Interlaboratory Proficiency Testing as a Tool for Improving Performance in Laboratories Diagnosing Bovine Mastitis

Pitkälä, Anna; Gindonis, Veera; Wallin, Harriet; Honkanen-Buzalski, T.

doi:10.3168/jds.s0022-0302(05)72717-x

Cited by 20 publications

(20 citation statements)

References 12 publications

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“…In general, PCR testing has proven to be a fast, sensitive and reliable test suitable for routine mastitis bacteriology [24, 28, 32]. An advantage of the PCR test is the comprehensive panel of pathogens, and uniform procedure and interpretation, in contrast to bacteriological culturing, where performance and procedures of laboratories may differ [33]. High costs of molecular methods such as PCR may still limit their use for mastitis diagnostics in many countries.…”

Section: Discussionmentioning

confidence: 99%

Bacteriological etiology and treatment of mastitis in Finnish dairy herds

et al. 2017

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BackgroundThe Finnish dairy herd recording system maintains production and health records of cows and herds. Veterinarians and farmers register veterinary treatments in the system. Milk samples for microbiological analysis are routinely taken from mastitic cows. The laboratory of the largest dairy company in Finland, Valio Ltd., analyzes most samples using real-time PCR. This study addressed pathogen-specific microbiological data and treatment and culling records, in combination with cow and herd characteristics, from the Finnish dairy herd recording system during 2010–2012.ResultsThe data derived from 240,067 quarter milk samples from 93,529 dairy cows with mastitis; 238,235 cows from the same herds served as the control group. No target pathogen DNA was detected in 12% of the samples. In 49% of the positive samples, only one target species and in 19%, two species with one dominant species were present. The most common species in the samples with a single species only were coagulase-negative staphylococci (CNS) (43%), followed by Staphylococcus aureus (21%), Streptococcus uberis (9%), Streptococcus dysgalactiae (8%), Corynebacterium bovis (7%), and Escherichia coli (5%). On average, 36% of the study cows and 6% of the control cows had recorded mastitis treatments during lactation. The corresponding proportions were 16 and 6% at drying-off. For more than 75% of the treatments during lactation, diagnosis was acute clinical mastitis. In the milk samples from cows with a recorded mastitis treatment during lactation, CNS and S. aureus were most common, followed by streptococci. Altogether, 48% of the cows were culled during the study. Mastitis was reported as the most common reason to cull; 49% of study cows and 18% of control cows were culled because of mastitis. Culling was most likely if S. aureus was detected in the milk sample submitted during the culling year.ConclusionsThe PCR test has proven to be an applicable method also for large-scale use in bacterial diagnostics. In the present study, microbiological diagnosis was unequivocal in the great majority of samples where a single species or two species with one dominating were detected. Coagulase-negative staphylococci and S. aureus were the most common species. S. aureus was also the most common pathogen among the culled cows, which emphasizes the importance of preventive measures.

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Section: Discussionmentioning

confidence: 99%

Bacteriological etiology and treatment of mastitis in Finnish dairy herds

et al. 2017

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“…For the sophisticated value of this access it became a part of the AQA (analytical quality assurance) systems of milk laboratories as well as their accreditation processes and audits. Different basic accesses and processes were published (Arndt et al, 1991;Leray, 1993;Heeschen et al, 1994;Wood, 1994;Pitkälä et al, 2005).…”

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confidence: 99%

Relationships between the results of various methods of urea analysis in native and enriched milk

Hering¹,

Hanuš²,

Frelich³

et al. 2008

Czech J. Anim. Sci.

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Milk urea concentration (MUC) is a suitable indicator of the health and nutrition state of dairy cows. MUC is in relation to their reproduction performance, longevity and technological milk indicators. The interpretation correctness of results depends on their reliability. There are a lot of principles of MUC analyses. Their results can be affected by a number of interferential factors. Disproportions were noticed in practice. Therefore the sources of variation in results are studied. The goal of this study was to investigate relationships between different methods of MUC determination with the use of standard samples of native milk with an artificial urea addition. After evaluation I (n = 7) the results of methods BI-1 and BI-2 (photometrical ones with diacetylmonoxime) were disqualified because of poor recovery (R), poor correlation (C) with other methods, higher random error (RER) and highest systematic error (SE). Evaluation II is more effective with stricter discrimination limits. Cs of all methods mutually (0.977 up to 0.998; P < 0.001) confirmed the methods as effective with the exception of BI-2 with poor Cs (0.713 up to 0.774), poor R (16.0 up to 69.0%) and high RER ±5.292 mg/100 ml. R of better methods was 44.0 up to 96.7%. The BI-1 method had good Cs (0.986 up to 0.994; P < 0.001), higher SE -7.546 mg/100 ml and poorer R (48.5 up to 75.3%). BI-1 method was a case of mistaken performance. BI method could be improved by the use of more samples in calibration. FT-MIR method (infra-analysis) has good addition R 69.5 up to 95.0% and Cs 0.981 up to 0.994 (P < 0.001). EH method (photometrical one with Ehrlich's agent) has good R 59.0 up to 96.7%, higher SE 4.755 (I) and 2.556 (II) mg/100 ml and close Cs 0.977 up to 0.994 (P < 0.001). UR method (ureolytical difference-conductometric) showed the best combination of results about R, C, SE and RER. MUC measurement was almost independent of fat in milk (r = 0.16 for UR and 0.01 for FT-MIR; P > 0.05) and MUC of both the methods did not increase significantly with lactose increase (r = 0.16 and 0.27; P > 0.05), which increased logically (r = -0.88; P < 0.001) during the fat concentration increase. The relationship of MUC results between UR and FT-MIR was significant (validation r = 0.96; P < 0.001) at average difference -0.93 ± 1.663 mg/100 ml. It is possible to see the result reliability as good after calibration performance of FT-MIR according to results of UR. It is not necessary to see the effects of fat, protein and lactose on MUC methods as substantial. FT-MIR method for MUC has good result reliability at the use of native milk samples, incidentally with urea additions. It is suitable to calibrate the FT-MIR method according to specific determination of MUC (UR). However, the most important for elimination of disproportions is the calibration method with concrete audited R, though nonspecific.

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“…isolation and identification of bacteria. Further, phenotyping methods are time consuming, have low sensitivity, lack interlaboratory standardization, and are not highly reliable (Pyöralä and Mattila, 1987;Sears et al, 1990;Phuektes et al, 2001;Pitkälä et al, 2005;Suojala et al, 2008), necessitating the development of better tests.…”

Section: Differentiation Of Staphylococcus Aureus and Staphylococcus mentioning

confidence: 99%

“…However, 30 to 50% of mastitic milk samples may not show any bacterial growth under conventional culture conditions (Dinsmore et al, 1992;Makovec and Ruegg, 2003;Bradley et al, 2007;Olde Riekerink et al, 2008;Taponen and Pyörälä, 2009). In addition, phenotypic methods have poor discriminatory power, as they frequently misidentify species due to overlapping phenotypes (Renneberg et al, 1995;Rhoden and Miller, 1995;Pitkälä et al, 2005;Zadoks and Watts, 2009).…”

Section: Differentiation Of Staphylococcus Aureus and Staphylococcus mentioning

confidence: 99%

Differentiation of Staphylococcus aureus and Staphylococcus epidermidis by PCR for the fibrinogen binding protein gene

Sunagar¹,

Deore²,

Deshpande

et al. 2013

Journal of Dairy Science

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Mastitis is one of the most common and burdensome diseases afflicting dairy animals. Among other causes of mastitis, staphylococci are frequently associated with clinical and subclinical mastitis. Although Staphylococcus aureus is the predominant species involved, Staphylococcus epidermidis and other coagulase-negative staphylococci are increasingly being isolated from cases of bovine mastitis. Although Staph. aureus and Staph. epidermidis can be easily differentiated based on their biochemical properties, such phenotypic identification is time consuming and laborious. This study aimed to rapidly identify Staph. aureus and Staph. epidermidis. Accordingly, a multiplex PCR was developed and we found that a single gene encoding the adhesin fibrinogen binding protein could be used to identify and differentiate the two species. Consequently, a multiplex reaction combining a triplex PCR for Staph. aureus and a duplex PCR for Staph. epidermidis was standardized, first using bacterial cultures and then with pasteurized milk spiked with live organisms or DNA extracted from the organisms. The test could specifically detect Staph. aureus and Staph. epidermidis even in the presence of a dozen other organisms. The limit of detection for detecting Staph. aureus and Staph. epidermidis separately was 10 to 100 cfu/mL for simplex PCR and 10 4 cfu/mL for multiplex PCR. Conversely, the limit was 10 6 cfu/ mL by multiplex PCR for simultaneous detection of both the organisms when spiked into culture medium or pasteurized milk. Overnight enrichment enhanced the assay sensitivity 100-fold. The assay had a high diagnostic sensitivity and specificity. The application of the test was verified on 602 field isolates of staphylococci that had been characterized earlier by phenotypic methods. Importantly, 25 coagulase-negative isolates were identified as Staph. aureus by the multiplex PCR. The test could be adapted for use in clinical diagnostic laboratories.

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Interlaboratory Proficiency Testing as a Tool for Improving Performance in Laboratories Diagnosing Bovine Mastitis

Cited by 20 publications

References 12 publications

Bacteriological etiology and treatment of mastitis in Finnish dairy herds

Bacteriological etiology and treatment of mastitis in Finnish dairy herds

Relationships between the results of various methods of urea analysis in native and enriched milk

Differentiation of Staphylococcus aureus and Staphylococcus epidermidis by PCR for the fibrinogen binding protein gene

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