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World Animal Protection Reveals a New Report Entitled: US Pork and the Superbug Crisis


Today, the World Animal Protection, a global animal-welfare organization with offices in 14 countries released US pork and the superbug crisis: how higher welfare farming is better for pigs and people. The new report reveals that bacteria resistant to antibiotics considered highly important or critically important to human health were present in pork products purchased at Walmart stores in the eastern US.

Antibiotic-resistant bacteria, also known as “superbugs,” pose a threat to all human life. The spread of antibiotic-resistant bacteria is a public health crisis affecting more and more people each day. The U.S. Centers for Disease Control and Prevention now estimate that more than 2.8 million antibiotic-resistant infections occur in the United States each year, and more than 35,000 people die as a result. Superbugs are emerging on farms from antibiotic overuse and entering our food chain and environment. When antibiotic-resistant superbugs are passed to people, they make us less able to fight disease.

“The presence of multidrug-resistant bacteria on pork products illustrates the role the pork supply chain plays in the global health crisis caused by antibiotic-resistant bacteria,” said Alesia Soltanpanah, Executive Director of World Animal Protection US. “The fact that pork purchased from several Walmart stores, one of the nation’s largest retailers, contains bacteria resistant to antibiotics critically important to human health is particularly alarming and should raise concerns for all Walmart customers.”

One of the biggest factors behind the growing problem of antibiotic resistance is that antibiotics are vastly overused in raising farmed animals. Globally, most antibiotics are used in animal farming. While the use of the drugs as growth promoters in feed and water is no longer permitted in the United States, antibiotics are still used on a routine basis to stop the spread of disease, particularly in low-welfare, factory farm systems where animals are confined in overcrowded and barren environments. Approximately 70 percent of all medically important antibiotics in the United States are sold for use in farmed animals.

The stressful and cruel conditions on factory farms created by pork producers are the perfect breeding ground for infection. Instead of creating a better environment for pigs, producers are overusing antibiotics to stop stressed or injured animals from getting sick, contributing to the rise of superbugs.  

World Animal Protection tested a total of 160 pork samples purchased from several stores of Walmart and a competing national retail chain in the mid-Atlantic region of the United States. The samples, 80 from each retailer, were analyzed by researchers at Texas Tech University (TTU) in 32 batches of five samples each for the presence of bacteria commonly found in pigs and pork: E. coli, Salmonella, Enterococcus, and Listeria. Bacteria isolated from the batches were then tested for susceptibility to antibiotics.

80% of the bacteria isolated from Walmart’s pork products were resistant to at least one antibiotic, including resistance to classes of antibiotics considered highly important or critically important by the World Health Organization. Furthermore, all of the bacteria resistant to four or more classes of antibiotics that we found and all bacteria resistant to the Highest Priority Critically Important Antimicrobials (HPCIAs) were found in Walmart’s samples. HPCIAs are antibiotics where there are few or no alternatives to treat people with serious infections—the Food and Agriculture Organization of the United Nations recommends that these classes should never be used in animal agriculture.

In total, across Walmart’s 15 batches there were 32 positive bacterial findings, including:

  • Enterococcus in 13 batches;
  • E. coli in 10 batches;
  • Salmonella in six batches, and;
  • Listeria in three batches.

All batches that tested positive for three or more bacteria were sold at Walmart.

While Walmart has not yet made a time-bound commitment to phase out sow stalls in its supply chain, several of its competitors have. Target and Costco have committed to the only partner with suppliers who do not use gestation crates by 2022 and Kroger by 2025. Walmart is lagging behind the times, and it needs to move forward by making animal welfare and human health a priority, as it is for its customers.

“By requiring higher welfare practices of all its pork suppliers, starting with a definitive timeline to end the use of gestation crates, Walmart can help eliminate the overuse of antibiotics to protect pigs and their customers,” said Soltanpanah. “In fact, 88 percent of Walmart customers surveyed agreed that supermarkets have a responsibility to ensure that pigs are treated well, and 78 percent would be more inclined to shop at a retailer that planned to eliminate cages from its pork supply.”

However, not enough is being done to address the overuse of antibiotics, which is leading to ever less-effective antibiotic medicines. The results of these tests have implications for all retailers, as well as pig producers and consumers of pork. World Animal Protection is calling for global supermarkets to improve the lives of pigs by only sourcing pork from high-welfare farms. World Animal Protection’s Raise Pigs Right campaign is calling for pigs to be spared painful mutilations, freed from cages, and not left to suffer in barren environments that promote disease. Rather, these highly intelligent animals should be allowed to live in groups, with room to move, and given opportunities to express their natural behaviors.

The work being done with leading global pig producers shows that change is possible and higher welfare systems are good for animals, good for people, and good for business, too. See our global business case studies on sows and pigs raised for meat.

Key Findings

Amongst the 32 batches of samples, 51 total isolates were detected: E. coli was detected in 14 (43.75%) batches; Enterococcus in 27 (84.38%) batches; Listeria in four (12.5%) batches; and Salmonella in six (18.75%) batches.

Of the 32 batches tested, 30 (94%) were positive for at least one of the four bacteria.

  • Twelve (37.5%) batches were positive for Enterococcus only;
  • one (3%) batch was positive for Listeria only; and,
  • one (3%) batch was positive for Salmonella only.

16 (50%) batches were positive for at least two bacteria:

  • eight (25%) were positive for both E. coli and Enterococcus;
  • two (6%) were positive for Enterococcus and Salmonella;
  • one (3%) was positive for E. coli and Listeria;
  • two (6%) were positive for E. coli, Enterococcus, and Salmonella;
  • one (3%) was positive for E. coli, Enterococcus, and Listeria; and,
  • one (3%) was positive for all four bacteria.

Antibiotic resistance results by species


Twenty-six (96.3%) of the Enterococcus isolates were resistant to at least one class of medically important antibiotics. The most common resistance was to lincosamides (lincomycin), streptogramins (quinupristin/dalfopristin), and/or tetracylines (tetracycline). All three classes are categorized as highly important.

Seventeen of those isolates (65.38%) were multi-drug resistant:

  • Thirteen isolates were resistant to lincosamides, streptogramins, and tetracyclines.
  • One isolate was resistant to lincosamides, streptogramins, and oxazolidinones.
    • Oxazolidinones are categorized as critically important.
  • One isolate was resistant to lincosamides, streptogramins, tetracyclines, and macrolides.
    • Macrolides are among the classes categorized as HPCIAs.
  • One isolate was resistant to lincosamides, quinolones, and nitrofuran derivates.
    • Quinolones are categorized as HPCIAs
  • One isolate was resistant to lincosamides, streptogramins, tetracyclines, amphenicols, macrolides, and aminoglycosides.
    • Aminoglycosides are categorized as critically important; amphenicols are considered highly important.


All four (100%) Listeria isolates present in the sample batches were resistant to lincosamides, which are listed as highly important.

One isolate (25%) was resistant to six total classes of antibiotics: lipopeptides, penicillins, streptogramins, macrolides, lincosamides, and glycopeptides.

  • Macrolides and glycopeptides are listed as HPCIAs.
  • Penicillins and lipopeptides are categorized as critically important.
  • Lincosamides and streptogramins are highly important.


Two of the Salmonella isolates (33.33%) were resistant to one antibiotic class, while the rest of the isolates were pan-susceptible.

The two resistant isolates were resistant to quinolones, which are categorized as HPCIAs.

  1. coli:

Nine E. coli isolates (64.29%) were resistant to at least one class of medically important antibiotics.

  • Four (28.57%) were resistant to tetracyclines alone, and one (7.14%) was resistant to tetracyclines and sulfanomides.
    • Tetracyclines and sulfanomides are considered highly important.
  • Another isolate (7.14%) was resistant to both tetracyclines and aminoglycosides.
    • Aminoglycosides are considered critically important.

Three E. coli isolates were multi-drug resistant:

  • One (7.14%) was resistant to tetracyclines, aminoglycosides, and penicillins.
    • Penicillins are categorized as critically important.
  • One (7.14%) was resistant to tetracyclines, sulfonamides, aminoglycosides, and amphenicols.
    • Amphenicols are categorized as highly important.
  • One (7.14%) was resistant to tetracyclines, sulfonamides, aminoglycosides, penicillins, macrolides, and cephalosporins (1st/2nd generation).

First and second-generation cephalosporins are categorized as highly important.

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