Shedding Pattern of Staphylococcus aureus from Bovine Intramammary Infections

Sears, P. M.; Smith, B. S.; English, Paul; Herer, Paula; González, R. N.

doi:10.3168/jds.s0022-0302(90)78964-3

Cited by 235 publications

(206 citation statements)

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“…The determination of the IMI based on a single result is most of the time not very accurate [37]. Some chronically infected quarters eliminate bacteria in milk sporadically, leading to possible false negative results [7,29,43]. Taking repeated samples limits the number of false-negative samples.…”

Section: Figure 8 Geometric Mean Scc (᭜) and Its 95% CI (-) Of Quartmentioning

confidence: 99%

Quarter milk somatic cell count in infected dairy cows: a meta-analysis

et al. 2002

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-The aim of this paper was to evaluate the effects associated with intramammary infection (IMI) by a bacterium or a group of bacteria (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, Staphylococci other than S. aureus, and Corynebacterium bovis) on the somatic cell count (SCC) in quarter milk of dairy cows. Papers selected for analysis had to provide SCC values associated with the natural infection in quarters by different bacteria. Sampling for measurement of SCC and determination of the infection had to be done on the same day. Only papers published in English or in French after 1971 were considered. Twenty-one papers fulfilled the selection criteria. The animals sampled, the measurement techniques for SCC and the bacteriological identification, as well as the definition of the infection, all differed widely among the selected studies. The meta-analysis method was used to estimate both the mean SCC (arithmetic and geometric) value and the average increase on SCC of each type of infection. The geometric mean SCC in bacteriologically negative quarters was 68 000 c/mL. In case of IMI, the retained SCC was 357 000, 857 000, 547 000, 1 024 000, 1 151 000, 138 000 and 105 000 c/mL in quarters infected by Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliforms, staphylococci other than S. aureus and Corynebacterium bovis, respectively. The variation factors that could influence these SCC values and the bacteriological results are discussed. dairy cow / mastitis / somatic cell count / meta-analysis Résumé -Méta-analyse des effets de l'infection sur la concentration en cellules somatiques du lait de quartier chez la vache laitière. Le présent article a pour objectif d'évaluer l'effet associé à l'infection intra-mammaire (IIM) par une bactérie ou par un groupe de bactéries (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, coliformes, 335

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Section: Figure 8 Geometric Mean Scc (᭜) and Its 95% CI (-) Of Quartmentioning

confidence: 99%

Quarter milk somatic cell count in infected dairy cows: a meta-analysis

et al. 2002

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“…Nevertheless, if a pathogen was recovered only in one pair of the duplicate, the quarter was considered as non-infected according to the microbiological results and was considered to display non--significant growth, except in the case of S. aureus or Streptococcus agalactiae infection. This exception was applied for S. agalactiae because it is regarded as a highly contagious obligate parasite of the bovine mammary gland (Keefe 1997) and for S. aureus due to its peculiar shedding pattern, particularly because the shedding pattern could be below the detection limit of the microbiological method employed (Sears et al 1990, Zecconi et al 1997, Godden et al 2002, Walker et al 2010. (B) Second, the milk sample was regarded as microbiologically positive if at least one of the duplicate samples (single S1 or S2) was microbiologically positive regardless of which mastitis pathogen was isolated.…”

Section: Methodsmentioning

confidence: 99%

Somatic cell count and mastitis pathogen detection in composite and single or duplicate quarter milk samples

et al. 2016

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The most acceptable criteria for diagnosing bovine intramammary infections include results of bacteriological culture and measures of inflammation. Therefore, information on the diagnostic characteristics of the procedures used to identify infected quarters is required. Thus, this study was designed to evaluate a set of criteria to classify the infectious status of an udder at the quarter (single and duplicate milk samples) and cow (composite milk sample) levels, and to compare the infectious status with somatic cell counts (SCCs) of the samples. Here, the SCC thresholds determined by receiver operating characteristic curve analysis had a higher Youden index using mammary quarter duplicate milk samples as the gold standard for testing compared with single quarter and composite milk samples, especially for samples for which at least one of the duplicates was microbiologically positive, regardless of the mastitis pathogen isolated. The kappa coefficient for bacteriological results of the single quarter milk samples (single S1 and S2) was 0.85+0.019, indicating that single quarter milk sampling can be useful in mastitis control programs. Therefore, the use of composite milk samples to detect mastitis pathogens may be limited to the detection of major pathogens, given their predictive values. Thus, our findings suggest that the milk SCCs and microbiological examinations, although regarded as the most reliable indicators of ongoing mastitis, should be used in an integrated manner in mastitis control programs. Furthermore, the accuracy of single, duplicate and composite microbiological analyses to diagnosis mastitis should be considered for its implications in mastitis control strategies.INDEX TERMS: Somatic cell count, mastitis, intramammary infection, sensitivity, specificity, udder health status, dairy cow.

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“…Although some investigators have used inoculums of 0.01 ml, others have increased inoculum volumes to 0.05-0.1 ml, thereby increasing the sensitivity of microbiologic screening. 4,8,9 Other investigators have reported variable inoculums within a single study using 0.1 and 0.05, 13 or 0.01-0.03 ml. 10 Considering the daily samples, although statistically significant, there was only a 2% difference in the sensitivity of culture using the larger inoculum.…”

Section: Introductionmentioning

confidence: 99%

“…Milk samples from S. aureus-positive quarters that were culture positive using 0.01 ml were unavailable for reculture using 0.1 ml and were considered positive at the larger inoculum for the analysis. Sensitivities and specificities of a single microbiologic culture in identifying S. aureus IMI and the comparison of the ability to detect a S. aureus IMI between the 2 inoculum volumes were calculated considering each quarter sample independently 13 (roctab, roccomp, STATA v. 11) b applying the definition of a S. aureus-positive quarter (at least 2 of the first 3 consecutive samples culture positive with $1 CFU of S. aureus/0.1 ml) and assuming a disease-free status in quarters defined as S. aureus negative. Quarters with no history of S. aureus, but repeatedly testing positive for S. aureus at some point after the third sample, were considered new infections and not included in the analysis (n 5 3).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Inoculum Volume on the Microbiologic Detection of Naturally OccurringStaphylococcus AureusIntramammary Infections

2010

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Abstract. Currently no standard definitions for the diagnosis of Staphylococcus aureus intramammary infection (IMI) exist. As a result, criteria applied in research to diagnose S. aureus IMIs have varied making comparisons between published works difficult. The goal of the current study was to define the optimal inoculum volume used in the diagnosis of naturally occurring S. aureus IMIs. Microbiologic results from 2 field studies examining S. aureus IMIs were used to examine the effects of inoculum volume on the microbiologic detection of S. aureus. A total of 1,583 milk samples were included in the analysis, and the results of using a 0.01-ml and a 0.1-ml inoculum are presented. Using a 0.01-ml inoculum resulted in a sensitivity of 91% (95% confidence interval [CI]: 88.6-93%) and a specificity of 99.4% (95% CI: 98.6-99.8%). Using the larger 0.1-ml inoculum resulted in a sensitivity of 96.8% (95% CI: 95.2-97.9%) and a specificity of 99.3% (95% CI: 98.4-99.7%). All false-positive samples were from S. aureus-negative quarters in S. aureuspositive cows. There were no false-positive cultures from S. aureus-negative cows. Of the false-negative samples, the majority (77%) were from 6 of the 34 S. aureus-positive quarters. Results from the current study of naturally occurring S. aureus IMIs support the hypothesis that, when using quarter level milk samples, a S. aureus IMI is most accurately diagnosed using a 0.1-ml inoculum. Regardless of inoculum volume, a single quarter sample culture that is positive with S. aureus ($1 colony-forming unit) is sufficient to diagnose a S. aureus IMI.

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Shedding Pattern of Staphylococcus aureus from Bovine Intramammary Infections

Cited by 235 publications

References 2 publications

Quarter milk somatic cell count in infected dairy cows: a meta-analysis

Quarter milk somatic cell count in infected dairy cows: a meta-analysis

Somatic cell count and mastitis pathogen detection in composite and single or duplicate quarter milk samples

The Effect of Inoculum Volume on the Microbiologic Detection of Naturally OccurringStaphylococcus AureusIntramammary Infections

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