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Resistance: Animal to Human

"But has use of antibiotics in animals caused Salmonella to become resistant?” asked Jeff.


Dr. Douglas handed Jeff two graphs from the National Antibiotic Resistance Monitoring System (NARMS). (See above) The data showed a trend towards higher resistance for certain antimicrobial agents in Salmonella from both animals and humans, with generally higher rates of resistance in animals. With Salmonella in animals showing more antimicrobial agents developing resistance, some feel this may translate into increased human resistance.

He also explained the heightened concern of an increase in multi-drug resistant strains in Salmonella serotypes Newport and Typhimurium. (See below)

"Salmonella that have an ACSSuT resistance pattern are resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline,” Dr. Douglas explained. “Some Salmonella Newport carry genes for resistance on a mobile plasmid that contains the genes for ACSSuT plus resistance to amoxicillin/clauvulanic acid, cephalothin, cefoxitin, ceftiofur (MDR AmpC). This resistance leaves physicians and veterinarians with few options for treatment." However, veterinarians can use the data gathered by NARMS to assist in their empiric treatment of Salmonella infections in animals. Reports are generated yearly that show the antimicrobial resistance trends in both animals and humans.

Dr. Douglas continued to explain that it is extremely difficult to find specific bacteria that develop resistance and track its pathway through the food chain. Fortunately, most veterinarians and public health practitioners accept the principles of judicious use of antibiotics that have been developed for animals and humans.

More importantly, it is vital for veterinarians to use every effort to preserve the limited tools available to fight bacterial infections. Few pharmaceutical companies are working to create new classes of antibiotics; therefore, veterinarians must learn to make the best use of what is available.


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