Occurrence of False-Positive Results of Inhibitor on Milk Samples Using the Delvotest SP Assay

2001 ◽  
Vol 64 (8) ◽  
pp. 1211-1215 ◽  
Author(s):  
JEONG-HUN KANG ◽  
FUSAO KONDO
Keyword(s):  
Heat Treatment ◽  
Positive Result ◽  
False Positive ◽  
Reading Time ◽  
False Positive Result ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Cell Counts ◽  
Bulk Tank ◽  
Positive Results

Three hundred twenty-one quarter, 207 whole udder, 310 bulk tank, and 93 tank-lorry milk samples were examined for confirmation of the presence of inhibitor by Delvotest SP assay. Four hundred twenty-six Holstein cows of no drug treatment for at least 30 days from January 1998 to September 1999 were used. Reading time was 2.50, 2.75, and 3.00 h, and results of sampling were recorded by four types according to comparison with the color of the well containing the control milk sample. False-positive outcome was identified by Delvotest SP assay in quarter (13 of 321), whole udder (9 of 207), and bulk tank milk samples (4 of 310), but was not shown on tank-lorry milk samples (0 of 93) at the reading time of 2.50 h. All of the 26 false-positive samples were negative from the examination after heat treatment at 82°C for 5 min. But, two bulk tank milk samples that appeared to have positive results in LacTek and Charm II tests were positive from the test following heat treatment. Somatic cell counts (SCC) were related to the probability of a false-positive result. The more SCC increased, the more the occurrence of a false-positive result increased. In our investigations, 4 of 310 bulk tank milk samples at the reading time of 2.50 h produced false-positive results, and no false-positive results were apparent at a reading time of 2.75 h. Also, the occurrence of false-positive results in quarter and whole udder milk samples decreased when agar was cultured for 2.75 to 3.00 h. There were no false-positive results from tank-lorry milk samples. These results indicate that the Delvotest SP assay may provide a suitable means for the detection of drug residues in not only quarter and whole udder milk of cows but also in bulk tank and tank-lorry milk following reading times of 2.75 to 3.00 h.

Evaluation of the Delvo-X-Press Assay for Detecting Antibiotic Residues in Milk Samples from Individual Cows

1999 ◽  
Vol 62 (10) ◽  
pp. 1183-1190 ◽  
Author(s):  
APOSTOLOS S. ANGELIDIS ◽  
THOMAS B. FARVER ◽  
JAMES S. CULLOR
Keyword(s):  
False Positive ◽  
Bovine Lactoferrin ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Lactating Cows ◽  
Bovine Plasma ◽  
Positive Linear Correlation ◽  
Lactam Antibiotic ◽  
Bulk Tank ◽  
Positive Results

Performance of the Delvo-X-Press β-lactam antibiotic assay was examined using bulk-tank milk samples and milk samples from individual cows. Bulk-tank milk samples fortified with bovine lactoferrin at a concentration of 1 mg/ml or more consistently tested positive. False-positive results were also obtained from bulk-tank milk samples fortified with bovine plasma at concentrations of 20 and 40%. The assay yielded positive results for milk with antibiotic concentrations as low as 2 ppb. Individual milk samples were collected from 144 healthy lactating cows and from 34 cows with chronic Staphylococcus aureus mastitis. Specificity estimates for samples from healthy and mastitic cows were 0.88 (95% confidence interval [CI], 0.82, 0.93) and 0.94 (95% CI, 0.86, 1.00), respectively. Individual milk samples were collected from three cows with experimentally induced mastitis for 21 consecutive days. False-positive results occurred as late as 12 days postchallenge. A moderate but significant (P < 0.01) positive linear correlation (r = 0.61) was observed between test result and somatic cell count (SCC) values in milk samples with SCCs of >106/ml.

scholarly journals Rapid Detection of Mycoplasma bovis, Staphylococcus aureus and Streptococcus agalactiae in Cattle Bulk Tank Milk in Cyprus and Relations with Somatic Cell Counts

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 841
Author(s):  
Maria Liapi ◽  
George Botsaris ◽  
Costas Arsenoglou ◽  
Nikolas Markantonis ◽  
Christodoulos Michael ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Somatic Cell ◽  
Real Time ◽  
Streptococcus Agalactiae ◽  
Mycoplasma Bovis ◽  
Bulk Tank Milk ◽  
Somatic Cell Counts ◽  
Milk Samples ◽  
Cell Counts ◽  
Bulk Tank

One hundred and seventy-seven (177) bulk tank milk samples were analyzed with a commercially available real-time polymerase chain reaction kit and 11 (6.21%), 41 (23.16%), and 58 (32.77%) tested positive for Mycoplasma bovis, Staphylococcus aureus, and Streptococcus agalactiae, respectively. Statistical analysis revealed a significant relationship between the presence of S. aureus and S. agalactiae. Enumeration of somatic cells was performed in the same samples by flow cytometry. The somatic cell counts were found higher in S. aureus and S. agalactiae positive samples. No association was found between M. bovis presence and somatic cells counts. Low internal assay control Ct values were found to be related with high somatic cell counts. Noticeably, this is the first report for the presence of M. bovis in Cyprus. Therefore, its presence was confirmed by bulk tank milk culture, conventional PCR, and next generation sequencing. Furthermore, M. bovis was typed with multilocus sequencing typing and was allocated to sequence type 29 (ST 29). Real-time PCR in bulk tank milk samples is a useful tool to detect mammary infections, especially for neglected pathogens such as M. bovis.

Performance of Various Tests Used to Screen Antibiotic Residues in Milk Samples from Individual Animals

1994 ◽  
Vol 77 (4) ◽  
pp. 862-870 ◽  
Author(s):  
James S Cullor ◽  
Alison Van Eenennaam ◽  
Ian Gardner ◽  
Lynn Perani ◽  
Jon Dellbvger ◽  
...  
Keyword(s):  
False Positive ◽  
Dairy Industry ◽  
Initial Therapy ◽  
Treatment Withdrawal ◽  
Quality Assurance Program ◽  
Antibiotic Residues ◽  
Withdrawal Time ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Bulk Tank

Abstract The 10-point Milk and Dairy Beef Quality Assurance Program was developed collaboratively by the National Milk Producers Federation and the American Veterinary Medical Association and is designed to promote and document the responsible use of antibiotics in the dairy industry. One area of emphasis in this program is testing of individual animals for antibiotic residues after a specified post-treatment withdrawal time. We examined the performance of various assay systems on milk samples from individual cows. These assays are used at present on bulk tank milk samples by regulatory agencies, processing plants, producers, and veterinarians to detect the presence of β-lactam antibiotics. A high proportion of false-positive results was obtained for both the pretreatment milk samples from cows with clinical mastitis and the milk samples obtained 21 days after initial therapy (nonantibiotic and antibiotic) for the treatment of mastitis. A high proportion of false-positive outcomes was obtained from the milk of clinically normal cows that had not received any medication for at least 30 days prior to evaluation. The results indicate a serious problem in the use of some assays that were designed to evaluate residues bulk tank milk samples to analyze samples from individual cows. This error in assay specificity results in the unjustifiable discarding of milk that meets regulatory standards and may be misused to accuse the producer or veterinarian of not adhering to regulatory guidelines. Maintaining a safe, high-quality milk supply is a constant goal of the dairy industry, which must be provided the appropriate tools and techniques to meet this challenge.

Accuracy of BRT and Delvotest Microbial Inhibition Tests as Affected by Composition of Ewe's Milk

2003 ◽  
Vol 66 (3) ◽  
pp. 473-478 ◽  
Author(s):  
RAFAEL ALTHAUS ◽  
ANTONIO TORRES ◽  
CRISTOFOL PERIS ◽  
M. CARMEN BELTRAN ◽  
NEMESIO FERNANDEZ ◽  
...  
Keyword(s):  
False Positive ◽  
Total Solids ◽  
Somatic Cell Counts ◽  
Milk Samples ◽  
Microbial Inhibition ◽  
Cell Counts ◽  
Lactoperoxidase System ◽  
Antimicrobial Residues ◽  
Ewe's Milk ◽  
Positive Results

The presence of drug residues in ewe's milk samples can be determined by microbial assays. The main limitation of these tests is the large number of false-positive results associated with them. False-positive results can be explained by the interaction of certain substances naturally existing in ewe's milk with the growth of the microorganism used in the test. In this study, milk chemical composition (fat, protein, lactose, total solids), somatic cell counts (SCCs), free fatty acid concentrations, and lactoperoxidase system components were determined in order to investigate their influence on the rate of false-positive results for the BRT and Delvotest microbiological inhibitor tests. Milk samples were obtained after morning milking of Manchega ewes at 15, 30, 45, 60, 75, 90, 105, 120, and 135 days after parturition. The animals did not receive any kind of treatment or medicated feed throughout the experiment. The false-positive rates for BRT and Delvotest were 3.75 and 2.4%, respectively. When the logistic regression model was applied, the percentages of total solids for positive samples were significantly different from those for negative samples (16.90 versus 18.42% for BRT, 16.05 versus 18.45% for Delvotest), while the SCC logarithmic transformation was significantly higher for the positive samples than for the negative samples (5.38 versus 5.11 log units for BRT, 5.32 versus 5.11 log units for Delvotest). Moreover, Delvotest-positive samples exhibited thiocyanate concentrations higher than those of Delvotest-negative samples (8.18 mg/liter versus 6.85 mg/liter). Further analyses are needed to confirm the possible presence of antimicrobial residues in this particular type of milk sample.

Streptococcus spp. from bulk-tank milk and milking machine teatcups on small ruminant farms, and factors potentially associated with their isolation

2020 ◽  
Vol 87 (3) ◽  
pp. 277-281
Author(s):  
Dimitris C. Chatzopoulos ◽  
Daphne T. Lianou ◽  
Charalambia K. Michael ◽  
Dimitris A. Gougoulis ◽  
Vasia S. Mavrogianni ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Small Ruminant ◽  
Milk Composition ◽  
Cell Counting ◽  
Bulk Tank Milk ◽  
Milk Samples ◽  
Streptococcus Uberis ◽  
Cell Counts ◽  
Bulk Tank ◽  
Milking Machine

AbstractThe objectives of this work were (a) to determine the presence of streptococci in samples from small ruminant dairy farms (bulk-tank milk and, where possible, teatcup swabs), (b) to investigate the potential adverse effects of streptococci on milk quality and (c) to investigate the importance of some husbandry factors for the isolation of streptococci. Bulk-tank milk samples and teatcups swab samples were examined bacteriologically for the presence of streptococci. Somatic cell counting and milk composition measurements were also performed. The husbandry factors present in each farm were assessed for potential associations with the isolation of streptococci. Streptococci were isolated from milk samples from 31.4% of sheep and 17.4% of goat farms and from 4.8% of sheep and 5.9% of goat teatcups. Streptococci were isolated more frequently from the upper part than the lower part of teatcups: 5.0% vs. 1.9%. Most isolates (57.9%) were identified as Streptococcus uberis. Most isolates (68.4%) were slime-producing; slime-production was more frequent among isolates from teatcups (83.3%) than from bulk-tank milk (55.0%). Somatic cell counts and milk composition did not differ between farms in which streptococci were or were not isolated. Machine-milking was associated with the isolation of streptococci from bulk-tank milk samples. The initial stage of the milking period (first two months) was found to be associated with the isolation of streptococci from milking machine teatcups in sheep farms only.

Collaborative Study to Determine Effects of Milk Composition on Somatic Cell Counts

1990 ◽  
Vol 53 (1) ◽  
pp. 67-71 ◽  
Author(s):  
J. S. HOGAN ◽  
K. LARRY SMITH ◽  
D. A. TODHUNTER ◽  
P. S. SCHOENBERGER
Keyword(s):  
Somatic Cell ◽  
Protein Content ◽  
Collaborative Study ◽  
Fat Content ◽  
Cell Counting ◽  
Bulk Tank Milk ◽  
Somatic Cell Counts ◽  
Milk Samples ◽  
Cell Counts ◽  
Bulk Tank

Quarter, composite, and bulk tank milk samples were analyzed in a three laboratory collaborative study to determine the relationship of milk fat and protein content with milk somatic cell counts. Milk somatic cell counts were determined by two Coulter counters, a Fossomatic counter, and by direct microscopic somatic cell counting. In general, variability among somatic cell counts measured by different procedures was not related to protein or fat content of milk. The greatest percentage of variation between counts that could be explained by fat content of milk was 20.2% between a Coulter and direct microscopic somatic cell counts. The greatest percentage of variation between counts that could be explained by protein content of samples was 12.9% between a Coulter and Fossomatic counts. Breed of cow from which samples were collected also had little influence on differences among milk somatic cell counts. Differences among milk somatic cell counts due to counting methods did vary among quarter, composite, and bulk tank milk samples.

scholarly journals Comparative research of diagnostic efficiency of ELISA test systems of domestic and foreign production for Animal brucellosis diagnostics

2019 ◽  
pp. 63-68
Author(s):  
B. T. Stegniy ◽  
S. S. Drahut ◽  
V. A. Kutsenko ◽  
T. P. Ramazanova ◽  
N. V. Marchenko ◽  
...  
Keyword(s):  
Positive Result ◽  
Francisella Tularensis ◽  
False Positive ◽  
Elisa Test ◽  
Farm Animals ◽  
Specific Antibodies ◽  
Milk Samples ◽  
Maximum Value ◽  
Test Kit ◽  
Positive Results

The purpose of the work. Comparison the diagnostic ability of the ELISA test kits «DIA®-Brucella ab. combi-V» and «ID Screen® Brucellosis Serum Indirect Multi-species» for the detection of antibodies to brucellosis pathogens in various farm animals. Materials and methods. For the analysis there were used 29 positive samples to brucellosis with specific antibodies in different concentrations, 26 of which are serums (22 — from cattle, 2 — from pigs, 1 — from goat, 1 — from camel) and 3 — milk samples from cows. There were used 32 serums (23 — from cattle, 6 — from sheep, 2 — from pigs, 1 — from goat), and 2 milk samples from cows that don’t contain antibodies to brucellosis pathogens for determining the ability of test kits to detect correctly negative samples. There were also used serums from cattle containing antibodies that can lead to false positive results, 1 sample with antibodies to Francisella tularensis, 1 — to Yersinia 03 and 1 — to Yersinia 09. To compare the results in the two test kits, comparative ratios were used that allowed to determine how many times the result obtained in both test kits was higher or less than cut off, that differentiated positive samples from negative. Results of the work. When analyzing 22 cattle serums containing antibodies to B. abortus, the “DIA®-Brucella ab. combi-V” kit determined all samples positive with a results 5.3–10.6 times higher than cut off. The “ID Screen® Brucellosis Serum Indirect Multi-species” test kit identified only 18 positive serums with a maximum value of 1.3 above the cut off. The result of the analysis of 3 samples was doubtful and 1 serum was negative. When analyzing 4 sera from different animals containing antibodies to brucellosis pathogens, the “DIA®-Brucella ab. combi-V” test kit identified all positive samples with the results 8.1–9.4 times higher than cut off. The “ID Screen® Brucellosis Serum Indirect Multi-species” test kit detected specific antibodies in only 3 serums — from pigs and camel. When the goat serum was tested, a doubtful (uncertain) result of the analysis was obtained. When analyzing 3 milk samples from cows containing antibodies to B. abortus in different concentrations there was received a positive result to brucellosis in both test kits. However, ability of the “DIA®-Brucella ab. combi-V” test kit to detect specific antibodies was significantly higher than in comparison test kit. When investigating 32 serums from different animals and 2 milk samples that didn’t contain antibodies to the brucellosis pathogens, a negative result of the analysis was obtained in both test kits. When analyzing cattle serums containing antibodies that can lead to false positive results, both test kits identified 1 sample with antibodies to Francisella tularensis and 1 serum with antibodies to Yersinia 03 with negative result. When analyzing 1 serum with antibodies to Yersinia 09 the result of the analysis was false positive. Conclusions. Studies have shown that the “DIA®-Brucella ab. combi-V” test kit has a high diagnostic capacity. When analyzing 29 blood serums, including samples from different animals, and milk samples from cows containing antibodies to brucellosis pathogens, the test kit identified all samples as positive with results 5.3–10.8 times above the cut off. The “ID Screen® Brucellosis Serum Indirect Multi-species” test kit detected antibodies to brucellosis pathogens only in 24 samples with a maximum value 1.3 times higher than cut off. When investigating 4 serums, 3 samples of which are from cattle and 1 — from goat, the result of the analysis was doubtful (uncertain), 1 cattle serum was identified as negative. The ability of test kits to detect correctly negative samples was comparable. When analyzing 32 serums from different animals and 2 milk samples from cows that do not contain antibodies to brucellosis pathogens, in both test kits, a negative result of the analysis was obtained. For the 3 negative cattle serums, the analysis of which on brucellosis may be incorrect (the presence of antibodies to Yersinia О3, Yersinia О9, Francisella tularensis), in both test kits, for 1 sample with antibodies to Yersinia О9 a false positive result was obtained

scholarly journals Bulk tank milk somatic cell count and sources of raw milk contamination with mastitis pathogens

2008 ◽  
Vol 52 (No. 6) ◽  
pp. 223-230 ◽  
Author(s):  
D. Rysanek ◽  
V. Babak ◽  
M. Zouharova
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Bulk Tank Milk ◽  
Somatic Cell Counts ◽  
Milk Samples ◽  
Cell Counts ◽  
Milk Contamination ◽  
A Cell ◽  
Bulk Tank ◽  
Mastitis Pathogens

The objective of this study was to probe the relationship between prevalence of selected principal mastitis pathogens and somatic cell counts in bulk tank milk samples. The sources of milk contamination were evaluated. The samples were collected from 298 dairy herds (with approximately 32 000 dairy cows). Only 48.3% of the bulk tank milk samples were free of contamination of pathogens of interest. Approximately 38.9% of the milk samples were contaminated with only one, 12.4% with two and 0.3% with three pathogens. The arithmetic mean of logarithmically transformed data of bulk tank milk somatic cell count rise in order: pathogen free, <i>Pseudomonas aeruginosa</i>, <i>Streptococcus uberis</i>, <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> (5.381; 5.413; 5.495; 5.518; 5.563, respectively). The arithmetic mean differences between bulk tank milk somatic cell counts in pathogen-free and single-pathogen contaminated samples have revealed a significance for the <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> groups (<i>P</i> &lt; 0.01). Using binary logistic regression, a statistically highly significant relationship (<i>P</i> &lt; 0.001) has been found between the number of contaminations of bulk tank milk samples with mastitis pathogens and bulk tank milk somatic cell counts. The relationship allows the determination of the probability of finding relevant mastitis pathogens in bulk tank milk samples with different levels of bulk tank milk SCC. A 63% probability can be defined at a cell count level of 400 000/ml and 20% at a cell count level of 100 000/ml. Analysis may reveal the potential sources of the bulk tank milk sample contamination, i.e. infected mammary glands or the environment. The presence of high levels of contamination along with a low bulk tank SCC may suggest an environmental source of contamination. The study clarified that a potential source of bulk tank milk contamination by relevant pathogens (the environment or the mammary gland) may be elucidated and the probability of the contamination of bulk tank milk samples with mastitis pathogens predicted by the analysis of relationship between the bulk tank milk somatic cell counts and the number of mastitis pathogen contaminations.

scholarly journals Crispr-cas 12a combination to alleviate the false-positive in loop-mediated isothermal amplification-based diagnosis of Neisseria meningitidis

2020 ◽  
Author(s):  
Ngo Tat Trung ◽  
Le Huu Phuc Son ◽  
Trinh Xuan Hien ◽  
Dao Thanh Quyen ◽  
Mai Hong Bang ◽  
...  
Keyword(s):  
Positive Result ◽  
Diagnostic Tool ◽  
False Positive ◽  
Isothermal Amplification ◽  
False Positive Result ◽  
Proof Of Concept ◽  
Specific Sequence ◽  
Neisseria Meningitides ◽  
Rna Sensors ◽  
Positive Results

Abstract Loop mediated Isothermal amplicafication (LAMP) was recently suggested as a diagnostic tool for the identification of Neisseria meningitides. Howevere, this isothermal amplification is challenged by the fact its amplification leads to risks of obtaining false-positive results. Whereas, with abilities to accurately recognize specific sequence, the CRISPR/Cas12a can forms complexes with cognate RNA sensors and cleave pathogen’s DNA targets complimerntary to its cognate RNA and acquires collateral activity to unbiasedly cut nearby off-target fragments. Therefore, if relevant fluorescent-quencher-nucleic probes are present in the reaction, the non-specific cleavage of probes releases fluorescences and establish diagnostic read-outs. In this study, we demonstrate a proof-of-concept that in relevant biochemical conditions, CRISPR/Cas12a and LAMP can work synchronously to identify genetics materials of Nesseria menitigistis at the level of 0.00004% in less than 2 h. Additionally, our clinical data also showed that the combinatory of CRISPR/Cas12a help to alleviate false positive result therefore enhance the specificity gained by the LAMP assays.

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