Highlights
- REPDBR01-1, REPDBR01-2, and REPDBR01-3 are persistent, extensively drug-resistant strains of Campylobacter jejuni bacteria (collectively referred to as “REPDBR01”).
- These strains have caused illnesses and outbreaks in the United States.
- In the past, REPDBR01 has spread to people through contact with dogs carrying these strains, especially puppies from pet stores.
- REPDBR01 infections may be impossible to treat with antibiotics commonly recommended for Campylobacter infection.
At a glance
Bacteria
Campylobacter jejuni
Antimicrobial resistance profile
Extensively drug resistant
Persistent strains
REPDBR01-1
REPDBR01-2
REPDBR01-3
First detection
June 2007
Illnesses reported in PulseNet
268
Outbreaks investigated
2
Identified outbreak sources
Pet store puppies (2 outbreaks)
Data last updated
June 30, 2024
Key findings
REPDBR01-1, REPDBR01-2, and REPDBR01-3 are persistent, extensively drug-resistant strains of Campylobacter jejuni bacteria (collectively referred to as "REPDBR01") that have caused illnesses and outbreaks in the United States.
Illness caused by these strains was first reported to PulseNet in 2007.
These strains of Campylobacter jejuni are relatively diverse genetically. Results from core genome multilocus sequence typing (cgMLST) reveal up to 53 allele differences within REPDBR01-1, 105 allele differences within REPDBR01-2, and 101 allele differences within REPDBR01-3. This is more genetically diverse than typical multistate outbreaks, in which bacteria generally fall within 10 allele differences of one another. Increased diversity can occur over time as strains pass among human hosts, animal hosts, and environmental settings, each with different selective pressures.
What the data show
Illnesses and outbreaks data
As of June 30, 2024, information on REPDBR01 infections in 268 people was reported to PulseNet.
The median age of ill people was 36 years (interquartile range, 20–53 years), and 65% were female. Among 245 ill people who provided race and ethnicity
- 87% were White non-Hispanic,
- 7% were Hispanic/Latino,
- 4% were Black non-Hispanic, and
- 2% were another non-Hispanic race.
The isolate source was stool in more than 99% of cases. Twenty-two percent (22%) of ill people were hospitalized for a median of 3 days (interquartile range, 2–4 days); no deaths were reported. Illnesses caused by these strains occur year-round.
In the past, REPDBR01 has spread to people through contact with dogs, especially puppies (typically younger than 6 months), carrying these strains. Ninety-seven (97%) percent of ill people reported contact with a dog before becoming ill. Among those with additional information
- 77% reported contact with a pet store puppy, and
- 7% reported contact with a puppy from another setting, such as a shelter or breeder.
Among those with contact with pet store puppies
- 65% were pet store customers,
- 30% were pet store employees,
- 5% were pet store visitors, and
- 2% had contact with a pet store puppy purchased by someone else.
Some of the associated puppies showed signs of illness, such as diarrhea, and some showed no signs of illness.
Outbreaks and other investigations
Although most enteric illnesses—including those caused by REPDBR01 strains—are not investigated as part of an outbreak, outbreak investigation provides information that increases our understanding of bacteria, sources, settings, and factors that contribute to illness. Moreover, lab-confirmed cases comprise only a small portion of the true number of illnesses that occur because most people do not seek medical care and even fewer submit a clinical (e.g., stool) specimen.
CDC and local, state, and federal health and regulatory partners have investigated two outbreaks of Campylobacter jejuni illnesses caused by REPDBR01 strains. These strains have been identified in pet store puppies, but the factors that influence why some puppies carry these strains are not completely understood. Evidence collected during outbreak investigations indicate these strains are widespread in the dog breeding industry.
Summary of selected multistate outbreaks and other investigations
| Outbreak | Dates people became ill | Outbreak source | Reported illnesses | Number of states with illnesses | More information |
|---|---|---|---|---|---|
| Outbreak A | January 12, 2016 – January 7, 2018 | Pet store puppies (confirmed) | 113 | 17 | CDC Investigation Notice |
| Outbreak B | January 6, 2019 – January 2, 2021 | Pet store puppies (confirmed) | 56 | 17 | CDC Investigation Notice |
Selected publications regarding REPDBR01 investigations
- All REPDBR01 – Evaluation of core genome and whole genome multilocus sequence typing schemes for Campylobacter jejuni and Campylobacter coli outbreak detection in the USA (2023)
- All REPDBR01 – Ongoing outbreak of extensively drug-resistant Campylobacter jejuni infections associated with US pet store puppies, 2016–2020 (2021)
- Outbreak A – Antimicrobial susceptibility testing and successful treatment of hospitalised patients with extensively drug-resistant Campylobacter jejuni infections linked to a pet store puppy outbreak (2021)
- Outbreak A – Comparison of molecular subtyping and antimicrobial resistance detection methods used in a large multistate outbreak of extensively drug-resistant Campylobacter jejuni infections linked to pet store puppies (2020)
- Outbreak A – Multidrug-resistant Campylobacter jejuni outbreak linked to puppy exposure – United States, 2016–2018 (2018)
Selected publications on Campylobacter jejuni are for reference; other publications regarding the bacteria are available.
Timeline
People with Campylobacter jejuni illnesses caused by the REPDBR01 strains, by month of isolate collection, January 2007–June 2024
Map
People with Campylobacter jejuni illnesses caused by the REDBR01 strains, by state, January 2007–June 2024
Laboratory Data
Whole genome sequencing analysis
Bacteria in these strains are within 53 allele differences (REPDBR01-1), 105 allele differences (REPDBR01-2), and 101 allele differences (REPDBR01-3) of one another by cgMLST. This is more genetically diverse than typical multistate outbreaks, in which bacteria generally fall within 10 allele differences of one another. Increased diversity can occur over time as strains pass among human hosts, animal hosts, and environmental settings, each with different selective pressures.
Isolates from food, animal, and environmental samples
| Year | Number of isolates | Isolate type | Geographic location of source | Reason collected |
|---|---|---|---|---|
| 2007 | 1 | Dog | Wyoming | Unknown |
| 2013 | 1 | Dog | Ohio | Unknown |
| 2017 | 10 | Dog | Florida, Ohio, Wisconsin | Outbreak A |
| 2017 | 5 | Dog | Florida, Wisconsin, Wyoming | Unknown |
| 2018 | 4 | Dog | Florida, Georgia | Outbreak A |
| 2018 | 3 | Dog | Florida, Ohio | Unknown |
| 2018 | 1 | Turkey (food animal) | Missouri | Routine sampling |
| 2020 | 2 | Dog | Iowa, Minnesota | Outbreak B |
| 2021 | 1 | Dog | New Hampshire | State investigation |
| 2021 | 1 | Chicken (food product) | Missouri | Routine sampling |
| 2023 | 2 | Dog | Florida, Ohio | State investigations |
| 2024 | 1 | Dog | Ohio | State investigation |
Genomic information
The National Center for Biotechnology Information (NCBI) advances science and health by providing access to biomedical and genomic information. To view the full SNP cluster, click on the link below; then within NCBI's platform click the link underneath the "SNP Cluster" column.
- SNP Cluster (REPDBR01-1) associated with isolate: PNUSAC003228
- SNP Cluster (REPDBR01-2) associated with isolate: PNUSAC012858
- SNP Cluster (REPDBR01-3) associated with isolate: PNUSAC009690
Antimicrobial-resistant isolates
The National Antimicrobial Resistance Monitoring System (NARMS) is a national public health surveillance system that tracks antimicrobial resistance for certain intestinal bacteria from ill people (CDC), food animals (USDA), and retail meats (FDA) in the United States. The NARMS program helps protect public health by providing information about emerging antimicrobial resistance in intestinal bacteria, the ways in which resistance is spread, and how resistant infections differ from susceptible infections.
People with mild illness may not require antibiotics. If antibiotics are needed, REPDBR01 infections may be impossible to treat with commonly recommended antibiotics and may require a different antibiotic choice.
These strains have developed antimicrobial resistance, which means that certain drugs are no longer effective for treatment. Bacteria from most ill people's samples showed resistance to multiple antibiotics, including several that are recommended for first-line or alternative treatment for Campylobacter infections (azithromycin, ciprofloxacin, and erythromycin).
Percentage of human Campylobacter jejuni REPDBR01 isolates that were antimicrobial resistant, by antimicrobial (268 isolates), as of June 30, 2024 — NARMS
Collaborate with CDC
Interested in collaborating on a project related to this strain? Contact CDC at REPStrains@cdc.gov.
About the data
Outbreak dates are based on reported or estimated illness onset dates.
Confirmed sources were implicated by epidemiologic plus traceback or laboratory data. More information about determining outbreak sources available in the latest summary of possible multistate enteric disease outbreaks.
Among the 113 illnesses in Outbreak A, only 48 were culture confirmed and met criteria for inclusion.
Most state public health laboratories do not routinely receive or sequence all Campylobacter isolates. Therefore, some cases of REPDBR01 infection may not have been detected.
Includes 268 human illnesses for which information was reported as of June 30, 2024.
The "by year" view of the timeline labels each bar as "January" because of a limitation in the data visualization. Switch to the "by month" view to see a more detailed breakdown of when people became ill.
PulseNet transitioned to using whole genome sequencing (WGS) as the standard subtyping method for Campylobacter in July 2019. Before then, not all Campylobacter reported to PulseNet had WGS data available. Isolates are identified as part of these strains based on WGS. As a result, the number of people with lab-confirmed illness caused by these strains before 2019 may be underrepresented.
Includes 268 human illnesses for which information was reported as of June 30, 2024.
Illness year is based on the date of isolate collection.
Most state public health laboratories do not routinely receive or sequence all Campylobacter isolates. Therefore, some cases of REPDBR01 may not have been detected.
The SNP (single nucleotide polymorphism) trees provided by NCBI's Pathogen Detection Pipeline in the link above may include isolates that are not considered part of these strains. The difference in allele vs. SNP thresholds occurs because NCBI's Pathogen Detection Pipeline uses an analysis pipeline different from the one used by CDC PulseNet.
The links are provided to give context to the overall genetic relatedness of these strains reported on this page, as well as to provide links to raw sequence files. Moreover, the SNP trees on NCBI's Pathogen Detection Pipeline are updated more frequently than this webpage.
Resistance was determined based on the results of antimicrobial susceptibility testing when available (84 isolates); otherwise, resistance was predicted based on whole genome sequencing (184 isolates).
For florfenicol, the resistance determination was based only on antimicrobial susceptibility testing.
For kanamycin and streptomycin, the resistance determination was predicted based only on whole genome sequencing.
Resources
Testing for dogs (including household pets or animals residing in a store or shelter) that had contact with a person infected with Campylobacter is available through the Veterinary Laboratory Investigation and Response Network. Contact Vet-LIRN at vet-lirn@fda.hhs.gov.
Recommendations for breeders, distributors, and pet store owners
Recommendations for pet owners
Recommendations for clinicians and public health professionals