Prevalence of extended-spectrum b-lactamase-producing Salmonella on retail chicken in six provinces and two national cities in the People's Republic of China

Abstract

Prevalence of extended-spectrum β-lactamase (ESBL)-producing Salmonella in food is not well documented. This study investigated the prevalence of ESBL-producing Salmonella in 699 Salmonella isolates recovered from 1,152 retail chickens collected from six provinces and two national cities in the People's Republic of China in 2011. ESBL-producing isolates were screened by double-disk synergy test and confirmed using PCR and DNA sequencing. Of the 699 isolates tested, 60 (8.58%) were identified to be ESBL-producing Salmonella. Prevalence of ESBL-producing Salmonella was the highest in Shanghai city (17 [24.64%] of 69), followed by Shaanxi (10 [15.38%] of 65), Fujian (9 [11.69%] of 77), Guangdong (9 [7.69%] of 117), Sichuan (5 [7.25%] of 69), Beijing (6 [5.17%] of 116), Henan (4 [4.65%] of 86), and Guangxi (0 [0%] of 100) province. Significant difference (P < 0.05) in the prevalence of ESBL-producing Salmonella was found among six provinces and two cities. No significant difference (P > 0.05) in the prevalence was found between wet markets and supermarkets or between whole chickens and chopped chickens. The prevalence of ESBL-producing Salmonella differed significantly (P < 0.05) among different seasons, being higher in autumn than in spring and winter. Overall, ESBL-producing Salmonella varied significantly (P < 0.05) among 12 detected Salmonella serotypes: Abony (1 [33.33%] of 3), Indiana (28 [28.57%] of 98), Edinburg (6 [24.00%] of 25), Shubra (2 [20.00%] of 10), Uppsala (1 [16.67%] of 6), Thompson (8 [14.81%] of 54), Haardt (1 [12.50%] of 8), Agona (3 [9.68%] of 31), Gueuletapee (1 [6.25%] of 16), Typhimurium (4 [5.56%] of 72), Heidelberg (1 [4.55%] of 22), and Enteritidis (4 [3.17%] of 126). This study revealed that ESBL-producing Salmonella do exist in retail chicken in the People's Republic of China and that the potential risk of their presence in foods needs further exploration.