BackgroundThis cross-sectional study determined the prevalence of Salmonella spp. and their serotypes on dressed chicken sold at retail outlets in Trinidad. The study also investigated the risk factors for contamination of dressed carcasses by Salmonella spp. at cottage poultry processor outlets where chickens are slaughtered and processed for sale.MethodsA total of 133 dressed, whole chickens and 87 chicken parts from 44 cottage poultry processors and 36 dressed, whole chickens and 194 chicken parts from 46 supermarket outlets were randomly collected throughout the country. Isolation and identification of Salmonella spp. were performed using standard bacteriological techniques. Serotyping was performed by a regional reference laboratory.ResultsThe prevalence of Salmonella spp. in chicken carcasses sampled from cottage poultry processors and supermarkets was 20.5% and 8.3% respectively (p <0.001). The frequency of isolation of Salmonella spp. at cottage poultry processors was 22.4%, 23.0%, 7.1%, and 10.0% for non-chilled whole chicken, non-chilled chicken parts, chilled whole chicken and chilled chicken parts respectively. Fresh, non-chilled chicken (22.6%) yielded a higher frequency of isolation of Salmonella spp. than chilled chickens (8.3%). For supermarket samples, the frequency of isolation of Salmonella spp. was 19.0%, 8.1%, 0.0% and 7.6% for chilled whole chickens, chill chicken parts, frozen whole chicken and frozen chicken parts respectively. The swab method of sampling yielded a statistically significantly (p = 0.029) higher frequency (3.2%) of Salmonella spp. than the rinse method (1.6%). The predominant serotypes isolated were Kentucky (30.9%) and Javiana (22.7%). Use of chilled water-bath to cool carcasses was the only risk factor significantly (p = 0.044) associated with isolation of Salmonella spp.ConclusionRaw chicken carcasses purchased from cottage poultry processors pose a significantly higher risk of contamination with Salmonella spp. than those sold at supermarkets.

This cross-sectional study determined the serovars, antimicrobial resistance genes, and virulence factors of Salmonella isolated from hatcheries, broiler farms, processing plants, and retail outlets in Trinidad and Tobago. Salmonella in silico serotyping detected 23 different serovars where Kentucky 20.5% (30/146), Javiana 19.2% (28/146), Infantis 13.7% (20/146), and Albany 8.9% (13/146) were the predominant serovars. There was a 76.0% (111/146) agreement between serotyping results using traditional conventional methods and whole-genome sequencing (WGS) in in silico analysis. In silico identification of antimicrobial resistance genes conferring resistance to aminoglycosides, cephalosporins, peptides, sulfonamides, and antiseptics were detected. Multidrug resistance (MDR) was detected in 6.8% (10/146) of the isolates of which 100% originated from broiler farms. Overall, virulence factors associated with secretion systems and fimbrial adherence determinants accounted for 69.3% (3091/4463), and 29.2% (1302/4463) counts, respectively. Ten of 20 isolates of serovar Infantis (50.0%) showed MDR and contained the blaCTX-M-65 gene. This is the first molecular characterization of Salmonella isolates detected along the entire broiler production continuum in the Caribbean region using WGS. The availability of these genomes will help future source tracking during epidemiological investigations associated with Salmonella foodborne outbreaks in the region and worldwide.

This study determined the frequency of resistance of 135 isolates of Salmonella, including 15 serotypes recovered from chickens purchased from retail outlets (cottage processors and supermarkets) across Trinidad. Resistance to 16 antimicrobial agents was determined by using the disk diffusion method. Resistance among the isolates was related to the type of retail outlet, location of outlets, type of sample, and isolate serotype. Overall, all isolates exhibited resistance to one or more of the 16 antimicrobial agents tested. All isolates were sensitive to cefoxitin and norfloxacin, with the overall frequency of resistance ranging from 1.1% (sulfamethoxazole-trimethoprim) to 100.0% (ceftiofur and doxycycline). The frequency of resistance to tetracycline, ampicillin, ceftriaxone, amoxycillin–clavulanic acid, and chloramphenicol was significantly (P &lt; 0.05) higher in isolates recovered from cottage processor outlets compared with those from supermarkets. The frequency of resistance to antimicrobial agents was significantly different only to kanamycin (P = 0.046) and enrofloxacin (P = 0.000) across seven counties in Trinidad). Regarding sample presentation (whole versus parts), the frequency of resistance was only significantly higher to gentamicin (P = 0.039) for chicken part isolates from cottage processor and to only tetracycline (P = 0.034) for isolates from whole carcasses from supermarkets. All the 135 Salmonella isolates exhibited multidrug resistance patterns. The high frequency of resistance to seven antimicrobial agents (erythromycin, streptomycin, ceftiofur, doxycycline, kanamycin, tetracycline, and ampicillin), some used in the poultry industry, coupled with the occurrence of multidrug resistance, may have potential therapeutic implications for broiler farmers in Trinidad.

This cross-sectional study determined the prevalence, characteristics, and risk factors for contamination of chicken with Salmonella at four operating broiler processing plants in Trinidad. Standard methods were used to isolate and characterize the Salmonella isolates. The overall prevalence of Salmonella at the four processing plants was 27.0% (107/396). The whole carcass enrichment (WCE) method yielded a statistically significantly (p = 0.0014) higher frequency of isolation (53.9%; 97/180) than the whole carcass rinse (35.0%; 63/180) and neck skin methods (42.2%; 38/90). S. enterica serotypes Enteritidis, Javiana, and Infantis were the predominant serotypes isolated accounting for 20.8%, 16.7% and 12.5%, respectively, of the serotyped isolates. Risk factors included the use of over 100 contract farmers (OR 4.4), pre-chiller (OR 2.3), addition of chlorine to chiller (OR 3.2), slaughtering sick broilers (OR 4.4), and flocks with >50% mortality. Multi-drug resistance was detected in 12.3% (14/114) of the isolates of Salmonella. Resistance was high to kanamycin (85.7%) and doxycycline (74.6%) but low to amoxicillin-clavulanic acid (2.4%) and sulphamethoxazole-trimethoprim (0.8%). The occurrence of resistant Salmonella in chickens processed at commercial broiler processing plants has implications for salmonellosis and therapeutic failure in consumers of improperly cooked contaminated chickens from these plants in the country.

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&gt;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 (&gt;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&lt;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.

Salmonella enterica is a highly important foodborne pathogen worldwide. We report the complete genome sequence of a sequence type 14 Salmonella enterica serotype Senftenberg strain carrying the mcr-9 gene in a plasmid isolated from broken chicken eggshells in Trinidad and Tobago, obtained by using a combination of long- and short-read sequencing.

Salmonella enterica is an important foodborne pathogen worldwide. We used long and short-read sequencing to close genomes of eight multidrug-resistant (MDR) S. enterica strains, belonging to serovars Infantis (2), Albany, Oranienburg, I 4,[5],12:i:-, Javiana, Schwarzengrund, and Kentucky from broiler chicken farms and processing plants in Trinidad and Tobago. They also belonged to seven different sequence types (STs- 32, 292, 1510, 19, 24, 152, and 96). Among the strains, seven had demonstrated multi-drug resistance with the presence of at least three AMR genes, whereas three isolates contained the quinolone resistance gene qnrB19 in plasmids (CFSAN103840, CFSAN103854, and CFSAN103872). The extended-spectrum β-lactamase genes blaCTX−M−65 (CFSAN103796) and blaTEM−1 (CFSAN103852) were detected in this study. The genomes closed in this study will be useful for future source tracking and outbreak investigations in Trinidad and Tobago and worldwide.

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