Multidrug-resistant Salmonella strains are spreading in poultry, study suggests

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Bacteria in raw poultry products — Manjurul / iStock

A genomic analysis of Salmonella isolates from retail poultry meat highlights the ongoing spread of multidrug-resistant (MDR) strains in the food supply chain, researchers reported today in Scientific Reports.

Using surveillance data collected by the National Antimicrobial Resistance Monitoring System (NARMS) from 2020 through 2024, researchers from North Carolina State University conducted antimicrobial susceptibility testing and whole-genome sequencing (WGS) on 132 Salmonella enterica isolates from retail poultry products sold in North Carolina.

Their aim was to investigate the prevalence of extended-spectrum beta-lactamase (ESBL) genes, particularly bla_CTX-M-65, which has been associated with MDR Salmonella strains. Salmonella is one of the leading causes of foodborne illness worldwide.

"The presence of bla_CTX-M-65 in Salmonella enterica serovars such as Indiana, Typhimurium, Infantis, and Senftenberg represents a significant public health challenge due to the potential for these strains to cause severe, difficult-to-treat infections," the study authors wrote. "This gene is often located on mobile genetic elements, such as plasmids, which facilitate horizontal gene transfer between different bacteria, exacerbating the spread of resistance within both clinical and environmental settings."

Surveillance, stewardship needed to curb spread of resistance in food

Among 132 isolates representing 25 serovars, 14 were resistant to three or more antibiotic classes and labeled as MDR. WGS revealed that all 14 isolates harbored bla_CTX-M-65 and belonged to three serovars—S Infantis (11 isolates), S I -:r:1,5 (2), and S Senftenberg (1)—with associated sequence types ST32 and ST14.

WGS also identified the presence of additional resistance determinants, including genes encoding resistance to aminoglycosides, tetracyclines, sulfonamides, and quinolones.

The authors say the detection of bla_CTX-M-65 across multiple serovars suggests that spread of the gene is not limited to one serovar or lineage and underscores the importance of routine surveillance for MDR Salmonella serovars.

"This study highlights the need for comprehensive strategies, including genomic monitoring and the prudent use of antibiotics, to curb the spread of resistance in food production settings," they wrote. "In addition to surveillance and antimicrobial stewardship, consumer education on proper food handling, cooking, and hygiene practices is essential to reducing the risk of Salmonella infections."

Measles traces detected in Austin wastewater as other states announce more cases

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Lisa Schnirring

In Texas, Austin Public Health yesterday announced that its wastewater surveillance in Travis County has detected measles, and it urged residents to make sure they are up to date with measles, mumps, and rubella (MMR) vaccination.

The detection hints at an undetected case or cases. So far this year, only two measles cases have been confirmed in Travis County residents, both of which involved exposure during international travel. In a statement, officials said the samples that tested positive were collected during the first week of July.

Earlier this month, Utah reported a positive wastewater sample from the Provo area, and over the past few months, health officials in New Mexico and Sacramento, California, reported positive detections, which were later followed by confirmed cases.

West Texas outbreak continues downward trend

Two states initially hit hardest by the West Texas outbreaks—Texas and New Mexico— reported no new cases today. However, Kansas, which has reported related cases, announced two more infections in an ongoing outbreak in the southwestern part of the state. The Kansas Department of Health and Environment yesterday upped its total to 90 cases, with 87 linked to the state’s outbreak.

Elsewhere, health officials in Montana’s Yellowstone County are investigating a suspected measles case in a child who may have exposed others at a vacation Bible school camp in Billings.

RiverStone Health, a medical clinic in Billings, said the unvaccinated child had recently traveled to an area where measles is spreading and that confirmation testing is under way at Montana State Laboratory.

China reports more H9N2 activity

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Stephanie Soucheray, MA

China has reported two more H9N2 cases, one from Guangdong province with a late May onset, and the other from Hubei province with a mid-June onset. The information is published in the latest weekly update from Hong Kong’s Centre for Heath Protection.

The patient’s ages are not noted, which differed from the 16 previous cases of H9N2 reported by Chinese authorities in 2025. The report also did not note how the case-patients were infected, but H9N2 cases typically involve contact with infected poultry.

Children have been the most affected in China’s H9N2 cases. Eleven of the 16 case-patients with known ages this year are 18 years or younger.

All 18 cases in 2025 have been reported from mainland China, with the most (six) reported in Hunan province. In 2024, the country reported 11 total cases.