Superbugs Found in Chicken: Is It Time to Stop Using Antibiotics in Livestock Feed?

by Dr Sam Girgis on July 12, 2012

Urinary tract infections (UTIs) occur when bacteria overgrow in the urine of the bladder.  Symptoms can include fever, burning and pain with urination, and frequent urination.  When the bacteria ascend the lower urinary tract to the kidneys, a condition termed acute pyelonephritis occurs and usually requires intravenous antibiotics to treat.  In the United States, there are approximately 6 to 8 million UTIs each year.  Women are more likely to become infected than men due to anatomy.  Almost 10% of all women will develop a UTI in any given year, and approximately 60% of all women will have a UTI in their lifetime.  UTIs are most commonly caused by a bacterium called Escherichia coli, although other bacteria, viruses, and fungi can cause the disease.  It is estimated that the health care cost for treating UTIs on a yearly basis approaches $2 billion.  In recent years, the emergence of antibiotic resistant E. coli, sometimes called superbugs, has made the treatment of the urinary infection more difficult and complicated.

Researchers, lead by Dr. Amee Manges from McGill University, have discovered that antibiotic fed chicken might serve as a reservoir for antibiotic resistant E. coli that is causing UTIs in humans.  The results of their research were published online in the journal Emerging Infectious Diseases.  The researchers examined E. coli isolates from beef, pork, and chicken and compared the bacteria’s genetic makeup to that of the genetic makeup of E. coli that was causing UTI in humans.  It was found that E. coli isolates from beef and pork were less likely to be similar to E. coli isolates obtained from humans with UTIs.  In contract, E. coli isolates from antibiotic fed chicken were found to be genetically identical to those isolated from humans with UTI in 71% of cases.  Finally, the researchers examined E.coli intestinal isolates from animals in slaughter houses and again the isolates from chicken were disproportionately higher than expected by chance alone.  This suggests that the source for antibiotic resistant E. coli in human may be the antibiotic fed chicken.  In addition, antibiotic fed chicken may be serving as a reservoir for these drug resistant strains of E. coli.

The authors wrote, “The results suggest that potential [extraintestinal pathogenic E. coli] transmission from food animal sources is likely to be implicated in human infections and that chicken is a major reservoir. The possibility that [extraintestinal pathogenic E. coli] causing UTIs and other extraintestinal infections in humans could originate from a food animal reservoir raises public health concern. New interventions may be needed to reduce the level of food contamination and risk for transmission”.

Several veterinary and food safety organizations have affirmed the safety of the antibiotic fed chicken supply and have questioned the validity of the study.  The study results due appear to be valid and accurate.  Regardless of the reproducibility of the study, a very important issue has been raised by the findings.  Should we continue to breed our livestock with antibiotic supplemented feed?  The Centers for Disease Control and Prevention estimates that approximately 80% of the antibiotics that are sold in the United States are given to livestock.  Should we begin to decrease the amount of antibiotics and other additives that we give to our livestock?  It appears that we are creating an environment for the selection of antibiotic resistant bacteria that will go on to become a public health problem for the country as a whole.  I believe that we should begin to re-examine the safety of antibiotic supplemented feed for our livestock.

See the ABC World News clip with Dr. Richard Besser on the topic below:

 

Reference:

Catherine Racicot Bergeron et al. “Chicken as reservoir for human extraintestinal pathogenic escherichia coliEmerg Infect Dis 2012; DOI: 10.3201/eid1803.111099

Image: FreeDigitalPhotos.net

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