Sokoine University of Agriculture

In-feed use of heavy metal micronutrients in U.S. Swine production systems and its role in persistence of multidrug-resistant Salmonellae

Show simple item record Medardus, J. J. Molla, B. Z. Nicol, M. Morrow, W. M. Rajala-Schultz, P. J. Kazwala, R. Gebreyes, W. A. 2018-06-26T15:16:06Z 2018-06-26T15:16:06Z 2014
dc.identifier.issn 0044-7897
dc.description ASM News- American Society for Microbiology Vol. 80,2014 Number 7;p. 2317–2325 en_US
dc.description.abstract The study aimed to characterize the role of heavy metal micronutrients in swine feed in emergence of heavy-metal-tolerant and multidrug-resistant Salmonella organisms. We conducted a longitudinal study in 36 swine barns over a 2-year period. The feed and fecal levels of Cu2+ and Zn2+ were measured. Salmonella was isolated at early and late finishing. MICs of copper sulfate and zinc chloride were measured using agar dilution. Antimicrobial susceptibility was tested using the Kirby-Bauer method, and 283 isolates were serotyped. We amplified pcoA and czcD genes that encode Cu2+ and Zn2+ tolerance, respectively. Of the 283 isolates, 113 (48%) showed Cu2+ tolerance at 24 mM and 164 (58%) showed Zn2+ tolerance at 8 mM. In multivariate analysis, serotype and source of isolates were significantly associated with Cu2+ tolerance (P < 0.001). Fecal isolates were more likely to be Cu2+ tolerant than those of feed origin (odds ratio [OR], 27.0; 95% confidence interval [CI], 2.8 to 250; P = 0.0042) or environmental origin (OR, 5.8), implying the significance of gastrointestinal selective pressure. Salmonella enterica serotypes Typhimurium and Heidelberg, highly significant for public health, had higher odds of having >20 mM MICs of Cu2+ than did “other” serotypes. More than 60% of Salmonella isolates with resistance type (R-type) AmStTeKm (32 of 53) carried pcoA; only 5% with R-type AmClStSuTe carried this gene. czcD gene carriage was significantly associated with a higher Zn2+ MIC (P < 0.05). The odds of having a high Zn2+ MIC (≥8 mM) were 14.66 times higher in isolates with R-type AmClStSuTe than in those with R-type AmStTeKm (P < 0.05). The findings demonstrate strong association between heavy metal tolerance and antimicrobial resistance, particularly among Salmonella serotypes important in public health. en_US
dc.language.iso en en_US
dc.publisher ASM News- American Society for Microbiology en_US
dc.subject Salmonella enterica serotypes en_US
dc.subject Food-borne illness en_US
dc.subject Multidrug-resistant en_US
dc.subject Micronutrients en_US
dc.subject U.S. Swine en_US
dc.subject Swine Production en_US
dc.subject Salmonellae en_US
dc.title In-feed use of heavy metal micronutrients in U.S. Swine production systems and its role in persistence of multidrug-resistant Salmonellae en_US
dc.type Article en_US
dc.url -consortium. en_US

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