Occurrence, Risk Factors, Serotypes, and Antimicrobial Resistance of Salmonella Strains Isolated from Imported Fertile Hatching Eggs, Hatcheries, and Broiler Farms in Trinidad and Tobago

Abstract

This cross-sectional study determined the occurrence, risk factors and characteristics of Salmonella isolated from imported broiler hatching fertile eggs, hatcheries, and broiler farms in Trinidad and Tobago. Standard methods were used to isolate and characterize Salmonella isolates from two broiler hatcheries and 27 broiler farms in the country. Salmonella was isolated from 0.0% (0/45), 7.6% (12/158) and 2.8% (24/866) of fertile hatching eggs (composite of 450), hatcheries and broiler farms, respectively (p=0.006). The highest frequency of Salmonella isolation was detected in stillborn chicks, 28.0% (7/28) and in cloacal swabs, 2.2% (15/675) in samples collected from the hatcheries and farms, respectively. None of the 15 farm management and production practices investigated was significantly (P>0.05) associated with the isolation of Salmonella . The predominant serotypes among Salmonella were Kentucky (83.3%) and Infantis (62.5%) for hatchery and farms isolates, respectively. The disc diffusion method revealed a frequency of antimicrobial-resistant Salmonella of 44.0% (11/25) and 87.5% (35/40) in isolates from the hatcheries and broiler farms, respectively (p=0.0002). Antimicrobial resistance was highest (28.0%) to doxycycline and kanamycin for hatchery isolates, while for farm isolates resistance was high (>65%) to sulphamethoxazole-trimethoprim, gentamycin, ceftriaxone, kanamycin, and doxycycline. Multi-drug resistance (MDR) was exhibited by 4.0% and 85.7% of Salmonella isolates from the hatcheries and farms, respectively (p<0.0001). The high antimicrobial resistance and MDR exhibited by Salmonella from broiler farms highlight the therapeutic implications and the potential to enter the food chain.

Molecular Characterization of Salmonella Detected along the Broiler Production Chain in Trinidad and Tobago

“…Whole-genome sequencing analysis has been used to investigate genetic characteristics and phylogenies among Salmonella strains isolated from different origins, such as humans, food, animals, and the environment [ 33 , 34 , 35 , 36 ]. The current study was comprised of isolates from four cross-sectional studies conducted at the level of retail outlets (2016–2017) [ 25 ], broiler processing plants (2018) [ 23 ], broiler farms, and broiler hatcheries (2019) [ 22 ]. Although several limitations exist with the use of cross-sectional instead of longitudinal studies, this approach provides valuable information on the status of Salmonella shedding and contamination at the four levels (hatcheries, farms, processing plants, and retail outlets) of the broiler production chain in the country.…”

“…A total of 146 isolates of Salmonella used in this study originated from prior studies conducted at hatcheries and broiler farms [ 22 ], broiler processing plants [ 23 ], and retail outlets (pluck shops and supermarkets) [ 24 , 25 ]. The type of samples collected from the various studies are as follows, hatcheries: broken eggshells, eggs in the hatcher, eggs in the incubator, hatcher environmental swabs, hatcher fluff, and stillborn chicks; broiler farms: boot swabs, cloacal swabs, litter drag swabs, feed, and water samples—in-house supply and storage tank; processing plants: chilled chicken parts, chilled whole carcasses, neck skins, pre-evisceration carcasses, and post-evisceration carcasses; retail outlets: chicken carcasses.…”

“…Conventional serotyping methods using the phase reversal technique described previously [ 22 , 23 , 25 ] were performed at the Public Health Laboratory, Ministry of Health, St. Michael, Barbados. Antimicrobial resistance determined by the disk diffusion method [ 22 , 23 , 24 ] described previously was also used. Data generated from these two methods were compared to the genomic data.…”

Phylogenetic analyses of Salmonella detected along the broiler production chain in Trinidad and Tobago

“…A total of 137 isolates of Salmonella selected for use in this study originated from studies conducted on hatcheries and broiler farms ( Khan et al, 2022a ), processing plants ( Khan et al, 2021 ), and retail outlets (pluck shops and supermarkets) ( Khan et al, 2018 ) over 4 yr. The following is a summary of the number of isolates included from earlier studies: hatcheries (n = 10), farms (n = 20), processing plant (n = 52), and retail outlets (n = 55).…”

Genomic Comparison of Eight Closed Genomes of Multidrug-Resistant Salmonella enterica Strains Isolated From Broiler Farms and Processing Plants in Trinidad and Tobago

“…Conventional serotyping methods using the phase reversal technique described previously (Khan et al, 2021 , 2022a ) were performed at the Public Health Laboratory, Ministry of Health, St. Michael, Barbados. The antimicrobial resistance was determined by the disk diffusion method as described previously (Khan et al, 2021 , 2022a ). Data generated from these two methods were compared to the genomic data.…”