Mastitis of sheep and goats

Evaluation of ARFI elastography for detecting active mastitis in sheep with previous fibrous lesions: a study of mammary parenchyma and supramammary lymph nodes

The aim of the study was to evaluate the use of Acustic Radiation Force Impulse (ARFI) elastography in mammary parenchyma and supramammary lymph nodes, for detection of active mastitis in sheep with naturally infected chronic fibrous lesions. 27 female sheep were included and B-mode ultrasound and ARFI elastography images were obtained, acquiring qualitative (echogenicity and echotexture) and quantitative (shear rate, depth and short/long axis ratio) variables of 48 mammary glands. The glands were divided into three experimental groups: control group (CG) - healthy animals; LSCC- animals that presented fibrous lesions and SCC (somatic cell count) less than 500 x 103 cls/mL; HSCC: animals that presented fibrous lesions and SCC (somatic cell count) more than 500 x 103 cls/mL; The qualitative variables using B-mode ultrasonography, including echotexture and echogenicity, showed no significant differences between the evaluated groups and tissues (p = 0.9336 and p = 0.233, respectively) .In healthy areas of the gland, it was an increasing in shear wave velocity (SWV) in LSCC than in HSCC (p=0.04). When comparing the fibrosis in the LSCC and HSCC groups with their respective normal areas, the velocity increased in both groups: LSCC (p= 0,0007) and HSCC (p= 0,0001). When comparing the areas of fibrosis in LSCC and HSCC with the CG parenchyma, there was an increase in LSCC (p=0.001) and HSCC (p=0.0001). B-mode ultrasound indicate predominance of hypoechoic echogenicity in lymph nodes and reduced short/long axis ratio in cases of active subclinical mastitis. The supramammary lymph node showed increased SWV when comparing the CG with HSCC groups (p=0.02) and GC with LSCC (p=0.04). B-mode ultrasonography is useful for evaluating the mammary parenchyma, however, its application as a standalone diagnostic technique is not recommended. ARFI elastography indicates potential cutoff points for differentiating subclinical mastitis from healed mastitis, highlighting its importance as a tool for distinguishing normal areas from fibrous parenchymal areas. While this study did not establish specific cutoff points due to sample size limitations, further research with larger sample sizes could explore and define these critical thresholds.

Environment rather than breed or body site shapes the skin bacterial community of healthy sheep as revealed by metabarcoding

BACKGROUND

The skin is inhabited by a variety of micro-organisms, with bacteria representing the predominant taxon of the skin microbiome. In sheep, the skin bacterial community of healthy animals has been addressed in few studies, only with culture-based methods or sequencing of cloned amplicons.

OBJECTIVES

The objectives of this study were to determine the sheep skin bacterial community composition by using metabarcoding for a detailed characterisation and to determine the effect of body part, breed and environment.

MATERIALS AND METHODS

Overall, 267 samples were taken from 89 adult female sheep, belonging to three different breeds and kept on nine different farms in Switzerland. From every individual, one sample each was taken from belly, left ear and left leg and metabarcoding of the 16S rRNA V3-V4 hypervariable region was performed.

RESULTS

The main phyla identified were Actinobacteriota, Firmicutes, Proteobacteria and Bacteriodota. The alpha diversity as determined by Shannon's diversity index was significantly different between sheep from different farms. Beta diversity analysis by principal coordinate analysis (PCoA) showed clustering of the samples by farm and body site, while breed had only a marginal influence. A sparse partial least squares discriminant analysis (sPLS-DA) revealed seven main groups of operational taxonomic units (OTUs) of which groups of OTUs were specific for some farms.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings indicate that environment has a larger influence on skin microbial variability than breed, although the sampled breeds, the most abundant ones in Switzerland, are phenotypically similar. Future studies on the sheep skin microbiome may lead to novel insights in skin diseases and prevention.

Antimicrobial Resistance Characteristics of Fecal Escherichia coli and Enterococcus Species in U.S. Goats: 2019 National Animal Health Monitoring System Enteric Study

Escherichia coli and Enterococcus species are normal bacteria of the gastrointestinal tract and serve as indicator organisms for the epidemiology and emergence of antimicrobial resistance in their hosts and the environment. Some E. coli serovars, including E. coli O157:H7, are important human pathogens, although reservoir species such as goats remain asymptomatic. We describe the prevalence and antimicrobial resistance of generic E. coli, E. coli O157:H7, and Enterococcus species collected from a national surveillance study of goat feces as part of the National Animal Health Monitoring System (NAHMS) Goat 2019 study. Fecal samples were collected from 4918 goats on 332 operations across the United States. Expectedly, a high prevalence of E. coli (98.7%, 4850/4915) and Enterococcus species (94.8%, 4662/4918) was found. E. coli O157:H7 prevalence was low (0.2%; 10/4918). E. coli isolates, up to three per operation, were evaluated for antimicrobial susceptibility and 84.7% (571/674) were pansusceptible. Multidrug resistance (MDR; ≥3 classes) was uncommon among E. coli, occurring in 8.2% of isolates (55/674). Resistance toward seven antimicrobial classes was observed in a single isolate. Resistance to tetracycline alone (13.6%, 92/674) or to tetracycline, streptomycin, and sulfisoxazole (7.0% 47/674) was the most common pattern. All E. coli O157:H7 isolates were pansusceptible. Enterococcus isolates, up to four per operation, were prioritized by public health importance, including Enterococcus faecium and Enterococcus faecalis and evaluated. Resistance to lincomycin (93.8%, 1232/1313) was most common, with MDR detected in 29.5% (388/1313) of isolates. The combination of ciprofloxacin, lincomycin, and quinupristin resistance (27.1%, 105/388) was the most common pattern detected. Distribution and characteristics of antimicrobial resistance in E. coli and Enterococcus in the U.S. goat population from this study can inform stewardship considerations and public health efforts surrounding goats and their products.

The Role of Prophage ϕSa3 in the Adaption of Staphylococcus aureus ST398 Sublineages from Human to Animal Hosts

Staphylococcus aureus sequence type (ST) 398 is a lineage affecting both humans and livestock worldwide. However, the mechanisms underlying its clonal evolution are still not clearly elucidated. We applied whole-genome sequencing (WGS) typing to 45 S. aureus strains from China and Canada between 2005 and 2014, in order to gain insight into their evolutionary pathway. Based on WGS phylogenetic analysis, 42 isolates were assigned to the human-associated clade (I/II-GOI) and 3 isolates to livestock-associated clade (IIa). Phylogeny of ϕSa3 sequences revealed five phage groups (Groups 1-5), with Group 1 carrying ϕSa3-Group 1 (ϕSa3-G1), Group 2 carrying ϕSa3-G2, Group 3 carrying ϕSa3-G3, Group 4 carrying ϕSa3-G4 and Group 5 lacking ϕSa3. ϕSa3-G1 was only found in strains that accounted for the most ancestral human clade I, while ϕSa3-G2, ϕSa3-G3 and ϕSa3-G4 were found restricted to sublineages within clade II-GOI. Some isolates of clade II-GOI were also found to be ϕSa3-negative or resistant to methicillin which are unusual characteristics for human-adapted isolates. This study demonstrated a strong association between phylogenetic grouping and phage type, suggesting an important role of ϕSa3 prophage in the evolution of human-adapted ST398 subclones. In addition, our results suggest that this subclone slowly began to adapt to animal hosts by losing ϕSa3 and acquiring methicillin resistance, which was observed in some strains of human-associated clade II-GOI, an intermediate human to livestock transmission clade.

Epidemiology and zoonotic potential of Livestock-associated Staphylococcus aureus isolated at Tamil Nadu, India

BACKGROUND

Staphylococcus aureus is part of normal flora and also an opportunistic pathogen responsible for a wide range of infections in both humans and animals. Livestock-associated S. aureus (LA-SA) has gained importance in recent years due to its increased prevalence in recent years, becoming a worry in public health view. This study aimed to study the epidemiology of LA-SA strains in Madurai district, Tamil Nadu, India.

METHODS

A total of 255 samples were collected from bovine and other small ruminants like goats and sheep nares (n = 129 and n = 126 respectively). Nasal swab samples were collected from study animals with sterile sample collecting cotton swabs (Hi-Media, Mumbai). Samples were transported to the lab in Cary-Blair Transport media for further analysis. The samples were tested for S. aureus using antibiotic selection and PCR-based assays. The pathogenicity of the bacteria was assessed using chicken embryo models and liver cross-sections were used for histopathology studies.

RESULTS

The prevalence rate in bovine-associated samples was 42.63% but relatively low in the case of small ruminants associated samples with 28.57% only. The overall prevalence of S. aureus is found to 35.6% and MRSA 10.98% among the study samples. The antibiogram results that LA-SA isolates were susceptible to aminoglycosides and tetracyclines but resistant to β-lactam drugs. The biofilm formation results showed that the LA-SA isolates are weak to high-capacity biofilm formers. The enterotoxigenic patterns revealed that most of the isolated strains are enterotoxigenic and possess classical enterotoxins. The survival analysis of chicken embryos suggested that the Bovine-associated strains were moderately pathogenic.

CONCLUSION

The study concluded that economically important livestock animals can act as reservoirs for multi-drug resistant and pathogenic which in-turn is a concern for public health as well as livestock health.

Colonization of Extramammary Sites with Mastitis-Associated S. aureus Strains in Dairy Goats

Staphylococcus aureus (S. aureus), a major mastitis pathogen in dairy goats, is classified as a contagious pathogen. Although previous research has shown that extramammary body sites can be colonized with S. aureus, it is unknown whether these sites are reservoirs for intramammary infections. The aim of this research was to determine whether extramammary sites can be colonized with mastitis-associated S. aureus strains in dairy goats. Milk samples were collected from 207 primiparous goats and from 120 of these goats, extramammary site samples (hock, groin, nares, vulva and udder) were collected from a large commercial dairy goat herd in the Netherlands during four sampling visits. Extramammary site swabs and milk samples were (selectively) cultured and S. aureus isolates were spa genotyped. The prevalence of colonization of the extramammary sites at goat level was 51.7% and the prevalence of S. aureus intramammary infections was 7.2%. The nares were colonized most frequently (45%), while the groin area was colonized the least (2.5%). Six spa genotypes were identified in this herd and there was no significant difference in the distribution of spa genotypes between the milk or the extramammary sites (p = 0.141). Both in the extramammary sites and in the milk, spa genotypes t544 (82.3% and 53.3%) and t1236 (22.6% and 33.3%) were the dominant genotypes. These results show that in goats, extramammary sites, particularly the nares, are frequently colonized with mastitis-associated S. aureus strains. Extramammary sites may, thus, be a source of S. aureus intramammary infections that are not targeted by the intervention measures aimed at preventing transmission from infected udder glands.

Utilization of 2D and 3D cell cultures for the modelling of intramammary infection in sheep

Ovine mastitis is defined as the inflammation of the sheep udder, most commonly caused in response to intramammary infections. Based on the occurrence of clinical signs, mastitis is characterized as either clinical or subclinical (SCM). The impact of ovine SCM on the overall sustainability of dairy sheep farms has been substantially documented underpinning the significance of efficient diagnosis. Although SCM can be detected in cows, the performance and the validity of the methods used do not transfer in dairy sheep. This fact challenges the development of evidence-based ovine udder health management protocols and renders the detection and control of ovine mastitis rather problematic. Currently, cell culture-based models are being successfully used in biomedical studies and have also been effectively used in the case of bovine mastitis. The objective of the present study was to culture ovine primary mammary cells for the development of 2D and 3D cell culture-based models for the study of ovine mammary gland and to focus on the first stages of the intramammary infection by common mastitis-inducing pathogens. Cells were infected by E. coli and S. aureus mimicking the first stages of natural intramammary infections. The secreted proteins were subjected to mass-spectrometry resulting in the identification of a total of 79 distinct proteins. Among those, several had already been identified in healthy or mastitic milk, while others had not been previously detected for in the ovine mammary secretome. Our results suggest that the development of cell-based models for studying specific stages of intramammary infection has the potential to be beneficial for the udder health management in dairy sheep.

Nb/Starch-Doped ZnO Nanostructures for Polluted Water Treatment and Antimicrobial Applications: Molecular Docking Analysis

Nb/starch-doped ZnO quantum dots (QDs) were prepared by a coprecipitation route. A fixed quantity of starch (st) and different concentrations (2 and 4%) of niobium (Nb) were doped in a ZnO lattice. To gain a better understanding of synthesized nanostructures, a systematic study was carried out utilizing several characterization methods. The goal of this research was to undertake methylene blue (MB) dye degradation with a synthetic material and also study its antibacterial properties. The phase structure, morphology, functional groups, optical properties, and elemental compositions of synthesized samples were investigated. Our study showed that ZnO QDs enhanced photocatalytic activity (PCA), resulting in effective MB degradation, in addition to showing good antimicrobial activity against Gram-negative relative to Gram-positive bacteria. Molecular docking study findings were in good agreement with the observed in vitro bactericidal potential and suggested ZnO, st-ZnO, and Nb/st-ZnO as possible inhibitors against dihydrofolate reductase (DHFR_E. coli) and DNA gyrase_E. coli.

Distinguishing the milk microbiota of healthy goats and goats diagnosed with subclinical mastitis, clinical mastitis, and gangrenous mastitis

Mastitis, mainly caused by bacterial intramammary infections, is the main problem in the breeding of dairy animals. The inflammations of the mammary gland is separated by types of mastitis, being subclinical, clinical, and the most severe, gangrenous mastitis. Here, we used 16S rRNA amplicon sequencing to characterize the bacterial microbiota of goat milk in the different types of goat mastitis caused by bacteria. We used 72 goat milk samples from a region of the state of Minas Gerais in Brazil, of which 12 were from clinically healthy animals, 42 from animals diagnosed with subclinical mastitis, 16 from animals with clinical mastitis, and 2 from animals with gangrenous mastitis. The group related to gangrenous mastitis was the most divergent in terms of alpha and beta diversity. The most abundant genus among samples of the groups was Staphylococcus spp., and we found a high abundance of Mycoplasma sp. in the milk of animals diagnosed with clinical mastitis. The most statistically relevant microorganisms among the groups were Prevotella sp., Ruminococcaceae, Prevotella ruminicola sp., and Providencia sp. We highlight a new association of bacterial agents in gangrenous mastitis among Escherichia sp./Shigella sp. and Enterococcus sp. and provide the second report of the genus Alkalibacterium sp., in milk samples. Only the taxa Staphylococcus sp., Bacteroides sp., Enterococcus, and Brevidabacterium sp., were present in all groups. The superpathway of L-tryptophan biosynthesis metabolites and the sucrose degradation III (sucrose invertase) pathway were the most prominent ones among the groups. In this study, we demonstrate how a rich microbiota of goat milk from healthy animals can be altered during the aggravation of different types of mastitis, in addition to demonstrating new bacterial genera in milk not previously detected in other studies as well as new associations between agents.

Genomic patterns of homozygosity and inbreeding depression in Murciano-Granadina goats

BACKGROUND

Inbreeding depression can adversely affect traits related to fitness, reproduction and productive performance. Although current research suggests that inbreeding levels are generally low in most goat breeds, the impact of inbreeding depression on phenotypes of economic interest has only been investigated in a few studies based on genealogical data.

RESULTS

We genotyped 1040 goats with the Goat SNP50 BeadChip. This information was used to estimate different molecular inbreeding coefficients and characterise runs of homozygosity and homozygosity patterns. We detected 38 genomic regions with increased homozygosity as well as 8 ROH hotspots mapping to chromosomes 1, 2, 4, 6, 14, 16 and 17. Eight hundred seventeen goats with available records for dairy traits were analysed to evaluate the potential consequences of inbreeding depression on milk phenotypes. Four regions on chromosomes 8 and 25 were significantly associated with inbreeding depression for the natural logarithm of the somatic cell count. Notably, these regions contain several genes related with immunity, such as SYK, IL27, CCL19 and CCL21. Moreover, one region on chromosome 2 was significantly associated with inbreeding depression for milk yield.

CONCLUSIONS

Although genomic inbreeding levels are low in Murciano-Granadina goats, significant evidence of inbreeding depression for the logarithm of the somatic cell count, a phenotype closely associated with udder health and milk yield, have been detected in this population. Minimising inbreeding would be expected to augment economic gain by increasing milk yield and reducing the incidence of mastitis, which is one of the main causes of dairy goat culling.

Milk proteins as mastitis markers in dairy ruminants - a systematic review

Mastitis is one of the most impacting diseases in dairy farming, and its sensitive and specific detection is therefore of the greatest importance. The clinical evaluation of udder and mammary secretions is typically combined with the milk Somatic Cell Count (SCC) and often accompanied by its bacteriological culture to identify the causative microorganism. In a constant search for improvement, several non-enzymatic milk proteins, including milk amyloid A (M-SAA), haptoglobin (HP), cathelicidin (CATH), and lactoferrin (LF), have been investigated as alternative biomarkers of mastitis for their relationship with mammary gland inflammation, and immunoassay techniques have been developed for detection with varying degrees of success. To provide a general overview of their implementation in the different dairy species, we carried out a systematic review of the scientific literature using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Our review question falls within the type “Diagnostic test accuracy questions” and aims at answering the diagnostic question: “Which are the diagnostic performances of mastitis protein biomarkers investigated by immunoassays in ruminant milk?”. Based on 13 keywords combined into 42 searches, 523 manuscripts were extracted from three scientific databases. Of these, 33 passed the duplicate removal, title, abstract, and full-text screening for conformity to the review question and document type: 78.8% investigated cows, 12.1% sheep, 9.1% goats, and 6.1% buffaloes (some included more than one dairy species). The most frequently mentioned protein was M-SAA (48.5%), followed by HP (27.3%), CATH (24.2%) and LF (21.2%). However, the large amount of heterogeneity among studies in terms of animal selection criteria (45.5%), index test (87.9%), and standard reference test (27.3%) resulted in a collection of data not amenable to meta-analysis, a common finding illustrating how important it is for case definitions and other criteria to be standardized between studies. Therefore, results are presented according to the SWiM (Synthesis Without Meta-analysis) guidelines. We summarize the main findings reported in the 33 selected articles for the different markers and report their results in form of comparative tables including sample selection criteria, marker values, and diagnostic performances, where available. Finally, we report the study limitations and bias assessment findings.

Use of photodynamic therapy and photobiomodulation as alternatives for microbial control on clinical and subclinical mastitis in sheep

Evaluate the effects of antimicrobial photodynamic therapy (aPDT) and photobiomodulation (PBM) as alternatives in the treatment of mastitis in sheep. A total of 100 sheep were evaluated, and four teats with clinical mastitis and 16 teats with subclinical mastitis were selected. Milk was collected for isolation and identification of microorganisms. They were grown on TSA, EMB, and MacConkey agar for 24 h, and the microorganisms were identified by Gram stain and biochemical tests. The ceilings were subdivided into four groups: G1, treatment with photosensitizer; G2, treatment with PBM (diode laser λ = 660 nm); G3, aPDT with methylene blue, and G4, control group. Milk samples were collected before, 24 and 48 h after treatments. Cases of subclinical mastitis presented coagulase-negative Staphylococcus and Streptococcus spp, and clinical mastitis had Escherichia coli grow from the samples. The treatments decrease the total bacterial count of negative coagulase Staphylococcus, Streptococcus spp, and Escherichia coli. Comparing the treatments, aPDT stood out, as it was able to photoinactivate all bacteria. Treatment with methylene blue photosensitizer, PBM, and aPDT induced the initial microbial reduction, but aPDT was more effective 48 h after treatment.

Animal-Based Indicators for On-Farm Welfare Assessment in Goats

Simple Summary

Welfare assessments for animals require the use of specific indicators. These indicators should be practical and easy to use in an on-farm environment while correctly reflecting on the animals’ welfare. Our aim was to review literature on such indicators for goats, as small ruminants have not received as much attention as other farm animals in the field of welfare assessment. Some indicators such as lameness are already well investigated and suitable for use in goat welfare assessments. Others, for example, lying behaviour, need more research, as the limited amount of knowledge restrains the information on validity or usefulness. As in other animals, the welfare of goats has become an increasingly important issue in public discourse. Our overview on indicators aids in developing tools to measure and improve the welfare of goats.

Abstract

This review describes the current state of knowledge relating to scientific literature on welfare indicators for goats. Our aim was to provide an overview of animal-based indicators for on-farm welfare assessments. We performed a literature search and extracted 96 relevant articles by title, abstract, and full-text screening. Out of these articles, similar indicators were aggregated to result in a total of 32 welfare indicators, some of which were covered in multiple articles, others in only a single one. We discuss a set of three established assessment protocols containing these indicators, as well as all individual indicators which were covered in more than one article. As single indicators, we identified lameness, body condition score (BCS), qualitative behaviour assessment (QBA), and human–animal relationship (HAR) tests with substantial evidence for sufficient validity to assess welfare in goats. A multitude of indicators (e.g., hair coat condition) was studied less intensively but was successfully used for welfare assessments. For some indicators (e.g., oblivion, lying behaviour), we highlight the need for future research to further validate them or to optimise their use in on-farm welfare assessments. Moreover, further investigations need to include kids, bucks, and meat and fibre goats, as well as extensively kept goats as the literature predominantly focuses on dairy goats in intensive production systems.

A novel Streptococcus species causing clinical mastitis in a pregnant donkey

An 8-y-old jenny was presented because of anorexia and mild depression. The jenny had weaned her colt 10 d before the admission. Upon arrival at the University of Illinois Veterinary Teaching Hospital, the heart rate was elevated, and the right udder was painful and swollen on palpation. Milk stripping of the affected side revealed purulent content; the contralateral udder had normal-appearing milk. Cytology of mammary gland secretions from the affected side revealed a large number of hypersegmented reactive neutrophils with phagocytized bacteria. Complete blood count, serum chemistry, and fibrinogen were within normal limits. A diagnosis of clinical mastitis was made, and the jenny was started on a 5-d course of broad-spectrum antibiotics, a non-steroidal anti-inflammatory, hydrotherapy, and milk stripping. Clinical signs reduced over time, and the cure was attained by 96 h post-admission. Aerobic culture and subsequent MALDI-TOF MS analysis identified a bacterium of the Streptococcus genus but not the species. Whole-genome analysis was performed, and 16S rDNA sequencing and analysis determined that our isolate 20-37394 clustered with 2 other Streptococcus strains (27284-01 and 28462). Single-nucleotide variations and phylogenetic tree analysis revealed that Streptococcus 20-37394 had 96.8% and 94.9% identities to Streptococcus strains 27284-01 and 28462, respectively; therefore, the bacteria isolated in our case was deemed as a new Streptococcus species.

Relationships between novel nucleotide variants within the colony-stimulating factor 1 receptor (CSF1R) gene and mastitis indicators in sheep

Colony-stimulating factor 1 receptor (CSF1R) plays an important role in the process of innate immunity and inflammation, thus it was hypothesized that the CSF1R gene might affect the occurrence of mammalian mastitis. The purpose of this study was to investigate the association between nucleotide variations of CSF1R gene and mastitis in Australian white sheep (AUWs). Two indel variants (Intron5-27 bp and Intron5-22 bp) within the CSF1R gene have been found in AUWs. The Chi-square test for different mastitis symptoms demonstrated that individuals without symptoms of mastitis had higher 'I' allele frequencies and 'II' genotype frequencies (p < 0.01). We found strong correlation between mastitis and lactation score through Pearson correlation analysis. Therefore, we also analyzed the relationship between the two indel loci and lactation, we found that the lactation ability of individuals with type II was stronger than that of DD genotype at the Intron5-22 bp (p < 0.05). Additionally, we found that the combined genotype of the two loci was significantly associated with mastitis (p < 0.01). These findings indicated that CSF1R mutations were significantly associated with mastitis, and could affect lactation performance, suggesting that two deletion sites could be used as the effective molecular markers against mastitis in sheep breeding.

Complete Genome Sequence of Community-Acquired Methicillin-Resistant Staphylococcus aureus Strain RJ1267, Isolated in Shanghai, China

Staphylococcal pathogens, especially multidrug-resistant Staphylococcus aureus, are responsible for various clinical infections. Multilocus sequence type 630 (ST630) methicillin-resistant Staphylococcus aureus has been shown to have augmented pathogenicity in humans. In this announcement, we report the complete genome sequence of community-acquired methicillin-resistant strain RJ1267 of Staphylococcus aureus ST630.

Staphylococcal pathogens, especially multidrug-resistant Staphylococcus aureus, are responsible for various clinical infections. Multilocus sequence type 630 (ST630) methicillin-resistant Staphylococcus aureus has been shown to have augmented pathogenicity in humans. In this announcement, we report the complete genome sequence of community-acquired methicillin-resistant strain RJ1267 of Staphylococcus aureus ST630.

Impact of Staphylococcus aureus infection on the late lactation goat milk proteome: New perspectives for monitoring and understanding mastitis in dairy goats

The milk somatic cell count (SCC) is a standard parameter for monitoring intramammary infections (IMI) in dairy ruminants. In goats, however, the physiological increase in SCC occurring in late lactation heavily compromises its reliability. To identify and understand milk protein changes specifically related to IMI, we carried out a shotgun proteomics study comparing high SCC late lactation milk from goats with subclinical Staphylococcus aureus IMI and from healthy goats to low SCC mid-lactation milk from healthy goats. As a result, we detected 52 and 19 differential proteins (DPs) in S. aureus-infected and uninfected late lactation milk, respectively. Unexpectedly, one of the proteins higher in uninfected milk was serum amyloid A. On the other hand, 38 DPs were increased only in S. aureus-infected milk and included haptoglobin and numerous cytoskeletal proteins. Based on STRING analysis, the DPs unique to S. aureus infected milk were mainly involved in defense response, cytoskeleton organization, cell-to-cell, and cell-to-matrix interactions. Being tightly and specifically related to infectious/inflammatory processes, these proteins may hold promise as more reliable markers of IMI than SCC in late lactation goats. SIGNIFICANCE: The biological relevance of our results lies in the increased understanding of the changes specifically related to bacterial infection of the goat udder in late lactation. The DPs present only in S. aureus infected milk may find application as markers for improving the specificity of subclinical mastitis monitoring and detection in dairy goats in late lactation, when other widespread tools such as the SCC lose diagnostic value.

Effects of enrofloxacin treatment on the bacterial microbiota of milk from goats with persistent mastitis

Antibiotic resistance has become a major concern for human and animal health. As fluoroquinolones have been extensively used in human and veterinary medicine, there has also been the rapid emergence and spread of antimicrobial resistance around the world. Here, we analysed the microbiome of goat milk using samples from healthy goats and those diagnosed with persistent mastitis and treated using the antibiotic enrofloxacin with 16S rRNA amplicon sequencing. We selected a group of 11 goats and 22 samples of milk that did not respond clinically to enrofloxacin treatment. Milk samples were evaluated before and after treatment to verify changes of the microbiota; the three first lactating goats were selected from the healthy control group. The milk samples from the healthy control animals presented a larger abundance of different species of bacteria of the Staphylococcus genus, but a smaller number of different genera, which indicated a more specific niche of resident bacteria. The Firmicutes phylum was predominantly different between the studied groups. Samples from before-treatment animals had a higher number of new species than those from the control group, and after being treated again. These microbiota received new bacteria, increasing the differences in bacteria even more in relation to the control group. Genotypes such as Trueperella and Mannheimia, between other genera, had a high abundance in the samples from animals with persistent mastitis. The dysbiosis in this study, with marked evidence of a complex microbiota in activity in cases of the failure of antimicrobial treatment for persistent chronic mastitis, demonstrates a need to improve the accuracy of pathogen identification and increases concern regarding antibiotic treatments in milk production herds.

Size of supernumerary teats in sheep correlates with complexity of the anatomy and microenvironment

Supernumerary nipples or teats (polythelia) are congenital accessory structures that may develop at any location along the milk line and have been implicated in the pathogenesis of mastitis. We describe the anatomy and histology of 27 spontaneously occurring supernumerary teats from 16 sheep, delineating two groups of teats - simple and anatomically complex - according to the complexity of the anatomy and microenvironment. Anatomically complex supernumerary teats exhibited significantly increased length and barrel diameter compared with simple supernumerary teats. A teat canal and/or teat cistern was present in anatomically complex teats, with smooth muscle fibres forming a variably well-organised encircling teat sphincter. Complex supernumerary teats also exhibited immune cell infiltrates similar to those of normal teats, including lymphoid follicle-like structures at the folds of the teat cistern-teat canal junction, and macrophages that infiltrated the peri-cisternal glandular tissue. One complex supernumerary teat exhibited teat end hyperkeratosis. These anatomical and histological features allow inference that supernumerary teats may be susceptible to bacterial ingress through the teat canal and we hypothesise that this may be more likely in those teats with less well-organised encircling smooth muscle. The teat cistern of anatomically complex teats may also constitute a focus of milk accumulation and thus a possible nidus for bacterial infection, potentially predisposing to mastitis. We suggest that size of the supernumerary teat, and relationship to the main teats, particularly in the case of 'cluster teats', should be considerations if surgical removal is contemplated.

STUDY ON THE EFFECTIVENESS OF INTRACISTERNAL ANTIBIOTIC TREATMENT FOR THE CONTROL OF MASTITIS IN GOATS

The aim of this study is to investigate the healing and prophylactic effect of drying-off antibiotic therapy using the selective and non-selective approach of administration of the antibiotics. First experimental group at the start of the dry period were treated non-selectively (all halves) intra-cisternally with antibiotics. In the second group, we only treated those halves that were diagnosed with subclinical mastitis. The control group of 9 goats was not treated. The number of somatic cells in treated groups after birth decreased from 2586 x 10³/ mL to 560 x 10³/mL in the first group and from 1978 x 10³/mL to 526 x 10³/mL in the second. Post partum, 10% of the halves were found to have subclinical mastitis. A healing effect was achieved in 25% (n=5) milk halves. New intramammary infections developed during the dry period also occurred in 5% (n=1) of the milk halves. In the second post-partum study, subclinical mastitis was observed only in 5% (n=1). Healing was achieved in 30% (n = 6) and the new intramammary infections (NIMIs) were 10% (n=2). In the control group, healing was only observed in 5% (n=1) and NIMI were 27.78% (n=5). The application of both treatment approaches, results in reduction in prevalence and manifestation of mastitis, as well as reduction of somatic cells in milk after kidding. The selective treatment method may be preferred, in order to reduce the cost of medications in conducting treatment and prophylaxis programs.

Short communication: Diversity of staphylococci isolated from sheep mastitis in northern Algeria

Mastitis in ruminants is an important disease with major effects on both the economy and animal welfare. It is caused by major pathogens such as Staphylococcus aureus and minor pathogens such as coagulase-negative staphylococci. The objective of this study was to identify and characterize staphylococci as a cause of sheep mastitis in Algeria. In this study, 123 milk samples were collected directly from the udder of sheep suffering from clinical mastitis in 2 provinces in Algeria. Recovered isolates were identified using MALDI-TOF mass spectrometry. Virulence-associated and antimicrobial resistance genes as well as clonal complexes (CC) of S. aureus were determined using microarray-based analysis. A total of 45 staphylococci isolates were cultivated from sheep milk samples, and 28 S. aureus were identified as methicillin susceptible (62.2%). Seventeen other Staphylococcus isolates of different species were identified using MALDI-TOF mass spectrometry. Subsequent microarray analysis typed the methicillin-susceptible S. aureus to 6 CC: CC8-MSSA, CC97-MSSA, CC130/521-MSSA, CC479-MSSA, CC522-MSSA, and CC705-MSSA. The accessory gene regulator agrIII and the ruminant leukocidin genes lukF-P83 and lukM were found in all isolates of CC130/521, CC479, CC522, and CC705. The toxic shock syndrome toxin gene tst1 was detected exclusively in CC130/521. Additionally, virulence-associated genes (sea, sed, sak, hld, hlgA, edinB, and others) were detected. The presence of antibiotic resistance genes [blaZ, erm(B), and tet(K)] was detected in small numbers of staphylococci. Staphylococci possessing these genes are considered potential hazards for farm animals, farmers, and consumers. Data concerning the prevalence and diversity of staphylococci causing mastitis in sheep from Algeria are lacking. Presented results on different aspects about staphylococci in Algerian sheep populations should at least partially close that gap. However, further extensive studies covering more geographical regions are needed to assess the epidemiological risk.

Staphylococcus aureus ST398 Virulence Is Associated With Factors Carried on Prophage ϕSa3

An increasing number of severe infections caused by Staphylococcus aureus ST398 strains has been observed. However, it has not been elucidated whether all ST398 strains are equally virulent. We collected 13 strains from China and Canada to test in a Caenorhabditis elegans infection model and compared their whole genome sequences (WGS) to explore potential insights into their virulence. All isolates belonged to ST398-methicillin-susceptible S. aureus (MSSA) with variant spa types (t034, t571, t1451, t1250). Pulsed field gel electrophoresis (PFGE) and WGS analyses showed that the 13 isolates clustered into 3 genomic types (Types A-C). WGS and prophage phylogenetic analyses also revealed that the strains could be divided into 3 phage groups (Groups 1–3), which correlated with high-, moderate-, and low-nematocidal activities, with mean killing rates of 94, 67, and 40%, respectively. Group 1 carried ϕSa3-Group 1 (ϕSa3-G1), Group 2 carried ϕSa3-G2, and Group 3 lacked ϕSa3. Interestingly, strain GD1706 (that genetically clustered within Type C) and strain GD487 (within Type B) both carried ϕSa3-G1 like phages and killed 92% of the nematodes, similar to the Type A strains carrying ϕSa3-G1. This study demonstrated that different ST398 sub-lineages possess variable virulence capacities, depending on the presence or absence, as well as the structure of the prophage ϕSa3 that carries virulence factors.

Complete Genome Sequence of GD1108, a Moderate-Virulence Strain of Human-Associated ST398 Methicillin-Susceptible Staphylococcus aureus

Staphylococcus aureus multilocus sequence type 398 (ST398) is responsible for an increasing number of severe infections in humans. There are no reports detailing if all ST398 strains are equally virulent. We present the genome sequence of the moderate-virulence ST398 methicillin-susceptible Staphylococcus aureus strain GD1108, determined in a Caenorhabditis elegans infection model, to reveal the ST398 sublineage virulence.

Complete Genome Sequence of GD487, a High-Virulence Strain of Human-Associated ST398 Methicillin-Susceptible Staphylococcus aureus

Multilocus sequence type 398 (ST398) methicillin-susceptible Staphylococcus aureus (MSSA) has been shown to have augmented pathogenicity in humans. However, it has not been determined whether all ST398 strains are equally virulent. We present here the genome sequence of a high-virulence ST398 MSSA strain, GD487, to explore potential insights into ST398 virulence.

Multilocus sequence type 398 (ST398) methicillin-susceptible Staphylococcus aureus (MSSA) has been shown to have augmented pathogenicity in humans. However, it has not been determined whether all ST398 strains are equally virulent. We present here the genome sequence of a high-virulence ST398 MSSA strain, GD487, to explore potential insights into ST398 virulence.

Staphylococcus aureus: setting its sights on the human innate immune system

Staphylococcus aureus has colonized humans for at least 10 000 years, and today inhabits roughly a third of the population. In addition, S. aureus is a major pathogen that is responsible for a significant disease burden, ranging in severity from mild skin and soft-tissue infections to life-threatening endocarditis and necrotizing pneumonia, with treatment often hampered by resistance to commonly available antibiotics. Underpinning its versatility as a pathogen is its ability to evade the innate immune system. S. aureus specifically targets innate immunity to establish and sustain infection, utilizing a large repertoire of virulence factors to do so. Using these factors, S. aureus can resist phagosomal killing, impair complement activity, disrupt cytokine signalling and target phagocytes directly using proteolytic enzymes and cytolytic toxins. Although most of these virulence factors are well characterized, their importance during infection is less clear, as many display species-specific activity against humans or against animal hosts, including cows, horses and chickens. Several staphylococcal virulence factors display species specificity for components of the human innate immune system, with as few as two amino acid changes reducing binding affinity by as much as 100-fold. This represents a major issue for studying their roles during infection, which cannot be examined without the use of humanized infection models. This review summarizes the major factors S. aureus uses to impair the innate immune system, and provides an in-depth look into the host specificity of S. aureus and how this problem is being approached.

Mammary gland health of Santa Inês ewes at the drying and puerperium and evaluation of a dry-off terapy with gentamicin

ABSTRACT: Mastitis represents an important health problem for Santa Inês breed, causing losses to the producer, due to loss of ewes or the decrease in weight gain of lambs. The aim of this work was to assess the health of the mammary gland of Santa Inês ewes at the drying and puerperium and to investigate the efficacy of a dry-off therapy with gentamicin. In this study, 64 ewes were divided in a control group (GC) and treatment group (GT), and the health of the mammary gland was assessed at the drying and puerperium. The GT ewes received 250mg of gentamicin (Gentocin® DryCow/Schering-Plough, product indicated for use in dairy cows) in each mammary half. For diagnosis, clinical examination, California Mastitis Test, somatic cell count and milk culture was performed. In the GC, of the 45 (70.3%) healthy mammary halves at the drying, 12 developed subclinical mastitis and nine clinical mastitis at the puerperium. In the GT, among 51 (79.7%) healthy mammary halves at the drying, six developed subclinical mastitis and 11 clinical mastitis at the puerperium. No association was observed between treatment and the occurrence of mastitis at puerperium. Of the 19 (29.7%) mammary halves of the GC that presented subclinical mastitis at the drying, three remained with subclinical mastitis and five developed clinical mastitis at the puerperium. In the GT, of the 13 (20.3%) mammary halves that had subclinical mastitis at the drying, four remained with subclinical mastitis and four developed clinical mastitis. No association was observed between treatment and cure or persistence of mastitis at the puerperium. The main microorganisms isolated, at the drying and puerperium, from animals with subclinical or clinical mastitis were Staphylococcus spp., predominantly coagulase negative Staphylococcus (CSN). At the puerperium, 29 cases of clinical mastitis occurred, 19 with isolation, where 10 were CNS and six S. aureus. Mannheimia haemolytica was isolated in one case of subclinical mastitis and other of clinical mastitis. News protocols and different ways of handling at drying and at puerperium must be investigated.

Corynebacterium pseudotuberculosis mastitis in Egyptian dairy goats

Background and Aim:

Mastitis is an important threat facing goat milk industry and is the most common cause of culling. Efficient control of mastitis, based on efficient diagnosis of diseased animals, would improve milk production and reproductive efficiency. In subclinical mastitis (SCM), infected goats demonstrate neither udder symptoms nor abnormal milk. Corynebacterium pseudotuberculosis is an infectious causative agent of mastitis, mostly results as an extension of infection from the supramammary lymph node, and causes financial losses in the goat industry. This study aimed to estimate the prevalence of SCM with emphasis on C. pseudotuberculosis mastitis in Egyptian dairy goats in the selected farms.

Materials and Methods:

A total of 336 half milk samples were collected from 177 dairy goats of various crossbreeds, in mid-to-late lactation period, after clinical examination. All samples were examined bacteriologically, while somatic cell count (SCC) was determined only in 180 half milk samples of the clinically healthy milk samples. The isolated and identified C. pseudotuberculosis was examined for evidence of virulence genes (Phospholipase D [pld] and β-subunit of RNA polymerase [rpoB]) by polymerase chain reaction (PCR).

Results:

The prevalence of clinical mastitis was 30.5%, while 69.5% of animals were apparently healthy and secreted milk was normal. Of those 180 clinically healthy half milk samples, 96 milk samples (53.33%) showed SCM as detected by SCC (SCC ≥1,000,000 cells/ml). Coagulase-negative staphylococci were the most prevalent bacteria (41.96%), then Staphylococcus aureus (37.5%) and C. pseudotuberculosis (7.14%). Molecular diagnosis of virulence genes revealed evidence of pld gene in 16 isolates (66.66%), and rpoB gene in 6 samples (25%) of the 24 bacteriologically isolated C. pseudotuberculosis. Here, we describe, for the 1^st time, isolation and identification of C. pseudotuberculosis from milk of does suffering from SCM in Egypt.

Conclusion:

C. pseudotuberculosis must be considered for routine bacteriological examination of milk from dairy goats, particularly herds with a history of caseous lymphadenitis. Pld gene-based PCR is more reliable than rpoB gene-based ones for the diagnosis of C. pseudotuberculosis.

Methicillin-Resistant Staphylococcus aureus: Molecular Characterization, Evolution, and Epidemiology

Staphylococcus aureus, a major human pathogen, has a collection of virulence factors and the ability to acquire resistance to most antibiotics. This ability is further augmented by constant emergence of new clones, making S. aureus a "superbug." Clinical use of methicillin has led to the appearance of methicillin-resistant S. aureus (MRSA). The past few decades have witnessed the existence of new MRSA clones. Unlike traditional MRSA residing in hospitals, the new clones can invade community settings and infect people without predisposing risk factors. This evolution continues with the buildup of the MRSA reservoir in companion and food animals. This review focuses on imparting a better understanding of MRSA evolution and its molecular characterization and epidemiology. We first describe the origin of MRSA, with emphasis on the diverse nature of staphylococcal cassette chromosome mec (SCCmec). mecA and its new homologues (mecB, mecC, and mecD), SCCmec types (13 SCCmec types have been discovered to date), and their classification criteria are discussed. The review then describes various typing methods applied to study the molecular epidemiology and evolutionary nature of MRSA. Starting with the historical methods and continuing to the advanced whole-genome approaches, typing of collections of MRSA has shed light on the origin, spread, and evolutionary pathways of MRSA clones.

Effects of intramammary infusion of sage (Salvia officinalis) essential oil on milk somatic cell count, milk composition parameters and selected hematology and serum biochemical parameters in Awassi sheep with subclinical mastitis

Aim:

The aims of this study were to evaluate the effects of intramammary infusion of sage (Salvia officinalis) essential oil (EO) on milk somatic cell count (SCC), milk composition parameters and selected hematology and serum biochemical parameters in 20 Awassi ewes affected with subclinical mastitis.

Materials and Methods:

The dried leaves of sage were used to extract the EO by hydrodistillation. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of sage EO against Staphylococcus aureus were determined by the broth dilution method. Ewes were divided randomly into three main groups and received one of the following treatments; Group 1 (n=5): Dimethyl sulfoxide (DMSO) alone (5 ml; 0.2 ml of DMSO in 4.8 ml of saline), Group 2 (n=5): Amoxicillin alone (3 ml), and Group 3 (n=10): Sage EO (5 ml of sage EO solution [0.2 ml DMSO+1 ml EO+3.8 ml sterile saline]). All treatments were administered by intramammary infusion into each teat twice per day for 3 consecutive days. Milk samples for SCC and milk components determination and whole blood samples for hematology and serum biochemical analyses were collected before treatment (T0) and at 24 (T24) and 48 (T48) h after the last treatment.

Results:

The MIC and MBC of sage EO against S. aureus were 12.5% and 6.1%, respectively. SCC was decreased significantly (p<0.05) at T24 and T48 h in sage EO and amoxicillin treated groups. Milk fat and lactose were increased significantly (p<0.05) in sage EO and amoxicillin treated ewes while no significant changes were observed in the percentages of solids-not-fat, protein and total solids. No significant effects of sage EO treatment on any of the hematology or serum biochemical parameters were observed. There were no local or systemic side effects observed in any of the treated ewes. However, further clinical trials are warranted to determine safety and possible withdrawal times in milk before its recommendation for use in organic operations.

Conclusion:

In this study, the intramammary infusion of sage EO to ewes affected with subclinical mastitis resulted in a significant decrease in SCC 24 h and 48 h posttreatment. In addition, milk fat and lactose were increased in animals that received the EO as well as in those treated with the antibiotic.

Immuno-Detection of C3a, a C3 Complement Activated Product in Mastitis Milk, a Potential Diagnostic Marker

The sub-clinical form of mastitis is difficult to detect and causes huge economic loss to the dairy industry. It has become a threat to public health at large, thus there is a need for definite diagnosis of the disease. Therefore, this study was undertaken to identify the novel diagnostic marker for the detection of the sub-clinical form of mastitis. Two-dimensional gel analysis of the whey protein fraction of normal and mastitis milk samples revealed the presence of proteose peptone component 3 precursor, Trypsin precursor, complement component-C3, Ig heavy chain precursors and a C-type lectin domain as differentially expressed protein during the early stage of mastitis. Of these proteins identified, complement component-C3 was tested for its diagnostic potential. Western blot analysis of the milk whey of sub-clinical mastitis cases (M+, M++ &amp; M+++) identified the accumulation of C3a, an activated product of complement component-C3. Further, the hemolytic activity of the above milk whey samples positively correlated with the somatic cell count. As C3a is already reported as an anaphylotoxic agent, it chemo tactically attracts lymphocytes at the site of inflammation, the detection of which in the milk whey can be of diagnostic importance for sub-clinical mastitis.

Mastitis in sheep--The last 10 years and the future of research

Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts.

Effects of intramammary infection on whey proteinograms of sheep during lactation

The study aimed to identify potential biomarkers of mammary gland infection in Santa Inês sheep. Commercial flocks of sheep provided the same hygiene, sanitary, and nutritional management under semi-intensive production systems were monitored during the lactation stage-and assessed 15, 30, 60, and 90 days after delivery (through the end of lactation and weaning). The California Mastitis Test (CMT) was performed on the mammary glands. Milk was collected for bacterial examination and protein analysis. Bacterial culture and biochemical characterization of the samples were performed. Forty-two milk samples from healthy glands (negative CMT and bacterial testing) and 43 milk samples from infected glands (positive CMT and bacterial testing) taken at the predefined time points were assessed. A rennin solution was used to obtain the whey. The proteins analysis was performed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which allowed for the quantification of nine whey proteins produced in healthy glands: serum albumin, lactoferrin, IgA, IgG heavy-chain (IgG HC), IgG light-chain (IgG LC), total IgG (IgG HC + IgG LC), α-lactalbumin, β-lactoglobulin, protein with MW 15.000 Da, protein with MW 29.000 Da and eleven whey proteins secreted by infected glands, including haptoglobin and α-1-acid glycoprotein. A comparison of whey proteins between healthy and infected glands showed increases (P<0.05) in the secreted and total contents of all proteins, except for IgG LC and α-lactoalbumin. The most significant changes were observed in α-1-acid glycoprotein, lactoferrin and haptoglobin, which showed three-, five-, and seven-fold increases in secretion, respectively. This study showed that haptoglobin, α-1-acid glycoprotein, lactoferrin, albumin, and the IgA and IgG immunoglobulins may serve as potential biomarkers for mammary gland infection in sheep.

Antibacterial activity of essential oils, their blends and mixtures of their main constituents against some strains supporting livestock mastitis

Ten of the most known and used commercial essential oils (Cinnamomum zeylanicum L., Citrus bergamia Risso, Eucalyptus globulus Labill., Foeniculum vulgare Mill., Origanum majorana L., Origanum vulgare L., Rosmarinus officinalis L., Satureja montana L., Thymus vulgaris L. ct. carvacrol, Thymus vulgaris L. ct. thymol) were tested against six bacteria strains Staphylococcus aureus, Staphylococcus chromogenes, Staphylococcus sciuri, Staphylococcus warneri, Staphylococcus xylosus and Escherichia coli, responsible for mastitis in animals. The best results were achieved by S. montana, T. vulgaris ct. thymol and O. vulgare. Two binary mixtures of essential oils (EOs) were prepared of S. montana and T. vulgaris ct. thymol (ST) and of S. montana and O. vulgare (SO). The ST mixture exhibited the best inhibitory activity against all the tested bacterial strains. Two artificial mixtures of carvacrol/thymol (AB) and carvacrol/thymol/p-cymene (CD) were prepared and tested against all of the bacterial strains used. The results exhibited a general reduction of the inhibitory activity of mixture AB, although not reaching the inhibition of the ST and SO mixtures. However the mixture CD presented an apparent strong inhibition against S. aureus and S. sciuri. The EO mixtures and the mixture CD represent promising phytotherapic approaches against bacteria strains responsible for environmental mastitis.

Fatores de risco, etiologia e aspectos clínicos da mastite em ovelhas de corte no Paraná

A mastite em ovelhas da raça Santa Inês apresenta-se como um problema de grande proporção e gravidade e é dificilmente tratada com sucesso. O objetivo deste estudo foi caracterizar aspectos clínicos, epidemiológicos e etiológicos da mastite clínica em ovelhas de corte criadas no norte do Paraná. O presente estudo foi realizado entre os meses de outubro de 2009 a setembro de 2010 envolvendo 54 rebanhos de ovinos de corte de diferentes raças. Durante as visitas às propriedades, um questionário foi preenchido com a finalidade de caracterizar o problema. Setenta ovelhas com mastite clínica foram examinadas e amostras de secreção láctea foram colhidas para exame microbiológico. A mastite foi considerada um problema relevante em 39 propriedades (72,3%), com frequência média de 6,74%. Casos crônicos e agudos de mastite foram observados em 69% e 31% das ovelhas examinadas, respectivamente. Em ambos os casos, a mastite flegmonosa foi a forma mais encontrada (65,5% dos casos). O agente etiológico mais prevalente foi Staphylococcus coagulase negativo (54,5%), seguido por S. aureus e A. pyogenes (11,5% cada). Mannheimia haemolytica foi isolada em dois casos. Sistema de criação não extensivo e raça Santa Inês foram identificados como fatores de risco para o desenvolvimento de mastite clínica. Secagem das fêmeas após 120 dias de lactação e separação de fêmeas doentes do rebanho foram associadas com menor ocorrência da doença. Recomenda-se a limpeza adequada das instalações e a secagem mais tardia, principalmente em rebanhos Santa Inês.

Comparative analysis of agr groups and virulence genes among subclinical and clinical mastitis Staphylococcus aureus isolates from sheep flocks of the Northeast of Brazil

Staphylococcus aureus is one of the most frequent mastitis causative agents in small ruminants. The expression of most virulence genes of S. aureus is controlled by an accessory gene regulator (agr) locus. This study aimed to ascertain the prevalence of the different agr groups and to evaluate the occurrence of encoding genes for cytotoxin, adhesins and toxins with superantigen activity in S. aureus isolates from milk of ewes with clinical and subclinical mastitis in sheep flocks raised for meat production The agr groups I and II were identified in both cases of clinical and subclinical mastitis. Neither the arg groups III and IV nor negative agr were found. The presence of cflA gene was identified in 100% of the isolates. The frequency of hla and lukE-D genes was high - 77.3 and 82.8%, respectively and all isolates from clinical mastitis presented these genes. The sec gene, either associated to tst gene or not, was identified only in isolates from subclinical mastitis. None of the following genes were identified: bbp, ebpS, cna, fnbB, icaA, icaD, bap, hlg, lukM-lukF-PV and se-a-b-d-e.

Improved understanding of factors driving methicillin-resistant Staphylococcus aureus epidemic waves

Methicillin-resistant Staphylococcus aureus (MRSA) remains one of the most important causes of nosocomial infections worldwide. Since the global spread of MRSA in the 1960s, MRSA strains have evolved with increased pathogenic potential. Notably, some strains are now capable of causing persistent infections not only in hospitalized patients but also in healthy individuals in the community. Furthermore, MRSA is increasingly associated with infections among livestock-associated workers, primarily because of transmission from animals to humans. Moreover, many MRSA strains have gained resistance to most available antibiotics. In this review, we will present current knowledge on MRSA epidemiology and discuss new endeavors being undertaken to understand better the molecular and epidemiological underpinnings of MRSA outbreaks.