Distribution of CNS Species on Teat Skin and in Milk Samples from Dairy Cows in Automatic Milking Systems

Yasser Mahmmod, Line Svennesen, Karl Pedersen, Ilka Klaas

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    Abstract

    Coagulase-negative staphylococci (CNS) frequently colonize teat skin and are one of the most common findings cultured from milk samples of cows with subclinical intramammary infections (IMI). Several species are related to IMI, but knowledge about the epidemiology of CNS species is limited. Cows in automatic milking systems (AMS) may have increased risk for teat colonization and IMI because more than 60 cows are milked several times daily with the same milking unit. The objectives of this study are (1) to investigate patterns of CNS species in milk samples and teat skin swabs in nine AMS herds and (2) to identify the predisposing cow level risk factors for specific CNS IMI and teat colonization. In each herd, 30- 40 cows with somatic cell counts > 200,000 cells/ml in the previous milk recording are randomly selected. Cows treated for mastitis during the time between milk recording and sampling are excluded. Teat skin swabs and aseptic quarter foremilk samples are taken from all quarters of all selected cows. Teat skin swabs are collected using the modified wet-dry method. Briefly, sterile swabs are rotated 360° around the teat canal orifice, first a wet swab immersed in ¼ Ringer’s solution, then a dry swab. Immediately after sampling, the tips of both swabs are transferred into one tube with 2 ml of ¼ Ringer’s solution. Samples are transported on ice for culturing in the laboratory. After vortexing, 0.01 mL of each quarter milk sample and 0.1 mL of each quarter teat swab are streaked simultaneously on Staphylococcus selective medium (SA Select) and calf blood agar. Colonies from quarters suspect of having CNS in milk and/or teat skin samples (cut-off five CFU) are subjected for MALDI-TOF assay for species identification. Only isolates from the right hind and left front quarters are analyzed by MALDI-TOF assay in this study. To date, preliminary results of milk and teat skin samples from 130 quarters (65 cows) are available. CNS species were identified in 86 quarters out of the total number (130), representing 69 teat skin swabs and 17 milk samples. Out of the CNS positive quarters (n= 86), 12 quarters (11 teat skin swabs and one milk sample) were harboring more than one type of the CNS species. Staphylococcus epidermidis and Staphylococcus equorum were the most frequently isolated CNS species from milk samples (7/17) and (5/17), respectively. Staphylococcus equorum, Staphylococcus haemolyticus and Staphylococcus xylosus were the most frequently isolated CNS species from teat skin swabs (56/69), (9/69), and (6/69), respectively. Staphylococcus cohnii (n= 2), Staphylococcus saprophyticus (n= 1) and Staphylococcus hominis (n= 1) were identified only in teat skin swabs while Staphylococcus simulans (n= 1) was only identified in milk samples. Staphylococcus chromogenes was detected in both milk (n= 2) and teat skin (n= 1) samples. Data collection will be finished in April 2017. The final results will give new insights into herd specific CNS species patterns and the microbial ecology and epidemiology of common CNS species from different habitats – teat skin and milk. We hope that our findings improve the udder health, milk quality and control of mastitis caused by different CNS species in dairy herds with AMS.
    Original languageEnglish
    Publication date2017
    Publication statusPublished - 2017
    Event2nd Seminar on Coagulase Negative Staphylococci - Novotel Ghent, Ghent, Belgium
    Duration: 18 May 201719 May 2017
    Conference number: 2

    Seminar

    Seminar2nd Seminar on Coagulase Negative Staphylococci
    Number2
    LocationNovotel Ghent
    Country/TerritoryBelgium
    CityGhent
    Period18/05/201719/05/2017

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