Estimation of test characteristics of real-time PCR and bacterial culture for diagnosis of subclinical intramammary infections with Streptococcus agalactiae in Danish dairy cattle in 2012 using latent class analysis

Mahmmod, Yasser S.; Toft, Nils; Katholm, J.; Grønbæk, Carsten; Klaas, Ilka Christine

doi:10.1016/j.prevetmed.2012.10.018

Cited by 34 publications

(24 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…DNA of CNS), apart from the detection target of BC. This comes in agreement with the findings of previous studies (Mahmmod et al ; Soltau et al ). One of the main different aspects between the qPCR analysis and BC is that qPCR analysis detects DNA, whereas BC detects only viable bacteria.…”

Section: Discussionsupporting

confidence: 94%

“…The diagnostic accuracy of PCR‐based methods has shown high sensitivity (Se) and specificity (Sp) in detection of bacteria in milk, compared to conventional BC for many udder pathogens such as Staph. aureus , Streptococcus agalactiae and Streptococcus uberis (Cederlof et al ; Mahmmod et al ,; Nyman et al ; Steele et al ; Holmøy et al ). Using latent class analysis (LCA) approach, Nyman et al () estimated the Se and Sp of PCR (PathoProof TM PCR) and BC for identification of IMI with CNS in Swedish dairy herds, although that PCR test type did not directly measure CNS but all Staphylococcus species that then were evaluated against the Staph.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Bayesian estimation of qPCR and bacterial culture accuracy for detection of bovine coagulase‐negative staphylococci from milk and teat apex at different test cut‐off points

Mahmmod

Svennesen

Katholm

et al. 2019

J of Applied Microbiology

View full text Add to dashboard Cite

Aim To primarily estimate the sensitivity (Se) and specificity (Sp) of the commercially available Mastit4 quantitative PCR (qPCR) assay and bacterial culture (BC) for diagnosis of intramammary infections (IMI) and teat apex colonization (TAC) with coagulase‐negative staphylococci (CNS) at different cut‐offs for qPCR cycle threshold values using Bayesian latent class analysis. A secondary objective was to evaluate two cut‐offs of BC for diagnosis of IMI and TAC with CNS. Methods and Results We randomly selected 13–20 cows with subclinical mastitis from eight dairy herds. Teat skin samples and aseptically collected foremilk samples were collected from the right hindquarters (n = 149) for BC and qPCR analysis. The Se of qPCR was always higher than BCSe in diagnosis of IMI, however; the Sp of BC was higher than qPCRSp. BCSe and BCSp showed no substantial difference between the tested BC cut‐offs. In contrast to IMI, estimates of BC and qPCR in diagnosing TAC were different. BCSe was higher than qPCRSe at all tested cut‐offs, however; qPCRSp was higher than BCSp. Conclusion The overall performance of qPCR is higher than BC in the diagnosis of IMI; however, the performance of BC is better than qPCR in diagnosis of TAC. The qPCR and BC are valid diagnostics for bovine IMI with CNS. However, for TAC, both techniques require further investigation to reduce the uncertainty of the true status of the quarter and teat skin. Significance and Impact of the Study We reported, for the first time, the diagnostic performance of new mastitis technology (Mastit4 PCR) and culture for detection of CNS in milk and nonmilk samples in dairy herds with automatic milking systems. Our findings will improve the interpretation of the test results of culture and qPCR assay and subsequently, will strengthen the control of IMI with CNS in dairy cows.

show abstract

Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Bayesian estimation of qPCR and bacterial culture accuracy for detection of bovine coagulase‐negative staphylococci from milk and teat apex at different test cut‐off points

Mahmmod

Svennesen

Katholm

et al. 2019

J of Applied Microbiology

View full text Add to dashboard Cite

show abstract

“…Although probably the milk dilution of pooled and milk samples and their potential contamination during collect can affect the sensibility and specificity of the PCR technique, there are several studies indicating their advantages regarding the classical bacterial cultures methods (Taponen and others 2009, Katholm and others 2012, Mahmmod and others 2013a,b, Zanardi and others 2014), notwithstanding different Ct-value cut-offs can change the mastitis infection definition (Cederlöf and others 2012). Reyher and Dohoo (2011) estimate the sensitivity and specificity of bacterial cultures techniques using composite milk samples, that is, from cow's four mammary quarters, for several milk pathogens or group pathogens (CNS, S aureus , E coli , S dysgalactiae , S uberis , Enterococcus species and Corynebacterium species).…”

Section: Discussionmentioning

confidence: 99%

Prevalence of bovine milk pathogens in Azorean pastures: mobile versus fixed milking machines

Azevedo

Pacheco

Soares³

et al. 2016

Veterinary Record Open

View full text Add to dashboard Cite

The aims of the present study were (1) to evaluate the influence of using mobile (n=47) or fixed (n=45) milking machines in Azorean herds on the apparent prevalence of several milk pathogens in bulk tank milk (BTM) and (2) to determine whether separated subclinical mastitic cows can serve, in real time, as predictors of milk pathogen prevalence for the remaining animals at the herd level. The use of a mobile or fixed milking machine influenced (P≤0.05) the prevalence of Staphylococcus aureus (72.3 per cent; n=34 v 51.1 per cent; n=23, respectively) and Klebsiella species (46.8 per cent; n=22 v 26.7 per cent; n=12, respectively). S aureus (95 per cent CI OR 1.1 to 6.0) and Klebsiella species (95 per cent CI OR 1.0 to 5.8) were 2.5 times more likely to increase in the BTM of herds using mobile milking machines. The prevalence of coagulase-negative staphylococci (100 per cent; n=92), Escherichia coli (75.0 per cent), Corynebacterium bovis (57.6 per cent), Enterococcus species (55.4 per cent), Streptococcus dysgalactiae (51.1 per cent), Streptococcus uberis (41.3 per cent), Actinomyces pyogenes or Peptostreptococcus indolicus (41.3 per cent) and Streptococcus agalactiae (32.6 per cent) in BTM remained similar among the herds. κ coefficients were always <0.70, indicating intra-herd disagreement of the prevalence of milk pathogens between BTM and separated milking cows. Milking hygiene should be improved in pastures, focusing specifically on herds that use a mobile milking machine. The segregated cows at milking time are not good predictors of milk pathogens in BTM.

show abstract

“…; Mahmmod et al . ). The objective of this study was to develop and optimize a SYBR Green qPCR assay to detect and quantify S. agalactiae in a piscine host.…”

Section: Introductionmentioning

confidence: 97%

“…However, most media used for isolating S. agalactiae are low selectivity, and performing cultures is time-consuming. Furthermore, these methods may misestimate the number of target bacteria as a result of the presence of other microbial competitors in analysed samples (Mahmmod et al 2013). To overcome these drawbacks, DNA-based methods such as PCR and loop-mediated isothermal amplification are increasingly being used (Jim enez et al 2011;Huy et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Development of a quantitative PCR assay for monitoring Streptococcus agalactiae colonization and tissue tropism in experimentally infected tilapia

Jiang

et al. 2015

Journal of Fish Diseases

View full text Add to dashboard Cite

Streptococcus agalactiae has become one of the most important emerging pathogens in the aquaculture industry and has resulted in large economic losses for tilapia farms in China. In this study, three pairs of specific primers were designed and tested for their specificities and sensitivities in quantitative real-time polymerase chain reactions (qPCRs) after optimization of the annealing temperature. The primer pair IGS-s/IGS-a, which targets the 16S-23S rRNA intergenic spacer region, was finally chosen, having a detection limit of 8.6 copies of S. agalactiae DNA in a 20 μL reaction mixture. Bacterial tissue tropism was demonstrated by qPCR in Oreochromis niloticus 5 days post-injection with a virulent S. agalactiae strain. Bacterial loads were detected at the highest level in brain, followed by moderately high levels in kidney, heart, spleen, intestines, and eye. Significantly lower bacterial loads were observed in muscle, gill and liver. In addition, significantly lower bacterial loads were observed in the brain of convalescent O. niloticus 14 days post-injection with several different S. agalactiae strains. The qPCR for the detection of S. agalactiae developed in this study provides a quantitative tool for investigating bacterial tissue tropism in infected fish, as well as for monitoring bacterial colonization in convalescent fish.

show abstract

Estimation of test characteristics of real-time PCR and bacterial culture for diagnosis of subclinical intramammary infections with Streptococcus agalactiae in Danish dairy cattle in 2012 using latent class analysis

Cited by 34 publications

References 16 publications

Bayesian estimation of qPCR and bacterial culture accuracy for detection of bovine coagulase‐negative staphylococci from milk and teat apex at different test cut‐off points

Bayesian estimation of qPCR and bacterial culture accuracy for detection of bovine coagulase‐negative staphylococci from milk and teat apex at different test cut‐off points

Prevalence of bovine milk pathogens in Azorean pastures: mobile versus fixed milking machines

Development of a quantitative PCR assay for monitoring Streptococcus agalactiae colonization and tissue tropism in experimentally infected tilapia

Contact Info

Product

Resources

About