Tetracycline

Tetracycline is a tetracycline antibiotic, a class of drugs that prevent the growth and spread of infection-causing bacteria. It is sold under the brand name Achromycin. Tetracycline is a commonly used livestock drug, often used subtherapeutically. The use of tetracycline in livestock leads to other issues, including antibiotic resistance among bacteria and pollution of tetracycline into the environment.

Why It's Prescribed
Tetracycline is prescribed for bacterial infections like pneumonia and other respiratory tract infections, acne, infections of skin, genital and urinary systems, and Helicobacter pylori (a bacteria that causes stomach ulcers).

Labeled uses for tetracycline include: Acne Vulgaris, Actinomycosis, Acute Gonococcal Cervicitis, Acute Gonococcal Urethritis, Acute Lower Genitourinary Gonorrhea, Acute Otitis Media Infection, Anthrax, Bronchitis, Brucellosis, Female Urethral Syndrome, Genitourinary Chlamydia Trachomatis Infection, Gingivostomatitis, Gonococcal Pharyngitis, Granuloma Inguinale, Inclusion Conjunctivitis, Inflammatory Disease of Female Pelvic Organs, Lymphogranuloma Venereum, Pharyngitis, Pneumonia, Psittacosis, Q Fever, Rectal Chlamydia Trachomatis Infection, Rectal Gonorrhea, Relapsing Fever, Rickettsialpox, Rocky Mountain Spotted Fever, Sexually Transmitted Epididymo-Orchitis, Sinusitis, Skin and Skin Structure Infection, Syphilis, Trachoma, Typhus Infections, Urinary Tract Infections, Yaws

Additionally unlabeled uses include: Acne Rosacea, Biliary Tract Infection, Chlamydial Infections, Chloroquine Resistant Plasmodium Falciparum Malaria, Infectious Disease of Abdomen, Malaria, Mycoplasmal Pneumonia, Ocular Rosacea, Peptic Ulcer due to H. Pylori, Plague, Tropical Sprue, Tularemia

Form, Route, and Dosage
Tetracycline is available as a capsule and suspension (liquid) to take orally. It is available in the strengths 250mg and 500mg. It's typically prescribed to be taken two to four times daily, up to a maximum adult dose of 2000mg.

Side Effects
Some patients who take tetracycline may suffer side effects, including:
 * upset stomach
 * diarrhea
 * itching of the rectum or vagina
 * sore mouth
 * redness of the skin (sunburn)
 * changes in skin color
 * severe headache
 * blurred vision
 * skin rash
 * hives
 * difficulty breathing or swallowing
 * yellowing of the skin or eyes
 * itching
 * dark-colored urine
 * light-colored bowel movements
 * loss of appetite
 * upset stomach
 * vomiting
 * stomach pain
 * extreme tiredness or weakness
 * confusion
 * joint stiffness or swelling
 * unusual bleeding or bruising
 * decreased urination
 * pain or discomfort in the mouth
 * throat sores
 * fever or chills

Veterinary Use
Tetracycline is also sold for veterinary uses, under the brand name Panmycin. Tetracycline is also included in some livestock feed for disease prevention and/or growth promotion. The widespread subtherapeutic use of tetracycline in livestock is a factor contributing to antibiotic resistance.

Antibiotic Resistance
The widespread subtherapeutic use of tetracycline in livestock contributes to antibiotic resistance among bacteria.

A 2006 study examined a hog confinement operation that used tetracycline-containing feed for over 20 years. The scientists examined bacteria found in the feed, hogs, hog houses, waste lagoon, soil, surface water and well water for antibiotic resistance. They concluded: "In this environment, 77% of E. coli and 68% of enterococci isolated were tetracycline resistant. Tetracycline resistance was found in 26 different bacterial genera and in 60 species."

A 2007 study examined wastewater lagoons at several cattle feedlots, looking for six different tetracycline-resistance genes among bacteria. The feedlots were divided into three categories based on tetracycline use: no-use, mixed-use, and high-use. The study found that "Absolute abundances of all six genes in the lagoons increased as presumed antibiotic use increased" and "All four [tetracycline-resistance] genes were 100–1000 times greater in the mixed-and high-use feedlot lagoons compared with no-use lagoons."

As a Pollutant
Because humans and animals often do not fully metabolize pharmaceuticals in their body, they can excrete drugs or their breakdown products, which may the enter the environment.

In Sewage Sludge
Tetracycline has been found in sewage sludge. In the Targeted National Sewage Sludge Survey, a 2009 test of 84 samples of sewage sludge from around the U.S., the EPA found tetracycline in 81 samples (96%) in concentrations ranging from 38.3 to 5,270 parts per billion. There are no federal regulations governing how much of this drug may be present in sewage sludge applied to land as fertilizer.

In Drinking Water
An Associated Press investigation found that, of 62 metropolitan areas in the U.S., only 28 tested for pharmaceuticals, and 24 found pharmaceuticals in the drinking water when they tested it. Of those tested, Philadelphia tested positive for tetracycline.

Breakdown In the Environment
A 2004 study looked at the ability of 18 antibiotics to biodegrade in a closed bottle test. The antibiotics tested were: Amoxicillin, Benzylpenicillin sodium salt, Ceftriaxone disodium, Cefuroxime sodium salt, Chlortetracycline hydrochloride, Clarithromycin, Clindamycin, Erythromycin, Gentamicin sulfate, Imipenem, Metronidazole, Monensin sodium salt, Nystatin, Ofloxacin, Sulfamethoxazole, Tetracycline, Trimethoprim naphthoate, and Vancomycin hydrochloride. The study concluded: "None of the antibiotics was readily biodegradable. Elimination in the environment by other mechanisms may happen, but will not completely mineralize the active compounds. The results of CFU determination showed that some of antibiotics have an inhibitory effect on the bacterial population. Our findings underline the need for more detailed investigating effects on antibiotics in the environment."

Related SourceWatch articles

 * Biosolids
 * Sewage sludge
 * Food Rights Network
 * Pharmaceuticals

External articles

 * Yvonne Agersø, Gitte Wulff, Elvira Vaclavik, Bent Halling-Sørensen, Lars Bogø Jensen, "Effect of tetracycline residues in pig manure slurry on tetracycline-resistant bacteria and resistance gene tet(M) in soil microcosms", May 17, 2006.