Molecular epidemiology of antimicrobial resistant non-typhoidal Salmonella isolated from retail chicken meat shops
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Date
2018-05
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The objective of this study was to determine the prevalence, antimicrobial resistance and virulence factors of non-typhoidal Salmonella. A total of742 samples viz. meat swabs (n=188), poultry faeces (n=214), hand swabs (n=78), knife swabs (n=83), meat rinsing water (n=35), cutting surface swabs (n=31), chopping board swabs (n=41), utensil swabs (n=70) and litter (n=2) were collected from 39 retail chicken meat shops located at 6 different cities. The overall prevalence Non Typhoidal Salmonella (NTS) was found to be 9.43% (n= 70). The highest prevalence of Salmonella was observed in chicken meat (28/188, 14.89%), followed by knife (11/83, 13.25%), utensils (8/70, 11.43%), chopping board (3/41, 7.32%), rinsing water (3/35, 8.57%), poultry feces (15/214, 7.01%) and cutting slab surface samples (2/31, 6.45%). Geographically, the highest prevalence was observed in Lalkuan (20.99%, 17/81) followed by Pantnagar (15.60%, 17/109), Nainital(10.83%, 13/120), Rudrapur (9.78%, 9/92), Bareilly (5.83%, 7/120), Haldwani (5.66%, 6/106) and Kiccha (0.88%, 1/114). Three serotypes of Salmonella were identified, Salmonella Kentucky (74.29%; 52/70), S. Virchow (17.14%; 12/70) and S. Typhimurium (7.14%; 5/70). All 70 Salmonella isolates (100%) were multidrug resistant (MDR). Highest resistance was observed against Tetracycline (70/70, 100%) and Erythromycin (70/70, 100%) followed by Nalidixic Acid (69/70;98.57%), Ampicillin (67/70;95.71%), Ciprofloxacin (58/70;82.86%), Gatifloxacin (57/70;81.43%), Cefazolin (53/70;75.71%), Cefotaxime (36/70; 51.43%), Levofloxacin (35/70;50%), Sulfisoxazole (33/70;47.13%), Streptomycin (19/70;27.14%) and Cefoxitin (11/70; 15.71%). Twenty nine (29/70, 41.43%) Salmonella isolates were identified as coresistant to ciprofloxacin and cefotaxime. The most common resistance patterns were NA CIP GAT CZ E AMP TE (7/70, 10%), NA CIP LE GAT CZ CTX E AMP TE (6/70, 8.57%), S NA CIP LE GAT CZ CTX E AMP TE and NA CTX E AMP TE SF (both 5/70, 7.14%).These isolates were also resistant to 4 other antimicrobial agents (NA, E, AMP, TE). Salmonella isolates were screened for 12 antimicrobial resistance genes. Out of 47 resistant and intermediate streptomycin isolates, aadA1 and aadA2 were found to be 80.85% and 2.13% respectively, while strB was present in 6.38% isolates. Sulfisoxazole resistance genes sul1 and sul2 were detected in 82.35% (28/34) and 8.82% (3/34) isolates, respectively. Out of the β-lactam resistance genes, blaTEM was the most predominant (25.37%) followed by blaPSE and blaCMY (1.49%). The tetracycline resistance gene, tetA was detected in all Salmonella isolates (100%, 70/70). All 70 isolates were screened for the presence of virulence genes using PCR. A total of 66 isolates harbored sipA (94.29%) followed by mgtC (52/70; 74.29%), sopE1 (26/70; 37.14%), stn (24/70; 34.29%), sopB (9/70; 12.86%) genes, fliC gene (2/70; 2.86% each), spvC and gipA genes (1/70; 1.43%). Risk factor analysis revealed that none of the potential risk factors included were significantly associated with the Salmonella prevalence in the chicken meat shops. Overall, our study detected very high prevalence of multidrug resistant Salmonella in the chicken meat shop environments. Higher resistance to “critically important” (3rd and 4th generation fluoroquinolones) and “highly important” (1st generation cephalosporins and tetracycline) antibiotics detected in Salmonella isolates of poultry origin is a serious threat to public health which highlights the irrational use of antimicrobials in the poultry production in India.
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