Animal production

Causes and mechanisms of antibiotic resistance

The phenomenon of antibiotic resistance is the result of not only excessive but also inappropriate use of antibiotics in both human and veterinary medicine, which among other things amounts to:

  • unjustified prescribing of a drug, e.g. “over the counter” or when the disease has a viral origin,
  • too late initiation of antibiotic therapy,
  • too short or too long a treatment period,
  • inclusion of an antibiotic for treatment with too narrow or too broad a spectrum of action,
  • the wrong dose of a drug.

It is not only the doctor or veterinarian who is responsible for the inappropriate use of antibiotics, but also the patient or grower who does not follow medical advice or acts on his or her own. This approach has led bacteria to develop multiple resistance mechanisms over time, consisting of:

  • enzymatic modification of antibiotic molecules – bacteria produce enzymes that alter the chemical structure of the antibiotic, thereby reducing or completely eliminating its effectiveness;
  • alteration of the permeability of cell envelopes – modification of bacterial cell wall proteins, which are responsible for the penetration of b – lactam antibiotics into cells;
  • enzymatic breakdown of the antibiotic – bacteria produce enzymes that hydrolyse antibiotics, weakening or inhibiting their effect;
  • active pumping out of active substance molecules (eflux), as a result of which the sensitivity of the bacteria to the antibiotic decreases;
  • the production by the bacterium of alternative metabolic pathways to those blocked by the antibiotic – a by-pass reaction.