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He Y, Chen R, Qi Y, Salazar JK, Zhang S, Tortorello ML, Deng X, Zhang W. Survival and transcriptomic response of Salmonella enterica on fresh-cut fruits. Int J Food Microbiol 2021; 348:109201. [PMID: 33930836 DOI: 10.1016/j.ijfoodmicro.2021.109201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 03/26/2021] [Accepted: 04/13/2021] [Indexed: 01/21/2023]
Abstract
Salmonella enterica is frequently implicated in foodborne disease outbreaks associated with fresh-cut fruits. In the U.S., more than one third of fruit-related outbreaks have been linked to two S. enterica serotypes Newport and Typhimurium. Approximately 80% of fruit-related human salmonellosis cases were associated with tomatoes, cantaloupes and cucumbers. In this study, we investigated the population dynamics of S. Newport and S. Typhimurium on fresh-cut tomato, cantaloupe, cucumber and apple under short-term storage conditions. We further compared the transcriptomic profiles of a S. Newport strain on fresh-cut tomato and cantaloupe using high-throughput RNA-seq. We demonstrated that both S. enterica Newport and Typhimurium survived well on various fresh-cut fruit items under refrigeration storage conditions, independent of inoculation levels. However, S. enterica displayed variable survival behaviors on different types of fruits. For example, at 7 d storage, the population of S. enterica reduced less than 0.2 log (p > 0.05) on fresh-cut tomato and cantaloupe, in contrast to ~0.5 log (p < 0.05) on cucumber and apple. RNA-seq analysis suggested that S. enterica mediates its survival on fresh-cut fruits through differentially regulating genes involved in specific carbon utilization and metabolic pathways. Several known bacterial virulence factors (e.g., pag gene) were found to be differentially regulated on fresh-cut tomato and cantaloupe, suggesting a link between the events of food contamination and subsequent human infection. Findings from this study contribute to a better understanding of S. enterica survival mechanisms on fresh-cut produce.
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Affiliation(s)
- Yingshu He
- Department of Food Science and Nutrition & Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, IL, USA; Center for Food Safety, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, GA, USA.
| | - Ruixi Chen
- Department of Food Science and Nutrition & Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, IL, USA
| | - Yan Qi
- Center for Food Safety, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, GA, USA
| | - Joelle K Salazar
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA
| | - Shimei Zhang
- Department of Food Science and Nutrition & Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, IL, USA
| | - Mary Lou Tortorello
- Division of Food Processing Science and Technology, U. S. Food and Drug Administration, Bedford Park, IL, USA
| | - Xiangyu Deng
- Center for Food Safety, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, GA, USA
| | - Wei Zhang
- Department of Food Science and Nutrition & Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, IL, USA
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Liang L, Haltli B, Marchbank DH, Fischer M, Kirby CW, Correa H, Clark TN, Gray CA, Kerr RG. Discovery of an Isothiazolinone-Containing Antitubercular Natural Product Levesquamide. J Org Chem 2020; 85:6450-6462. [PMID: 32363877 DOI: 10.1021/acs.joc.0c00339] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Antitubercular agent levesquamide is a new polyketide-nonribosomal peptide (PK-NRP) hybrid marine natural product isolated from Streptomyces sp. RKND-216. The structure contains a rare isothiazolinone moiety which has only been reported in collismycin SN. Structure elucidation by NMR spectroscopy was a significant challenge due to a deficiency of protons in this aromatic moiety. Therefore, the genome of Streptomyces sp. RKND-216 was sequenced to identify the levesquamide biosynthetic gene cluster (BGC). Analysis of the BGC provided structural insights and guided stable-isotope labeling experiments, which led to the assignment of the fused pyridine-isothiazolinone moiety. The BGC and the labeling experiments provide further insights into the biosynthetic origin of isothiazolinones. Levesquamide exhibited antimicrobial activity in the microplate alamarBlue assay (MABA) and low oxygen recovery assay (LORA) against Mycobacterium tuberculosis H37Rv with minimum inhibitory concentration (MIC) values of 9.65 and 22.28 μM, respectively. Similar activity was exhibited against rifampicin- and isoniazid-resistant M. tuberculosis strains with MIC values of 9.46 and 9.90 μM, respectively. This result suggests levesquamide has a different mode of action against M. tuberculosis compared to the two first-line antitubercular drugs rifampicin and isoniazid. Furthermore, levesquamide shows no cytotoxicity against the Vero cell line, suggesting it may have a useful therapeutic window.
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Affiliation(s)
| | - Bradley Haltli
- Nautilus Biosciences Croda, 550 University Avenue, Regis and Joan Duffy Research Centre, Charlottetown, PE C1A 4P3, Canada
| | - Douglas H Marchbank
- Nautilus Biosciences Croda, 550 University Avenue, Regis and Joan Duffy Research Centre, Charlottetown, PE C1A 4P3, Canada
| | - Maike Fischer
- Charlottetown Research & Development Centre, Agriculture and Agri-Food Canada, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada
| | - Christopher W Kirby
- Charlottetown Research & Development Centre, Agriculture and Agri-Food Canada, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada
| | - Hebelin Correa
- Nautilus Biosciences Croda, 550 University Avenue, Regis and Joan Duffy Research Centre, Charlottetown, PE C1A 4P3, Canada
| | - Trevor N Clark
- Department of Chemistry, University of New Brunswick, 30 Dineen Drive, Fredericton, NB E3B 5A3, Canada
| | - Christopher A Gray
- Department of Chemistry, University of New Brunswick, 30 Dineen Drive, Fredericton, NB E3B 5A3, Canada.,Department of Biological Sciences, University of New Brunswick, 100 Tucker Park Road, Saint John, NB E2L 4L5, Canada
| | - Russell G Kerr
- Nautilus Biosciences Croda, 550 University Avenue, Regis and Joan Duffy Research Centre, Charlottetown, PE C1A 4P3, Canada
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Xiang Y, Li F, Dong N, Tian S, Zhang H, Du X, Zhou X, Xu X, Yang H, Xie J, Yang C, Liu H, Qiu S, Song H, Sun Y. Investigation of a Salmonellosis Outbreak Caused by Multidrug Resistant Salmonella Typhimurium in China. Front Microbiol 2020; 11:801. [PMID: 32411120 PMCID: PMC7200987 DOI: 10.3389/fmicb.2020.00801] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/03/2020] [Indexed: 01/05/2023] Open
Abstract
The rapid emergence of multidrug resistant Salmonella is a global public-health concern as outbreaks in recent years have mostly been caused by multidrug resistant strains. Here, we evaluated an outbreak in China caused by multidrug resistant Salmonella enterica serovar Typhimurium (S. Typhimurium) by employing an epidemiological and laboratory investigation using conventional methods and whole genome sequencing (WGS). Eleven of the 12 people who participated in a banquet showed gastrointestinal symptoms, and 8S. Typhimurium strains were recovered. Isolated outbreak strains showed multidrug resistance (MDR), and decreased susceptibility to ciprofloxacin, a first-line drug recommended by WHO for clinical treatment of intestinal infections. Antimicrobial resistance (AMR) gene analysis indicated that the MDR phenotype of these outbreak strains may be due to the presence of a number of AMR genes, including the blaOXA-1 and blaTEM-1 β-lactamase genes, which are often plasmid-borne and easily transferred. Further virulence gene analysis indicated that these outbreak strains also carried a large number of virulence genes, including 2 types of Salmonella pathogenicity islands (SPI-1 and SPI-2) and many adhesion-related virulence genes. Cluster analysis based on pulse-field gel electrophoresis data and phylogenetic analysis based on WGS revealed that the outbreak clone was closely related to and thus probably derived from local strains. This outbreak caused by multidrug resistant S. Typhimurium highlights the need for government improved strategies for the prevention and control of Salmonella infections.
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Affiliation(s)
- Ying Xiang
- Academy of Military Medical Sciences, Beijing, China.,Chinese PLA Center for Disease Control and Prevention, Beijing, China.,Center for Disease Control and Prevention of Southern Theatre Command, Guangzhou, China
| | - Fuxiang Li
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Nian Dong
- Xingcheng Special Service Recuperation Center of PLA Strategic Support Force, Huludao, China
| | - Sai Tian
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Haoran Zhang
- Academy of Military Medical Sciences, Beijing, China
| | - Xinying Du
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Xuan Zhou
- Second Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Xuebin Xu
- Shanghai Municipal Center for Disease Control and Prevention, Shanghai, China
| | - Hongxia Yang
- Shanxi Province Center for Disease Control and Prevention, Taiyuan, China
| | - Jing Xie
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Chaojie Yang
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Hongbo Liu
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Shaofu Qiu
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Hongbin Song
- Chinese PLA Center for Disease Control and Prevention, Beijing, China
| | - Yansong Sun
- Academy of Military Medical Sciences, Beijing, China
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