Prevalence, Risk Factors, Antimicrobial Resistance and Molecular Characterization of Salmonella in Northeast Tunisia Broiler Flocks.

Walid Oueslati,Abdelfettah Ettriqui,Fatma Souissi,Hayet Benyedem,Mohamed Ridha Rjeibi,Aymen Mamlouk,Rachid Selmi

doi:10.3390/vetsci9010012

Walid Oueslati, Abdelfettah Ettriqui + Show 5 more

Open Access

https://doi.org/10.3390/vetsci9010012

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Abstract

This study was conducted in northeastern Tunisia to estimate both the prevalence and the risk factors of Salmonella in broiler flocks as well as to characterize the isolated multidrug-resistant (MDR) Salmonella strains. In the present study, a total number of 124 farms were sampled; Salmonella isolates were identified by the alternative technique VIDAS Easy Salmonella. The susceptibility of Salmonella isolates was assessed against 21 antimicrobials using the disk diffusion method on Mueller–Hinton agar using antimicrobial discs. Some antimicrobial resistance genes were identified using PCR. The prevalence rate of Salmonella infection, in the sampled farms, was estimated at 19.9% (64/322). Moreover, a total number of 13 different serotypes were identified. High rate of resistance was identified against nalidixic acid (82.85%), amoxicillin (81.25%), streptomycin (75%), and ciprofloxacin (75%). Alarming level of resistance to ertapenem (12.5%) was noticed. A total of 87.5% (56/64) of isolated strains were recognized as MDR. Three MDR strains were extended-spectrum β-lactamases (ESBL)-producers and three MDR strains were cephalosporinase-producers. The blaCTX-M gene was amplified in all the three ESBL strains. The qnrB gene was not amplified in fluoroquinolones-resistant strains. The tetA and tetB genes were amplified in 5% (2/40) and 2.5% (1/40) of tetracycline-resistant strains, respectively. The dfrA1 gene was amplified in five of the 20 trimethoprim-resistant strains. The mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes were not amplified in any of the phenotypically colistin-resistant strains. In terms of integrase genes int1 and int2, only gene class 2 was amplified in 11% (7/64) of analyzed strains. Risk factors, such as the poor level of cleaning and disinfection, the lack of antimicrobial treatment at the start of the breeding, and a crawl space duration lower than 15 days, were associated with high Salmonella infection in birds. These data should be considered when preparing salmonellosis control programs in Tunisian broiler flocks.

Highlights

According to numerous surveys, undercooked poultry meat is often reported as responsible for non-typhoid Salmonella gastroenteritis outbreaks with Salmonella Typhimurium and Salmonella Enteritidis being the most frequently isolated serotypes [1,2,3]
For a 95% confidence interval: n = 1.96 Pexp (1 − Pexp )/D2, where Pexp : expected prevalence which was estimated to 17% [14] and D: the precision that was fixed to 5%
The results of our study showed that broiler infection prevalence with Salmonella spp

Summary

Introduction

According to numerous surveys, undercooked poultry meat is often reported as responsible for non-typhoid Salmonella gastroenteritis outbreaks with Salmonella Typhimurium and Salmonella Enteritidis being the most frequently isolated serotypes [1,2,3]. The Centers for Disease Control and Prevention (CDC) estimated that Salmonella bacteria cause, yearly, 1.35 million infections, 26,500 hospitalizations, and 420 deaths in the United States [4]. In Europe, since 2014, Salmonella spp. has been the second-highest bacterial agent, after Campylobacter, causing gastroenteritis in humans [6]. In Sub-Saharan Africa, non-typhoid salmonellosis, mostly caused by S. Enteritidis, is a major public health problem [2]. In Tunisia, Salmonella food-borne infections are an emerging public health problem [7], with S. Anatum being the most identified serotypes in poultry meat [8]

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