# Ceftriaxone-resistant Salmonella Panama ST48 detected in poultry food chain: A phylogeographical analysis

## TL;DR

A ceftriaxone-resistant Salmonella Panama strain was found in poultry in Brazil, raising concerns about antibiotic resistance spread through the food chain.

## Contribution

Identification of a ceftriaxone-resistant Salmonella Panama ST48 clone with CTX-M-8 ESBL in the poultry food chain.

## Key findings

- A ceftriaxone-resistant Salmonella Panama ST48 strain was detected in a Brazilian slaughterhouse.
- The strain carries the blaCTX-M-8 ESBL gene on an IncM1 plasmid and shows fluoroquinolone resistance mutations.
- Phylogeographic analysis links the strain to human and animal isolates in Brazil and the USA, indicating One Health concerns.

## Abstract

Salmonella Panama is a clinically relevant serovar isolated from food sources, particularly poultry and swine, being also reported in human gastrointestinal and extraintestinal disease globally. The emergence of broad-spectrum cephalosporin-resistant Salmonella has been considered a One Health matter that demands continuous microbiologic and genomic surveillance for a comprehensive understanding and mitigation actions. During a local surveillance study conducted to monitoring WHO priority Salmonella spp. in the Brazilian poultry food chain, a ceftriaxone-resistant Salmonella strain (PN2) exhibiting a positive extended-spectrum beta-lactamase (ESBL) phenotype was recovered from a chicken sample, in a slaughterhouse under federal inspection. Clinically relevant genomic data confirmed Salmonella Panama sequence type (ST) 48 carrying the blaCTX-M-8 ESBL gene into the broad-host range IncM1conjugative plasmid, and displaying point mutations in the quinolone determining resistance region (QRDR), related to fluoroquinolone non-susceptibility. Phylogeographical analysis of publicly available global genomes of S. Panama ST48 revealed a potential concern for One Health issues due to its zoonotic nature, clustering PN2 (52–153 cgSNP differences) along with genomically related S. Panama strains isolated from human infections, food products, and farm animals, in the United States of America and Brazil. Interestingly, using Bayesian clustering method, the PN2 strain was grouped in the main clade C4, along with a CTX-M-55-producing S. Panama strain isolated from a human stool sample in Taiwan. In summary, we alert for the potential risk of dissemination of a neglected serovar that has contributed to the Salmonella global disease burden through the food supply chain.

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•WHO critical priority Salmonella in the poultry food chain has been investigated.•Ceftriaxone-resistant S. panama producing CTX-M-8 ESBL was identified.•Genomic analysis revealed emergence of ST48 clone carrying IncM1/blaCTX-M-8 plasmid.•Phylogeographical analysis of global S. panama ST48 revealed One Health distribution.•Potential risk of dissemination of the emergent S. panama ST48 is discussed.

WHO critical priority Salmonella in the poultry food chain has been investigated.

Ceftriaxone-resistant S. panama producing CTX-M-8 ESBL was identified.

Genomic analysis revealed emergence of ST48 clone carrying IncM1/blaCTX-M-8 plasmid.

Phylogeographical analysis of global S. panama ST48 revealed One Health distribution.

Potential risk of dissemination of the emergent S. panama ST48 is discussed.