Data Summary: Persistent Strain of Salmonella Newport (REPJJP01)

At a glance

Key findings

REPJJP01 is a persistent, multidrug-resistant strain of Salmonella Newport bacteria that has caused illnesses and outbreaks in the United States and in other countries.

Illness caused by this strain was first reported to PulseNet in late 2015. Illnesses caused by this strain occur year-round but are less common in winter.

This strain of Salmonella Newport is relatively diverse genetically. Bacteria in this strain are within 24 allele differences of one another by whole genome sequencing. This is more diverse than typical multistate foodborne outbreaks where 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 September 30, 2024, information from 3,129 people with laboratory-confirmed REPJJP01 infection was reported to PulseNet, a national laboratory network that tests for and tracks enteric pathogens in humans.

Among 1,947 people with information available, 31% were hospitalized. Among 1,800 people with information on the outcome of infection, fewer than 1% died.

Among 1,831 ill people:

• 61% self-identified as Hispanic/Latino,
• 35% self-identified as non-Hispanic/Latino White, and
• 4% self-identified as non-Hispanic/Latino and another race.

The median age of ill people was 38 years (interquartile range, 22–55 years) and 56% were female.

Among 1,949 people with available travel information:

• Almost half (48%) reported traveling to Mexico,
• Fewer than 1% reported traveling to Guatemala, and
• 51% reported no international travel before their illness began.

People with REPJJP01 infections also have reported consuming beef products from the United States and Mexico and consuming cheese obtained in Mexico (including queso fresco and Oaxaca cheese).

Although most enteric illnesses – including those caused by REPJJP01 – are not part of an outbreak, investigation of outbreaks provides information that increases our understanding of germs, 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 stool specimen.

Starting in 2016, CDC and local, state, and federal health and regulatory partners have investigated several outbreaks of Salmonella Newport illnesses caused by the REPJJP01 strain.

Summary of selected multistate outbreaks

Selected outbreak publications

• Outbreak B - Outbreak of Salmonella Newport infections with decreased susceptibility to azithromycin linked to beef obtained in the United States and soft cheese obtained in Mexico — United States, 2018–2019
• Outbreaks C and F - Strain of multidrug-resistant Salmonella Newport remains linked to travel to Mexico and U.S. beef products — United States, 2021–2022
• Outbreak J – Foodborne outbreak of Salmonella: An uninvited wedding reception guest

Timeline

People with Salmonella Newport illnesses caused by the REPJJP01 strain, by date illness began, 2015–2024

Map

Salmonella Newport illnesses caused by the REPJJP01 strain, by state, 2015–2024

Laboratory data

Bacteria in REPJJP01 are within 24 allele differences of one another by core genome multilocus sequence typing (cgMLST). This is more diverse than typical multistate foodborne outbreaks where bacteria generally fall within 10 allele differences of one another.

Isolates from food, animal, and environmental samples

Information from 87 REPJJP01 isolates from animals and food products has been reported to PulseNet (Table). Most isolates were obtained from beef products and cecal samples from the large intestines of cattle and were detected as part of routine surveillance performed by the United States Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) and the USDA Agricultural Marketing Service (USDA-AMS), or as part of sampling performed by the National Antimicrobial Resistance Monitoring System (NARMS). One isolate from a papaya and six isolates from pet treats were detected as part of routine surveillance performed by the United States Food and Drug Administration (FDA).

Genomic information

The National Center for Biotechnology Information (NCBI) advances science and health by providing access to biomedical and genomic information.

SNP Cluster associated with isolate: PNUSAS003661

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 sick people (CDC), retail meats (FDA), and food animals (USDA) in the United States. The NARMS program helps protect public health by providing information about emerging antimicrobial resistance, the ways in which resistance is spread, and how resistant infections differ from susceptible infections.

Bacteria from most ill people's samples showed resistance to antibiotics, including several that are recommended for first-line or alternative treatment: ampicillin, azithromycin, ciprofloxacin, and trimethoprim-sulfamethoxazole. Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, some REPJJP01 illnesses may be difficult to treat with commonly recommended antibiotics and may require a different antibiotic choice. Learn more about the management of infections with this strain.

Percentage of Salmonella Newport REPJJP01 isolates from ill people that were antimicrobial resistant, by antibiotic (n = 3,094), as of September 30, 2024 — NARMS

Collaborate with CDC

Interested in collaborating on a project related to this strain? Contact CDC at [email protected].

About the data

Resources

Suggested citation

Centers for Disease Control and Prevention. (2024). Data Summary: Persistent Strain of Salmonella Newport (REPJJP01).