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Healthy People 2020 Progress Report
Nontyphoidal Salmonella and Campylobacter are the major bacterial pathogens transmitted commonly through food. Most of the enteric infections caused by these pathogens resolve with supportive care alone; however, antibiotic treatment is recommended for severe infections. Ciprofloxacin and ceftriaxone are commonly recommended for nontyphoidal Salmonella infections and macrolides, such as erythromycin and azithromycin, are recommended for Campylobacter infections.
The National Antimicrobial Resistance Monitoring System (NARMS) is a collaboration among the Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration, the U.S. Department of Agriculture, and state and local health departments, that was established to monitor levels of antimicrobial resistance in human, retail meat, and food animal isolates of enteric bacteria transmitted commonly by food. Public health laboratories in 54 state and local health departments submit every 20th human nontyphoidal Salmonella isolate, which they receive from reference and clinical laboratories as part of public health surveillance, to CDC for antimicrobial susceptibility testing. Public health laboratories in 10 states that participate in the Foodborne Diseases Active Surveillance Network submit a frequency-based sample of Campylobacter isolates received from a convenience sample of reference and clinical laboratories.
NARMS data were used to assess progress towards the Healthy People 2020 (HP2020) food safety (FS) topic area objectives related to antibiotic resistance in nontyphoidal Salmonella and Campylobacter jejuni isolates from humans. We defined six HP2020 objectives to track antibiotic resistance. The goal was to prevent an increase in the proportion of nontyphoidal Salmonella and Campylobacter jejuni isolates with clinically relevant resistance.
Five objectives track resistance in nontyphoidal Salmonella:
- FS 3.1: reduced susceptibility to ciprofloxacin (includes results with resistant or intermediate interpretations)
- FS 3.2: resistance to ceftriaxone
- FS 3.3: resistance to gentamicin
- FS 3.4: resistance to ampicillin
- FS 3.5: resistance to three or more classes of antimicrobial drugs
FS 3.6 tracks resistance to erythromycin in Campylobacter jejuni.
Methods
HP2020 baselines were determined using the average percentage of resistant isolates among those collected from 2006–2008. These baselines were used to set targets for 2020. To assess progress towards the HP2020 targets, we compared the percentage of resistant isolates in 2015 with the 2006–2008 baseline. We determined changes in the percentage of resistant isolates using methods outlined in the NARMS annual report. We defined resistance using criteria from the Clinical and Laboratory Standards Institute. For FS 3.5, we included nine drug classes described in the NARMS report. More information on resistance among Salmonella and Campylobacter is available in the 2015 NARMS report.
Key Findings
- In 2015, there were increases in resistance for four of six objectives. These were reduced susceptibility to ciprofloxacin, increased resistance to ampicillin and to three or more drug classes among nontyphoidal Salmonella, and increased resistance to erythromycin among C. jejuni (see Table).
- Among nontyphoidal Salmonella, the overall increase in resistance was due to an increase in resistance among a few specific serotypes.
- An increased percentage of serotype Enteritidis isolates had reduced susceptibility to ciprofloxacin and an increased percentage of serotype
I 4,[5],12:i isolates had multidrug resistance.
- An increased percentage of serotype Enteritidis isolates had reduced susceptibility to ciprofloxacin and an increased percentage of serotype
- Among nontyphoidal Salmonella, resistance to ceftriaxone and gentamicin did not change; however, the percentage of isolates with ceftriaxone resistance increased among Salmonella serotypes Infantis and I 4,[5],12:i:-.
Progress Report on Healthy People 2020 Food Safety Topic Area Objectives: Antimicrobial Resistance in Nontyphoidal Salmonella and Campylobacter
Objective FS-3: Prevent an increase in the proportion of nontyphoidal Salmonella and Campylobacter jejuni isolates from humans that are resistant to antimicrobial drugs
| Pathogen | Drug/drug class (Objective no.) | Healthy People 2020 target resistance (2006–2008)* | 2015 resistance | Change compared with 2006–2008 baseline* | |
|---|---|---|---|---|---|
| Significant change?† | Percentage over time | ||||
| Nontyphoidal Salmonella | Ciprofloxacin‡ (3.1) |
2.6% | 5.8% |  Significant increase |
See graph |
| Ceftriaxone (3.2) |
3.3% | 2.7% |  No significant change |
See graph | |
| Gentamicin§ (3.3) |
1.9% | 1.8% | No significant change |
See graph | |
| Ampicillin (3.4) |
10.3% | 12.4% | Significant increase |
See graph | |
| 3 or more drug classes (3.5) |
10.8% | 12.3% | Significant increase |
See graph | |
| Campylobacter jejuni | Erythromycin
(3.6) |
1.6% | 2.7% | Significant increase |
See graph |
*2006–2008 were the baseline years used to establish Healthy People 2020 targets
†Statistical significance was determined by logistic regression modeling, to compare the 2015 percentage to the average percentage during 2006–2008
‡FS-3.1 has been revised to track reduced susceptibility to ciprofloxacin (originally tracked resistance to nalidixic acid)
§Included for tracking antibiotic resistance but is not recommended for the treatment of Salmonella infections
Objective 3.1: Percentage of nontyphoidal Salmonella with reduced susceptibility to ciprofloxacin, 2006–2015
Objective 3.2: Percentage of nontyphoidal Salmonella resistant to ceftriaxone, 2006–2015
Objective 3.3: Percentage of nontyphoidal Salmonella resistant to gentamicin, 2006–2015
Objective 3.4: Percentage of nontyphoidal Salmonella resistant to ampicillin, 2006–2015
Objective 3.5: Percentage of nontyphoidal Salmonella resistant to 3 or more drug classes, 2006–2015
Objective 3.6: Percentage of Campylobacter jejuni resistant to erythromycin, 2006–2015
Conclusion
Overall, the proportion of nontyphoidal Salmonella and Campylobacter jejuni isolates with clinically important resistance increased in 2015 compared with baseline levels. Antibiotic resistance poses a serious threat to public health and the HP2020 interim findings highlight the need for continued efforts to control and prevent the spread of antimicrobial resistance and reduce inappropriate antibiotic use wherever possible. These efforts include appropriate food handling and animal contact safety, stewardship programs, improvements in animal husbandry, and development of alternatives to antibiotics. NARMS is a unique multi-agency surveillance system that will continue to track trends in antibiotic resistance in enteric bacteria and document the effectiveness of interventions to limit resistance.
- Bennett JE, Dolin R, Blaser MJ, editors. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, 8 ed. Philadelphia, PA: Elsevier/Saunders, 2015.
- Centers for Disease Control and Prevention. National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS): Human Isolates Surveillance Report for 2015 (Final Report). Atlanta, Georgia: U.S. Department of Health and Human Services, CDC, 2018.
- Performance Standards for Antimicrobial Susceptibility Testing, 28th ed. CLSI supplement M100. Wayne, PA: Clinical and Laboratory Standards Institute, 2018.
- Healthy People 2020. Food Safety. [cited 2017 Oct 27] https://www.healthypeople.gov/2020/topics-objectives/topic/food-safety
- Karp BE, Tate H, Plumblee JR, Dessai U, Whichard JM, Thacker EL, et al. National Antimicrobial Resistance Monitoring System: two decades of advancing public health through integrated surveillance of resistance. Foodborne Pathog Dis. 2017 Oct;14(10):545-557.
- The National Antimicrobial Resistance Monitoring System: NARMS Integrated Report, 2015. Laurel, MD: U.S. Department of Health and Human Services, FDA, 2017.
- Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, et al. Foodborne illness acquired in the United States—major pathogens. Emerg Infect Dis. 2011;17:7–15.