Page 496 - The Veterinary Laboratory and Field Manual 3rd Edition

chapter 12

Antimicrobial resistance:

a threat to human and animal health

Niamh Caffrey and Karen Tang

Bacterial, viral, fungal and protozoal infections year worldwide due to AMR, with a total cost
are common in both human and veterinary medi- of US$50 trillion (The Review on Antimicrobial
cine, and are often treated with antimicrobial Resistance, 2016). AMR is now recognized
medications. These microorganisms can change as one of the biggest threats to human health
or mutate, to develop antimicrobial resistance globally.
(AMR), making usual treatments ineffective. In
this section, we will focus on a specific type of
AMR – antibiotic resistance in bacteria. Bacteria 12.1 Contributors to AMr
can develop AMR naturally, and resistance genes
can also be transferred from one microorganism antibiotic use in humans
to another. Antibiotic use has resulted in the
rapid rise of AMR, due to selective pressure in Antibiotic use in humans contributes to the
which antibiotic-resistant bacteria are more likely development of antibiotic resistance. Individuals
to survive compared to non-resistant ones. This have the highest risk of bacteria developing
allows antibiotic-resistant bacteria to thrive and resistance to an antibiotic within 1 month of use
multiply within the host and in the environment. of that antibiotic, though the risk is still there
Antibiotic-resistant bacterial infections can for up to 12 months (Costelloe et al., 2010).
have serious health consequences in humans The association between antibiotic use and
and animals. Not only do they result in a delay resistance is present not just at the individual
of effective treatment and an increased risk of level, but also at the community, regional and
treatment failure, they are also associated with country levels. That is, greater use of antibiotics
increased length of stay in hospital for human in a region is associated with greater antibiotic
patients admitted to hospital, increased risk of resistance in bacteria isolated from residents of
requiring admission to the intensive care unit that region, regardless of whether those indi-
and increased risk of death. Infections with viduals used the antibiotics themselves. Though
antibiotic-resistant bacteria are also expensive, antibiotics are an important and effective treat-
with medical care, hospitalization, therapy and ment for bacterial infections, it is estimated that
loss of productivity all contributing to excess 20% of all outpatient prescriptions for antibi-
cost for public health authorities. By 2050, it otics are unnecessary, such as when they are
is estimated that 10 million human deaths per given for viral respiratory infections (Belongia

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