الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
A total of 150 freshly dressed native chicken carcasses were purchased from various poultry shops with various sanitation levels in Mansoura city, Egypt wherein the bacteriological analysis for Salmonella was performed immediately. Only 129 isolates were confirmed as Salmonella depending on molecular identification of the Salmonella marker gene: invA gene. All the 129 isolates were serologically identified into 12 different Salmonella serotypes. S. Kentucky, S. Enteritidis, S. Typhimurium, and S. Molade were the most prevalent serotypes with an incidence of 19.4% (25/129), 17.1% (22/129), 17.1% (22/129), and 10.9% (14/129), respectively while the less common serotypes were S. Giza (2.3%, 3/129), S. Chester (2.3%, 3/129), and S. Apeyeme (1.6%, 2/129).All Salmonella isolates tested were positive for both invA and stn genes, while only 31.8% (41/129) of isolates examined were positive for the spvC gene, respectively. The frequency distribution of the spvC gene among the 12 different Salmonella serovars identified indicated that S. Kentucky (n = 12) harbored a high frequency of the spvC gene, followed by S. Enteritidis (n = 10), S. Typhimurium (n = 9), S. Tsevie (n = 3), S. Takoradi (n = 2), S. Muenster (n = 2), S. Giza (n = 2), and S. Chester (n = 1), while spvC gene is absent in S. Molade, S. Inganda, S. Labadi, and S. Apeyeme.The antibiotic susceptibility of the 129 molecularly confirmed Salmonella isolates were tested against a panel of 16 antibiotics. Salmonella isolates showed a high resistance rate of 92.3% (119/129), 82.9% (107/129), 82.2% (106/129), 82.2% (106/129), and 63.6% (82/129) against vancomycin, nalidixic acid, cefepime, colistin, and cefotaxime, respectively. The lower resistance rates of 32. 6% (42/129), 31% (40/129), 28.7% (37/129), 11.6% (15/129), and 10.1% (13/129) were observed towards gentamicin, sulfamethoxazole/trimethoprim, fosfomycin, azithromycin, and meropenem, respectively. Amazingly, the resistance of Salmonella isolates against cephalosporins followed the order: cefepime (fourth-generation cephalosporin) > cefotaxime (third-generation cephalosporin) > cefaclor (second-generation cephalosporin) > cephalothin (first-generation cephalosporin), which indicates the improper use and overuse of the third- and fourth-generation cephalosporins in poultry industry.The antimicrobial resistance pattern of all Salmonella isolates examined toward 16 antimicrobial agents revealed 48 different patterns. Furthermore, 3.9% (5/129), 14.7% (19/129), 75.2% (97/129), and 6.2% (8/129) of the 129 Salmonella isolates examined were categorized according to their antibiotic resistance phenotype into pan-drug-resistant, extensively drug-resistant, multidrug-resistant, and low drug-resistant, respectively. Amazingly, five isolates (3.9%, 5/129) revealed resistance to all antimicrobial agents tested with a MAR index equal to 1.Thirty-one out of 82 cefotaxime-resistant Salmonella isolates tested were β- lactamase producers and had at least one β-lactamase resistance genes. The blaTEM gene was the most predominant β-lactamase resistance gene and was identified in 25.6% (21/82) of isolates.