Typeability of MALDI-TOF assay for identification of non-aureus staphylococci associated with bovine intramammary infections and teat apex colonization

Mahmmod, Yasser S.; Nonnemann, Bettina; Svennesen, Line; Pedersen, Karl; Klaas, Ilka Christine

doi:10.3168/jds.2018-14579

Cited by 34 publications

(29 citation statements)

References 52 publications

(85 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Mixed staphylococci species were found significantly more often in teat canal swabs samples (19.1%) than in milk samples (3.6%), except in herd C. The high presence of flies in this herd, as observed during the regular herd visits and the longitudinal study preceding the current study (23), might influence the bacteria population on teats and in teat canals since they may transmit bacteria causing IMI (43, 44). The same definition for mixed staphylococcal species was used in our above-mentioned previous study and also by Mahmmod et al (24). In order to avoid preclusion of potentially relevant information, considering that the teat canal—similar to teat apices—harbors many different NAS species (8, 15–18) and taking into account the duality of its role—as a barrier against IMI on one side and potential reservoir for NAS species causing IMI on the other—the decision to include culture results with up to three Staphylococcus species was made.…”

Section: Discussionmentioning

confidence: 96%

See 1 more Smart Citation

Non-aureus Staphylococci Species in the Teat Canal and Milk in Four Commercial Swiss Dairy Herds

et al. 2019

View full text Add to dashboard Cite

Non-aureus staphylococci (NAS) are frequently found in milk samples as well as on the teat apex and in the teat canal and are known to be a cause of subclinical mastitis. The objective of this study was to investigate the relationship between NAS species colonizing the teat canal and those causing intramammary infection (IMI) in four commercial dairy herds. Teat canal swabs were obtained and thereafter milk samples were aseptically collected and evaluated for the presence of staphylococci using selective agar plates. Species identification was performed using matrix-assisted laser desorption/ionization time–of–flight mass spectrometry. The relationship between NAS species distribution and sample type (teat canal vs. milk samples) was quantified using hierarchical multivariable logistic regression models. The most prevalent NAS species in teat canal swabs were S. xylosus (35%), S. vitulinus (10%), and S. chromogenes (7%), whereas in milk samples S. chromogenes (5%), S. xylosus (5%), and S. haemolyticus (4%) were most prevalent. There were significantly higher odds for S. vitulinus (OR = 215), S. xylosus (OR = 20), S. sciuri (OR = 22), S. equorum (OR = 13), and S. succinus (OR = 10) to be present in teat canal swabs than in milk samples. Differences between herds in NAS species distribution were found and were most pronounced for S. succinus and a S. warneri -like species. This information aids in the understanding of NAS species as an etiology of IMI and should be taken into account when interpreting milk culture results.

show abstract

Section: Discussionmentioning

confidence: 96%

“…Teat canal swabs and milk samples with more than three different NAS species on the selective agar plates were considered as mixed staphylococcal species (23, 24). Incidentally growing non-staphylococci species were not considered for further analysis.…”

Section: Methodsmentioning

confidence: 99%

Non-aureus Staphylococci Species in the Teat Canal and Milk in Four Commercial Swiss Dairy Herds

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Therefore, nowadays, veterinary diagnostic laboratories favour mass spectrometry (for instance, matrix‐assisted laser desorption‐ionization–time of flight mass spectrometry or MALDI‐TOF MS ® ) for the identification of bacterial species. The MALDI‐TOF MS databases for the different bacterial genera and families in veterinary medicine are indeed progressively validated like recently the database of staphylococcal species associated with bovine mastitis (Cameron et al, , ; Mahmmod et al, ; Nonnemann et al ). However, a delay of 24–72 h, that is not often compatible with the dairy industry, is still necessary to obtain results.…”

Section: Introductionmentioning

confidence: 99%

Comparison of quantitative PCR and MALDI‐TOF mass spectrometry assays for identification of bacteria in milk samples from cows with subclinical mastitis

et al. 2019

View full text Add to dashboard Cite

Aims: The objective of this study was to compare qualitatively and quantitatively the results of identification of the bacteria present in milk samples from cows with subclinical mastitis using multiplex qPCR assay and matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS â ) after bacteriological growth. Methods and Results: A total of 182 samples were aseptically collected from 119 cows with high somatic cell counts (>2Á10 5 SCC per ml) on 11 farms in Belgium in 2014. The mutiplex qPCR assay was carried out on 350 µl of milk with the PathoProof â Complete-16kit. Ten microlitre of milk was streaked on Columbia blood agar and three selective agar plates. Growing colonies were identified by MALDI-TOF MS. Of the 182 samples, 90 gave positive results with either or both tests for one or two bacterial species/genera. Total qualitative agreement of the bacteria identified was observed in 41 mono-or bi-bacterial samples (46%) and partial agreement in 19 bi-bacterial samples at both or either tests (21%). The results of both tests on those mono-and bibacterial samples were not significantly different (McNemar test; P = 0Á395) with a fair agreement (Cohen's kappa test; k = 0Á375; P = 0Á055). Moreover, quantitative correlation between the qPCR intensity and the numbers of growing colonies was observed in half of the 60 samples with qualitative matching results. Conclusions: Both methods give identical qualitative and quantitative results with approximately a half and a quarter of the mono-and bi-bacterial samples respectively. Several reasons can explain the differences. The multiplex qPCR assay only targets the most important mammary gland pathogens and can detect DNA of bacteria both alive and dead. Conversely, bacteria only grow when alive and the MALDI-TOF MS databases do not include all bovine milkassociated bacterial species yet. Significance and Impact of the Study: This study further highlights the limitations and complementarity of the genetic and phenotypic tests for the identification of bacteria present in milk samples.

show abstract

Section: Discussionmentioning

confidence: 99%

“…The results showed that the qPCR assay identifies successfully all the submitted CNS isolates with high accuracy indicating that the reported low Se is probably due to the effect of the sampling technique. We reported the full description of 15 CNS species isolated from the teat skin samples in Mahmmod et al (2018b) Skjølstrup et al (2018) reported that Se of qPCR on teat skin was 30% for the identification of Staph. aureus compared with 91% for a sampling method where special qPCR swabs 'FLOQ swabs' were directly applied on the teat skin for swabbing.…”

Section: Estimates Of Qpcr and Bc For Tacmentioning

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

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

Typeability of MALDI-TOF assay for identification of non-aureus staphylococci associated with bovine intramammary infections and teat apex colonization

Cited by 34 publications

References 52 publications

Non-aureus Staphylococci Species in the Teat Canal and Milk in Four Commercial Swiss Dairy Herds

Non-aureus Staphylococci Species in the Teat Canal and Milk in Four Commercial Swiss Dairy Herds

Comparison of quantitative PCR and MALDI‐TOF mass spectrometry assays for identification of bacteria in milk samples from cows with subclinical mastitis

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

Contact Info

Product

Resources

About