US: OVER-USE OF ANTIBIOTICS THREATENS HUMANS
by Danielle Knight
Washington,11 Oct. 99 (IPS) -- An increase in fatal drug-resistant infections in the United States can be traced to the over-use of antibiotics, especially in agriculture, say public health scientists.
"There is a global public health problem of antibiotic resistance," says Fred Angulo, a public health scientist with the US Centers for Disease Control and Prevention (CDC).
The threat of untreatable infections is growing in hospitals, communities generally and on the farm, he says. "We need to use these drugs more prudently wherever they are used to slow the progression of resistance."
Antibiotics, introduced more than 50 years ago, have saved countless lives worldwide.
Before the development of these drugs, death through bacterial infections in even minor wounds was a frightening possibility in this country. Now, because of resistance to antibiotics, once- treatable infections again are becoming fatal.
More than 90 percent of strains of Staphyloccous aureus bacteria, a common cause of hospital "Staph" infections, are now resistant to penicillin, according to Angulo.
Four children died in the last few years from common Staph infections resistant to antibiotics, according to the CDC. More than 30 percent are resistant not only to penicillin but also to every other antibiotic used to treat Staph infections - except one known as vancomycin.
Last year, however, vancomycin-resistant strains of Staph appeared in the United States, starting with a man dying in New York .
"Uses of antibiotics creates selective pressures which result in dissemination and spread of bacteria resistant to antibiotics," Angulo says.
Use of the so-called "miracle" drugs is widespread in the United States. In 1954, this country produced two million pounds of antibiotics; for 1999, the figure exceeds 50 million pounds.
The problem of resistance partially is due to doctors over-prescribing antibiotics for humans, says Angulo. The CDC estimates that about one-third of the 150 million outpatient prescriptions for antibiotics every year are unnecessary.
But a lesser-known problem of over-use occurs on farms. More than half of the antibiotics used in the United States are estimated to be used in animal feed for poultry, hogs, and cattle.
Some 30 antibiotics - such as tetracycline, penicillin and streptomycin - are approved by the FDA for many uses in livestock.
But, in 80 percent of cases, instead of being used to treat sick animals the drugs are used to fatten the animals faster, according to Rebecca Goldburg, senior scientist with the Environmental Defense Fund.
"This indiscriminate and non-essential use of antibiotics in agriculture dangerously increases the possibility that these antibiotics and other closely related ones will be ineffective when needed to treat people," she says.
Between 40,000 and 50,000 pounds of tetracycline and streptomycin - both used to treat infections in humans - are sprayed to control bacterial disease among fruit trees, she says.
In comparison, one pound would be enough to treat around 450 people.
Antibiotics that are effective in human medicine are also used for treatment of bacterial infections in salmon, catfish, trout and other commercially-raised fish.
In the United States more than 55 million pounds of farmed salmon are produced per year. Goldburg estimates that nearly 150 pounds of antibiotic are applied per acre of salmon.
"Since pens are placed in natural sea waters, antibiotics and the resulting resistant bacteria have contact with other marine life and end up spreading into surrounding streams, lakes and rivers," she says.
"This increases the odds that humans will develop resistance to antibiotics or come in contact with fatal resistant bacteria," says Goldberg.
Antibiotic resistance can move from animals and plant disease to human bacteria, she says. E-coli and Salmonella, for example, are in the same bacteria family as Erwinia, a fruit tree disease.
According to the Food and Drug Administration (FDA) and the CDC, resistant strains of three specific organisms that cause disease in humans - Salmonella, Camphylobacter and E-coli - are directly linked to the use of antibiotics in animals.
Bacteria in this family can exchange genes from plants with similar genes in humans, therefore increasing resistance to antibiotics, Goldberg warns.
In 1997, the World Health Organisation recommended ending the use in animal feed of all antibiotics used in human medicine, as well as closely related drugs. In response, the use of four antibiotics in animal feed was banned throughout Europe in 1998.
"Sweden banned all non-therapeutic use of antibiotics in agriculture in 1986, and the country has evolved a highly successful system of meat production that does not depend on such drugs," adds Goldberg.
In March, five national environmental and public interest organisations, including the Environmental Defense Fund and the Union of Concerned Scientists, filed a petition with the FDA to ban the use of antibiotics on livestock used to promote growth that are used - or related to those used - in human medicine.
The list includes penicillin, tetracyclines, erythromycin, lincomycin, tylosin, and virginiamycin.
The agency itself has proposed limiting new uses of antibiotics in agriculture. This has been strenuously opposed by powerful pharmaceutical and agricultural interests while public health experts say that, despite being a "good start", it is too weak.
"It is not sufficient merely to limit new uses of antibiotics," says Goldberg. "The current overuse of antibiotics both in human medicine and in animal feed must be quickly curtailed.
The above article by the Inter Press Service appeared in the South- North Development Monitor (SUNS) .