Etiology Of Mastitis Research Articles

Distribution and Etiology of Mastitis in Cows, Economic Damage

Distribution and Etiology of Mastitis in Cows, Economic Damage

The rumen microbiota contributed to the development of mastitis induced by subclinical ketosis

BackgroundMastitis is a serious disease which affects animal husbandry, particularly in cow breeding. The etiology of mastitis is complex and its pathological mechanism is not yet fully understood. Our previous research in clinical investigation has revealed that subclinical ketosis can increase the number of somatic cell counts (SCC) in milk, although the underlying mechanism remains unclear. Recent studies have further confirmed the significant role of mastitis. ResultsIn this study, we aimed to examine the SCC, rumen microbiota, and metabolites in the milkmen of cows with subclinical ketosis. Additionally, we conducted a rumen microbiota transplant into mice to investigate the potential association between rumen microbiota disturbance and mastitis induced by subclinical ketosis in dairy cows. The study has found that cows with subclinical ketosis have a higher SCC in their milk compared to healthy cows. Additionally, there were significant differences in the rumen microbiota and the level of volatile fatty acid (VFA) between cows with subclinical ketosis and healthy cows. Moreover, transplanting the rumen microbiota from subclinical ketosis and mastitis cows into mice can induce mammary inflammation and liver function damage than transplanting the rumen flora from healthy dairy cows. ConclusionsIn addition to the infection of mammary gland by pathogenic microorganisms, there is also an endogenous therapeutic pathway mediated by rumen microbiota. Targeted rumen microbiota modulation may be an effective way to prevent and control mastitis in dairy cows.

Overexpression of the Mas1 gene mitigated LPS-induced inflammatory injury in mammary epithelial cells by inhibiting the NF-κB/MAPKs signaling pathways.

Breast infection is the primary etiology of mastitis in dairy cows, leading to a reduction in the quality of dairy products and resulting in substantial economic losses for animal husbandry. Although antibiotic treatment can eliminate the pathogenic microorganisms that induce mastitis, it cannot repair the inflammatory damage of mammary epithelial cells and blood milk barrier. Mas1 is a G protein-coupled receptor, and its role in lipopolysaccharide (LPS) -induced inflammatory injury to mammary epithelial cells has not been studied. LPS treatment of EpH4 EV cells led to a significant downregulation of Mas1 transcript levels, which attracted our great interest, suggesting that Mas1 may be an important target for the treatment of mastitis. Therefore, this study intends to verify the role of Mas1 in the inflammatory injury of EpH4 EV cells by gene overexpression technology and gene silencing technology. The findings demonstrated that the overexpression of the Mas1 gene effectively reversed the activation of the nuclear factor-κB/mitogen-activated protein kinase (NF-κB/MAPK) signaling pathways induced by LPS, while also suppressing the upregulation of pro-inflammatory mediators. Furthermore, overexpression of the Mas1 gene reversed the downregulation of zonula occludens 1 (ZO-1), Occludin, and Claudin-3 caused by LPS, suggesting that Mas1 could promote to repair the blood-milk barrier. However, the silencing of the Mas1 gene using siRNA resulted in a contrasting effect. These results indicated that Mas1 alleviated the inflammatory injury of mammary epithelial cells induced by LPS.

Etiology of severe mastitis in French dairy herds

Severe clinical mastitis is not so frequent in dairy cows, but it can have a significant economic impact due to its high mortality rate and adverse effects on milk production. Surveys about the cause of mastitis typically provide overall findings without connecting them to a specific medical condition. There are few studies on the specific etiology of severe mastitis. Only etiological results obtained during field studies are available in France, and the number of mastitic milk samples analyzed is always low. In recent years, veterinary clinics have improved their ability to identify bacteria causing bovine mastitis using a widely used method. This in-clinic milk culture made it possible to better understand the etiology of mastitis according to the symptoms observed. Regarding clinical mastitis, veterinarians treat severe cases differently than less severe ones. Based on data from nineteen veterinary clinics in France and over 2000 severe mastitis cases, the current study revealed that Enterobacteriaceae, particularly Escherichia coli, is the most common cause, isolated on average from 53.9% of milk samples. This information is highly reliable for practitioners to quickly and effectively treat the condition, because early and targeted treatment is crucial to avoid the complication of endotoxic shock.

Interrogating the role of the milk microbiome in mastitis in the multi-omics era.

There is growing interest in a functional understanding of milk-associated microbiota as there is ample evidence that host-associated microbial communities play an active role in host health and phenotype. Mastitis, characterized by painful inflammation of the mammary gland, is prevalent among lactating humans and agricultural animals and is associated with significant clinical and economic consequences. The etiology of mastitis is complex and polymicrobial and correlative studies have indicated alterations in milk microbial community composition. Recent evidence is beginning to suggest that a causal relationship may exist between the milk microbiota and host phenotype in mastitis. Multi-omic approaches can be leveraged to gain a mechanistic, molecular level understanding of how the milk microbiome might modulate host physiology, thereby informing strategies to prevent and ameliorate mastitis. In this paper, we review existing studies that have utilized omics approaches to investigate the role of the milk microbiome in mastitis. We also summarize the strengths and challenges associated with the different omics techniques including metagenomics, metatranscriptomics, metaproteomics, metabolomics and lipidomics and provide perspective on the integration of multiple omics technologies for a better functional understanding of the milk microbiome.

The influence of violations in the work of mechanized milking operators on the quality of milk and the occurrence of mastitis

Mastitis is the most common disease on livestock farms. The reasons leading to the occurrence of mastitis and a decrease in the quality of milk are diverse. Violation of milking technology, maintenance, principles of mastitis prevention, untimely diagnosis and its defective treatment causes significant economic damage to dairy farms. The object of research was cattle milk. In the milk samples, the number of somatic cells and the number of mesophilic aerobic and facultive atianaerobic microorganisms were taken into account using standard techniques [1, 3]. The analysis of the organization of milking was carried out in the hall of the rotary type "Carousel". The purpose of the work: to improve the quality of milk and reduce the amount of mastitis by eliminating shortcomings in the work of machine milking operators. During the study, it was found that at the time of milking on the platform "Carousel" there were animals with contamination of the limbs and mammary gland. We have identified the following shortcomings in the analysis of the milking routine: a small amount of milking of the first trickles of milk, poor-quality cleaning and drying of nipples with a scrubber, connection of animals to the milking machine with an incomplete milk ejection reflex, violation of animal milking hygiene, repeated connections to the milking machine, non-compliance with the rules of nipple treatment after milking. The available data obtained during the study make it possible to better understand the etiology of mastitis, the problem of increased numbers of bacteria and somatic cells in milk due to violations of the work of machine milking operators. The results obtained allow us to state the need for the use of informative diagnostic methods in the practical activities of specialists at dairy enterprises in the Russian Federation. We have developed practical recommendations and rules for the prevention of mastitis and improving the quality of milk. As a result of the introduction of the created recommendations and rules into practice, it was possible to reduce the number of animals with mastitis, reduce bacterial contamination and the number of somatic cells in milk.

Некоторые аспекты эпизоотологии и патогенеза субклинического и клинического мастита

Clinical and subclinical forms of mastitis are widespread in dairy cows and cause premature slaughter of animals due to lack of milk, agalactia, atrophy and hardening of the udder. The incidence of mastitis in dairy cows averages about 25 %, but the manifest form of mastitis occurs in 50 % of lactating cows. Culling large numbers of dairy cows can have a negative impact on production profits. The early slaughter of dairy cows is influenced by various factors, mainly violations of veterinary and zootechnical husbandry rules. It should be noted that veterinary measures for the prevention and treatment of mastitis are not always effective. Statistics from the veterinary department show that the average age of Russian dairy cows is 2,7 lactations. The decisive role in the etiology of mastitis depends on three interrelated factors (infectious agent, protective properties of the macroorganism and environmental influences). At the onset of the disease, a sterile inflammatory process occurs, which is then complicated by the microbial community. Opportunistic microorganisms accumulate in the tip of the nipple and the nipple canals, penetrate the nipple and suprapapillary cisterns and cause an infectious process. Inflammatory processes in the intestines, organs of the reproductive system, etc. can also lead to infection of the mammary glands. The part of the udder that produces the most milk is most often affected. Microorganisms penetrate the mammary gland in three ways (mammary, hematogenous and lymphatic). During the inflammatory process, under the influence of microorganisms, milk proteins are destroyed, the pH of the environment changes, and clots and flakes appear. Subsequent changes depend on the severity of the inflammatory process. If timely measures are taken, the physiological processes and structure of the breast tissue can be restored, otherwise atrophy of one lobe (quarter) of the mammary gland will occur. The clinical symptoms of subclinical mastitis are unknown. Serous-catarrhal exudate appears in the alveoli, the components of which are lymphocytes, plasma cells and multinucleated cells. The protein composition of milk undergoes significant changes, which are characterized by a decrease in the content of total protein and casein, an increase in the concentration of whey protein, an increase in the alkalinity of milk, and an increase in the number of somatic cells. If cows with subclinical mastitis are left untreated, they resolve spontaneously in 12–20 % of cases and develop clinical signs in 15–20 %.

ETIOPATHOGENETIC ASPECTS OF SHEEP MASTITIS

Mastitis in sheep is a serious problem that leads to poor milk quality and is the cause of intestinal disorders in lambs. The etiology of mastitis in sheep is still poorly understood and there is no general opinion on the causative agent of mastitis. There is a little of information in the literature about biofilm-forming mastitis pathogens. The biofilm of microorganisms is the most important virulence factor and contributes to the protection of the pathogen from antimicrobial drugs, thereby reducing the effectiveness of therapeutic drugs.This study aimed to determine the main causative agents of mastitis in sheep in two form: subclinical and clinical from farms of Almaty region, to identify biofilm-forming strains among them, and to study the pathological process in the udder by conducting histological studies.132 samples of milk from various farms in the Almaty region were examined. To determine subclinical mastitis, the express test "Milkotest" was used. The subclinical form of mastitis occurs in farms more often than the clinical form, 20.8% and 13.4%, respectively. In subclinical mastitis, coagulase-negative staphylococci dominated, and in the clinical form, cultures of S. aureus were more often isolated, cultures of E. coli were isolated to a lesser extent. The biofilm formation was determined by a statistical method. Among the isolated cultures, 149 isolates were able to generate biofilm. It has been shown that coagulase-negative staphylococci and S. aureus had a greater potential to produce a biofilm compared to the isolated E. coli cultures. It was also found that the nature of the inflammatory process and pathological and anatomical changes in the udder of animals in mastitis depend on the type of the pathogen

Gene expression adjustment of inflammatory mechanisms in dairy cow mammary gland parenchyma during host defense against staphylococci

Abstract The aim of the study was to identify differences in the expression of splice variants of the PRMT2, LTF and C4A genes in the mammary glands of healthy dairy cows and those infected with staphylococci. An expression study was conducted on 38 Polish Holstein-Friesian dairy cows who were removed from the herd owing to subclinical and chronic mastitic or reproductive issues. Two days before slaughter, milk samples were taken for microbiological analysis and examined for the presence of bacteria. The mammary gland parenchyma samples with a predominance of secretory tissue were taken; these were divided into three groups according to the health status of the mammary gland: H (without pathogenic bacteria in milk), CoNS (with coagulase-negative staphylococci in milk), and CoPS (with coagulase-positive staphylococci in milk). Two of the investigated genes, LTF and C4A, demonstrated variants unequivocally expressed in infected tissue. Two LTF gene variants were found to be associated with cow health status, and with the type of bacteria causing mastitis (CoPS or CoNS). In addition, the expression of C4A isoforms differed with regard to mastitis etiology groups. The comprehensive evaluation of PRMT2 transcript suggested that the gene may also be involved in course of mastitis: two of four PRMT2 transcripts showed increased expression in the mammary gland of the CoPS group compared to controls. The obtained results are important for the knowledge on the etiology of bovine mastitis. The effects of the identified mastitis-relevant splice variants need to be further explored on the protein level to verify the suitability of splice variants and recognize their contribution towards the disease phenotypes and course.

Etiology of Mastitis and Antimicrobial Resistance in Dairy Cattle Farms in the Western Part of Romania.

The present study aimed to determine the bacteria isolated from bovine mastitis and their antimicrobial resistance in the western part of Romania. Clinical mastitis was diagnosed based on local inflammation in the udder, changes in milk, and when present, generalized symptoms. Subclinical mastitis was assessed using a rapid test—the California Mastitis Test. The identification of bacterial strains was performed based on biochemical profiles using API system tests (API 20 E, API Staph, API 20 Strep, API Coryne, API 20 NE (bioMerieux, Marcy l’Etoile, France), and MALDI-TOF mass spectrometry (MS). The prevalent isolated bacteria were Staphylococcus spp. (50/116; 43.19%), followed by Streptococcus spp. (26/116; 22.41%), E. coli (16/116; 13.79%), Corynebacterium spp. (9/116; 7.75%), Enterococcus spp. (10/116; 8.62%), and Enterobacter spp. (5/116; 4.31%). Phenotype antimicrobial resistance profiling was performed used the disc diffusion method. Generally, Gram-positive bacteria showed low susceptibility to most of the antimicrobials tested, except cephalothin. Susceptibilities to penicillins and quinolones were fairly high in Gram-negative bacteria, whereas resistance was observed to macrolides, aminoglycosides, and tetracyclines. The highest number of isolates were multidrug resistant (MDR), the resistance pathotypes identified including the most frequently antimicrobials used in cow mastitis treatment in Romania.

Prevention of Bovine Mastitis through Vaccination.

Cow mastitis is one of the main factors of economic damage in modern animal husbandry. It is registered to affect almost everywhere, taking into account the subclinical form from 30% to 50% of the livestock per year. Economic losses of farms from the diseases of cows with mastitis are due to a decrease in milk productivity, precocious cow disposal, a decrease in the grade and sale price of market milk, and treatment costs. This study aimed to use a safer method in the prevention and control of mastitis in cows, and vaccinations could be a solution to this problem. Vaccination promotes acquired immunity to a specific pathogen and also has few side effects. A bacteriological study of clinical and subclinical forms of mastitis was conducted to study the etiology of mastitis in cows in various farms of Kazakhstan. A total of 1,068 milk samples from 767 cows were examined. The studies were carried out according to "Guidelines for bacteriological studies of milk and udder secretions of cows". The primary selection of cultures was carried out based on growth characteristics on media and microscopy of preparations from individual colonies. Morphological, cultural, and biochemical properties of the isolated cultures were studied according to generally accepted schemes. Identification of the selected cultures was carried out using Bergey's determinant. The strain numbers of Staphylococci, Streptococci, Escherichia, Klebsiella, Diplococci, and Protea were 590 (55.2%), 240 (22.4%), 151 (14.1%), 50 (4.7%), 24 (2.3%), and 13 (1.3%), respectively. The greatest strain numbers of Staphylococci (n=351) and Streptococci (n=129) were isolated from cow's milk with subclinical mastitis. The effectiveness of the polyvalent vaccine used was determined by the manifestation of clinical and subclinical forms of mastitis. Out of 600 immunized cows, 9 (1.5%) and 13 (2.3%) animals developed subclinical and clinical mastitis, respectively. Furthermore, out of 150 cows taken into control, 12 (8%) and 10 (6.6%) animals developed subclinical and clinical mastitis, respectively. Furthermore, out of 12 cows with clinical mastitis, 5 cows previously had a subclinical form. Vaccination takes a significant place in the control of infectious diseases. The success of vaccine prevention depends on the quality of vaccines and timely vaccination coverage of threatened populations. Modern immunology and vaccine prevention have summed up the theoretical basis and outlined ways to improve vaccines in the direction of creating new harmless effective vaccines.

Antimicrobial Susceptibility Profile of Bacteria in Mastitis Cow Milk Samples

Bovine mastitis is a cause of major financial losses in the dairy industry worldwide. Bovine mastitis is defined as the inflammatory response of the udder tissue due to either physical trauma or infections caused by different microorganisms, especially bacteria. More than 135 pathogenic agents have been identified from bovine mastitis. The aim of the study was to identify the bacterial genera involved in mastitis etiology in cattle and to test the antimicrobial susceptibility to antibiotics. The samples were collected before morning milking and evaluated by microscopic and cultural examination, and further identified using biochemical methods. The evaluation of antimicrobial susceptibility was performed using Kirby-Bauer disk diffusion test. Overall, Staphylococcus spp., Bacillus spp., Streptococcus spp., Micrococcus spp., Escherichia spp. and Trueperella spp. were identified. The most frequent bacterial associations were observed for Staphylococcus-Bacillus, Bacillus-Streptococcus and Staphylococcus-Micrococcus. Regarding the antimicrobial sensitivity profile, the majority of the bacterial strains we have isolated were classified as sensitive, with the exception of Escherichia coli, with one strain being resistant to all tested antibiotics. Among the antimicrobials, the Amoxicillin and clavulanic acid was the most efficient one and Trimethoprim/Sulfamethoxazole did not exhibit an inhibitory activity in 19 milk samples.

Effects of a mastitis treatment strategy with or without on-farm testing

The etiology of mastitis is crucial information to use antimicrobials prudently for control and treatment. This study aimed to evaluate the effects of mastitis diagnosis and treatment strategies with on-farm testing, on cure, new intramammary infections (IMI), somatic cell count (SCC), and antimicrobial use, compared with farmers' current diagnosis and treatment strategies. The on-farm tests used, CHROMagar Mastitis (CHROMagar, Paris, France) and Minnesota Easy Culture System II Tri-plate (University of Minnesota, St. Paul, MN), both had etiological groups of IMI as result, being gram-positive growth, gram-negative growth, or culture negative. Two randomized controlled trials were conducted on 15 herds: trial 1 prospectively enrolled 155 cows with clinical mastitis, and trial 2 cross-sectionally included 78 cows with subclinical mastitis. In both trials, cows were randomly distributed over 3 equal-sized groups: a test group using CHROMagar, a test group using Minnesota, and a control group not using on-farm tests. Farmers decided whether or not to treat, and which antimicrobial treatment would be applied, using information available on the day of enrollment (control group), complemented with the on-farm test result 1 d after enrollment (both test groups). For clinical mastitis, an antimicrobial treatment was given in 58% of cases that used CHROMagar, in 80% that used Minnesota, and in 86% of the controls. For subclinical mastitis, an antimicrobial treatment was given in 50% of cases that used CHROMagar, in 54% that used Minnesota, and in 4% of the controls. Bacteriological cure rate of clinical mastitis was lowest in the CHROMagar group [odds ratio 0.18 (95%CI 0.03-0.99)] compared with the controls. Using the Minnesota on-farm test for subclinical mastitis diagnosis and treatments resulted in fewer new IMI on d 21 [odds ratio 0.06 (95%CI 0.00-0.74)] compared with the controls. Clinical cure rate, percentage of new IMI, and SCC on d 21 of clinical mastitis were comparable among the groups. Using on-farm tests in farmers' decision-making process resulted in more treatments in accordance with the etiology of mastitis than without on-farm testing. A diagnosis and treatment strategy with on-farm testing is advised in cows with clinical mastitis to enhance prudent antimicrobial use. For subclinical mastitis, however, on-farm testing may lead to an unacceptable increase in use of antimicrobials and thus should not be advised as the common approach.

Diagnosing Disease Of Cow Mastitis And Method Of Using Diffusion-Precipitation Reaction In Agar Gel

The microbial factor is essential in the etiology of mastitis. In this regard, bacteriological diagnostics is one of the decisive moments in the recognition and differentiation of pathological conditions of the mammary gland. However, it takes a lot of time to make a diagnosis using general methods, special culture media and reagents.

Identification of Gene Modules and Hub Genes Involved in Mastitis Development Using a Systems Biology Approach.

ObjectiveMastitis is defined as the inflammation of the mammary gland, which impact directly on the production performance and welfare of dairy cattle. Since, mastitis is a multifactorial complex disease and the molecular pathways underlying this disorder have not been clearly understood yet, a system biology approach was used in this study to a better understanding of the molecular mechanisms behind mastitis.MethodsPublicly available RNA-Seq data containing samples from milk of five infected and five healthy Holstein cows at five time points were retrieved. Gene Co-expression network analysis (WGCNA) approach and functional enrichment analysis were then applied with the aim to find the non-preserved module of genes that their connectivity were altered under infected condition. Hub genes were identified in the non-preserved modules and were subjected to protein-protein interactions (PPI) network construction.ResultsAmong the 25 modules identified, eight modules were non-preserved and were also biologically associated with inflammation, immune response and mastitis development. Interestingly most of the hub genes in the eight modules were also densely connected in the PPI network. Of the hub genes, 250 genes were hubs in both co-expression and PPI networks and most of them were reported to play important roles in immune response or inflammatory pathways. The blue module was highly enriched in inflammatory responses and STAT1 was suggested to play an important role in mastitis development by regulating the immune related genes in this module. Moreover, a set of highly connected genes were identified such as BIRC3, PSMA6, FYN, F11R, NFKBIZ, NFKBIA, GRO1, PHB, CD3E, IL16, GSN, SOCS2, HCK, VAV1 and TLR6, which have been established to be critical for mastitis pathogenesis.ConclusionThis study improved the understanding of the mechanisms underlying bovine mastitis and suggested eight non-preserved modules along with several most important genes with promising potential in etiology of mastitis.

Study on prevalence and bacterial etiology of mastitis, and effects of subclinical mastitis and stage of lactation on SCC in dairy goats in Egypt.

In Egypt, inadequate information on prevalence and epidemiology of caprine mastitis is available. This study was designed to investigate prevalence and etiological agents of caprine mastitis and assess the efficacy of somatic cell count (SCC) as marker of subclinical mastitis (SCM) in dairy goats. This study was carried out on 249 randomly selected lactating goats in different lactation stages and examined clinically. Of these animals, 477 milk samples were aseptically collected and screened for bacterial carriage. SCC was assessed in 234 apparently normal milk samples, and SCC ≥ 106cells/ml was indicator for SCM. Prevalence of clinical mastitis (CM) was 33.73% and 16.87% at animal and udder-half levels, respectively. SCM was 52.56% in the apparently healthy halves. Culture results proved single infection in 49.69% of samples, mixed infection in 23.9% of samples, and 26.41% of samples were negative. Coagulase negative staphylococci (CNS) were the most predominant bacteria (58.75%), then Staphylococcus aureus (S. aureus) (24.375%), and Streptococci (1.875%) were the least. No significant difference was recorded between mean of SCC in bacteriologically positive and negative samples, neither in those with SCC ≤ 106 nor with SCC ≥ 106cells/ml both in middle and late lactation stages. Besides, the percentage of animals harboring SCC ≥ 106cells/ml and negative for bacteriology in late lactation stage was 3 times (28.57%) more than in midlactation (9.3%). We can assume that SCC is not proper indicator for intra-mammary inflammation (IMI) in goats, and bacteriological examination remains more efficient, despites being time consuming and expensive.

МИКРОБНЫЙ ПЕЙЗАЖ ПРИ МАСТИТАХ У КОРОВ

Despite the subdivision of livestock farms in the process of agricultural reform, obstetric and gynecological diseases in farm animals, including mastitis, remain key problem for veterinary medicine specialists. Studies on the bacterial etiology of mastitis in cows were conducted in 12 farms in the Moscow region with a population of 12254 cattle, including 4445 cows. When studying microbiocenoses during mastitis in cows on farms in the Moscow region, it was found that the microbial landscape of cow udder secretions in mastitis is very diverse and heterogeneous. Thus, 486 pathogenic and conditionally pathogenic microorganisms were isolated from 103 cows with mastitis, which were referred to 11 species. More often, during mastitis in cows, representatives of Streptococcus SP. p., Staphylococcus sp. p., Lactobacillus sp. p. and Escherichia sp. p. were isolated from udder secretions. – 25,7 %; 20,8 %; 18,3 % and 9.6 %, respectively. It was established that mastitis in cows is caused not by a single pathogen, but by microbial associations, which include from 2 to 7 isolates. When serotyping E. coli cultures, it was established that from the milk of cows with mastitis, O8 and O18 were most often isolated by 7 (15.2 %), O78 – 6 (13.1 %), and O101 and O126 by 5 (10.9 %) cases out of the total number of isolated serotypes. Of the udder secretions of cows with mastitis, 37 (80.4 %) isolates from the total number of Escherichia coli also had hemolysin-producing properties. In the milk of cows with mastitis, the highest concentration contains representatives of the species Staphylococcus sp. p.; Escherichia sp. p.; Pseudomonas sp. p. and Streptococcus sp. p., respectively, 5.67±0.08 lg; 4.37±0.32 lg; 4.24±0.20 lg and 4.13±0.15 lg. Fungi of Candida species varied at the level of 102 CFU. More often, pathogenic properties were found in cultures of S. aureus 48 (27.7 %), E. coli 22 (12.7 %), S. uberis 18 (10.3 %) and S. dysgalactiae 17 (9.8 %) of the total number of pathogenic isolates for white mice. Of the 11 isolated cultures of Candida fungi, 5 (2.9 %) isolates were pathogenic. The highest antimicrobial activity was observed in enrofloxacin, cephalexin, norfloxacin, cobactan and ofloxacin. The number of microbial isolates sensitive to these antimicrobial agents was 466 (98,1 %); 455 (95,8 %); 440 (92,6 %); 438 (92,2 %) and 432 (90.9 %). The most effective antimycotic agent was intraconazole, which showed activity to all 11 (100.0 %) isolated fungi.

Characterization and molecular epidemiology of Staphylococcus aureus strains resistant to beta-lactams isolated from the milk of cows diagnosed with subclinical mastitis.

Background and Aim:The term ESKAPE, recognized by the WHO, is an acronym, which refers to the pathogens Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp., which is extremely virulent and multidrug-resistant. Although the term is used to designate nosocomial pathogens, in a milking environment, strains of Methicillin-resistant S. aureus have been isolated from cattle diagnosed with clinical and subclinical mastitis. Resistant strains may be involved in the transfer of genes conferring resistance to beta-lactam antimicrobials among the species of microorganisms related to mastitis etiology. This study aimed to trace the phenotypic and genotypic profiles of susceptibility to beta-lactams in S. aureus isolated from milk of cattle diagnosed with subclinical mastitis obtained from different rural properties located in the North of Minas Gerais State, Brazil.Materials and Methods:Sixteen microorganisms previously identified as S. aureus isolated from milk of cattle diagnosed with subclinical mastitis were submitted to matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF), mass spectrometry, and polymerase chain reaction (PCR) analysis for microbial species confirmation. The S. aureus beta-lactams antimicrobial phenotypic resistance profile was investigated by disk diffusion method. PCR methods were also performed to investigate the S. aureus genotypic beta-lactams resistance profile. For this purpose, blaZ, mec A, mecALGA251, blaOxa23, and blaKPC genes were screened among S. aureus isolates. The genetic diversity of S. aureus by fingerprint random amplified polymorphic DNA (RAPD)-PCR was also performed in this study.Results:All isolates showed phenotypic resistance to at least three beta-lactams, among which was meropenem. None of the isolates tested positive for the genes mecALGA251, blaOxa23, and blaKPC; however, the presence of the genes blaZ and mecA was detected among the isolates. The fingerprint analysis divided isolates into two distinct groups and 15 different subgroups. Despite the presence of clonality among the isolates, the PCR-RAPD analysis unveiled a heterogeneous profile with genetic diversity among the S. aureus isolates.Conclusion:In this study, we identified beta-lactams resistant S. aureus strains isolated from the milk of cows diagnosed with subclinical mastitis. The S. aureus beta-lactams resistance was investigated using a phenotypic and genotypic approach. We believe that molecular epidemiology, improved knowledge, and genetic basis of resistance to beta-lactams might assist in asserting guidelines for better management practices of dealing with subclinical mastitis and mapping of origin of resistant pathogens in the studied Brazilian area.

The Etiology of Mastitis and its Impact on Lipid Peroxidation Product of Dairy Cows

Worldwide, intramammary infection - mastitis is still one of the most important disease in the dairy sector...

The occurrence of mastitis and its effect on the milk malondialdehyde concentrations and blood enzymatic antioxidants in dairy cows

Early identification of mastitis is a serious challenge for dairy farmers and veterinarians in ensuring the health of an animal and the hygienic quality of the produced milk. The purpose of this study was to detect the occurrence and aetiology of mastitis in a dairy herd of 15 milked cows localised in a farm in west Slovakia. During the complex investigation, 606 quarter milk samples were examined (6 quarters were discarded) and classified based on the clinical status, the presence of abnormal udder secretions, the result of the California mastitis test (CMT), the somatic cell count (SCC) and the bacteriological identification of the pathogens causing the intramammary infection (IMI). The study was augmented by the detection of malondialdehyde (MDA) in the milk and the measurements of the blood enzymatic activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) as potential biomarkers for the udder health screening. A positive CMT score was recorded in 19.5% (118) of the examined quarters and 12.5% (76) of the quarters were infected with bacterial pathogens causing latent mastitis (LM; 1.3%), subclinical mastitis (SM; 8.3%), and clinical mastitis (CM; 2.9%). The most commonly isolated bacteria from the infected quarters were coagulase-negative staphylococci (55.2%), Staphylococcus aureus (11.8%) and streptococci (10.5%). The concentration of MDA and SCC were significantly higher from both the SM and CM cases than in the milk samples from the healthy cows, while the blood activities of SOD and GPx were lower in the cows with CM compared to the healthy cows. The higher MDA concentrations in the SM and CM milk observed in this study showed the presence of an oxidative stress in the infected milk, accompanied by a decrease in the antioxidative enzymatic activity in the blood of the cows. Therefore, the measurement of the milk MDA concentration and the activity of the blood SOD and GPx may prove insightful for the better screening of the udder health in the early diagnosis of mastitis.