EPIDEMIOLOGY Antibiotic Resistance in Salmonella from Retail Foods of Animal Origin and Its Association with Disinfectant and Heavy Metal Resistance Wenwen Deng, 1 Yuan Quan, 2 Shengzhi Yang, 1 Lijuan Guo, 1 Xiuli Zhang, 3 Shuliang Liu, 4 Shujuan Chen, 4 Kang Zhou, 4 Li He, 4 Bei Li, 5 Yunfu Gu, 1 Shaohua Zhao, 6 and Likou Zou 1 This study aims to demonstrate the antibiotic resistance and its association with disinfectant and heavy metal resistance in 152 Salmonella isolates recovered from retail foods of animal origins. Susceptibility testing demonstrated that 92.8% isolates were resistant to at least one antibiotic, and the resistance was highest to oxytetracycline (80.9%), followed by trimethoprim (64.5%), amoxicillin (28.9%), ampicillin (28.3%), levo- floxacin (21.7%), ciprofloxacin (16.4%), and gentamicin (10.5%), respectively. The bla TEM and tetA genes (44.7%) were commonly present. The qacF and qacED1 genes were detected in 18.4% and 8.6% of all isolates. The Cu-resistance genes pcoR, pcoC, and pcoA were the most prevalent (20.4–40.8%), followed by Hg- resistance gene merA (17.8%) and As-resistance genes arsB (6.6%). The antibiotic resistance was highly associated with disinfectant or certain heavy metal resistance genes. Most notably, the association among Cu- resistance genes ( pcoC, pcoR), disinfectant resistance genes (qacF, qacED1), and tetracycline and sulfonamide resistance genes (tet, sul) was significant ( p < 0.05). Pulsed-field gel electrophoresis revealed that Salmonella isolates was associated with supermarkets indicating the possibility of crosscontamination in farms or pro- cessing environment. This study indicated that retail meats may be a reservoir for the dissemination of antibiotic-resistant Salmonella and using disinfectants for decontamination or metals in livestock may provide a pressure for coselecting strains with acquired resistance to other antimicrobials. Keywords: antibiotic, disinfectant, heavy metal, resistance, Salmonella Introduction S almonella is recognized as a common bacterial cause of foodborne diarrheal illness worldwide. 1–3 Every year, *42,000 cases of salmonellosis are reported through the Centers for Disease Control and Prevention in the United States; these cases have resulted in high morbidity and eco- nomic costs. 4,5 In China, the increase in consumption of food products of animal origin also increased potential exposure to Salmonella. 6,7 The genus Salmonella encompasses a large taxonomic group with more than 2,600 different serotypes. 8 Although all serotypes of Salmonella may be regarded as po- tential human pathogens, the vast majority of infections are caused by a limited number of serotypes, of which Salmonella Enteritidis and Salmonella Typhimurium are the two most common serotypes associated with gastrointestinal disease in humans. 9,10 Approaches to prevent and control salmonellosis in livestock have been dependent on the use of antibiotics for many years. However, numerous antibiotic-resistant bacte- ria have been reported in different countries. 11–13 Most of the antibiotic-resistant Salmonella are of zoonotic origin and acquire their resistance in food animal hosts, which might cause human infections through the food chain. 14 Therefore, antibiotic resistance in pathogenic bacteria from animals can be a serious threat to public health. 15 1 Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, People’s Republic of China. 2 Clinical Laboratory, Taizhou Second People’s Hospital, Jiangyan, People’s Republic of China. 3 Inspection and Testing Center, Henan Center for Disease Control and Prevention, Zhengzhou, People’s Republic of China. 4 College of Food Science, Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China. 5 Lab of Microbiology, Dujiangyan Campus of Sichuan Agricultural University, Dujiangyan, Sichuan, People’s Republic of China. 6 Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, Laurel, Maryland. MICROBIAL DRUG RESISTANCE Volume 00, Number 00, 2017 ª Mary Ann Liebert, Inc. DOI: 10.1089/mdr.2017.0127 1 Downloaded by Gothenburg University Library from online.liebertpub.com at 10/20/17. For personal use only.