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

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dc.creatorMedardus, J. J.
dc.creatorMolla, B. Z.
dc.creatorNicol, M.
dc.creatorMorrow, W. M.
dc.creatorRajala-Schultz, P. J.
dc.creatorKazwala, R.
dc.creatorGebreyes, W. A.
dc.date.accessioned2018-06-26T15:16:06Z
dc.date.accessioned2025-08-05T07:22:49Z
dc.date.available2018-06-26T15:16:06Z
dc.date.created2018-06-26T15:16:06Z
dc.date.issued2014
dc.description.abstractThe 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.
dc.identifier0044-7897
dc.identifierhttps://www.suaire.sua.ac.tz/handle/123456789/2450
dc.identifier.urihttp://repository.costech.or.tz/handle/20.500.14732/97331
dc.languageen
dc.publisherASM News- American Society for Microbiology
dc.subjectSalmonella enterica serotypes
dc.subjectFood-borne illness
dc.subjectMultidrug-resistant
dc.subjectMicronutrients
dc.subjectU.S. Swine
dc.subjectSwine Production
dc.subjectSalmonellae
dc.titleIn-feed use of heavy metal micronutrients in U.S. Swine production systems and its role in persistence of multidrug-resistant Salmonellae
dc.typeArticle

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