Antibiotic Resistance in Our Pets

Staphylococcus aureus

            You hear about how widespread use of antibiotics in humans is pressuring microorganisms to adapt and develop resistance to the drugs administered for various illnesses but are our pets suffering the same fate? When an antibiotic is administered for an infection overtime the microorganisms are selectively pressured to change in such a way that they can fight back against the drug. This occurs over a long period and depends on how often the drug is used. If the antibiotic is used consistently over time the bacteria will become unaffected by it thus continuing to cause the animal harm.

            The European Union has banned the use of Antibiotic growth promoters (AGPs) given to farm animals¹. This is mainly because these AGPs are pressuring the microbes to build up resistance to the AGPs. Some of the microorganisms that have been found to be resistant to these antibiotics are zoonotic. Meaning the little guys can actually make humans sick. Many of these animals are used in the food industry, which increases the risk to humans.  The point of this is prevention may not necessarily be a good thing and if farm animals can have antibiotic resistant bacteria then other animals that live by our side may have them too.

Sheep and Goat Pox

            One study found that the prevalence on Multi-drug Resistant Salmonella sp. was quite high ². The researchers used birds, fish, reptiles and mammals. They concluded that 83.3% of the birds had Salmonella sp. that are resistant to streptomycin and 100% of all other animals except fish had streptomycin resistant Salmonella sp. As you may already know, Salmonella is a health risk for humans and animals alike depending on the dosage amount.

            Another question is how exposed are our beloved pets to these antibiotic resistant microbes? Well one study indicated that one mode of transfer is through contact with other animals in a veterinary setting. Often times in small animal veterinary hospitals pets are kept as residents in the hospital; this poses a serious threat of creating a mode of transmission for microbes harmful to other animals and people. Fecal samples were taken from six cats from various small animal hospitals³.  The fecal samples were tested for various species of Enterococci. 48.9% of all the Enterococci isolated were Multi-drug resistant.  More alarming was the tests that followed. Researchers found the same isolates on the cage doors, thermometers, and stethoscopes of the corresponding small animal hospitals. This suggests a mode for these bacteria to spread to other animals. Our pets.

            Looking into the issue a little more I found that dogs seem to carry antibiotic resistant strains of Staphylococcus aureus ⁴ and Enterococcus faecium ⁵. The staphylococci seemed to be resistant to methicillin and the Enterococci were resistant to ampicillin. Both types of microorganisms have the possibility of causing problems in humans. This suggests that these particular microbes may possibly be acquired outside of the hospital (veterinary or human) setting do to the widespread nature of both types of microbes.

Enterococcus faecalis

            From this information, we see that bacteria are building up resistance in many other living things. With time if antibiotics are used freely and not administered with proper care, the very problems that are affecting humans could become a huge problem for our pets too. We might find ourselves fighting not only a battle for our own health but one for our animals too. The only problem with this is many of the same microbes that are now resistant to antibiotics found in animals can cause serious illness in humans. This is a difficult situation and it is hard to evaluate the current severity of the issue because the particular information is scarce. Most of the research that I have found deals with microbes that could pose a threat to humans but I wonder about the ones that our pets can only get and how resistant these organisms are. For instance, your puppy, bird, or kitty cat might get an upper respiratory infection from a bacterium that most antibiotics will not help with. Scary thought, if you ask me.        

References

1.         Casewell, M., Friis, C., Marco, E., McMullin, P. & Phillips, I. The European Ban on Growth-Promoting Antibiotics and Emerging Consequences for Human and Animal Health. J. Antimicrob. Chemother. 52, 159–161 (2003).

2.         Seepersadsingh, N. & Adesiyun, A. A. Prevalence and Antimicrobial Resistance of Salmonella spp. in Pet Mammals, Reptiles, Fish Aquarium Water, and Birds in Trinidad. Journal of Veterinary Medicine, Series B 50, 488–493 (2003).

3.         Ghosh, A., KuKanich, K., Brown, C. E. & Zurek, L. Resident Cats in Small Animal Veterinary Hospitals Carry Multi-Drug Resistant Enterococci and are Likely Involved in Cross-Contamination of the Hospital Environment. Front Microbiol 3, (2012).

4.         Epstein, C. R., Yam, W. C., Peiris, J. S. M. & Epstein, R. J. Methicillin-resistant commensal staphylococci in healthy dogs as a potential zoonotic reservoir for community-acquired antibiotic resistance. Infection, Genetics and Evolution 9, 283–285 (2009).

5.         Damborg, P. et al. Dogs Are a Reservoir of Ampicillin-Resistant Enterococcus Faecium Lineages Associated with Human Infections. Appl. Environ. Microbiol. 75, 2360–2365 (2009).