Effect of milk sample collection strategy on the sensitivity and specificity of bacteriologic culture and somatic cell count for detection of Staphylococcus aureus intramammary infection in dairy cattle

Buelow, Kenneth L.; Thomas, Chester B.; Goodger, W. J.; Nordlund, Ken; Collins, Michael T.

doi:10.1016/0167-5877(95)00518-8

Cited by 29 publications

(28 citation statements)

References 9 publications

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“…Further, misdiagnosis due to the SCV being confused with other bacterial genera is possible. Pre‐enrichment in liquid broth before isolation, freeze–thawing, increasing the volume of plated milk from 0.01 to 0.1 ml or duplicate quarter milk samples reduces the proportion of false‐negative results (Artursson et al., ; Buelow, Thomas, Goodger, Nordlund, & Collins, ; Godden et al., ; Sol et al., ; Zecconi et al., ). However, cost and, in some instances, turnaround time remains a limitation for implementation of bacteriological techniques on a large scale.…”

Section: Main Means Of Prevention Detection and Controlmentioning

confidence: 99%

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

Rainard

Foucras

Fitzgerald

et al. 2017

Transbound Emerg Dis

178

202

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SummaryThis study assessed knowledge gaps and suggested research priorities in the field of Staphylococcus aureus mastitis. Staphylococcus aureus infecting the mammary gland remains a major problem to the dairy industry worldwide because of its pathogenicity, contagiousness, persistence in the cow environment, colonization of skin or mucosal epithelia, and the poor curing efficacy of treatments. Staphylococcus aureus also constitutes a threat to public health due to food safety and antibiotic usage issues and the potential for bidirectional transmission of strains between humans and dairy animals (cows and small ruminants). Gaps have been identified in

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Section: Main Means Of Prevention Detection and Controlmentioning

confidence: 99%

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

Rainard

Foucras

Fitzgerald

et al. 2017

Transbound Emerg Dis

178

202

View full text Add to dashboard Cite

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“…Some other authors used a personal procedure derived from the previous ones. Methodological issues which could impair the sensitivity or specificity of the bacteriological procedures were checked: the volume of milk spread over a fixed area [12], the storage of samples, especially the freezing of samples [39,70], and the type of growth medium used (selective medium or not).…”

Section: Bacteriological Proceduresmentioning

confidence: 99%

Incidence of intramammary infections during the dry period without or with antibiotic treatment in dairy cows – a quantitative analysis of published data

2006

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-The study was aimed at summarising the literature that compares the incidence levels of spontaneously occurring intramammary infections (IMI) during the dry period, without versus with antibiotic dry cow treatment (DCT). A meta-analytic relative risk (RR) calculation was implemented when a priori relevant. Two main categories of comparison were used in the 36 selected papers. In the first category, the udder quarters were randomly allocated (at quarter or cow level) to an untreated or a treated group. Quarter incidence averaged 12.8% (weighted mean) in untreated quarters, and depending on the DCT used, from 6.6 to 8.0% in treated quarters. The meta-analytic RR of new IMI for untreated versus treated quarters varied from 1.54 to 1.94, depending on the DCT used. DCT was mainly found effective against IMI due to streptococci and coagulase-positive staphylococci. Based on only a few papers, the application of an internal teat sealer was associated to a quite similar (or possibly better) protection against IMI than DCT, but only in a subpopulation of particular (selected) cows. In the second category of studies, a selective dry cow or quarter antibiotic-treatment (selective DCT or DQT), according to cow or quarter selection criteria, was compared to blanket DCT. The meta-analytic RR of new IMI was 1.71 for selective DCT versus blanket DCT. Selective DQT seemed to be more at risk than selective DCT, but consisted of treating a much lower proportion of quarters. The summary-results provided by our meta-analysis should only be used with caution, due to possibly low external validity. More research seems to be relevant on the risk factors of new IMI during the dry period to make the outcomes of omission of DCT in selected cows more predictable under field conditions. dairy cow / mastitis / risk / dry-cow treatment / meta-analysis

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“…Studies have shown ranges of sensitivity (Se) between 0.75 to 0.93 for single samples analyzed with BC [7,8]. S. aureus are known to be shed in a cyclic pattern from infected quarters [7] and repeated sampling over time can be necessary in order to increase the Se [7,9]. However, a recent study showed that culture of a single milk sample resulted in the highest Se and specificity (Sp), 0.904 and 0.998 respectively for S. aureus, when IMI was defined as one or more colonies in pure or mixed culture [10].…”

Section: Introductionmentioning

confidence: 99%

Latent class analysis of the diagnostic characteristics of PCR and conventional bacteriological culture in diagnosing intramammary infections caused by Staphylococcus aureus in dairy cows at dry off

Cederlöf¹,

Toft

Aalbæk

et al. 2012

Acta Vet Scand

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BackgroundStaphylococcus aureus is one of the most common causes of intramammary infections in dairy cows at dry off. Reliable identification is important for disease management on herd level and for antimicrobial treatment of infected animals. Our objective was to evaluate the test characteristics of PathoProof ™ Mastitis PCR Assay and bacteriological culture (BC) in diagnosing bovine intramammary infections caused by S. aureus at dry off at different PCR cycle threshold (Ct)-value cut-offs.MethodsSterile quarter samples and non-sterile composite samples from 140 animals in seven herds were collected in connection with the dairy herd improvement (DHI) milk recording. All quarter samples were analyzed using BC whereas all composite samples were analyzed with PathoProof ™ Mastitis PCR Assay. Latent class analysis was used to estimate test properties for PCR and BC in the absence of a perfect reference test. The population was divided into two geographically divided subpopulations and the Hui-Walter 2-test 2-populations model applied to estimate Se, Sp for the two tests, and prevalence for the two subpopulations.ResultsThe Se for PCR increased with increasing Ct-value cut-off, accompanied by a small decrease in Sp. For BC the Se decreased and Sp increased with increasing Ct-value cut-off. Most optimal test estimates for the real-time PCR assay were at a Ct-value cut-off of 37; 0.93 [95% posterior probability interval (PPI) 0.60-0.99] for Se and 0.95 [95% PPI 0.95-0.99] for Sp. At the same Ct-value cut-off, Se and Sp for BC were 0.83 [95% PPI 0.66-0.99] and 0.97 [95% PPI 0.91-0.99] respectively. Depending on the chosen PCR Ct-value cut-off, the prevalence in the subpopulations varied; the prevalence increased with increasing PCR Ct-value cut-offs.ConclusionNeither BC nor real-time PCR is a perfect test in detecting IMI in dairy cows at dry off. The changes in sensitivity and prevalence at different Ct-value cut-offs for both PCR and BC may indicate a change in the underlying disease definition. At low PCR Ct-value cut-offs the underlying disease definition may be a truly/heavily infected cow, whereas at higher PCR Ct-value cut-offs the disease definition may be a S. aureus positive cow.

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Effect of milk sample collection strategy on the sensitivity and specificity of bacteriologic culture and somatic cell count for detection of Staphylococcus aureus intramammary infection in dairy cattle

Cited by 29 publications

References 9 publications

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

Knowledge gaps and research priorities inStaphylococcus aureusmastitis control

Incidence of intramammary infections during the dry period without or with antibiotic treatment in dairy cows – a quantitative analysis of published data

Latent class analysis of the diagnostic characteristics of PCR and conventional bacteriological culture in diagnosing intramammary infections caused by Staphylococcus aureus in dairy cows at dry off

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