A Longitudinal Field Study to Evaluate the Diagnostic Properties of a Quantitative Real-Time Polymerase Chain Reaction–Based Assay to Detect Staphylococcus aureus in Milk

Studer, Edgar; Schaeren, W.; Naskova, J.; Pfaeffli, H.; Kaufmann, Thomas; Kirchhofer, M.; Steiner, Adrian; Graber, H.U.

doi:10.3168/jds.2007-0485

Cited by 35 publications

(40 citation statements)

References 17 publications

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“…PCR was used in lieu of culture methods for three reasons: (i) the specific pathogen under investigation could be quantified (i.e. culture methods may not adequately distinguish between the pathogen under investigation from other bacteria); (ii) PCR-based assays are more rapid than conventional assays; and (iii) results obtained from quantitative PCR-based assays correlate highly with bacteriological assays and have been termed 'synonymous' (Studer et al, 2008). Our assays are not the first quantitative PCR assays used for S. aureus, E. coli and K. pneumoniae.…”

Section: Discussionmentioning

confidence: 99%

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Effects of an immunomodulatory feed additive on the development of mastitis in a mouse infection model using four bovine-origin isolates

Rowson¹,

Wang²,

Aalseth

et al. 2011

Animal

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The goal of this study was to examine the ability of a commercially available feed additive (OmniGen-AF) to reduce mammary infections caused by a single strain of mastitic pathogens (Streptococcus uberis, Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae) and to examine the effects of the additive on markers of mammary immunity. Four experiments were completed using a murine model of bovine mastitis. Infection progression was examined using Sybr-green-and TaqMan-based quantitative PCR assays of 16S ribosomal DNA. Infection of the mammary gland with all pathogens caused rapid (24 to 48 h) appearance of pathogen DNA in mammary tissue. Provision of the feed additive for 2 weeks before infection significantly (P , 0.05) reduced the extent of pathogen DNA accumulation in models of S. uberis, E. coli and S. aureus infection. The additive was ineffective in reducing mammary infections caused by K. pneumoniae. We examined mechanisms of action of the additive through assessment of mammary concentrations of mammary myeloperoxidase (MPO), major histocompatibility complex 2 class II (MHC) and macrophage inflammatory protein-1a (MIP) messenger RNA (mRNA) concentrations and by examining serum complement C3 concentration. Infection of the mammary gland increased concentrations of MPO and MHC mRNAs (P , 0.05). Ability of the pathogen to elicit changes in mammary MPO and MHC gene expression was enhanced by the provision of the additive for 2 weeks before infection. These data imply that the additive increased the mammary inflammatory response and increased antigen presentation during a mammary infection. Value of the additive in preventing mastitis in cattle awaits additional studies using a bovine model and further evaluation of additional strains of the pathogens used in this study.

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Section: Discussionmentioning

confidence: 99%

“…Our assays are not the first quantitative PCR assays used for S. aureus, E. coli and K. pneumoniae. Previous reports on the use of quantitative PCR for these pathogens include Studer et al (2008;S. aureus), Li and Drake (2001), Shannon et al (2007;E.…”

Section: Discussionmentioning

confidence: 99%

Effects of an immunomodulatory feed additive on the development of mastitis in a mouse infection model using four bovine-origin isolates

Rowson¹,

Wang²,

Aalseth

et al. 2011

Animal

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“…5,11 Although there have been no published reports explaining the inconsistencies, the cost and perceived inaccuracy of diagnosis, as well as producer motivation, are acknowledged hurdles in the broad application of effective control programs. 19 The control of S. aureus is contingent on accurate diagnosis of IMI, yet there remains disagreement on what constitutes a definitive diagnosis of a S. aureus IMI. 1 Complicating efforts to define a S. aureus IMI is the perception that S. aureus is shed intermittently, thus regularly evading diagnosis.…”

Section: Introductionmentioning

confidence: 99%

Variation in daily shedding patterns ofStaphylococcus aureusin naturally occurring intramammary infections

et al. 2011

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Abstract. The goal of the current prospective field study was to examine the shedding patterns of naturally occurring Staphylococcus aureus intramammary infections and the association of pulsed field gel electrophoresis pulsotype with shedding. Milk samples from 5 multiparous and 2 primiparous cows identified with S. aureus intramammary infections were collected for 21 consecutive days, 3 times throughout the lactation (63 days total). Cyclicity of each quarter was evaluated using a locally weighted regression. Pulsed field gel electrophoresis was used for genotypic cluster comparisons to evaluate the association of strain type and shedding patterns. Although the amount of shedding varied greatly, 97.5% of the samples were culture positive. There were notable differences in S. aureus shedding patterns among cows as well as within cows; however, no consistent cyclic pattern was identified. Quarters infected with S. aureus isolates grouped in genotypic cluster 1 appeared to shed at consistently higher levels with a median cfu/0.01 ml of 154 (ln[cfu] = 5.0). In comparing ln(cfu)/0.01 ml between genotypic clusters over the first 21-day sample period, accounting for the effect of sample day, samples collected from quarters infected with S. aureus in genotypic cluster 1 had a 1.5 times greater ln(cfu) than those collected from quarters infected with strains in genotypic cluster 2. The ability to detect S. aureus from day to day was very consistent. The current study examining naturally occurring intramammary infections would support the conclusions of other studies suggesting that a single quarter sample would be adequate in determining S. aureus intramammary infections status.

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“…Although milk is animal friendly and a routine source in the dairy industry (D'Angelo et al, 2007), inhibitors in milk such as fats and proteins render it difficult source for extracting high quantity and quality DNA (Lipkin et al, 1993;Amills et al, 1997;Murphy et al, 2002;Feligini et al, 2005;Cremonesi et al, 2006). To date, different commercial kits for improved DNA extraction are available for many kinds of tissues except for milk (Biase et al, 2002;Studer et al, 2008;O'Grady et al, 2008;Gao et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Comparison of methods for high quantity and quality genomic DNA extraction from raw cow milk

Usman¹,

Yu²,

Liu³

et al. 2014

Genet. Mol. Res.

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ABSTRACT. Isolation of sufficient quantities of high quality DNA is a prerequisite for molecular studies. Milk somatic cells can be used; however, inhibitors such as fats and proteins make milk a difficult medium for extracting large amounts of quality DNA. We optimized, evaluated and compared three methods, Modified Nucleospin Blood Kit method, Modified TianGen Kit method and Phenol-Chloroform method for genomic DNA extraction from bovine milk. Individual cows' milk and bulk milk samples were collected from a China agricultural university dairy farm. Genomic DNA extracted from each milk sample by the three methods was evaluated for quantity and purity by spectrophotometry and gel electrophoresis, as well as PCR and sequencing. All the three methods were found suitable for genomic DNA isolation from bovine milk, PCR applications, and sequencing. Comparing the three methods, we found that the Modified Nucleospin Blood Kit method was significantly better than the Phenol-Chloroform method in terms of quantity as well as quality (amount, concentration, 260/280nm and 260/230nm absorbance ratio), whereas, the Modified TianGen Kit method was more efficient than the Phenol-Chloroform method and cheaper than the Modified Nucleospine Blood Kit method; it yielded reasonably good quantities of good quality DNA and would be suitable for large-scale genotyping of lactating cows.

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A Longitudinal Field Study to Evaluate the Diagnostic Properties of a Quantitative Real-Time Polymerase Chain Reaction–Based Assay to Detect Staphylococcus aureus in Milk

Cited by 35 publications

References 17 publications

Effects of an immunomodulatory feed additive on the development of mastitis in a mouse infection model using four bovine-origin isolates

Effects of an immunomodulatory feed additive on the development of mastitis in a mouse infection model using four bovine-origin isolates

Variation in daily shedding patterns ofStaphylococcus aureusin naturally occurring intramammary infections

Comparison of methods for high quantity and quality genomic DNA extraction from raw cow milk

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