Field Observations on the Variation of Streptococcus uberis Populations in a Pasture-Based Dairy Farm

Abstract

Microbiological and molecular tools were used to monitor Streptococcus uberis populations on farm tracks and paddocks on a dairy farm during different seasons of a year to identify and profile potential environmental niches of Strep. uberis in a pasture-based dairying system. Farm tracks of high or low cow traffic were sampled every 2 wk for an entire year and Strep. uberis numbers were enumerated from a selective medium. During each season of the year, paddocks were sampled for the presence of Strep. uberis before and after grazing by dairy cows. Farm tracks of high cow traffic generally had greater concentrations of Strep. uberis isolated compared with tracks with less cow traffic, but there was also significant variation in the concentrations of Strep. uberis contamination among seasons, being highest in winter and lowest in summer. The bacterium was detected in paddocks only after cow grazing had occurred, but the bacteria could still be detected in soil for up to 2 wk following grazing in winter. Multilocus sequence typing showed great heterogeneity, with some commonality between farm track and milk isolates, which may help explain cow-to-environment or environment-to-cow transmission of the bacterium in the dairy setting.

Application of a Dot Blot Hybridization Platform to Assess Streptococcus uberis Population Structure in Dairy Herds

“…Although largely regarded as an environmental pathogen, characterized by different clonal lineages causing disease (Lundberg et al, 2014), S. uberis can also behave as a contagious pathogen (Zadoks et al, 2001; Rato et al, 2008). The typical environmental reservoirs where S. uberis can be found include grass, straw bedding and also the skin, gut, and genital tract of cattle (Leigh, 1999; Lopez-Benavides et al, 2007). The ability of this pathogen to survive in a wide range of substrates decreases the effectiveness of typical herd hygiene and disease prevention methods, since these are mostly aimed at controlling contagious pathogens.…”

Virulence-associated genes and molecular typing of Streptococcus uberisassociated with bovine mastitis in northern Thailand

“…S. uberis is associated with subclinical and clinical intramammary infection (IMI) at any period of lactation (4) and in pregnant heifers (5). The major source of infection of this microorganism originates from the cow's environment, including body sites, manure, pastures, and bedding materials (6); consequently, the eradication of this species is particularly problematic.…”

Streptococcus uberis-specific T cells are present in mammary gland secretions of cows and can be activated to kill S. uberis

“…Production of IFN-γ and lymphocyte proliferation were low in all cows examined, although the expansion of S. uberis-specific T cells could be performed using IL-2. The presence of such cells is probably due to the ubiquitous nature of S. uberis in the dairy environment (Lopez-Benavides et al 2007).…”

“…Mastitis caused by S. uberis is highly problematic due to the ubiquitous presence of this pathogen in the dairy environment (Leigh 2000;Lopez-Benavides et al 2007). S. uberis is a common isolate from clinical mastitis cases in first-lactation heifers and dry cows in pasture-based dairying systems.…”