Duration of Infection and Strain Variation in Streptococcus uberis Isolated from Cows’ Milk

McDougall, S; Parkinson, TJ; Leyland, M. J.; Anniss, F.M.; Fenwick, Stan

doi:10.3168/jds.s0022-0302(04)70024-7

Cited by 48 publications

(59 citation statements)

References 21 publications

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“…We developed an MLST scheme for the bovine udder pathogen S. uberis based on four housekeeping genes, a putative virulence gene (oppF), and an established virulence gene (pauA). While previous reports on development of MLST-based subtyping methods have used various numbers of isolates from as few as 28 (57) to as many as 294 (26), we show that use of a well-defined smaller collection of isolates can allow for initial development and validation of an MLST scheme, particularly in the case of an organism like S. uberis, which was previously known to be highly diverse (29,34,53). MLST-based subtyping of S. uberis was superior to banding pattern-based methods in terms of discriminatory ability, concordance with epidemiological data, and quantitative information regarding relatedness of isolates.…”

Section: Discussionmentioning

confidence: 63%

“…These isolates were considered to be epidemiologically unrelated and should represent diverse sources, since BTM harbors S. uberis from mastitic cows as well as from the environment (19). Because previous reports have shown that the same S. uberis strain is rarely found in different herds (2,34,53), we also expected these isolates to be genetically unrelated. An additional 20 S. uberis isolates from The Netherlands, which originated from quarter milk samples from cows in two herds and represent well-defined epidemiological relationships (herd, cow, quarter, and time of isolation), were also included in our study to determine the ability of subtyping methods to provide epidemiologically relevant results; these isolates had previously been characterized by RAPD typing (56).…”

Section: Methodsmentioning

confidence: 99%

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Multilocus Sequence Typing of Streptococcus uberis Provides Sensitive and Epidemiologically Relevant Subtype Information and Reveals Positive Selection in the Virulence Gene pauA

Zadoks

Schukken

Wiedmann³

2005

J Clin Microbiol

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Control of the bovine mastitis pathogen Streptococcus uberis requires sensitive and epidemiologically meaningful subtyping methods that can provide insight into this pathogen's epidemiology and evolution. Development of a multilocus sequence typing (MLST) scheme based on six housekeeping and virulence genes allowed differentiation of 40 sequence types among 50 S. uberis isolates from the United States (n ‫؍‬ 30) and The Netherlands (n ‫؍‬ 20). MLST was more discriminatory than EcoRI or PvuII ribotyping and provided subtype data with better epidemiological relevance, e.g., by discriminating isolates with identical ribotypes obtained from different farms. Phylogenetic analyses of MLST data revealed indications of reticulate evolution between genes, preventing construction of a core phylogeny based on concatenated DNA sequences. However, all individual gene phylogenies clearly identified a distinct pauA-negative subtaxon of S. uberis for which housekeeping alleles closely resembled those of Streptococcus parauberis. While the average GC content for five genes characterized was between 0.38 and 0.40, pauA showed a considerably lower GC content (0.34), suggesting acquisition through horizontal transfer. pauA also showed a higher nonsynonymous/synonymous rate ratio (d N /d S ) (1.2) compared to the other genes sequenced (d N /d S < 0.12), indicating positive selection in this virulence gene. In conclusion, our data show that (i) MLST provides for highly discriminatory and epidemiologically relevant subtyping of S. uberis; (ii) S. uberis has a recombinatorial population structure; (iii) phylogenetic analysis of MLST data reveals an S. uberis subtaxon resembling S. parauberis; and (iv) horizontal gene transfer and positive selection contribute to evolution of certain S. uberis genes, such as the virulence gene pauA.

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Section: Discussionmentioning

confidence: 63%

Section: Methodsmentioning

confidence: 99%

Multilocus Sequence Typing of Streptococcus uberis Provides Sensitive and Epidemiologically Relevant Subtype Information and Reveals Positive Selection in the Virulence Gene pauA

Zadoks

Schukken

Wiedmann³

2005

J Clin Microbiol

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“…Moreover, the low incidence rate in our study (Hogan et al, 1989a) together with the high prevalence rate (specifically for subclinical infections), indicates that the main problem of the organic herd is the chronification of the infections. The duration of mastitis in our organic herd was longer that in other studies (Zadoks et al, 2001;McDougall et al, 2004), especially if we take into account that the prevalent pathogens were environmental (Escobal et al, 2004). However, our data may have been overestimated since they were calculated over the period of study and not over the period of lactation, that means infections reaching drying off and persisting after calving (accounting for a 30% of the total) were counted as a single process.…”

Section: Single-quarter Somatic Cell Countsmentioning

confidence: 66%

Dynamics of mammary infections in organic dairy farms in Northern Spain

Villar¹,

Gradillas²,

Fernández-Ruiz³

et al. 2016

Span. j. agric. res.

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The objective of this paper is to evaluate the microbiological state and the dynamics of the mammary infections of organic farms in North Spain to discover if the high somatic cell count (SCC) observed in these farms is associated to a high incidence of mastitis. Microbiological cultures and SCC were performed in 8,496 foremilk samples collected from 160 cows in five representative organic farms from February 2006 to January 2008. Even though 79.3% of cultures were positive, only 21.2% of the total fit our diagnosis of mastitis (clinical, subclinical and chronic). The great prevalence of Corynebacterium bovis (teat canal-region pathogen) in the positive cultures that did not fit the mastitis diagnosis criteria (nearly 70%) compared with those that did (27%) was found to be related to lack of post-milking teat disinfection. The study prevalence of mastitis was 69.2% (66.7% subclinical mastitis, 27.8% clinical mastitis); the mean monthly prevalence was 47.4%; the mean monthly incidence was 12.9% and the mean duration of infection was 3.84 ± 3.98 months The high SCC in foremilk samples from old cows (three or more lactations) not diagnosed as mastitis compared to the heifers, reflects a worsening health status of the animals over time. When compared with the conventional sector in Northern Spain, these parameters indicate a poorer udder health in the studied organic herds with a high presence of chronic subclinical processes.

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“…High variability of strains is typical of opportunistic, environmental pathogens (19,25). Opportunistic udder infections in dairy cows can occur when there is a decrease in host resistance or an increase in exposure or by chance.…”

Section: Discussionmentioning

confidence: 99%

Molecular Epidemiology of TwoKlebsiella pneumoniaeMastitis Outbreaks on a Dairy Farm in New York State

et al. 2007

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Klebsiella spp. have become an important cause of clinical mastitis in dairy cows in New York State. We describe the occurrence of two Klebsiella mastitis outbreaks on a single dairy farm. Klebsiella isolates from milk, feces, and environmental sources were compared using random amplified polymorphic DNA (RAPD)-PCR typing. The first mastitis outbreak was caused by a single strain of Klebsiella pneumoniae, RAPD type A, which was detected in milk from eight cows. RAPD type A was also isolated from the rubber liners of milking machine units after milking of infected cows and from bedding in the outbreak pen. Predominance of a single strain could indicate contagious transmission of the organism or exposure of multiple cows to an environmental point source. No new cases with RAPD type A were observed after implementation of intervention measures that targeted the prevention of transmission via the milking machine as well as improvement of environmental hygiene. A second outbreak of Klebsiella mastitis that occurred several weeks later was caused by multiple RAPD types, which rules out contagious transmission and indicates opportunistic infections originating from the environment. The diversity of Klebsiella strains as quantified with Simpson's index of discrimination was significantly higher for isolates from fecal, feed, and water samples than for isolates from milk samples. Several isolates from bedding material that had the phenotypic appearance of Klebsiella spp. were identified as being Raoultella planticola and Raoultella terrigena based on rpoB sequencing.

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Duration of Infection and Strain Variation in Streptococcus uberis Isolated from Cows’ Milk

Cited by 48 publications

References 21 publications

Multilocus Sequence Typing of Streptococcus uberis Provides Sensitive and Epidemiologically Relevant Subtype Information and Reveals Positive Selection in the Virulence Gene pauA

Multilocus Sequence Typing of Streptococcus uberis Provides Sensitive and Epidemiologically Relevant Subtype Information and Reveals Positive Selection in the Virulence Gene pauA

Dynamics of mammary infections in organic dairy farms in Northern Spain

Molecular Epidemiology of TwoKlebsiella pneumoniaeMastitis Outbreaks on a Dairy Farm in New York State

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