SDSU & NARMS, 2017-18: Looking for Foodborne Germs and Antibiotic Resistance; Part 1 – Poultry Back »

Written collaboratively by Russ Daly, Alan Erickson, Laura Ruesch, Zachary Lau, and Deb Murray.

Are foodborne disease-causing germs becoming more resistant to antibiotics? Finding the answer to that question is the mission of the National Antimicrobial Resistance Monitoring System (NARMS). Since 1996, this multi-agency program has examined certain food-associated germs that can cause intestinal illness in people. Germ isolates from sick people (monitored by the Centers for Disease Control and Prevention), animals (monitored by the US Department of Agriculture), and retail meat products (monitored by the Food and Drug Administration) are part of the annual surveillance program.

South Dakota State University is in its second year of participation in NARMS, with their Food Safety Microbiology (SD-FSM) lab (part of the Animal Disease Research and Diagnostic Laboratory in Brookings) working with the FDA in the retail meat portion of the program. The SD-FSM tests these meat products, purchased in grocery stores in North and South Dakota, for the presence of these germs. The germs identified are then further tested for resistance to common antibiotics that might be used in treating human illness.

Partnering with the SD-FSM to obtain retail meat products for testing are the South Dakota Animal Industry Board Meat Inspection Service, and the North Dakota Meat and Poultry Inspection Program. Staff members from these agencies travel to grocery stores in 7 different cities in the 2 states to purchase fresh chicken, ground turkey, ground beef, and pork chops, which are then sent to the SD-FSM for testing.

The NARMS program looks for 4 different germs. Two of these (Salmonella and Campylobacter) are significant causes of foodborne illness in the US, while the other 2 (generic E. coli and Enterococcus, both found more routinely in meat products) are examined as indicator organisms for antibiotic resistance.

The SD-FSM has recently compiled NARMS results for the period from June 2017 through May 2018, their first full year of participation. This article summarizes the results for the poultry products. Results from ground beef and pork chops will be provided in separate reports.

A. Fresh Chicken

Prevalence of bacteria in chicken from North and South Dakota grocery stores.

Overall, investigators identified Salmonella in 0.8% (4/480) of the fresh chicken samples, and Campylobacter in 8.3% (20/239 – Table 1). Campylobacter was found more frequently in samples from North Dakota (12.0%) than in samples from South Dakota (5.8%). Levels of E. coli and Enterococcus were similar between the states, with an overall incidence of 21.7% and 23.3%, respectively.

Since national statistics for the same time period aren’t yet available, it’s not possible to directly compare data from the Dakotas with national data. However, information from 2015 – the most recent year available – showed that 2017-18 levels in the Dakotas were much lower than the 2015 national averages, which were 6.2% for Salmonella, and 24.0% for Campylobacter.

Levels for the indicator bacteria E. coli and Enterococcus found in chicken from stores in the Dakotas were also much lower than the 2015 national averages, which were 63.4% for E. coli and 74.6% for Enterococcus.

Table 1. Prevalence of bacteria in chicken from North and South Dakota grocery stores, June 2017-May 2018.

 
North Dakota
South Dakota
Dakotas Total
2015 National
% Pos.
Bacteria No.
Tested
Pos. % No.
Tested
Pos. % No.
Tested
Pos. %
Salmonella 200 0 0 280 4 1.4% 480 4 0.8% 6.2%
Campylobacter 100 12 12.0% 139 8 5.8% 239 20 8.3% 24.0%
E. coli 24 4 16.7% 36 9 25.0% 60 13 21.7% 63.4%
Enterococcus 24 6 25.0% 36 8 22.2% 60 14 23.3% 74.6%

 

Antimicrobial resistance in bacteria from chicken from stores in North and South Dakota.

Isolates (individual growths) of the 4 germ species were submitted to the FDA for antimicrobial resistance testing. Data isn’t available yet for the June 2017-May 2018 time period; however, the resistance of germs found from February 2017 through May 2017, is summarized below (Table 2).

The FDA analyzes the action of 14 different relevant antimicrobial drugs on Salmonella isolates, and 9 drugs on Campylobacter isolates. A germ is classified as “Multi-Drug Resistant” (MDR) if it is resistant to 3 or more different classes of antimicrobials. During this time period, only 2 out of 319 total meat samples tested positive for Salmonella, both from chicken, and both classified as MDR. During the same period, 7 Campylobacter isolates were obtained from fresh chicken, only 1 of which was MDR.

For the indicator organisms E. coli and Enterococcus, the action of 14 and 16 antibiotics respectively, is measured. During the February-May 2017 time period, 18 E. coli isolates were obtained from chicken, with 7 of them being MDR. Antibiotic resistance of these E. coli isolates was most commonly toward the drugs streptomycin (50% of isolates resistant), tetracycline, and sulfasoxazole (44.4% each). Seven Enterococcus isolates were obtained from chicken during the same time period, with 4 of them MDR isolates. Antibiotic resistance of these gram-positive isolates was most commonly toward lincomycin and nitrofurantoin, with 71.4% of isolates resistant to both these drugs.

Table 2. Antibiotic resistance in bacterial isolates from chicken from North and South Dakota grocery stores, February-May 2017.

 
State collected
 
# of antibiotics that isolates were resistant to
# of MDR
isolates
Bacteria ND SD Total 0 1 2 3 4 5 6 7 8
Salmonella 0 2 2 - - - 1 - - 1 - - 2/2
Campylobacter 1 6 7 4 1 1 - 1 - - - - 1/7
E. coli 6 12 18 5 4 2 2 3 1 - - 1 7/18
Enterococcus 2 5 7 - 1 2 1 - 1 1 1 - 4/7

 

B. Ground Turkey

Prevalence of bacteria in ground turkey from North and South Dakota grocery stores.

Salmonella rates weren’t much higher in ground turkey compared to chicken samples, with a low overall prevalence of 1.7% (4/240 – Table 3). Campylobacter rates in ground turkey were much lower than in chicken, though: 0.4% (1/240). No real prevalence differences between samples from North Dakota and South Dakota were evident. Levels of the indicator bacteria E. coli and Enterococcus in ground turkey were higher than those found in chicken, with an overall incidence of 81.3% and 72.9%, respectively. Enterococcus was found at higher rates in ground turkey from South Dakota stores (85.2% vs. 57.1%).

In comparing this data from the Dakotas with 2015 national statistics, Salmonella recovery from ground turkey was lower compared to nationally (1.7% vs. 6.1%), while Campylobacter levels were very low in the Dakotas as well as nationally.

E. coli levels in ground turkey were slightly higher in the Dakotas than nationally, while Enterococcus levels were lower. Once again, it is not possible to make direct comparisons since current national data is not yet available.

Table 3. Prevalence of bacteria in ground turkey from North and South Dakota grocery stores, June 2017-May 2018.

 
North Dakota
South Dakota
Dakotas Total
2015 National
% Pos.
Bacteria No.
Tested
Pos. % No.
Tested
Pos. % No.
Tested
Pos. %
Salmonella 101 2 2.0% 139 2 1.4% 240 4 1.7% 6.1%
Campylobacter 101 0 0% 139 1 0.7% 240 1 0.4% 0.2%
E. coli 21 17 81.0% 27 22 81.5% 48 39 81.3% 76.7%
Enterococcus 21 12 57.1% 27 23 85.2% 48 35 72.9% 89.0%

 

Antimicrobial resistance in bacteria from ground turkey from stores in North and South Dakota.

As with chicken, germ isolates from ground turkey were submitted to the FDA for antimicrobial resistance testing. Once again, this report covers the antibiotic resistance of germs found during the period of February, 2017 through May 2017. 

During this time period, none of the ground turkey samples tested positive for Salmonella or Campylobacter (Table 4). 

For the indicator organisms E. coli and Enterococcus, the action of 14 and 16 antibiotics respectively, is measured. During the February-May 2017 time period, 27 E. coli isolates were obtained from ground turkey, with 17 of them being MDR. Antibiotic resistance of these E. coli isolates were most commonly toward tetracycline (81.5% of isolates resistant) and ampicillin (59.2%). Twenty-four Enterococcus isolates were obtained from ground turkey during the same time period, with all but 3 of them MDR isolates. Antibiotic resistance for Enterococcus isolates was most commonly noted against lincomycin (95.8%) and tetracycline (75%).

Table 4. Antibiotic resistance in bacteria from ground turkey, North and South Dakota grocery stores, Feb. 2017 – May 2017.

 
State collected
 
# of antibiotics that isolates were resistant to
# of MDR
isolates
Bacteria ND SD Total 0 1 2 3 4 5 6 7 8 9
Salmonella 0 0 0 - - - - - - - - - - -
Campylobacter 0 0 0 - - - - - - - - - - -
E. coli 11 16 27 5 2 3 4 6 5 2 - - - 17/27
Enterococcus 10 14 24 - - 3 10 1 3 3 2 1 1 21/24

 

Summary

South Dakota State University’s involvement with NARMS is off to a successful start. This year’s work has produced new information about the prevalence of potentially illness-causing germs in poultry and other meat products in North and South Dakota. This year’s data indicates that the presence of Salmonella and Campylobacter in chicken and ground turkey is relatively uncommon in the Dakotas, with overall levels quite similar between the states. Comparing this 2017-2018 data with contemporary national data (once it’s available) will provide even better information regarding food safety in the Dakotas.

The project is also measuring levels of antibiotic resistance in those germs and certain indicator germs. As changes occur in poultry production, monitoring germ resistance to antibiotics will become important to determine the effect, if any, of shifts and declines in antibiotic use in poultry production.

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