# Microbiological Monitoring and Microbial Susceptibility of Salmonella from Aquacultured Tambaqui Hybrids (Colossoma macropomum): Implications for Food Safety

## TL;DR

This study examines Salmonella in farmed tambaqui hybrids and finds no dangerous strains or antibiotic resistance, suggesting low food safety risk.

## Contribution

The study provides new insights into the antimicrobial susceptibility of Salmonella in Amazonian aquaculture species.

## Key findings

- No clinically important Salmonella serotypes were detected in the isolates.
- All 55 isolates were susceptible to 14 tested antimicrobials.
- The findings suggest a low risk of pathogenic or resistant Salmonella in farmed tambaqui hybrids.

## Abstract

Background: Salmonellosis is a foodborne illness typically associated with gastroenteritis following the ingestion of products contaminated with Salmonella enterica. Although the aquatic environment is not a natural reservoir for Salmonella spp., its occurrence has been reported in various aquacultured species worldwide, including species from the Amazon Basin in South America. The World Health Organization has classified the emergence of multidrug-resistant (MDR) Salmonella strains as a global priority, underscoring the importance of monitoring antimicrobial resistance to mitigate public health risks. This study aimed to detect Salmonella spp. serotypes of clinical relevance to humans (S. Typhi, S. Paratyphi, S. Typhimurium, and S. Enteritidis) in farmed tambaqui hybrids and to assess the antimicrobial susceptibility of the isolates. Methods: A total of 55 Salmonella spp. strains, previously isolated from tambaqui hybrids (Colossoma macropomum) produced in fish farms in Mato Grosso, Brazil, were evaluated. Identification and susceptibility profiling were performed using the VITEK®2 Compact automated system (BioMérieux, Marcy l’Étoile, France), testing 14 commonly used antimicrobials, including amoxicillin–clavulanic acid, piperacillin–tazobactam, cephalexin, cefuroxime axetil, ceftriaxone, cefepime, meropenem, ertapenem, amikacin, gentamicin, ciprofloxacin, and sulfamethoxazole–trimethoprim. Results: All isolates were confirmed as Salmonella spp., with no detection of clinically important serotypes. Moreover, all 55 strains were susceptible to the 14 antimicrobials tested. Conclusions: These findings indicate a low risk of pathogenic or resistant Salmonella from farmed tambaqui hybrids under the evaluated conditions. Nevertheless, ongoing microbiological monitoring remains essential, particularly in light of regulatory standards that prohibit the presence of Salmonella spp. in fish products and the potential emergence of MDR strains.