Agriculture and humanity in general has some celebrating to do. The most recent National Antimicrobial Resistance Monitoring System (NARMS) report showed that drug-resistant Salmonella was down in humans and chickens in 2011 (most recent complete data). Also, retail ground beef had one of its best years in 2011 in terms of non-resistant E. coli.
Last Monday, the Food and Drug Administration, in partnership with the Centers for Disease Control and the USDA, released its annual NARMS report. Given the volume of data to be processed, the NARMS reports lag several years. Last Monday’s report detailed the findings from 2011. The goal of the NARMS report is to track the presence of four key bacteria in humans, animals for slaughter, and retail meat, as well as to track trends in the antibiotic-resistance of those bacteria. The report looks at Salmonella, Campylobacter, Enterococcus, and E. coli. On the retail meat side, the report looks at chicken, ground turkey, ground beef and pork chops.
Beef and E. coli
According to the report, incidence of E. coli in retail ground beef declined in 2011. Out of the 480 samples of retail ground beef tested, 215 cultured positive for E. coli, 44.8 percent. Though still high—and still outdone by pork chops which saw only a 30.4 percent infection rate— this is a sharp decline from past years. See Figure 1.
In addition to the declining incidence of E. coli infection in retail ground beef, an admirable amount of those positive cultures showed no resistance to any antibiotic covered by the study. Of the 215 positive ground beef samples for E. coli, 171 samples or 79.5 percent had no detectable resistance to antibiotics. This was the second-best “no-resistance” level behind 2005, which had 80.4 percent of positive samples come up with no detectable resistances.
In those isolates where resistance was found, the most pressing is in what the report calls ACSSuT resistance; namely resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole/sulfisoxazole, and tetracycline.
This resistance measurement has been a part of NARMS for some time as those drugs involved are important to human medicine.
For 2011, ACSSuT resistance was found in 0.9 percent (2 samples) in positive E. coli samples taken from ground beef. While this is a relatively good, low number, this is up from prior years. In years 2008 and 2009, none of the positive samples were found to have ACSSuT resistance, and in 2010, only one or 0.4 percent of the positive samples had it.
When it came to resistances in E. coli found in beef samples, the largest area of resistance was to tetracycline at 17.7 percent of the positive samples. While higher than it should be, there is a silver lining to this. In the world of human medicine, tetracycline has been declining in its primacy for treatment, meaning it is not as important to human health as other antibiotics, nor is it as important to human health as it used to be.
Salmonella was a big focus of this year’s NARMS report, specifically non-typhoidal Salmonella that causes human illness. Non-typhoidal Salmonella is implicated in 1.2 million people becoming ill each year in the U.S., with an estimated 23,000 resulting in hospitalization and 450 deaths. According to the report, many of these infections are foodborne.
Unlike E. coli, Salmonella is tested in humans, animals presented for slaughter, and retail meat. In the 2,344 positive human samples taken for Salmonella, 85 percent of them had no detectable antibiotic resistance. The most common serotype in humans was enteritidis.
In retail meat, 1,320 samples were taken from each of the four meat types. In retail chicken and ground turkey, 12 percent of each sample was found infected with Salmonella. Chicken’s most common serotypes were closer to those of human samples, but the most common serotypes found in ground turkey were very different from the human samples. Only nine ground beef samples (0.7 percent) cultured positive for Salmonella. Pork was slightly higher at 2.1 percent or 28 samples.
Multi-drug resistance—defined as bacteria resistant to three or more classes of antibiotics—declined in most of the areas tested, save for in retail chicken, retail ground turkey, and retail pork. Of the retail meats, ground beef was the only one to see a decline in multi-drug resistant Salmonella. See Figure 2.
Though the data is from three years ago, and data on more recent years won’t be out for several years to come, the trend from 2011 is hopeful. The matter of antibiotic resistance is a key issue in greater human affairs and animal agriculture has an important role in that. — Kerry Halladay, WLJ Editor