Antibiotic resistance in domestic animals

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Antibiotic resistance in domestic animals

The term "antibiotic resistance" refers to changes in bacterial microbes that lower an organism's susceptibility to an antibacterial drug. Antibiotic resistance represents a facet of the larger concept of antimicrobial resistance, which encompasses resistance to additional organisms such as fungi, viruses, and parasites. The dangers posed by resistant microbes to both humans and animals vary from minimal risk to potentially life-threatening. Practitioners of medicine, for humans as well as animals, are increasingly encountering infections that are more difficult, or even impossible, to treat with available pharmaceutical therapies. Within the last decade or so, greater attention has been paid to resistant infections in both livestock animals and household pets. Increasing research in the field continues to demonstrate that antibiotic-resistant organisms can be transferred from humans to animals, and vice versa.

Causes

Overuse/Misuse of antimicrobials

The overuse and/or misuse of antibiotics has previously been documented in human medicine as well as veterinary medicine to contribute to the emergence of resistant organisms. Prescribing antibiotics to animals prophylactically to prevent infection can lead to microorganisms which are resistant to entire classes of pharmaceutical drugs. Additionally, the inappropriate prescription of drugs can significantly contribute to resistant organisms; veterinarians prescribing antibacterial drugs in cases of viral infection, for instance, can lead to bacterial infections in which the organisms are resistant to previously prescribed medications. It should be noted, however, that in cases of viral infection, veterinarians may prescribe antibiotics to animals when necessary to prevent secondary bacterial infection, as in cases of parvoviral infections in dogs. It is also crucially important that when antibiotics are prescribed, their mechanism of action and effectiveness for the location of the infection is considered. Antibiotic drugs are most effective at treating infections in the body systems and anatomical regions in which they have the greatest mechanism of action. The antibiotic drugs used should, whenever possible, be catered to the specific microorganism present, and for the body system(s) the microorganism inhabits.

Pet owners may also be responsible for the emergence of drug-resistant microorganisms due to misuse of prescribed antibiotic drugs. Failing to complete a drug course, not following prescription instructions resulting in under- or over-dosing of drugs, administering drugs originally prescribed to a different animal, or administering expired antibiotics all significantly contribute to resistance in household animals.

Risks

To domestic animals

The risk to domestic animals of acquiring or harboring antibiotic-resistant organisms largely depends on the type of organism, the organism's susceptibility to antibiotic drugs, severity and location of infection, and the available pharmaceutical drugs. With such variability present and the limited number of available studies, it is difficult to make generalizations regarding the overall risk to household pets. Drug resistant infections have been reported in both dogs and cats, in the form of skin infections, urinary tract infections, and surgical site infections. These infections can be severe, and in some cases, life-threatening.

To humans

As in companion animals, varying levels of risk exist to pet owners of acquiring antibiotic-resistant organisms or infections from their pets. Risk is largely dependent on the type of microbes present, route of transmission, the severity of the microbe's resistance to pharmaceuticals, and the health status of the pet owner. With basic hygienic practices, most pet owners are not at a significant risk in acquiring a resistant microbe or infection. However, the very young, elderly, and immunocompromised persons may be at a greater risk than the average, healthy adult. National and international organizations including the United States Department of Agriculture (USDA), Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), and World Health Organization have published information regarding the risks posed by antibiotic resistant organisms.

Antibiotic-resistant bacteria may be transmitted to pet owners either directly (direct skin-to-skin contact, contact with saliva, feces, etc.) or indirectly from household surfaces (food bowls, bedding, countertops, litter boxes, etc.)

Prevention

Use of antimicrobials for active or likely infection

To prevent the emergence of resistant organisms, it is critical that antibiotics are prescribed for cases of active or likely infection. In some cases, particularly for healthy animals with no pre-existing health conditions, an appropriate immune response may prevent an active infection from occurring. Antibiotics should be reserved for animals who: 1) have an active bacterial infection, 2) are highly likely to develop an infection without pharmaceutical intervention, due to the nature of the injury or disease, and/or potential for infection by microorganisms, and/or 3) are immunocompromised in such a way as to warrant prophylactic administration.

Appropriate prescription

Veterinarians should exercise care when prescribing antibiotics in cases of microbial infection, as well as in prophylactic administration when viral infection is present. Antibiotics should be selected given the location (body system) of the infection, the likelihood or severity of infection, the necessary and effective dosage, and the duration of prescription. A multitude of resources exist to guide veterinarians in the determination of antibiotic prescription, including literature detailing treatment protocols, veterinary association guidelines and recommendations, product inserts, and a number of reliable, published pharmacological references.

Owner compliance

Owner compliance in the administration of veterinarian-prescribed antibiotics is essential in combatting resistance in companion animals. Failure to complete the prescribed antibiotic course, under- or over-dosing the prescribed animal against prescription instructions, missed doses, or administering prescribed antibiotics to another animal may be contributing factors to antibiotic resistance in household animals.

Stewardship programs/Monitoring programs

With such high incidences of antibiotic resistance reported in humans, authorities in the field have repeatedly suggested a nationwide monitoring program to document and track the usage of these pharmaceutical drugs. The World Health Organization (WHO) has been highly involved in the prevention of antimicrobial resistance in both humans and animals by releasing their "Global action plan on antimicrobial resistance" which includes five objectives:

1. To improve awareness and understanding of antimicrobial resistance.
2. To strengthen surveillance and research.
3. To reduce the incidence of infection.
4. To optimize the use of antimicrobial medicines.
5. To ensure sustainable investment in countering antimicrobial resistance.

Additionally, the WHO has pioneered the Global Antimicrobial Resistance Surveillance System (GLASS), as well as partnered with other organizations to promote the development of new antibiotic drugs and improve communications between organizations involved in preventing antibiotic resistance.

The USDA has also published a similar "action plan" to combat antibiotic resistance, including three objectives:

1. Determine and/or model patterns, purposes, and impacts of antibiotic use in food-producing animals.
2. Monitor antibiotic drug susceptibilities of selected bacterial organisms in food-producing animals, production environments, and meat and poultry.
3. Identify feasible management practices, alternatives to antibiotic use, and other mitigations to reduce AMR associated with food-producing animals and their

production environments.

In addition to the generation of their action plan, the USDA has also actively participated in fostering the One Health Initiative alongside such organizations as the American Medical Association, the American Veterinary Medical Association, the CDC, the United States National Environmental Health Association (NEHA), and others. The One Health Initiative "is a worldwide strategy for expanding interdisciplinary collaborations and communications in all aspects of health care for humans, animals and the environment. The synergism achieved will advance health care for the 21st century and beyond by accelerating biomedical research discoveries, enhancing public health efficacy, expeditiously expanding the scientific knowledge base, and improving medical education and clinical care. When properly implemented, it will help protect and save untold millions of lives in our present and future generations." While objectives of the One Health Initiative expand far beyond antimicrobial resistance, the subject is of significant interest to all participating organizations in the prevention of its occurrence.

As reports of resistant microbes in veterinary medicine increase as well, organizations such as the Center for Infectious Disease Research and Policy (CIDRAP) and the American Veterinary Medical Association (AVMA) have followed suit. CIDRAP has developed an Antimicrobial Stewardship Project (ASP) which provides resources to veterinarians regarding multiple aspects of antimicrobial resistance. The CIDRAP ASP website offers brochures, podcasts and webinars, a newsletter, journal highlights, policy updates, bibliographies and online resources, and an events calendar to provide education and guidance on the prevention of antibiotic resistance in veterinary medicine. The AVMA has also published similar resources via their website, including an official strategy regarding the use of antimicrobial drugs and various reports on the matter.

Instances of Antimicrobial Resistance

MRSA/MSSA/MRSP

In 2006, a research study identified multiple resistant Staphylococcus strains isolated from samples of healthy and diseased dogs and cats. Staphylococcus aureus was isolated from dogs with skin infections, Staphylococcus epidermidis was isolated from one dog with an infected wound, Staphylococcus epidermidis was isolated from a healthy cat, Staphylococcus haemolyticus from two healthy dogs and one healthy cat, Staphylococcus warneri from healthy dogs, and Staphylococcus hominis from a healthy dog. Of 252 animals sampled, 10 harbored methicillin-resistant organisms, including the species identified above. Sequencing of these isolates showed significant homology to isolates collected from humans.

A 2010 study of nasal swabs collected from veterinarians attending a conference showed transmission of MSSA/MRSA/MRSP organisms between companion animals and their veterinarians. Of 128 nasal swabs from veterinarians, two MRSA isolates were identified, as well as 5 methicillin resistant Staphylococcus pseudintermedius (MRSP) isolates. Sequencing of the isolates identified homology between MRSA and MRSP isolates commonly found in dogs and cats.

In 2011, researchers in Taiwan were able to demonstrate the transfer of MRSA/MSSA Staphylococcus aureus organisms between companion animals and their owners. 114 S. aureus isolates were identified from nasal swabs of companion animals and their owners. Of the 141 isolates, 42.8% were resistant to at least one antibiotic drug, with 8.8% being resistant to multiple antibiotics. Phylogenetic analyses of the isolates from companion animals and owners demonstrated the transfer of resistant organisms between humans and their pets.

A 2014 study conducted in the United Kingdom demonstrated that livestock animals, dogs, and cats were reservoirs for methilcillin-resistant Staphylococcus aureus (MRSA) bacteria. While researchers demonstrated that the animals were originally infected by humans carrying the resistant bacteria, the organisms were readily transferred between species.

E. coli

Resistant Escherichia coli bacteria have been previously documented in many species of livestock animals. In 2016, researchers in China documented antibacterial resistant E. coli in a pet shop worker, as well as four dogs and two cats in his care.

A 2005-2006 study of fecal samples collected from 138 dogs in Ontario, Canada demonstrated antimicrobial resistant E. coli and Salmonella organisms. 515 bacterial isolates were recovered from fecal samples. 13.3% of Salmonella isolates and 1.3% of E. coli isolates demonstrated resistance to at least one of the tested antibiotics. 70.7% of E. coli isolates and 29.3% of Salmonella isolates were resistant to two or more antibiotics.

Enterococcus faecium

In 2009, researchers collected fecal samples from 208 dogs in the United Kingdom and Denmark. The fecal samples were subsequently tested for ampicillin-resistant Enterococcus faecium (AREF). 23% of dogs from the United Kingdom, and 76% of dogs from Denmark were determined to be carriers of AREF. Sequencing of the AREF isolates showed that 76% of isolates belonged to two sequence types commonly found in European hospitals. The researchers additionally studied 18 of the dog owners, of which one person was revealed to be a carrier of the same type of AREF as the household dog. From the results of the study, researchers concluded that dogs are frequent carriers of AREF, and may be a significant contributing factor to cases of AREF in humans.

Campylobacter jejuni

A 2009 study of C. jejuni isolates recovered in Ireland demonstrated multi-drug resistant organisms in both household pets and shelter animals. A total of 31.4% of isolates were resistant to at least one antibiotic drug, of which 9.8% were resistant to three or more antibacterial drugs. Lesser, but significant, percentages were resistant to five or six antibiotic drugs. Of 361 samples, three animal samples were resistant to five or six antibiotic drugs, and sixteen were resistant to two or more antimicrobial drugs.

See also

• antibiotic misuse
• antibiotic use in livestock

References

This article "Antibiotic resistance in domestic animals" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:Antibiotic resistance in domestic animals. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.

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