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Antibiotic resistance in dogs & cats

Resistance is the ability of bacteria to survive and divide their cells in the presence of an antimicrobial substance. Multiple drug-resistant (MDR) bacterial strains are frequently seen today. MDR has made it difficult to treat diseases successfully on a global scale, casting doubt on the use of antibiotics in all animals.

Common disease causing bacteria
Common disease causing bacteria

Numerous bacteria often found on the skin are not harmful and do not usually cause any issues. One of these bacteria is Staphylococcus. As part of their regular body flora, all humans and animals have Staphylococcus bacteria on their skin, and up to three out of every hundred (3%), people carry resistant bacteria without being aware of it or experiencing any issues. According to statistics, one per cent of cats and between two and nine per cent of canines carry resistant germs.


Bacteria, bacterial infection, antibiotics resistant bacteria

Resistant bacteria are spread through direct contact between sick humans and animals, healthy humans and animals, or, less frequently, healthy humans and animals. Zoonotic diseases can be carried by a wide variety of bacteria, viruses, and fungi, however opportunistic bacterial infections are frequently the main source of concern.


What is the difference between antibiotics and antimicrobials?

 

Medicines known as antibiotics are used to both prevent and treat bacterial infections. When bacteria adapt to the use of antibiotics, antibiotic resistance develops. Humans or animals do not develop antibiotic resistance but it is the bacteria that develop the resistance. These bacteria are more difficult to treat than non-resistant germs.


A broader term, antimicrobial resistance, includes resistance to medications used to treat diseases brought on by various microorganisms, such as parasites, viruses, and fungi.

Excessive growth of antibiotic resistant bacteria
Excessive growth of antibiotic resistant bacteria

In light of difficult-to-treat diseases, potential pressure to use antimicrobials crucial to human medicine, and potential zoonotic transmission, antimicrobial resistance (AMR) is a growing issue in companion animals. Though the scope and significance of AMR in companion animals are poorly understood, it is evident that resistance is an issue in many pathogens and commensals, including staphylococci, enterococci, Escherichia coli, and Salmonella.


How do antibiotics work?

 

Chemotactic signals guide phagocytic cells, pinpointing the location of an infection. Superoxide radicals are produced during a "respiratory burst" that occurs as a result of the phagocytosis of microorganisms. This results in the secretion of novel proteins, abnormal iron uptake, and the release of lipocalins. Each one of these offers a mechanism through which antibiotics can bind to, aggregate, and be maintained at an active site of pathogen infection or tumour growth.

How does antibiotic/antimicrobial resistance develop?

 

Antibiotic resistance happens when bacterial strains alter (mutate) and develop resistance to particular antibiotics. Antibiotics may also alter the body's regular flora, giving resistant germs the chance to proliferate. Antibiotic resistance may also be facilitated by the overuse of antibiotics, such as when they are used to treat minor ailments or when a recommended course of treatment is not finished. Antibacterial medications are degraded by enzymes, bacterial proteins that are targets for antibiotics are changed, and membrane permeability to antibiotics is altered. These three processes constitute the three basic mechanisms of antimicrobial resistance.

Plasmid-mediated antibiotic resistance or bacterial chromosome-maintained resistance are also possible. Antibiotic hydrolysis caused by the bacterial enzyme beta-lactamase is the main method of resistance to penicillins and cephalosporins. By being exposed to beta-lactam medications, the expression of chromosomal beta-lactamase can either be stimulated or steadily suppressed.


How many different kinds of bacterial resistance exist?

 

Mobile genetic elements in bacteria that include plasmids, transposons, and integrons are involved in the transfer of antimicrobial determinants between various bacteria and are involved in antibiotic resistance (AR) pathways. Antibiotic resistance can either be natural or acquired.


Natural resistance

 

There are three types of natural resistance, i.e., inherent, point mutations and chromosomal mutations.

  1. Inherent: Some classes of antibiotics, e.g., aminoglycosides, cannot pass through strict anaerobes (bacteria that survive in a low oxygen environment) because they lack oxygen-dependent transporters, while others possess multidrug efflux systems, e.g. Pseudomonas aeruginosa and Escherichia coli

  2. Point Mutations: Typically random, point mutations can take place without the bacteria being exposed to antimicrobial agents.

  3. Chromosomal mutations: Target site modification, e.g. changes in penicillin-binding proteins (PBPs), result in resistance to ß-lactam drugs) by reducing permeability or uptake of the antimicrobial agent by bacteria. De-repression, the cause of a gene to cease to be repressed, is caused by deactivating the depressor gene of multidrug efflux systems or the metabolic by-pass gene in certain bacteria, e.g. the overproduction of dihydrofolate reductase resulting in trimethoprim resistance.


Acquired (mutational or extra-chromosomal) resistance

 

The acquisition of acquired resistance by previously susceptible bacteria can take place both vertically through mutation and horizontally through transformation, transduction, or conjugation from other bacteria that already have it. Transposons (transposable elements in the bacterial genome, plasmid, or prophage) and plasmids (extra mini-chromosomes) can transmit resistance to different antimicrobial treatments quickly and effectively. Due to this process, certain bacteria evolve metabolic bypasses like trimethoprim-resistant dihydrofolate reductase or efflux systems that render medications inert, such as aminoglycosides and ß-lactams.


How do pets contract antibiotic-resistant infections?

 

Antibiotic-resistant bacteria are frequently seen on the skin of otherwise healthy animals. These germs can be obtained through contact with an infected person or animal, direct contact with a carrier, or by visiting a hospital or veterinary facility (where antibiotic-resistant germs are more common than in the "normal" environment).

According to reports, animals who live with individuals who are more likely to be exposed to antibiotic-resistant bacteria, such as healthcare workers, veterinary professionals, and persons with impaired immune systems, are more likely to become infected.


What are the signs of antibiotic-resistant infections?

 

Individuals infected with antibacterial-resistant bacteria may exhibit skin symptoms that include infections and spots, and more serious cases might appear in surgical wounds. A veterinarian or a human medical doctor would need to collect a swab from the diseased region and send it for laboratory culture and identification in order to make a diagnosis.

English Bulldog breed dog with a severe case of skin infection
English Bulldog breed dog with a severe case of skin infection

A pet that develops a persistent skin infection (which may appear as itchiness, pustules, boils or ulcers) that does not improve after receiving normal antibiotic treatment, should be taken as an infection that is resistant to antibiotics or antimicrobials. Severe infections and sepsis brought on by these antibiotic-resistant illnesses can be fatal.


How are antibiotic-resistant infections treated?

 

Antibiotic-resistant infections are those that are resistant to several commonly used antibiotics, making them more challenging to treat than other infections. These infections can be successfully treated, though.

Effective antibiotics must be found in order to combat germs that are resistant to them. The veterinarian collects swabs from the animal and delivers them to a lab for testing in order to determine which germs are present and which medications the animal is sensitive to and resistant to. This will allow the veterinarian to determine the best course of action. Furthermore, maintaining proper hygiene is crucial. For example, cleaning and cleansing the wound can be beneficial because these bacteria like to dwell in filthy, enclosed spaces with little access to oxygen.


How are antibiotic-resistant infections prevented?

 
  1. The creation of novel medicines that are resistant to antibiotic-resistant bacteria is the strategy for overcoming antibiotic resistance.

  2. Antimicrobial agents should only be used when it is absolutely necessary.

  3. The probability of acquiring resistance is decreased by administering antibiotics for a shorter period of time. However, there are some conditions where long-term use is required, including some urinary tract infections and some bacterial skin diseases.

  4. Whenever possible, an antimicrobial agent should be chosen based on test results with the narrowest spectrum.

  5. The chosen dosing regimen should not endanger the treated animal and should stop the spread of germs that are resistant to antibiotics or the genes that cause such resistance.

  6. Pet owners need to understand the importance of compliance. Estimates show that just 44% of pet owners entirely follow the instructions for administering oral antibacterial drugs for a brief period of time.

  7. Dose rates used by doctors should be chosen using a pharmacokinetic-pharmacodynamic index to maximize the efficacy for bacteriological cure and provide the least amount of chance for the development, selection, and transmission of resistant organisms.

The veterinary industry has the opportunity to learn a lot from what has transpired in the field of human medicine. Antibiotics must be safeguarded in order to continually benefit from them in the future. If your veterinarian prescribes antibiotics for your pet, be careful to strictly adhere to his or her instructions and always finish the course of medication—even if your pet appears to be recovering.


References

 

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Dafale NA, Srivastava S, Purohit HJ. Zoonosis: An Emerging Link to Antibiotic Resistance Under "One Health Approach". Indian J Microbiol. 2020 Jun;60(2):139-152. doi: 10.1007/s12088-020-00860-z. Epub 2020 Mar 4. PMID: 32255846; PMCID: PMC7105526.


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Gutteridge, J. M. C., Quinlan, G. J., & Kovacic, P. (2020). Phagomimetic action of antibiotics: Revisited. How do antibiotics know where to go?. Biochemical and biophysical research communications, 521(3), 721–724. https://doi.org/10.1016/j.bbrc.2019.10.152

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