Latent class analysis of real time qPCR and bacteriological culturing for the diagnosis of Streptococcus agalactiae in cow composite milk samples

2018 ◽  
Vol 154 ◽  
pp. 119-123 ◽  
Author(s):  
Ingrid H. Holmøy ◽  
Nils Toft ◽  
Hannah J. Jørgensen ◽  
Tormod Mørk ◽  
Liv Sølverød ◽  
...  
Keyword(s):  
Latent Class Analysis ◽  
Real Time ◽  
Streptococcus Agalactiae ◽  
Latent Class ◽  
Class Analysis ◽  
Milk Samples ◽  
Real Time Qpcr

Comparison of an on-farm point-of-care diagnostic with conventional culture in analysing bovine mastitis samples

2019 ◽  
Vol 86 (2) ◽  
pp. 222-225 ◽  
Author(s):  
Geoff Jones ◽  
Olaf Bork ◽  
Scott A Ferguson ◽  
Andrew Bates
Keyword(s):  
Latent Class Analysis ◽  
Latent Class ◽  
Point Of Care ◽  
Bacterial Species ◽  
Class Analysis ◽  
Sensitivity Testing ◽  
Milk Samples ◽  
Streptococcus Uberis ◽  
Standard Culture ◽  
On Farm

AbstractThe performance of a new point-of-care diagnostic (Mastatest), an on-farm test designed to identify bacteria and provide antibiotic sensitivity testing information from milk samples, was compared with standard microbiological culture methods. A total of 292 milk samples from clinical mastitis cases in dairy cows on New Zealand dairy farms were examined, and latent class analysis was used to estimate the performance characteristics of both tests. Two hundred and fifty-six samples (87.7%) demonstrated bacterial infection in standard culture, and 269 (92.1%) using the point-of-care diagnostic. The most common bacterial species detected was Streptococcus uberis, found in 195 samples (66.8%) using standard culture and 190 samples (65.1%) using the point-of-care diagnostic. Latent class analysis found no significant differences in test characteristics between the point-of-care diagnostic and standard culture. The estimated sensitivity and specificity of the point-of-care diagnostic against all targets combined were 94.6 and 72.1% respectively; the corresponding estimates for standard culture were 90.5 and 73.9%. Comparison of antibiotic susceptibility testing using the point-of-care diagnostic and the reference method showed similar trends and, in some cases, identical MIC50 and MIC90 values, with at most one antibiotic dilution difference.

scholarly journals Comparison of two commercial and one in-house real-time PCR assays for the diagnosis of bacterial gastroenteritis

2020 ◽  
Vol 10 (4) ◽  
pp. 210-216
Author(s):  
Konstantin Tanida ◽  
Andreas Hahn ◽  
Hagen Frickmann
Keyword(s):  
Latent Class Analysis ◽  
Real Time ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Latent Class ◽  
Class Analysis ◽  
Cohen's Kappa ◽  
Bacterial Gastroenteritis ◽  
Pcr Assays ◽  
Inter Assay Variation

AbstractIntroductionThe aim of the study was a comparative evaluation of in-house real-time PCR and commercial real-time PCR (Fast Track Diagnostics (FTD), ampliCube/Mikrogen) targeting enteropathogenic bacteria from stool in preparation of Regulation (EU) 2017/746 on in vitro diagnostic medical devices.MethodsBoth 241 stool samples from patients and 100 samples from German laboratory control schemes (“Ringversuche”) were used to comparatively assess in-house real-time PCR, the FTD bacterial gastroenteritis kit, and the ampliCube gastrointestinal bacterial panels 1&2 either with the in-house PCRs as gold standard and as a test comparison without gold standard applying latent class analysis. Sensitivity, specificity, intra- and inter-assay variation and Cohen’s kappa were assessed.ResultsIn comparison with the gold standard, sensitivity was 75–100% for strongly positive samples, 20–100% for weakly positive samples, and specificity ranged from 96 to 100%. Latent class analysis suggested that sensitivity ranges from 81.2 to 100% and specificity from 58.5 to 100%. Cohen’s kappa varied between moderate and nearly perfect agreement, intra- and inter-assay variation was 1–3 to 1–4 Ct values.ConclusionAcceptable agreement and performance characteristics suggested replaceability of the in-house PCR assays by the commercial approaches.

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