The primary purpose of the NARMS retail meat surveillance program is to monitor the prevalence of antimicrobial resistance among foodborne bacteria. In 2007, surveillance for antimicrobial resistance included Salmonella and Campylobacter from 9 states that comprise the Foodborne Diseases Active Surveillance Network (FoodNet). In addition to Salmonella and Campylobacter, 3 FoodNet states also collected Enterococcus and Escherichia coli. The results generated by the NARMS retail meat program serve as a reference point for identifying and analyzing trends in antimicrobial resistance among these organisms.
Highlights of the 2007 Report
Due to the low recovery rate of Salmonella from ground beef and pork chops, statistical analysis of trends in resistance from these sources should be considered with caution.
The percentage of Salmonella isolates susceptible to all antimicrobials by meat type (Table 8) was as follows:
47.5% Chicken Breast
15.3% Ground Turkey
92.3% Ground Beef
44.4% Pork Chops
First-line antimicrobial agents recommended for treating salmonellosis are ciprofloxacin, ceftriaxone and trimethoprim-sulfamethoxazole (IDSA, Practice Guidelines for the Management of Infectious Diarrhea. Clinical Infectious Diseases 2001; 32:331–50). Macrolides and fluoroquinolone are used in the treatment of Campylobacter infections.
- 2.6% (5/190) of Salmonella from ground turkey were resistant to nalidixic acid compared with 8.1% (6/74) in 2002. Nalidixic acid resistance was not present in Salmonella from chicken breast in 2007. Resistance to nalidixic acid corresponds to decreased fluoroquinolone susceptibility; however, fluoroquinolone resistance has never been detected in Salmonella recovered from any retail meat since the program began in 2002. One isolate (0.5%) from ground turkey was resistant to both nalidixic acid and ceftiofur.
- 5.3% (10/190) of Salmonella isolated from ground turkey showed resistance to ceftiofur in 2007, compared with 8.1% (6/74) in 2002.
- There is a highly statistically significant increasing trend of ampicillin resistant Salmonella isolated from ground turkey going from 16.2% (12/74) in 2002 to 42.6% (81/190) in 2007.
- 16.2% (16/99) of Salmonella isolates from chicken breast were resistant to the third-generation cephalosporin ceftiofur compared with 10% (6/60) in 2002. Resistance to this agent corresponds to decreased susceptibility to ceftriaxone.
- More than 95% of Campylobacter are recovered from chicken breast each year (Table 10).
- There is a consistent and marked difference in resistance patterns among C. jejuni and C. coli isolated from chicken breast. Macrolide resistance is much higher in C. coli than C. jejuni for all years from 2002 to 2007, with 6.3% (9/143) resistance to azithromycin for 2007 compared to 0.6% (2/332) in C. jejuni. Similarly, resistance to ciprofloxacin in C. coli (25.9% [37/143]) is significantly higher than in C. jejuni (17.2% [57/332]).
- Another notable trend is that Campylobacter coli from chicken meat has shown a highly statistically significant (p < 0.0001) increasing trend in resistance to ciprofloxacin from 10% (9/90) in 2002 to 25.9% (37/143) in 2007.
- 48.6% (161/332) of C. jejuni isolates were resistant to tetracycline, up from 38.4% (76/198) in 2002 (p = 0.02).