I also conduct research investigating how infections in animals respond to antimicrobial medicines.

All my projects are targeted to improve animal health, but monitoring the response of animal infections to antimicrobials has implications not just for the animals, but for the health of people as well.

To simplify things I’ll confine my discussions to bacteria.

Bacterial infections consist of many millions of the same infective units, but because there are so many infective units, there will be a very small percentage of units with slight differences in their genome (mutations) and these genomic changes/mutations may make them resistant to an antibacterial medicine. Administration of any the correct antibacterial medicine to the patient will kill most bacteria but not the ‘resistant’ mutants which then multiply and become the dominant population. So every time an antibacterial medicine is administered there is the risk of selecting one or more mutant populations to survive and multiply. We rely on the fact that the antibacterial medicine kills the major population of infective units leaving small mutant populations and the body’s other defenses such as the white blood cells then have the capacity to kill the mutant populations.

Another aspect to consider is when we administer antibacterial medicines to animals or people, some of the medicine will go out in the feces and urine…. such tiny minuscule amounts will find their way into the water or other environmental sectors, where they can possibly accumulate and find their way into the human and animal food chains. Such small amounts of antibacterial medicines in the environment when ingested can kill the bacteria that are susceptible to these small medicinal amounts but those bacteria that are resistant to these small amounts once again survive and multiply.

So if we are going to use antibacterial medicines we need to make sure that are having a significant effect in killing infections in people and humans and have a minimal effect on proliferating the mutant bacterial strains.

So I do a quite a few studies to monitor that antibacterial medicines are being effective in pets, especially dogs and cats. If medicines are not having the desired effect then they are a risk to the pet as well as the greater community.

Key results from our most recent study

Our most recent study led by Alexander Bogdanovski, investigated the bacteria Escherichia coli (known as E. coli) susceptibility to the new antibacterial drug Convenia. These E. coli isolates were collected from the urinary tracts of dogs and cats.

We found 25.3 % of the canine and 17.9% of the feline E. coli isolates are resistant to Cefovecin.

We have also found that the concentration of amoxicillin-clavulanate (known as Clavulox or AmoxyClav or Augmentin) required to inhibit multiplication of E. coli isolates has statistically increased over the last ten years. This means that it takes a higher concentration of this medicine to kill all E. coli than it did ten years ago.

These data are surprising, perhaps somewhat alarming. We are collecting and testing more E.coli isolates from pets in 2017 to confirm that these observations are correct.


I would like to thank the Australian Companion Animal Health Foundation (ACAHF) for financially supporting these studies.