Prevalence, Serotypes, and Antimicrobial Resistance of Salmonella from Mink Feces and Feed in the United States

Epidemiology of Salmonella enterica subspecies enterica serotypes, isolated from imported, farmed and feral poultry in the Cayman Islands

Non-typhoidal Salmonellae (NTS) are common foodborne pathogens throughout the world causing acute gastroenteritis. Compared to North America and Europe, there is little information on NTS in the Caribbean. Here we investigated the prevalence and characteristics of NTS present in the local poultry of the Cayman Islands to determine the public health risk. In total, we collected 156 samples. These were made up of boot swabs of 31 broiler farms and 31 layer farms (62 samples), paper bedding from 45 imported chick boxes, and 49 pooled cecum samples from feral chickens, each sample representing 10 individual chickens. Salmonella was isolated using the ISO 6579 protocol and isolates were characterized using Whole Genome Sequencing (WGS) analysis. Eighteen Salmonella isolates were obtained and comprised six S. enterica subspecies enterica serotypes and one subspecies houtenae serotype. Serotypes were: S. Kentucky (n = 9), S. Saintpaul (n = 5), S. Javiana (n = 1), S. Senftenberg (n = 1), S. Poona (n = 1) and S. Agona (n = 1). S. Kentucky strains were all ST152 and clonally related to poultry strains from the United states. S. Saintpaul ST50 strains showed clonality to North American strains. Over half of the strains (n = 11) contained resistance genes to at least two antibiotic groups and five strains were MDR, mainly those from imported day-old chicks. The blaCMY-2 gene was found in S. Kentucky from day-old chicks. Strains from feral poultry had no acquired AMR genes. While serotypes from feral poultry have been identified in human infections, they pose minimal risk due to their low virulence.

Prevalence and whole-genome sequencing characterization of Salmonella in urban karst groundwater and predominantly groundwater-fed surface waters for serotypes and antimicrobial resistance

Karst aquifers provide a significant source of drinking water around the world; however, they are prone to bacterial contamination. We investigated the prevalence, serotypes, and antimicrobial resistance genes (ARGs) of Salmonella in urban karst groundwater and groundwater-fed surface waters. Weekly water samples (n = 443) were collected from nine groundwater sites and the Barren River in Bowling Green, KY. Additionally, cross-sectional samples were collected from 45 sites, including groundwaters and two rivers, in Tampa, FL. Salmonella was detected in 14.5% of Bowling Green samples resulting in 176 isolates representing 18 serotypes. Two (4.4%) of the Tampa samples were positive yielding eight isolates representing two serotypes. In Bowling Green, Salmonella prevalence varied by sampling site, week, month, and season, with the highest prevalence in surface water in the month of November and during summer. Salmonella Newport was the most common serotype detected. Nine of the serotypes detected in the study were among the top 20 serotypes commonly associated with human infections in the United States. Isolates were clustered with human clinical isolates, or isolates obtained from food animals, suggesting the importance of humans and agricultural practices as a source of water contamination. ARGs were detected in 12.5% (n = 176) of the Bowling Green isolates; overall, 81.8% (n = 22) of these were multidrug-resistant (resistance to ≥3 antimicrobial classes). Notably, the four Salmonella Agona isolates were resistant to four antimicrobial classes, mercury, and quaternary ammonium compounds. Seasonality and the widespread occurrence of Salmonella both in the groundwater and groundwater-fed surface waters is a potential risk to public health.

Tetracycline- and Macrolide-Resistant Enterococcus Species Isolated from a Mink Farm in the United States

Enterococcus species are a normal flora of animals and humans. However, life-threatening opportunistic infections can be caused by antimicrobial resistant strains. Fecal (n = 42) and feed (n = 8) samples were obtained from a mink farm and cultured for the enumeration and detection of erythromycin-resistant (a macrolide; ERY^r)- and tetracycline-resistant (TET^r) enterococci. ERY^r and TET^r enterococci were detected from all fecal (mean concentrations = 6 and 7 logs, respectively) and feed (mean concentrations = 5 and 4 logs, respectively) samples. While Enterococcus faecalis and Enterococcus faecium were detected at equal proportions among the fecal TET^r isolates, E. faecium predominated among ERY^r fecal isolates. All ERY^r and 90% of the TET^r isolates (n = 50) were multidrug resistant (resistant to three or more antimicrobial classes). Among ERY^r isolates, while 83% of E. faecalis (n = 12) were positive for erm(B), 58% of E. faecium (n = 38) isolates were positive for msr(C). Among ERY^r isolates, tet(M) was detected from 92% of E. faecalis (n = 12) and 97% of E. faecium (n = 38) isolates. Conversely, however, erm(B) was detected in 18% of E. faecalis (n = 22) and 33% of E. faecium (n = 27) TET^r isolates. Our study provides a baseline for future efforts to reduce antimicrobial resistance and improve antimicrobial stewardship in commercial mink production facilities.