ORCID Profile
0000-0002-9216-1308
Current Organisation
The Ohio State University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: American Society for Microbiology
Date: 11-2005
DOI: 10.1128/AEM.71.11.6926-6933.2005
Abstract: We report here the development, validation, and use of three real-time PCR assays to quantify the abundance of the following three groups of tetracycline resistance genes: tet (A) and tet (C) tet (G) and tet genes encoding ribosomal protection proteins, including tet (M), tet (O), tetB (P), tet (Q), tet (S), tet (T), and tet (W). The assays were validated using known numbers of s le-derived tet gene templates added to microbiome DNA. These assays are both precise and accurate over at least 6 log tet gene copies. New tet gene variants were also identified from cloned tet licons as part of this study. The utility of these real-time PCR assays was demonstrated by quantifying the three tet gene groups present in bovine and swine manures, composts of swine manure, lagoons of hog house effluent, and s les from an Ekokan upflow biofilter system treating hog house effluent. The bovine manures were found to contain fewer copies of all three groups of tet genes than the swine manures. The composts of swine manures had substantially reduced tet gene abundance (up to 6 log), while lagoon storage or the upflow biofilter had little effect on tet gene abundance. These results suggest that the method of manure storage and treatment may have a substantial impact on the persistence and dissemination of tet genes in agricultural environments. These real-time PCR assays provide rapid, quantitative, cultivation-independent measurements of 10 major classes of tet genes, which should be useful for ecological studies of antibiotic resistance.
Publisher: American Society for Microbiology
Date: 15-07-2007
DOI: 10.1128/AEM.02799-06
Abstract: Erythromycin and tylosin are commonly used in animal production, and such use is perceived to contribute to the overall antimicrobial resistance (AR) reservoirs. Quantitative measurements of this type of AR reservoir in microbial communities are required to understand AR ecology (e.g., emergence, persistence, and dissemination). We report here the development, validation, and use of six real-time PCR assays for quantifying six classes of erm genes (classes A through C, F, T, and X) that encode the major mechanism of resistance to macrolides-lincosamides-streptogramin B (MLS B ). These real-time PCR assays were validated and used in quantifying the six erm classes in five types of s les, including those from bovine manure, swine manure, compost of swine manure, swine waste lagoons, and an Ekokan upflow biofilter system treating hog house effluents. The bovine manure s les were found to contain much smaller reservoirs of each of the six erm classes than the swine manure s les. Compared to the swine manure s les, the composted swine manure s les had substantially reduced erm gene abundances (by up to 7.3 logs), whereas the lagoon or the biofilter s les had similar erm gene abundances. These preliminary results suggest that the methods of manure storage and treatment probably have a substantial impact on the persistence and decline of MLS B resistance originating from food animals, thus likely affecting the dissemination of such resistance genes into the environment. The abundances of these erm genes appeared to be positively correlated with those of the tet genes determined previously among these s les. These real-time PCR assays provide a rapid, quantitative, and cultivation-independent measurement of six major classes of erm genes, which should be useful for ecological studies of AR.
Publisher: Elsevier BV
Date: 05-2021
DOI: 10.4315/JFP-20-347
Publisher: Frontiers Media SA
Date: 02-06-2017
Publisher: Wiley
Date: 18-01-2022
DOI: 10.1111/AVJ.13146
Abstract: Food for human and animal consumption can provide a vehicle for the transfer of pathogenic and antimicrobial‐resistant bacteria into the food chain. We investigated the antimicrobial susceptibility of 453 Salmonella isolates collected from raw feed components, equipment and finished feed from 17 commercial feed mills in Australia between 2012 and 2021. Previous studies have found Salmonella prevalence and the ersity of Salmonella serotypes are greatest in the raw feed components. We, therefore, hypothesised that we would find a greater proportion of antimicrobial‐resistant Salmonella isolates in the raw feed components compared to other s le types. We found that of 453 isolates tested, 356 (0.80) were susceptible to all antimicrobials tested, 49 (0.11) were nonsusceptible to streptomycin only and 48 (0.11) were resistant to two or more antimicrobials. Of the 48 antimicrobial‐resistant isolates, 44 were found in feed milling equipment, two in raw feed components and two in finished feed. Statistical analysis, using a logistic regression with random effects model, found that the population‐adjusted mean probability of detecting antimicrobial‐resistant Salmonella isolates from feed milling equipment of 0.39, was larger than the probability of detecting resistant isolates in raw feed components 0.01, (P 0.001) and in finished feed, 0.11, (P = 0.006). This propensity for antimicrobial‐resistant bacteria to colonise feed milling equipment has not been previously reported. Further studies are required to understand the ecology of antimicrobial‐resistant Salmonella in the feed milling environment.
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.PREVETMED.2021.105546
Abstract: Salmonella contamination of livestock feed is a serious veterinary and public health issue. In this study we used a systematic review to assess the prevalence and characterization of Salmonella isolates detected in raw feed components, feed milling equipment and finished feed from 97 studies published from 1955 to 2020 across seven global regions. Eighty-five studies were included in a meta-analyses to estimate the combined prevalence of Salmonella detection and to compare the risk of contamination associated with different s le types. We found the overall combined prevalence estimate of Salmonella detection was 0.14 with a prevalence of 0.18 in raw feed components, 0.09 in finished feed and 0.08 in feed milling equipment. Animal based raw feed components were 3.9 times more likely to be contaminated with Salmonella than plant based raw feed components. Differences between studies accounted for 99 % of the variance in the prevalence estimate for all s le types and there was no effect of region on the prevalence estimates. The combined prevalence of Salmonella detection in raw feed components decreased from 0.25 in 1955 to 0.11 in 2019. The proportion of Salmonella isolates that were resistant to antimicrobials was largest for amikacin (0.20), tetracycline (0.18) streptomycin (0.17), cefotaxime (0.14) and sulfisoxazole (0.11). The prevalence of Salmonella contamination of animal feed varies widely between in idual studies and is an ongoing challenge for the commercial feed industry. Control relies on the vigilant monitoring and control of Salmonella in each in idual mill.
Publisher: Wiley
Date: 22-07-2019
DOI: 10.1111/AVJ.12851
Abstract: The availability of safe, commercially prepared stock feed for production animals is an important step in ensuring animal health and welfare and the safety of food animal products for human consumption. Animal feed quality assurance programs include microbiological monitoring of raw materials, mill equipment and finished feed. Over a period of 16 years, 23,963 s les for Salmonella culture and serotyping were collected from 22 stock feed mills. A multivariable generalized linear mixed model (GLMM) was used to identify mill and s le type factors that increase the odds of detecting Salmonella. The odds of detecting a Salmonella positive s le was greatest in s les from raw materials and in mills that processed restricted animal material (RAM). The percentage of positive s les ranged from 7.2% in 2003 to 2.8% in 2017. Of the 1,069 positive s les, 976 were serotyped with 61 different Salmonella serotypes isolated. The serotype most frequently isolated from raw materials was S. Agona, (n = 108) whilst S. Anatum was the serotype most frequently isolated from equipment and finished feed (n = 156). The ersity of Salmonella serotypes differed between mills and different stages of the production line. Microbiological monitoring in the commercial preparation of animal feed in Australian stock feed mills guides the implementation of quality control measures and risk mitigation strategies thereby reducing the prevalence and ersity of potentially zoonotic bacteria such as Salmonella, enhancing food safety for both animal and consumer.
Publisher: Wiley
Date: 14-08-2020
DOI: 10.1111/JVIM.15866
No related grants have been discovered for Thomas Wittum.