Antibiotic Resistance

Antibiotics are drugs which kill or inhibit the growth of bacteria.

While many bacteria are good for us, there are also bacteria that cause disease – the ‘bad bugs’. They can cause illness ranging from minor to life-changing or life-threatening, and it is for these infections that antibiotics are prescribed.

Antibiotics either kill bacteria (bactericidal antibiotics) or prevent their growth (bacteriostatic antibiotics).

When bacteriostatic drugs are used, they stop bacterial growth allowing the body to kill off the infection itself; in these cases the antibiotics work alongside the body’s own defences.

Problems can arise if, for any reason, the antibiotic is only partially effective. The weakest bacteria are killed but the stronger ones, who can fight off the attack, multiply. The bacterial population now contains stronger and more resistant bacteria than it did before treatment started. The body, now working alone, may not be able to eliminate the infection.

• Prescribing the wrong antibiotic for the infection – sensitivity tests help vets identify the best drug to use.
• Failure to use the antibiotics exactly as directed by the vet.
• Giving a too-low dose for the type of infection
• Stopping the treatment too early, before the infection is fully gone
• Failure to recognise and treat concurrent problems that will reduce the antibiotic’s ability to kill or slow the growth of the bacteria. 

Resistance of bacteria to antibiotics (antimicrobial resistance) is becoming an increasingly serious health concern.

Resistance to antibiotics is increasing and in the future we may enter a time where there is no effective treatment for serious bacterial infections. This will mean relatively minor infections, that are currently easily treated, may kill in the future because there is no drug available to treat them.

In addition, overuse of antibiotics can result in the emergence of drug-resistant infections in pets, and drug-resistant bacteria may be transferable from pets to owners and vice versa.

The responsibility to prescribe and use antibiotics appropriately is therefore crucial. 

It is generally accepted that bacterial resistance is increasing in human and veterinary health because antibiotics are being prescribed to too many patients (human and animal) who do not need them.

Up until around the 1990s, new antibiotics had been developed as the older ones became less effective. However, there have been no truly new antibiotics developed for quite some time.

The difficulty vets face is in being certain whether a patient does or does not have a bacterial infection.

They may be concerned that if they don’t prescribe an antibiotic to a patient who does turn out to have a bacterial infection, then that patient could be more unwell than they might have been, or could even die.

There are too many instances where a pet is prescribed an antibiotic for a clinical problem that is rarely, if ever, caused by a bacterial infection such as:

• Vomiting
• Acute diarrhoea
• Cystitis (bladder inflammation) in cats under ten years old
• Kennel cough 

Some bacterial infections can even be made worse through inappropriate use of antibiotics. In cases of intestinal infections with Salmonella bacteria, antibiotic therapy can actually prolong infection and increase the length of time the body takes to stop shedding bacteria. 

One challenge facing vets is that clinical signs of bacterial or viral diseases can look similar.

Viruses are not affected by antibiotics, so their use in a viral infection is not only a waste of time and money, but may also disturb the patient’s normal bacterial balance in the gut and contribute to the development of drug-resistant strains of ‘bad’ bacteria.

Testing is a great way for vets to determine if there is a bacterial infection present.