Molecular biological tools applied for identification of mastitis causing pathogens

Abstract

The molecular diagnostic tools became the gold standard of mastitis diagnosis in the last few years. They enable rapid, qualitative, quantitative and large scale diagnosis. In addition to their role in diagnosis, they can identify pathogens at the subspecies level which is necessary for the epidemiological studies. They are increasingly used in mastitis control programs through identification of suitable candidates for vaccine production and through the selection of mastitis resistant cattle breeds. The present molecular techniques are continuously improved and new techniques are developed in order to provide higher sensitivity and specificity and to minimize the costs. The present work aims to provide an overview of the modern molecular tools, discuss why they replaced the traditional tools and became the new gold standard in mastitis diagnosis through comparing both traditional and molecular tools, explore the prospective of the molecular diagnostic techniques in mastitis diagnosis and control and to explore new horizons of using molecular assays in near future.

Test Agreement among Biochemical Methods, Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry, and 16S rRNA Sequencing for Identification of Microorganisms Isolated from Bovine Milk

“…This was a study of test agreement rather than of test accuracy (sensitivity and specificity). This is because there is no agreed-upon gold standard for "true" bacterial or yeast identification (4,5). No culture-negative samples were included.…”

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

“…Contagious mastitis is caused by bacterial species living on the udder skin and/or in the infected udder, such as Staphylococcus aureus , Streptococcus agalactiae and Mycoplasma bovis . On the other hand, the majority of environmental mastitis is caused by bacterial species present in the intestinal and faecal microbiota, such as Escherichia coli , Klebsiella sp., Enterobacter sp., Streptococcus uberis and Streptococcus dysgalactiae (El‐Sayed et al, ). The former bacterial species are more frequently associated with chronic inflammation and subclinical mastitis with high somatic cell counts (SCC) and drop in milk production whereas the latter most often cause acute inflammation and clinical mastitis, coupled with macroscopic alteration of the milk (Gussmann et al, ).…”

“…The former bacterial species are more frequently associated with chronic inflammation and subclinical mastitis with high somatic cell counts (SCC) and drop in milk production whereas the latter most often cause acute inflammation and clinical mastitis, coupled with macroscopic alteration of the milk (Gussmann et al, ). Nevertheless several other bacterial species of environmental origin can also be associated with subclinical mastitis, such as different non‐ aureus staphylococci, nonclassical streptococci/enterococci or corynebacteria (Reyher et al, ; El‐Sayed et al, ). The consequence of mastitis is high financial costs due to decreased milk production, penalty for high SCC (>4·10 5 cells per ml), application of different antibiotic treatments and the culling of incurable cases (Yalcin et al, ; Halasa et al, ; Reyher et al, ; Ashraf and Imran, ).…”

“…Today, several dairy routine diagnostic laboratories resort to genetic assays, mainly multiplex quantitative (q)PCR assays, that can be applied directly to milk samples skipping the step of growing the bacteria present in the samples. Though qPCR assay kits detect a limited number of bacterial species, these are the most frequent and pathogenic ones (Koskinen et al, ; Cederlöf et al, ; El‐Sayed et al, ).…”

Novel Biomarkers of Mastitis in Goat Milk Revealed by MALDI-TOF-MS-Based Peptide Profiling

“…However, the outcome and interpretation of these diagnostic tests were neither reliable nor specific or confirmatory [26,27]. Recently, molecular diagnostics [28] including PCR [29], qRT-PCR [30], loop-mediated isothermal amplification [31,32], nucleotide sequencing [33] and lateral flow assays [34] were used for overcoming above-mentioned shortcomings and for specific diagnosis of mastitis in bovine and goat. However, accuracy, sensitivity and specificity remain the main concern for all such tests [25,35].…”