By: Heather Williams

What do chicken and urinary tract infections have in common?  More than you might think.  Research is making the unlikely connection between poultry consumption and antibiotic resistant urinary tract infections.  How could these two be linked?  Research is pointing to prophylactic antibiotic use in chicken farming.

Urinary tract infections (UTIs) rank the second most common type of infection in the human body.  This accounts for around $1- 2 billion each year in health care related costs.  That is quite a lot of doctor visits.  8.1 million, in fact.  It is estimated that around 85% of these urinary tract infections are the extraintestinal pathogenic Escherichia coli, or ExPEC kind.  Historically doctors have attributed this connection as coming from the patient’s own intestines, though new research is bringing new light to this mystery.

In the past decade drug-resistant E. coli has increased substantially.  This has made managing simple UTIs much more complicated.  UTIs, left untreated or undertreated, can lead to other illness such as bacteremia, sepsis, or pyelonephritis.  Overuse of antibiotics and antibiotics in our food have been indicated as playing a large role in this occurrence.

Separate studies have considered the connection between ExPEC found in chickens compared to those found in humans and the presence of drug-resistant E. coli and infections found in humans.  When exposed, the link is clear.  There is something to be said for the link between chicken consumption and resistant UTIs.

Chicken and ExPEC.  A Human Connection

A study published in the Center for Disease Control and Prevention (CDC) Emerging Infectious Diseases periodical makes the connection of “Chickens as reservoir for Extraintestinal Pathogenic Escherichia coli in humans.”  While scientists in this particular study suspected chicken to be charged as a possible reservoir for ExPEC, they didn’t want to rule out other retail meat.  To perform a thorough investigation, they tested beef and pork samples as well.  The study found that the ExPEC found in chickens were more genetically similar to the ExPEC found in humans with E. coli than those found in beef and pork.  Scientists found that the genetic similarities between E. coli found in chickens and in ExPEC causing UTIs in humans makes them likely responsible for human infection.

These difficult to treat UTIs were originally thought to originate in the host’s intestinal tract.  This study examined the genetic similarities between human to human E. coli strains and animal source E. coli strains by comparing ExPEC found in humans and those found in the cecal content of chicken, cows, and pigs.  The cecal content of potential animal reservoirs was chosen as a sample source to rule out potential contamination during the meat preparation process by food handlers.  The cecal content would be the most likely contaminant caused by slaughterhouse originating infection, as most foodborne contamination originates from this source.  The study found that the ExPEC found in humans with UTIs was more genetically similar to the ExPEC found in cecal content of chickens than those found in the gut of humans or cecal content of pigs and cows.

Antibiotic Resistance and Chicken

A study out of Alberta Canada took a look at resistance phenotypes (how the bacteria behaved) and resistance genes (the genetic makeup of the bacteria) from E. coli isolates from retail meats such as chicken, turkey, beef, and pork.  The purpose of this study was to identify potential sources of resistant bacteria on the foods that we consume.

The phenotypic analysis was achieved by a sensitivity study.  This type of study consists of exposing the isolated E. coli bacteria to media enriched with common antibiotics such as tetracyclines, sulfonamides, aminoglycosides, ciprofloxacin, and β-lactamase.  Fortunately, no resistance to ciprofloxacin was found in any of the bacterial isolates.  Amoxicillin-clavulanic acid and ceftriaxone did generate some positive results.  In this case, positive is not a good thing.  With 16.8% of isolates resistant to the common amoxicillin-clavulanic acid and 12.6% resistant to ceftriaxone along with others, scientists were concerned.  This could have serious human consequences, as these are antibiotics used for medical use in humans.

Further, a connection was made between chicken and a higher instance of resistances, particularly resistances to multiple antibiotics, occurring 32% more often in chicken than other retail meat types.  Multiple antibiotic resistance makes treating infections much harder for healthcare professionals.

Genetic indications of resistance indicated a connection to expression resistance for tetracycline, sulfonamides, and aminoglycosides.  Data indicated these resistance genes present in poultry-derived E. coli at a higher rate that other retail meats.

Antibiotic Use in Chicken Feed Generating Concern

While we’ve certainly come a long way from archaic practices such as “acronization, we’ve still got a big problem.  What is acronization?  It was the shocking practice employed in the 1950s and early 1960s that involved dipping chicken in a bath of antibiotics and then sealing it up in packages with the expectation that it would extend the shelf life of the poultry product.  What could go wrong?

An antibiotic bath is not an accepted practice used in modern poultry processing, but what we are doing isn’t much better.  Instead of applying antibiotics externally we are now feeding it to food animals.  In fact, eighty percent of the antibiotics sold in the United States go to food animals such as pigs, cows, chickens, and turkeys.  That’s a lot of antibiotics.

If antibiotics were given in response to an infection or a medical need, the use would be at a much smaller scale and this question and conversation would be non-existent.  The percentage of antibiotics sold would not go mostly to food animals.  Instead, antibiotics are given in large farms as a sort of prophylaxis.  A preventative measure.  What is the impact on humans?  That begins with the way in which antibiotics are administered.

Antibiotics are administered, for the most part, in food and water.  In this way the bacteria goes directly into the animal’s gut.  This can produce antibiotic resistant bacteria in the animal’s gut.  The slaughter process is generally where meat products become contaminated, generating foodborne illness that, in this case might be antibiotic resistant.

So Where Does That Lead Us?

If antibiotic use in animals is on the rise, and antibiotic resistant bacterial infections is becoming increasingly difficult to treat, what can be done.  A serious look at food animal management is in order.  Legislation has slowly evolved as more information becomes available.  There has to be a compromise between effective feedlot animal management and responsible discretion to animal derived antibiotic resistant human bacterial infections.