Page 497 - The Veterinary Laboratory and Field Manual 3rd Edition

434 Niamh Caffrey and Karen Tang

Figure 12.1 Potential mechanisms of transmission of antibiotic resistance from animals to humans.

and Schwartz, 1998). Further, when individuals transmission of resistance from
can access antibiotics without a prescription, animals to humans
as is the case in many countries, this contrib-
utes to inappropriate and excess use, leading to Resistant bacteria can infect humans from a
increased antibiotic resistance. number of sources including the environment,
other humans and animals. Transmission of
resistance from animals to humans occurs
antibiotics used in animals and through a number of routes including the fol-
agriculture lowing (Figure 12.1):

Antibiotics are used commonly for veterinary 1 direct contact with contaminated animal
reasons, to treat pets, farm animals and in products
aquaculture. They may be used to treat disease 2 cross-contamination between contaminated
(particularly gastrointestinal and pulmonary animal products and other food products in
infections, organ abscesses and mastitis), to processing plants, kitchens, retail markets,
prevent disease, and to promote growth and and restaurants
increase feed efficiencies. Many of the antibiot- 3 direct contact between humans and live animals
ics used in animals are similar, or identical, to 4 contamination of the environment, examples
those used in humans. About 50% of all antibi- include:
otics that are produced worldwide are used for
veterinary reasons (Teuber, 2001). Not only does i animal excretions and secretions in the
antibiotic use in animals contribute to resistance environment
in animals and agriculture, these resistance ii slurry used for fertilization
genes may also spread to the environment and iii spills, leakages, and contamination of water
to humans. It is therefore important to consider sources from slurry.
veterinary contributions to the antibiotic resis-
tance problem in humans. This can result in contamination of water sources
and other food products such as fruits and veg-
etables.

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