Well, it could be any animal raised in massive numbers, really. But the
report released by PNAS as about pigs. Particularly about antibiotic use and antibiotic resistant genes. The report is titled
Diverse and abundant antibiotic resistance genes in Chinese swine farms, and the abstract reads:
Antibiotic resistance genes (ARGs) are emerging contaminants posing a
potential worldwide human health risk. Intensive animal
husbandry is believed to be a major
contributor to the increased environmental burden of ARGs. Despite the
volume of antibiotics
used in China, little information is
available regarding the corresponding ARGs associated with animal farms.
We assessed
type and concentrations of ARGs at three
stages of manure processing to land disposal at three large-scale
(10,000 animals
per year) commercial swine farms in China.
In-feed or therapeutic antibiotics used on these farms include all
major classes
of antibiotics except vancomycins.
High-capacity quantitative PCR arrays detected 149 unique resistance
genes among all of
the farm samples, the top 63 ARGs being
enriched 192-fold (median) up to 28,000-fold (maximum) compared with
their respective
antibiotic-free manure or soil controls.
Antibiotics and heavy metals used as feed supplements were elevated in
the manures,
suggesting the potential for coselection
of resistance traits. The potential for horizontal transfer of ARGs
because of transposon-specific
ARGs is implicated by the enrichment of
transposases—the top six alleles being enriched 189-fold (median) up to
90,000-fold
in manure—as well as the high correlation (r2
= 0.96) between ARG and transposase abundance. In addition, abundance
of ARGs correlated directly with antibiotic and metal
concentrations, indicating their
importance in selection of resistance genes. Diverse, abundant, and
potentially mobile ARGs
in farm samples suggest that unmonitored
use of antibiotics and metals is causing the emergence and release of
ARGs to the
environment.
The problem is that regulation and research haven't kept pace with the explosion of IFAPs (Industrial Food Animal Production) and the techniques they use to speed the production line of animal flesh. Canada, Europe, and America are in the same boat here; in the US about 80% of antibiotics are used for animal production--usually in sub-clinical doses which seem expressly designed to breed resistant bacteria.
Thankfully, there is a solution. Politically unpalatable, perhaps, certainly not one that will thrill everybody. But one that looks a lot better than losing drug treatments for infections. And that is going organic. Industrial chicken farms that go organic have significantly lower levels of resistant bacteria according to
an article in Environmental Health Perspectives. From the abstract:
The percentages of resistant Enterococcus faecalis and resistant Enterococcus faecium were significantly lower (p
< 0.05) among isolates from newly organic versus conventional
poultry houses for two (erythromycin and tylosin) and five
(ciprofloxacin, gentamicin, nitrofurantoin, penicillin, and
tetracycline) antimicrobials, respectively. Forty-two percent of E. faecalis
isolates from conventional poultry houses were multidrug resistant
(MDR; resistant to three or more antimicrobial classes), compared with
10% of isolates from newly organic poultry houses (p = 0.02); 84% of E. faecium isolates from conventional poultry houses were MDR, compared with 17% of isolates from newly organic poultry houses (p < 0.001).
Conclusions:
Our findings suggest that the voluntary removal of antibiotics from
large-scale U.S. poultry farms that transition to organic practices is
associated with a lower prevalence of antibiotic-resistant and MDR Enterococcus.
So, smaller operations run on organic principles with resultant lower meat consumption and higher prices equals a better world. Or, you know, just raise a couple of chickens in your backyard.
