotic therapy: 

  • –  Is the infection caused by bacteria or virus?
  • –  Will the infection heal on its own or is treatment necessary? 

If antibiotics are used unnecessarily the risk of developing more resistant bacterial strains increases, which over time may make it impossible to treat certain infections. In principle, each course of antibiotic treatment results in the occasional resistant bacterium and such bacteria may persist in the body for up to two years after treatment.

Impetigo is a relatively mild bacterial infection for which antibiotic treatment has historically resulted in several resistant bacterial strains.

Impetigo is a superficial skin infection that often afflicts children. Impetigo is caused by bacteria like staphylococci or streptococci. Usually the infection causes no symptoms other than rash, blisters and lesions Read more about Impetigo by clicking here.

Different treatments for impetigo are available. Although impetigo is not a dangerous disease, topical antibiotics have routinely been used as treatment for many years. Historically speaking, antibiotic creams are facing the same fate. Due to development of resistance, nowadays fusidic acid or mupirocin-containing antibiotic creams previously used to treat impetigo are no longer recommended. Until recently the Swedish Medical Products Agency recommended instead the use of a new antibiotic. However, owing to the risk of resistance development the recommendation was changed since 2011 so that even this new antibiotic is not recommended for routine treatment of impetigo. Läkemedelsboken 2011–2012, “Antibiotic creams not recommended for routine use due to risk of resistance.” 

Restrictive use of antibiotics which is often practiced in Sweden is necessary to retain effective antibiotics even in the future for treatment of severe infections where there are no other options. Generally speaking, antibiotic use becomes more liberal as you travel south in Europe.


Site updated 2016-01-15

Good to know

Antibiotics are drugs used to kill or inhibit bacterial growth. Antibiotics have no effect on infections caused by viruses or fungi. Consequently, use of antibiotics to treat influenza is completely ineffective.