Author: Sam Linsen

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Antibiotic of the week: Sulfadimethoxine

Antibiotics Pollution Index: 73 (11 September 2017)
What is the Antibiotics Pollution Index?

What it does
It prevents bacteria to form folic acid. Folic acid is crucial for cell division of bacteria; without folic acid, a bacterium cannot multiply and thereby spread the infection. It does not kill the bacteria directly.

Who gets it
Pets, cattle, poultry and fish. It is given to treat skin infections, urinary tract infections, respiratory infections and even parasitic (non-bacterial) infections. It is also used to treat “Bovine Respiratory Disease”, in cows. This disease  is caused by a combination stress, a mix of infections, and other unknown triggers. This disease is costing the USA alone USD 500 million/year.

Where may it be produced?
China, Japan, Poland, Switzerland.

And, SquaredAnt, does it pollute?
Yes, it does. We found publications about sulfadimethoxine in rivers in across the USA, and in waste-water and soil around farms in the USA and China. Around farms, the concentrations lie around 1 nanogram per gram. For a small farm, this is sufficient for 10 dosages for an animal that weighs 800 kg (see table below).

Farm size 100,000 square meter
Top soil mass 1000 kg/ cubic meter
Penetration of antibiotic (estimation) 0.1 meter
Concentration 0.000001 gram / kg
Product by multiplication 10 gram
(Equals to ~10 dosages for a cow)

Conservative estimation of Sulfadimethoxine pollution on a polluted farm

Warning lights
In 2015, the article “The Ocean as a Global Reservoir of Antibiotic Resistance Genes” described a number of lagoons and bays, where scientists found bacteria that were resistant against sulfadimethoxine. This is remarkable, as sulfadimethoxine is not produced in nature: it is a synthetic molecule. Apparently, some marine bacteria carry resistance against this non-natural antibiotic – in vast amounts, as the ocean harbors so many bacteria.
Coastal waters are increasingly put to use for humans. Creating a meeting point for resistant bacteria from the sea (via seafood, recreation, shipping, or desalination) and sulfadimethoxine residue (via meat, vegetables, pet excretion and surface waters) gives microbes a dream start to spread resistance among each other and should be avoided.

Any common sense in this antibiotic?
It is hopeful that as of 2017, sulfadimethoxine has changed status from OTC to prescription drug for veterinarian use in the USA. Before, gallon-sized bottles were available for anyone. When these are disposed of, and the residue has run off the land, then the pollution level may decrease.

Sources