Frequency of non-aureus staphylococci and mammaliicocci species isolated from quarter clinical mastitis: A 6-year retrospective study

Non-aureus staphylococci and mammaliicocci (NASM) are the most frequently isolated bacterial group from bovine milk samples. Most studies focus on subclinical mastitis caused by NASM; however, NASM can cause clinical mastitis (CM) as well. We evaluated retrospective data from 6 years (2017-2022) to determine the species and frequency of NASM isolated from quarter bovine CM. The data was comprised of microbiological results from quarter CM samples routinely submitted to Quality Milk Production Services at Cornell University for microbial identification by MALDI-TOF mass spectrometry. A total of 9,909 microbiological results from 410 dairy herds were evaluated. Our results showed that 29 distinct NASM species were identified, with the 8 most prevalent NASM species being Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus simulans, Staphylococcus epidermidis, Staphylococcus sciuri (now Mammaliicoccus sciuri), Staphylococcus agnetis/Staphylococcus hyicus, Staphylococcus borealis, and Staphylococcus xylosus. The NASM distribution remained similar among seasons, but the frequency of NASM CM cases was higher during the summer. Our results showed different patterns of variations in the isolation frequency over time, depending on the bacterial species: increasing or decreasing trends, cyclic fluctuations, and, except for Staphylococcus borealis, a significant seasonality effect for our study's most prevalent NASM. This study showed that Staphylococcus chromogenes remains the most frequent (43%) NASM species identified from bovine CM, followed by Staphylococcus haemolyticus (18%), and Staphylococcus simulans (12%).

Genomic Characterization of Mycoplasma arginini Isolated from a Housefly on a Dairy Farm and Comparison with Isolates from Bovine Milk and Lung Tissue

Mycoplasma mastitis can be highly contagious, unresponsive to treatment, and cause severe economic problems in affected herds. Notable routes of Mycoplasma spp. transmissions are contaminated milking equipment and animal contact through respiratory secretions. Only a few studies report the environment as a possible source of infection. Our group studied the presence of pathogens in houseflies (Musca domestica) in a New York State dairy in the United States. Among others, a Mycoplasma spp. was found in the gut of a housefly captured in the sick pen and identified as M. arginini. Here, we characterized its genome and investigated its relatedness with eight isolates from milk, one isolate from lung tissue collected in the same dairy, and five other dairies in New York State. We applied whole-genome sequencing and phylogenetic analysis based on the sequences of the 16S rRNA gene and 76 conserved proteins. We also assessed an in silico virulence profile by considering a panel of 94 putative virulence genes. As a result of the genome analysis, the housefly M. arginini isolate was highly similar to the milk isolates; interestingly, the similarity was highest with M. arginini isolated from milk on the same dairy farm where the housefly was captured. The housefly and milk M. arginini isolates possessed 54 of the 94 pathogenicity genes considered. Our data support the hypothesis that houseflies are carriers of Mycoplasma spp. and can be considered within the possible roots of environmental transmission of infection in dairy cows. Nevertheless, M. arginini pathogenicity will need to be investigated with dedicated studies. IMPORTANCE It is critical to control the spread of bovine mastitis caused by Mycoplasma spp., as this disease can be highly contagious and have a severe economic impact on affected dairies. A better understanding of possible transmission routes is crucial for infection control and prevention. Based on our data, the composite milk isolates are genetically similar to the housefly isolate. This provides evidence that the same Mycoplasma species found in milk and associated with mastitis can also be isolated from houseflies captured in the dairy environment.

The untargeted lipidomic profile of quarter milk from dairy cows with subclinical intramammary infection by non-aureus staphylococci

This observational study determined the lipidome of cow milk during subclinical intramammary infection (IMI) by non-aureus staphylococci (NAS), also defined as coagulase-negative staphylococci, using an untargeted approach. Among the pathogens causing bovine IMI, NAS have become the most frequently isolated bacteria from milk samples. Although the application of system biology approaches to mastitis has provided pivotal information by investigating the transcriptome, proteome, peptidome, and metabolome, the milk lipidome during mammary gland inflammation remains undisclosed. To cover this gap, we determined the milk lipidome of 17 dairy cows with IMI caused by NAS (NAS-IMI), and we compared the results with those of healthy quarter milk from 11 cows. The lipidome was determined following a liquid chromatography-quadrupole time-of-flight mass spectrometry approach. Sixteen subclasses of lipids were identified in both groups of animals. From 2,556 measured lipids, the abundance of 597 changed more than 10-fold in quarter milk with NAS-IMI compared with healthy quarters. The results demonstrate the influence of NAS-IMI on the milk lipidome, implying significant changes in lipid species belonging to the family of triacylglycerols and sphingomyelins, and contribute to the understanding of inflammatory processes in the bovine udder, highlighting potential novel biomarkers for improving mastitis diagnostics.

Mycoplasma species isolated from bovine milk collected from US dairy herds between 2016 and 2019

Determining the species of mycoplasma isolated from culture-positive milk samples is important for understanding the clinical significance of their detection. Between August 2016 and December 2019, 214,518 milk samples from 2,757 dairy herds were submitted to Quality Milk Production Services (QMPS) at Cornell University for mycoplasma culture. From these samples, 3,728 collected from 204 herds were culture positive. Based on the request of herd managers, owners, or veterinarians, 889 isolates from 98 herds were subjected to molecular identification by PCR and amplicon sequencing. The largest proportion of the identified isolates were from New York State (78.1%), while the others came from the eastern United States (17.8%), Texas (2.0%), and New Mexico (2.1%). As expected, Mycoplasma spp. were the most common (855 isolates, 96.2%) and Acholeplasma spp. accounted for the remainder (34 isolates, 3.8%). Mycoplasma bovis was the most prevalent Mycoplasma species (75.1%), followed by M. bovigenitalium (6.5%), M. canadense (5.9%), M. alkalescens (5%), M. arginini (1.7%), M. californicum (0.1%), and M. primatum (0.1%). A portion of the isolates were confirmed as Mycoplasma spp. other than M. bovis but were not identified at the species level (16 isolates, 1.8%) because further information was not requested by the manager, owner, or veterinarian. Mycoplasma bovis was the only species identified in 59 of the 98 herds. However, more than 1 Mycoplasma sp. was identified in 29 herds, suggesting that herd infection with 2 or more mycoplasmas is not uncommon. Moreover, a Mycoplasma sp. other than M. bovis was the only species identified in 8 herds. From the subset of 889 mycoplasma culture-positive isolates from 98 herds, we determined that over a third of the herds had either more than 1 Mycoplasma sp. or a Mycoplasma sp. other than M. bovis detected in their milk samples. In conclusion, we observed that M. bovis is the most common pathogenic Mycoplasma species found in mastitic milk, but other Mycoplasma species are not uncommon. Our results suggest that it is critical to test milk samples for mycoplasmas using diagnostic tests able to identify both the genus and the species.

The value of the biomarkers cathelicidin, milk amyloid A, and haptoglobin to diagnose and classify clinical and subclinical mastitis

Timely and objective diagnosis and classification of mastitis is crucial to ensure adequate management and therapeutic decisions. Analyzing specific biomarkers in milk could be advantageous compared with subjective or semiquantitative criteria, such as palpation of the udder in clinical mastitis cases or evaluation of somatic cell count using cow side tests (e.g., California Mastitis Test) in subclinical mastitis quarters. The objective of this study was to investigate the diagnostic value of 3 biomarkers; cathelicidin, milk amyloid A, and haptoglobin for the diagnosis of subclinical and clinical mastitis. Furthermore, the suitability of these biomarkers to differentiate between mild, moderate, and severe clinical mastitis and the influence of different pathogens on biomarker levels was tested. A total of 67 healthy cows, 119 cows with subclinical mastitis, and 212 cows with clinical mastitis were enrolled in the study. Although cathelicidin, haptoglobin, and milk amyloid A were measured in all samples from healthy cows and those with subclinical mastitis, haptoglobin, and cathelicidin results were only available from 121 out of 212 cows with clinical mastitis. Milk amyloid A was measured in all samples. In cows with clinical mastitis, the mastitic quarter and a second healthy quarter serving as a healthy in-cow control quarter were sampled. It was possible to differentiate between healthy quarters, quarters with subclinical mastitis, and quarters with clinical mastitis using all 3 biomarkers. Concerning cathelicidin, thresholds were 0.000 [sensitivity (Se) = 0.83, specificity (Sp) = 0.97] and 0.053 (Se = 0.98, Sp = 0.99) for normalized optical density at 450 nm (NOD450) for differentiating between healthy quarters and quarters with subclinical or clinical mastitis, respectively. Thresholds of 1.28 µg/mL (Se = 0.65, Sp = 0.76) and 1.81 µg/mL (Se = 0.77, Sp = 0.83) for milk amyloid A and 3.65 µg/mL (Se = 0.92, Sp = 0.94) and 5.40 µg/mL mL (Se = 0.96, Sp = 0.99) for haptoglobin were calculated, respectively. Healthy in-cow control quarters from cows with CM showed elevated milk amyloid A and haptoglobin levels compared with healthy quarters from healthy cows. Only the level of milk amyloid A was higher in severe clinical mastitis cases compared with mild ones. In contrast to clinical mastitis, cathelicidin and haptoglobin in subclinical mastitis quarters were significantly influenced by different bacteriological results. The measurement of cathelicidin, milk amyloid A, and haptoglobin in milk proved to be a reliable method to detect quarters with subclinical or clinical mastitis.

Liver proteome dataset of Sparus aurata exposed to low temperatures

We report the proteomic dataset of livers from Sparus aurata exposed to low temperature during growth. Gilthead sea bream juveniles were reared in Recirculating Aquaculture Systems (RAS) and exposed to a temperature ramp made of two phases of four weeks each: a Cooling phase from 18 °C (t0) to 11 °C (t1) and a Cold Maintenance phase at 11 °C (t1-t2) in a 8 week feeding trial. At the end of the experiment, sea bream livers were collected and analyzed with a shotgun proteomics approach based on filter-aided sample preparation followed by tandem mass spectrometry, peptide identification carried out using Sequest-HT as search engine within the Proteome Discoverer informatic platform, and label-free differential analysis.

The mass spectrometry data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD011059 (Vizcaíno et al., 2016; Deutsch et al., 2017; Perez-Riverol et al., 2016). The dataset described here is also related to the research article entitled “Liver proteomics of gilthead sea bream (Sparus aurata) exposed to cold stress” (Ghisaura et al., 2019).

Liver proteomics of gilthead sea bream (Sparus aurata) exposed to cold stress

The gilthead sea bream (Sparus aurata, L.) is very sensitive to low temperatures, which induce fasting and reduced growth performances. There is a strong interest in understanding the impact of cold on fish metabolism to foster the development and optimization of specific aquaculture practices for the winter period. In this study, an 8 week feeding trial was carried out on gilthead sea bream juveniles reared in a Recirculated Aquaculture System (RAS) by applying a temperature ramp in two phases of four weeks each: a cooling phase from 18 °C to 11 °C and a cold maintenance phase at 11 °C. Liver protein profiles were evaluated with a shotgun proteomics workflow based on filter-aided sample preparation (FASP) and liquid chromatography-mass spectrometry (LC-ESI-Q-TOF MS/MS) followed by label-free differential analysis. Along the whole trial, sea breams underwent several changes in liver protein abundance. These occurred mostly during the cooling phase when catabolic processes were mainly observed, including protein and lipid degradation, together with a reduction in protein synthesis and amino acid metabolism. A decrease in protein mediators of oxidative stress protection was also seen. Liver protein profiles changed less during cold maintenance, but pathways such as the methionine cycle and sugar metabolism were significantly affected. These results provide novel insights on the dynamics and extent of the metabolic shift occurring in sea bream liver with decreasing water temperature, supporting future studies on temperature-adapted feed formulations. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD011059.

Evaluation of milk cathelicidin for detection of bovine mastitis

Mastitis due to intramammary infection is one of the most economically relevant diseases in dairy cows, causing reductions in milk quality and quantity. Currently, mastitis monitoring is based on somatic cell count (SCC) and bacteriologic culture (BC) of milk. Nevertheless, inflammation-specific protein markers might provide more sensitive and reliable assays, enabling immunoassay-based screening strategies. Cathelicidin is an inflammatory protein released in milk that has recently demonstrated fair reliability and diagnostic potential for ewe mastitis. To assess its performance in cows, 531 quarter milk samples from 2 herds were tested using cathelicidin ELISA, SCC, and BC. We found that 29.0% of samples were positive for cathelicidin, 18.8% had SCC >200,000 cells/mL, and 13.7% were BC-positive. Cathelicidin showed a strong positive correlation with SCC as demonstrated by receiver operating characteristics curve analysis and by the clustering of cathelicidin-negative and cathelicidin-positive samples in association with low and high SCC values, respectively. For evaluating the diagnostic performance of a novel test, BC cannot be considered a reliable gold standard for true disease status because of its known limitations. Therefore, we assessed the sensitivity (Se) and specificity (Sp) of the milk cathelicidin ELISA using a latent class analysis approach together with BC and SCC by considering different diagnostic thresholds to identify the preferred Se/Sp combination. We modeled conditional dependence of cathelicidin and SCC to account for their close association. The cathelicidin ELISA showed higher Se than SCC and BC for almost all threshold combinations. In fact, at the best-performing threshold combination, the Se of cathelicidin was 80.6%, 6.2 percentage points higher than that of SCC >200,000 cells/mL (74.4%) and similar to that of SCC >100,000 cells/mL (80.2%). Most importantly, this Se was obtained with a loss in Sp of only 1.4 percentage points compared with SCC >200,000 cells/mL (94.9% Sp for cathelicidin vs. 96.3% for SCC >200,000). The limited Se of BC (38.8%) was also confirmed in this study, and BC showed a slightly lower Sp than both cathelicidin and SCC for most of threshold combinations. This study confirmed that cathelicidin is released in the milk of cows with mastitis and that its presence is highly correlated with SCC. The measurement of cathelicidin by ELISA may hold significant potential for improving the sensitivity of mastitis detection in dairy cows while maintaining high specificity.

The bovine milk microbiota: insights and perspectives from -omics studies

Recent findings and future perspectives of -omics studies on the bovine milk microbiota, focusing on its impact on animal health.

Effect of whey concentration on protein recovery in fresh ovine ricotta cheese

Ricotta cheese, particularly the ovine type, is a typical Italian dairy product obtained by heat-coagulation of the proteins in whey. The aim of this work was to investigate the influence of whey protein concentration, obtained by ultrafiltration, on yield of fresh ovine ricotta cheese. Ricotta cheeses were obtained by thermocoagulation of mixtures with protein content of 1.56, 3.10, 4.16, and 7.09g/100g from the mixing of skim whey and ultrafiltered skim whey. A fat-to-protein ratio of 1.1 (wt/wt) was obtained for all mixtures by adding fresh cream. The initial mixtures, as well as the final ricotta cheeses, were analyzed for their composition and by SDS-PAGE. Protein bands were quantified by QuantityOne software (Bio-Rad, Hercules, CA) and identified by liquid chromatography-tandem mass spectrometry. Significant differences in the composition of the ricotta cheese were observed depending on protein concentration. Particularly, ricotta cheese resulting from the mixture containing 7.09g/100g of protein presented higher moisture (72.88±1.50g/100g) and protein (10.18±0.45g/100g) contents than that prepared from the mixture with 1.56g/100g of protein (69.52±1.75 and 6.70±0.85g/100g, respectively), and fat content was lower in this sample (12.20±1.60g/100g) compared with the other treatments, with mean values between 15.72 and 20.50g/100g. Each protein fraction presented a different behavior during thermocoagulation. In particular, the recovery of β-lactoglobulin and α-lactalbumin in the cheese increased as their content increased in the mixtures. It was concluded that concentrating ovine rennet whey improved the extent of heat-induced protein aggregation during the thermal coagulation process. This resulted in a better recovery of each protein fraction in the product, and in a consequent increase of ricotta cheese yield.

Identification and characterization of novel Mycoplasma spp. belonging to the hominis group from griffon vultures

Mycoplasmas are commensals and pathogens of various avian species, and are also regularly found in birds of prey, although their significance to birds' health remains unclear. Here we describe two novel Mycoplasma isolated from the upper respiratory tract of four Eurasian griffon vultures (Gyps fulvus) housed in a wildlife recovery centre in Sardinia (Italy). By sequencing the 16S rRNA gene and the entire 16S/23S intergenic spacer region, the new strains were classified within the Mycoplasma taxonomy at the group and cluster levels, showing that the two isolates fall into the Mycoplasma synoviae and Mycoplasma hominis clusters of the hominis group, respectively. We combined molecular tools and immunoblotting methods in order to further characterize these isolates, and antigenic analyses overall confirmed the molecular findings. Different levels of pathogenicity and prevalence of these strains might have different implications for the conservation and reintroduction of vultures.

Mycoplasma hominis and Trichomonas vaginalis symbiosis: multiplicity of infection and transmissibility of M. hominis to human cells

We recently reported that most Trichomonas vaginalis isolates cultured in vitro are infected by Mycoplasma hominis. In this work, we have characterized some aspects of the relationships between the two microorganisms. PCR, cultivation, and immunological methods revealed that the number of M. hominis organisms carried by T. vaginalis in culture varied from isolate to isolate, suggesting a specific multiplicity of infection. Moreover, infected T. vaginalis isolates were able to pass bacteria not only to M. hominis-free protozoa, but also to human-derived epithelial cells. The in vitro transmission of the bacterium from T. vaginalis to both uninfected parasite isolates and human epithelial cells suggests a role for T. vaginalis as a carrier of the M. hominis infection in vivo.

Host and tissue specificity of Trichomonas vaginalis is not mediated by its known adhesion proteins

Adhesion of Trichomonas vaginalis is believed to be dependent on four adhesion proteins, which are thought to bind to vaginal epithelial cells in a specific manner with a ligand-receptor type of interaction. However, the specific receptors on the host cell have not yet been identified. In this work, the ability of the T. vaginalis adhesins to bind to cells of different histologic derivations and from different species has been studied. HeLa, CHO, and Vero cell lines; erythrocytes from different species; and a prokaryote without a cell wall, Mycoplasma hominis, were employed in order to investigate the cell specificity of the T. vaginalis adhesins. We observed that the T. vaginalis adhesins are able to bind to the different cell types to the same extent, suggesting that the host and tissue specificity of T. vaginalis adhesion should not be due to specificity of the parasite adhesins. Our results suggest that the data published to date on the subject are probably artifactual and that the experiments reported in the literature are not appropriate for identification of protozoan adhesins.

Identification of Trichomonas vaginalis alpha-actinin as the most common immunogen recognized by sera of women exposed to the parasite

A study on presence of antibodies to Trichomonis vaginalis in serum was done on a group of 500 pregnant, asymptomatic Angolan women. A serologic screening, done by ELISA, revealed that 41% of the women had IgG and IgM against the parasite. Analysis of sera by immunoblotting revealed that 94.4% of sera with anti-T. vaginalis IgG class antibodies were reactive against a common immunogenic protein of 115 kDa. The common immunogen was identified as the protozoan alpha-actinin. All sera recognizing the 115-kDa antigen were reactive against both native and recombinant T. vaginalis alpha-actinin and nonreactive against human alpha-actinin. The findings presented in this work offer a new tool for epidemiologic studies and open new perspectives for vaccination.

The flagellated parasite Trichomonas vaginalis: new insights into cytopathogenicity mechanisms

Our knowledge concerning cytopathogenicity of Trichomonas vaginalis has been enriched in the past by numerous findings. In this paper, we review the latest advances in the field and discuss the different mechanisms and molecules responsible for the parasite's virulence.

Cloning and molecular characterization of a cDNA clone coding for Trichomonas vaginalis alpha-actinin and intracellular localization of the protein

We have identified and sequenced a cDNA clone coding for Trichomonas vaginalis alpha-actinin. Analysis of the obtained sequence revealed that the 2,857-nucleotide-long cDNA contained an open reading frame encoding 849 amino acids which showed consistent homology with alpha-actinins of different species. Such homology was particularly significant in regions which have been reported to represent the actin-binding and Ca2+-binding domains in other alpha-actinins. The deduced protein was also characterized by the presence of a divergent central region thought to play a role in its high immunogenicity. A study of protein localization performed by immunofluorescence revealed that the protein is diffusely distributed throughout the T. vaginalis cytoplasm when the cell is pear shaped. When parasites adhere and transform into the amoeboid morphology, the protein is located only in areas close to the cytoplasmic membrane and colocalizes with actin. Concomitantly with transformation into the amoeboid morphology, alpha-actinin mRNA expression is upregulated.

Contact-dependent disruption of the host cell membrane skeleton induced by Trichomonas vaginalis

This report presents evidence showing that the pathogenetic process of the protozoan parasite Trichomonas vaginalis involves degradation of the target cell membrane skeleton; spectrin, the most representative protein within this structure, has been identified as the main molecular target. Degradation of the target cell spectrin is accomplished only upon contact with the parasite, and immunochemical and immunofluorescence studies performed with the erythrocyte as a model demonstrate that degradation of the protein takes place before target cell lysis. A preliminary characterization of the effectors involved has led to the identification of a nonsecreted 30-kDa proteinase which is characterized by a high specificity for spectrin. This molecule is suggested as the main effector responsible for cytoskeletal disruption.

Extracellular release by Trichomonas vaginalis of a NADP+ dependent malic enzyme involved in pathogenicity

This report presents evidence showing that Trichomonas vaginalis releases in the extracellular environment a functional form of NADP(+)-dependent malic enzyme. The protein which is likely responsible for the oxidative decarboxilase activity had already been identified in previous studies as P65, one of the five adhesive proteins of the protozoan. The same protein had also been described as AP65 by other authors, which identified it as one of the four surface proteins specifically responsible for binding of the parasite to the target cell in a ligand-receptor fashion. Gene characterization studies performed on P65 by different authors revealed that the nucleotide sequences of the genes coding for P65 display a striking homology with the ones coding for the trichomonad malic enzyme. The experiments performed in this work demonstrate that P65 is secreted and retains its adhesive properties in the extracellular environment, being able to bind both erythrocytes and HeLa cells. Therefore, an oxidative decarboxylase activity assay was performed on T. vaginalis cell-free filtrates, in order to assess if the released P65 displays cathalitic properties. The assay revealed that parasite-free supernatants exhibit an oxidative decarboxylase activity which is NADP(+)-dependent. On the basis of the most recent findings on T. vaginalis pathogenetic mechanism, which involves pH-dependent perforins, a role for the secreted enzyme as part of the system is proposed.

Trichomonas vaginalis haemolysis: pH regulates a contact-independent mechanism based on pore-forming proteins

There is a controversy in literature about involvement of secreted factors in the pathogenetic mechanisms of Trichomonas vaginalis, described mostly as contact-dependent. We found that the protozoan, under triggering conditions, is able to release molecules that lead to lysis without direct contact between parasite and target cells as a prerequisite. In this paper we characterize contact-independent cytotoxicity using the red blood cell as a cellular model. Contact-independent haemolysis is a phenomenon were pH exerts a key role, triggering the secretion of a lytic molecule and regulating its activity. A partial physicochemical characterization of the haemolytic factor suggests that a protein of M(r) > 30 kDa could be the effector responsible for damage. Furthermore, the parasite-induced membrane permeabilization, detected by measuring potassium escape from the target cell, and an effective osmotic protection by carbohydrates allowed us to relate the previously described pore-forming mechanism involved in contact-dependent cytotoxicity with the contact-independent lysis.