Antibiotic resistance

About antimicrobial resistance

Resistance of bacteria against antibiotics can be "natural". This means that the antimicrobial is not capable of attacking the bacteria adequately, for example because the bacteria does not display the right target points, penetration of the antibiotic is insufficient or because the bacterium produces neutralizing enzymes.

Resistance can also be "acquired". The bacteria has acquired a characteristic that makes the antibiotic less (or no longer) effective because of a change in the genetic material or obtaining new DNA material.

The use of antimicrobials provokes the development and selection of acquired resistances in bacteria against these antibiotics. By co-selection (co-resistance or cross-resistance) bacteria can also become resistant to other (similar) antibiotics.

Furthermore different risk factors are of importance in the persistence and spread of antimicrobial resistance. For example stress, feed, hygiene and housing.

Risks due to resistance in animals

The development of antimicrobial resistance In veterinary medicine causes therapy failure in animals. This results in a lowering of productivity, loss of animals, decreased animal welfare and increased costs.

In human medicine problems may arise because resistant bacteria can be transferred from animals to humans. This is possible via direct transfer through zoonotic bacteria (bacteria of animal origin that can cause disease in humans) or indirect through resistant animal bacteria that exchange resistance genes with human bacteria or through a common environment.

Use of antibiotics

Use of antibiotics is the most important factor causing resistance development. Although not proven, it is often considered that under dosing stimulates resistance development. More, but also correct dosing will not stop resistance development.


Solutions to act against resistance or even to ban resistance are not always readily available. In general it is considered that reduction of the use of antibiotics and responsible antibiotic use will result in a decrease of the occurrence of antimicrobial resistance.

Reduction of antibiotic use mainly means that in general the antibiotic use must be diminished, thinking in the first place of prophylactic group treatments. Prevention of illnesses by means of an ameliorated biosecurity, vaccination, etc will have to become more important.

Responsible antibiotic use means that antibiotics are only set in if there is a medical need after diagnosis of a veterinarian, preferably confirmed by complementary research (bacteriology and antimicrobial sensitivity testing), that broad spectrum antibiotics are used carefully and very potential products are only used as last remediation.

Examples of resistances

MRSA: Methicillin Resistant Staphylococcus Aureus

MRSA in de varkensstal, een bedreiging voor de volksgezondheid? - BCFI Vet, Folia Veterinaria (Dutch)

Methicillin resistant Staphylococcus aureus - Veterinary and Agrochemical Research Centre

Nationale surveillance van Methicilline-Resistente Staphylococcus aureus (MRSA) – Wetenschappelijk Instituut Volksgezondheid (Dutch)

Methicillin-resistant Staphylococcus aureus (MRSA) in food production animals - Vanderhaeghen, Wannes; Hermans, Katleen; Haesebrouck, Freddy; Butaye, Patrick - EPIDEMIOLOGY AND INFECTION (2010)

Comparison of Fingerprinting Methods for Typing Methicillin-Resistant Staphylococcus aureus Sequence Type 398 - G. Rasschaert, W. Vanderhaeghen, I. Dewaele, N. Janezˇ, X. Huijsdens, P. Butaye and M. Heyndrickx - JOURNAL OF CLINICAL MICROBIOLOGY (Oct. 2009)

"Alle antibiotica bannen is een utopie" (03/05/2010) - Interview Dr. Marc Heyndrickx (ILVO) en Dr. Davy Persoons (UGent) (Dutch)

"Preventief antibioticagebruik bevordert resistentie" (19/01/2011) – Interview Dr. Davy Persoons (Dutch)