NARMS Interim Data Updates
What are NARMS Interim Data Updates?
NARMS interim data updates provide a summary of recent unusual or concerning antimicrobial resistance findings in enteric bacteria found through surveillance of retail meats. These updates are based upon using whole-genome sequence (WGS) analysis to screen for bacterial genes associated with resistance to one or more medically important antibiotics. Findings that would lead to a data update include but are not limited to
- Resistance to antimicrobials typically used to treat infections in humans (e.g., ceftriaxone and ciprofloxacin for treatment of severe Salmonella infections),
- Resistance to antimicrobials used as last-resort treatments (e.g., colistin), and
- Emergence of extensively drug-resistant clones.
NARMS interim data updates do not serve as notice of product recalls, alerts, or outbreaks of foodborne illness. Information about these events can be found at
NARMS Retail Meat Testing Notification: Multidrug-Resistant (MDR) Salmonella Senftenberg
New Finding
NARMS sampling of retail ground turkey has identified a Salmonella serotype Senftenberg isolate (19GA12GT11-S) with a plasmid carrying a cephalosporin resistance gene. This plasmid is similar to the mega-plasmid (pESI) found in a multidrug-resistant Salmonella Infantis strain that has become increasingly prevalent in U.S. poultry and cases of human illnesses. This cephalosporin-resistant Senftenberg strain was first detected by NARMS in 2019 (1 sample) and again in 2021 (3 samples) and 2022 (3 samples), but the plasmid and its similarity to the pESI in multidrug-resistant Salmonella Infantis was only recently confirmed through further genomic analysis. CDC has identified two cases of human illness caused by this strain since June 2022. One patient reported consuming ground turkey in the seven days before illness began, and the other had no known turkey exposure.
This Salmonella serotype Senftenberg strain is resistant to 8 out of 14 antibiotics on the NARMS Salmonella panel (see Table). Ceftriaxone (a cephalosporin) is considered a critically important drug for treating severe Salmonella infections, especially for children. The development and spread of resistance to critically important antimicrobials is a serious public health concern (CDC, 2022). To increase public health awareness, the FDA is sharing this information via this notification, and the USDA and FDA have also proactively updated representatives from the turkey industry about this finding.
MDR profile of the NARMS isolate 19GA12GT11-S
| Class | Antimicrobial Agent | Resistant | Genes |
|---|---|---|---|
| Aminoglycosides | Gentamicin | X | aac(3)-IV |
| Aminoglycosides | Streptomycin | X | aadA1, aph(3')-Ia, aph(3'')-Ib |
| Beta-lactam combination agents | Amoxicillin-Clavulanic Acid | ||
| Cephems | Cefoxitin | ||
| Cephems | Ceftriaxone | X | blaCTX-M-65 |
| Folate pathway antagonists | Sulfisoxazole | X | sul1,sul2 |
| Folate pathway antagonists | Trimethoprim-Sulfamethoxazole | X | dfrA14; sul1,sul2 |
| Macrolides | Azithromycin | ||
| Penems | Meropenem | ||
| Penicillins | Ampicillin | X | blaCTX-M-65 |
| Phenicols | Chloramphenicol | X | floR |
| Quinolones | Ciprofloxacin | ||
| Quinolones | Nalidixic Acid | ||
| Tetracyclines | Tetracycline | X | tet(A) |
Fast Facts
Isolate(s): 19GA12GT11-S, 21NC10GT04-S, 21NY01GT05-S1, 21NM11GT05-S1, CFSAN119630, PNUSAS276269, 22MO06GT03-S1
Organism: Salmonella Senftenberg
Source: Retail ground turkey
Location(s): GA, MD, MO, NC, NM, NY, PA
Date collected: 2019, 2021, and 2022
Other strains from different lineages of Salmonella Senftenberg have been associated with outbreaks of human illness linked to pistachios (FDA Investigation) and to peanut butter (FDA Investigation). Salmonella Senftenberg has been routinely detected in NARMS retail testing of ground turkey (55 total isolates from 2016 to 2021 testing period). Additional information on Salmonella Senftenberg from turkey that are genetically similar to 19GA12GT11-S can be found on NCBI’s Pathogen Detection Portal.
Consumer Safety
This notification is to inform stakeholders of this novel finding. Although this rare finding by itself does not signify elevated risk, the public is advised to continue practicing safe handling of raw meats, as recommended by the USDA, and proper hygiene around animals as recommended by the CDC.
NARMS Retail Meat Testing Interim Data Update: Multidrug-Resistant (MDR) Salmonella I 4,[5],12:i:-
New Finding
In November of 2019, NARMS collected a retail pork sample that yielded a Salmonella serotype I 4,[5],12:i:- isolate (19MN11PC02) that is resistant to 10 out of 14 antibiotics on the NARMS Salmonella panel (see Table). Further genetic characterization of this isolate revealed a plasmid carrying both cephalosporin and fluoroquinolone resistance genes which is uncommon in Salmonella in the United States. To our knowledge, this is the first time this combination of resistance genes has been found in NARMS retail meat testing and raises concern since ceftriaxone (a cephalosporin) and ciprofloxacin (a fluoroquinolone) are critical drugs to treat severe Salmonella infections (CDC, Antibiotic Resistance Threats in the United States, 2019).
MDR profile of the NARMS isolate 19MN11PC02
| Class | Antimicrobial | Resistant | Genes |
|---|---|---|---|
| Aminoglycosides | Gentamicin | X | aac(3)-IIa |
| Aminoglycosides | Streptomycin | X | aadA1, aph(3')-Ia, aph(3'')-Ib, aph(6)-Id |
| Beta-lactam combination agents | Amoxicillin-Clavulanic Acid | ||
| Cephems | Cefoxitin | ||
| Cephems | Ceftriaxone | X | blaCTX-M-15 |
| Folate pathway antagonists | Sulfisoxazole | X | sul2 |
| Folate pathway antagonists | Trimethoprim-Sulfamethoxazole | X | dfrA14 |
| Macrolides | Azithromycin | ||
| Penems | Meropenem | ||
| Penicillins | Ampicillin | X | blaCTX-M-15, blaOXA-1, blaTEM-1 |
| Phenicols | Chloramphenicol | X | catA1, catB3 |
| Quinolones | Ciprofloxacin | X | aac(6')-Ib-cr5, qnrB1 |
| Quinolones | Nalidixic Acid | X | qnrB1 |
| Tetracyclines | Tetracycline | X | tet(A), tet(B) |
Fast Facts
Isolate: 19MN11PC02.
Organism: Salmonella I 4,[5],12:i:-
Source: Retail pork chop
Location(s): MN
Date collected: November 2019
Additional information on genetically similar Salmonella I 4,[5],12:i:- from pork and human clinical specimens can be found at NCBI’s Pathogen Detection Portal. At this time, the resistance pattern in Salmonella I 4,[5],12:i:-reported here is considered a rare finding in the United States.
Over the past decade, Salmonella I 4,[5],12:i:- has emerged as a major public health threat in Europe and the United States. In 2019, it ranked fifth among laboratory diagnosed nontyphoidal Salmonella infections in the United States (CDC).
Next Steps
FDA is performing additional genomic testing to better understand the origins of genes that caused the extensive resistance profile in 19MN11PC02 and other related I 4,[5],12:i:- isolates.
Consumer Safety
This notification is to inform stakeholders of this novel finding. While this rare finding by itself does not signify elevated risk, the public is advised to continue practicing safe handling of raw meats, as recommended by the USDA, and proper hygiene around animals as recommended by the CDC.