Staphylococcal mastitis in dairy cows

Bovine mastitis is one of the most common diseases of dairy cattle. Even though different infectious microorganisms and mechanical injury can cause mastitis, bacteria are the most common cause of mastitis in dairy cows. Staphylococci, streptococci, and coliforms are the most frequently diagnosed etiological agents of mastitis in dairy cows. Staphylococci that cause mastitis are broadly divided into Staphylococcus aureus and non-aureus staphylococci (NAS). NAS is mainly comprised of coagulase-negative Staphylococcus species (CNS) and some coagulase-positive and coagulase-variable staphylococci. Current staphylococcal mastitis control measures are ineffective, and dependence on antimicrobial drugs is not sustainable because of the low cure rate with antimicrobial treatment and the development of resistance. Non-antimicrobial effective and sustainable control tools are critically needed. This review describes the current status of S. aureus and NAS mastitis in dairy cows and flags areas of knowledge gaps.

Efficacy of novel staphylococcal surface associated protein vaccines against Staphylococcus aureus and non-aureus staphylococcal mastitis in dairy cows

Mastitis is an inflammation of the mammary gland commonly caused by bacteria or fungi. Staphylococcus aureus is a major bacterium that causes mastitis in dairy cows. Non-aureus staphylococci are also increasingly reported, with Staphylococcus chromogenes being the most common species. Current staphylococcal mastitis control programs are not fully effective, and treatment with antibiotics is not sustainable. Non-antibiotic sustainable control tools, such as effective vaccines, are critically needed. We previously developed S. aureus surface-associated proteins (SASP) and S. chromogenes surface-associated proteins (SCSP) vaccines that conferred partial protective effects. We hypothesized that vaccination with SASP or SCSP would reduce the incidence of S. aureus mastitis throughout the lactation period. The objective of this study was to evaluate the efficacy of SASP and SCSP vaccines against S. aureus and non-aureus staphylococcal mastitis under natural exposure over 300 days of lactation. Pregnant Holstein dairy cows (n = 45) were enrolled and assigned to receive SASP (n = 15) or SCSP (n = 16) vaccines or unvaccinated control (n = 14). Cows were vaccinated with 1.2 mg of SASP or SCSP with Emulsigen-D adjuvant. Control cows were injected with phosphate-buffered saline with Emulsigen-D adjuvant. Three vaccine injections were given subcutaneously at 60, 40, and 20 days before the expected calving. Booster vaccinations were given at 120 and 240 days in milk. Cows were monitored for mastitis at quarter and cow levels, staphylococcal mastitis incidence, changes in serum and milk anti-SASP and anti-SCSP antibody titers, bacterial counts in milk, adverse reactions, milk yield and milk somatic cells count over 300 days of lactation. The SCSP vaccine conferred a significant reduction in the incidence of staphylococcal mastitis. Milk and serum anti-SASP and anti-SCSP antibody titers were increased in the vaccinated cows compared to unvaccinated control cows. Anti-SASP and anti-SCSP antibody titers decreased at about 120 days in milk, indicating the duration of immunity of about four months. In conclusion, the SASP and SCSP vaccines conferred partial protection from natural infection.

The combination of vaccines and adjuvants to prevent the occurrence of high incidence of infectious diseases in bovine

As the global population grows, the demand for beef and dairy products is also increasing. The cattle industry is facing tremendous pressures and challenges. The expanding cattle industry has led to an increased risk of disease in cattle. These diseases not only cause economic losses but also pose threats to public health and safety. Hence, ensuring the health of cattle is crucial. Vaccination is one of the most economical and effective methods of preventing bovine infectious diseases. However, there are fewer comprehensive reviews of bovine vaccines available. In addition, the variable nature of bovine infectious diseases will result in weakened or even ineffective immune protection from existing vaccines. This shows that it is crucial to improve overall awareness of bovine vaccines. Adjuvants, which are crucial constituents of vaccines, have a significant role in enhancing vaccine response. This review aims to present the latest advances in bovine vaccines mainly including types of bovine vaccines, current status of development of commonly used vaccines, and vaccine adjuvants. In addition, this review highlights the main challenges and outstanding problems of bovine vaccines and adjuvants in the field of research and applications. This review provides a theoretical and practical basis for the eradication of global bovine infectious diseases.

Alternatives to Antimicrobial Treatment in Bovine Mastitis Therapy: A Review

Despite preventive and therapeutic measures, mastitis continues to be the most prevalent health problem in dairy herds. Considering the risks associated with antibiotic therapy, such as compromised effectiveness due to the emergence of resistant bacteria, food safety issues, and environmental impact, an increasing number of scientific studies have referred to the new therapeutic procedures that could serve as alternatives to conventional therapy. Therefore, the aim of this review was to provide insight into the currently available literature data in the investigation of non-antibiotic alternative approaches. In general, a vast number of in vitro and in vivo available data offer the comprehension of novel, effective, and safe agents with the potential to reduce the current use of antibiotics and increase animal productivity and environmental protection. Constant progress in this field could overcome treatment difficulties associated with bovine mastitis and considerable global pressure being applied on reducing antimicrobial therapy in animals.

Immune response during the onset of coliform mastitis in dairy cows vaccinated with STARTVAC®

The immune response during the onset of coliform mastitis in vaccinated cows was investigated by measuring lactoferrin (LF), interleukin-8 (IL-8), and interleukin-1β (IL-1β) concentrations and somatic cell counts in 28 milk samples at the onset of acute coliform mastitis (ACM) and 73 milk samples at the onset of peracute coliform mastitis (PCM). Vaccinated ACM, unvaccinated ACM, and vaccinated PCM showed significantly higher values for LF and IL-1β levels than unvaccinated PCM (p < .01). The IL-8 concentration was lower in vaccinated PCM than in unvaccinated PCM (p < .05). There was no significant difference in somatic cell counts for each parameter. There were no significant differences in the parameters between vaccinated and unvaccinated ACM cows, or vaccinated ACM and PCM cows. From the above results, it is suggested that mastitis vaccination improved the early immune response, particularly at the onset of PCM, and played a large role in host defense against the initial infection.

Evaluation of the Efficacy of a Cholera-Toxin-Based Staphylococcus aureus Vaccine against Bovine Intramammary Challenge

Staphylococcus aureus (S. aureus) is a primary agent of bovine mastitis and a source of significant economic loss for the dairy industry. We previously reported antigen-specific immune induction in the milk and serum of dairy cows following vaccination with a cholera toxin A₂ and B subunit (CTA₂/B) based vaccine containing the iron-regulated surface determinant A (IsdA) and clumping factor A (ClfA) antigens of S. aureus (IsdA + ClfA-CTA₂/B). The goal of the current study was to assess the efficacy of this vaccine to protect against S. aureus infection after intramammary challenge. Six mid-lactation heifers were randomized to vaccinated and control groups. On days 1 and 14 animals were inoculated intranasally with vaccine or vehicle control, and on day 20 animals were challenged with S. aureus. Clinical outcome, milk quality, bacterial shedding, and somatic cell count (SCC) were followed for ten days post-challenge. Vaccinated animals did not show signs of clinical S. aureus mastitis and had lower SCCs compared to control animals during the challenge period. Reductions in bacterial shedding were observed but were not significant between groups. Antibody analysis of milk and serum indicated that, upon challenge, vaccinated animals produced enhanced IsdA- and ClfA-CTA₂/B specific immunoglobulin G (IgG) responses, while responses to CTA₂/B alone were not different between groups. Responses after challenge were largely IgG1 against the IsdA antigen and mixed IgG1/IgG2 against the ClfA antigen. In addition, there was a significant increase in interferon gamma (IFN-γ) expression from blood cells in vaccinated animals on day 20. While preliminary, these findings support evidence of the induction of active immunity by IsdA + ClfA-CTA₂/B, and further assessment of this vaccine is warranted.

Vaccination with a live-attenuated small-colony variant improves the humoral and cell-mediated responses against Staphylococcus aureus

Staphylococcus aureus is known to produce persistent and chronic infections in both humans and animals. It is recognized that small-colony variants (SCVs), which produce higher levels of biofilm and that are capable of intracellular persistence, contribute to the chronicity or recurrence of infections and that this phenotype is inherent to the pathogenesis process. Prevention of S. aureus infections through vaccination has not yet met with considerable success. Some of the current vaccine formulations for S. aureus bovine mastitis consist of inactivated S. aureus bacteria, sometimes combined to E. coli J5. As such, the stimulation of cell-mediated immunity by these vaccines might not be optimal. With this in mind, we recently engineered a genetically stable double mutant SCV (ΔvraGΔhemB), which was highly attenuated in a mastitis model of infection. The present work describes the immune responses elicited in mice by various experimental vaccine compositions including the live-attenuated SCV double mutant and its inactivated form, combined or not with inactivated E. coli J5. The live-attenuated SCV was found to provoke a strong and balanced humoral response in immunized mice, as well as strong proliferation of ex-vivo stimulated splenocytes isolated from these animals. These splenocytes were also found to release high concentration of IL-17 and IFN-γ when compared to every other vaccination formulation. Inversely, the inactivated whole-cell vaccine, alone or in combination with the E. coli J5 bacterin, elicited lower antibody titers and failed to induce Th1 or Th17 cell-mediated responses in the splenocyte proliferation assay. Our results suggest that live-attenuated SCVs can trigger host immunity differently than inactivated bacteria and could represent a suitable vector for inducing strong humoral and cell-mediated immune responses, which are crucial for protection. This could represent an important improvement over existing vaccine formulations for preventing S. aureus bovine mastitis and other infections caused by this pathogen.

Evaluating the effectiveness of two bovine mastitis vaccines and their influences on oxidant and antioxidant capacities of milk

The aim of the current study was to investigate the efficacy of two commercial mastitis vaccines (Startvac® and Mastivac®) and their influence on oxidant and antioxidant capacities of milk samples in a dairy farm. A total of 165 Holstein dairy cows were recruited into the study and were divided into Startvac®, Mastivac®, and control groups. The effects on the incidence and severity of clinical mastitis cases, duration of treatment, infection status, bacteriologic culture, somatic cell count, 5-thio-2-nitrobenzoic acid assay and ferric reducing antioxidant power assay, incidence of metritis and endometritis, and milk yield were evaluated within the first 90 days of lactation. The incidence of clinical mastitis was not significantly different among groups. The mean SCCs during the first, second, and third months of lactation did not differ significantly. The percentage of cured cows did not differ significantly. TNB and FRAP assays were used to know whether or not vaccination against mastitis has an effect on oxidant and antioxidant capacity of milk samples, which did not differ significantly. In conclusion, we observed no significant difference in the abovementioned variables. However, it is possible that applying mastitis vaccines within the specific conditions may have positive effects considering the results of previous studies.

Staphylococcus aureus-specific IgA antibody in milk suppresses the multiplication of S. aureus in infected bovine udder

Background

Bovine mastitis caused by Staphylococcus aureus (S. aureus) is extremely difficult to control and new methods for its prevention and management are required. Nasal vaccines may prevent initial bovine mastitis infection caused by S. aureus. However, limited information is available regarding induction of mucosal immune response through nasal immunization with antigen and its suppression of S. aureus multiplication during bovine mastitis. This study sought to investigate whether induction of immunoglobulin A (IgA) in milk by nasal immunization could suppress multiplication of S. aureus in the bovine udder.

Results

Nasal immunization with formalin-killed S. aureus conjugated with a cationic cholesteryl-group-bearing pullulan-nanogel was performed. Anti-S. aureus-specific IgA antibodies were significantly more abundant in the milk of immunized cows than in non-immunized animals (P < 0.05). S. aureus counts in the quarter were negative in both non-immunized and nasal-immunized cows 1 week after mock infusion. In S. aureus-infused quarters, S. aureus multiplication was significantly suppressed in immunized compared with non-immunized cows (P < 0.05). Furthermore, a significant negative correlation was found between S. aureus-specific IgA antibodies and S. aureus counts in infused quarters of both non-immunized and nasal-immunized cows (r = − 0.811, P < 0.01).

Conclusion

In conclusion, the present study demonstrates that S. aureus-specific IgA antibodies in milk successfully suppressed the multiplication of S. aureus in infected bovine udders. Although the exact mechanism explaining such suppressive effect remains to be elucidated, nasal vaccines that can induce humoral immunity may help prevent initial infection with S. aureus and the onset of bovine mastitis.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-2025-3) contains supplementary material, which is available to authorized users.

Immunological responses and evaluation of the protection in dairy cows vaccinated with staphylococcal surface proteins

Bovine mastitis is a significant cause of economic losses in the dairy industry. Staphylococcus aureus is one of the most common contagious mastitis pathogens, whereas Staphylococcus chromogenes increasingly became a significant cause of subclinical mastitis in dairy cows. Current mastitis control measures are not effective on all mastitis pathogens. There is no effective vaccine to control Staphylococcal mastitis in dairy cows. The objective of this study was to evaluate the immune responses and protection in dairy cows vaccinated with S. aureus surface proteins (SASP) or S. chromogenes surface proteins (SCSP). We divided eighteen Holstein dairy cows randomly into three groups of 6 animals each. We vaccinated group 1 and 2 animals with SASP and SCSP with Emulsigen-D adjuvant, respectively. We injected control (group 3) animals with PBS (pH 7.2) in Emulsigen®-D. We vaccinated animals three times at 28 and 14 days before drying off, and at dry off. Two weeks after the third vaccination, we challenged each animal by dipping all teats in S. aureus culture suspension once daily for 14 consecutive days. We evaluated milk or mammary secretion and serum antibody titers during vaccination and challenge periods. We evaluated milk samples for the number of bacteria shedding and somatic cell counts (SCC). Out of six cows vaccinated with SASP, one cow was removed from the study due to injury, two were infected clinically, another two were infected subclinically, and the remaining cow was not infected. No SCSP vaccinated cows developed clinical or subclinical mastitis. Out of six control cows, two developed clinical mastitis whereas four were infected subclinically. The SCSP vaccine cross-protected against S. aureus mastitis and reduced number of S. aureus shedding in milk. We concluded that the SCSP is a promising vaccine to control Staphylococcal mastitis in dairy cows.

Local and systemic humoral response to ovine mastitis caused by Staphylococcus epidermidis

Objectives:

Mastitis is responsible for a decrease in milk yield and quality. Disease control is vital for producers’ profit and for consumer’s welfare. This study aimed at investigating the immune response to Staphylococcus epidermidis intramammary infection.

Methods:

A total of 14 S. epidermidis isolates from milk collected from ewes with subclinical mastitis were used. Protein extracts were prepared and analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis. Immunoblotting assay was performed for the detection of specific IgG and IgA in blood and milk from S. epidermidis mastitic ewes and from healthy animals.

Results:

The presence of pathogen-specific IgG was detected in blood of both infected and healthy animals. However, in milk, pathogen-specific IgG was only identified in infected animals, while IgA was found in both groups. Proteins with 59 and 43 kDa were recognized by all immunoglobulins screened in blood and milk provided by both healthy and mastitic ewes. In addition, in milk, IgG and IgA for proteins with 35 kDa were also detected.

Conclusion:

The results have lead to propose a theory for immunoglobulin dynamics in mammary gland’s defence: blood IgG1, specifically targeting intestinal antigens, is transported to the mammary gland with the main purpose of protecting the newborn, while IgG2 is specific for mammary pathogens and is transported to the mammary gland exclusively during inflammation. This study suggests that only local immunization should trigger IgG-producing cells in the mammary gland as a response to mastitis antigens. Moreover, IgA seems to be of crucial value for the defence of the ewe mammary gland, and stimulation strategies towards an increase in IgA should be addressed for mastitis prevention.

A 100-Year Review: Mastitis detection, management, and prevention

Mastitis is the most frequent disease of dairy cows and has well-recognized detrimental effects on animal wellbeing and dairy farm profitability. Since the beginning of modern dairy farming, producers have sought effective methods to minimize the occurrence of mastitis in their herds. The objective of this paper is to review and highlight important advances in detection, management, and prevention of mastitis that have occurred since the first volume of the Journal of Dairy Science was published in 1917. Initial research efforts were directed at understanding the nature of pathogenic bacteria that were responsible for most intramammary infections. For decades, researchers worked to identify effective strategies to control mastitis caused by Streptococcus agalactiae and Staphylococcus aureus. To develop successful control programs, mastitis workers first had to identify mechanisms of infection, define the clinical and subclinical states of the disease, discover appropriate screening tests, determine likely points of exposure, identify pathogen-specific characteristics, and develop effective procedures for machine milking. Pioneering researchers eventually recognized that mastitis control was based on preventing new infections from occurring in healthy cows and reducing the duration that cows remained infected. Development of a control program that incorporated post-milking teat dipping, hygienic milking procedures, and strategic use of antibiotic therapy at dry-off resulted in widespread control of contagious pathogens. As herd management changed, researchers were tasked with defining control of mastitis caused by opportunistic pathogens originating from environmental sources. As mastitis pathogens have evolved, researchers have sought to define antimicrobial usage that will maintain animal wellbeing while minimizing unnecessary usage. During the last century, tremendous significant advances in mastitis control have been made but changing herd structure and more rigorous processor standards ensure that mastitis will remain an important subject focus of future research.

Identification of a novel mechanism of action of bovine IgG antibodies specific for Staphylococcus aureus

Staphylococcus aureus is a major pathogen that causes subclinical mastitis associated with huge economic losses to the dairy industry. A few vaccines for bovine mastitis are available, and they are expected to induce the production of S. aureus-specific antibodies that prevent bacterial adherence to host cells or promote opsonization by phagocytes. However, the efficacy of such vaccines are still under debate; therefore, further research focusing on improving the current vaccines by seeking additional mechanisms of action is required to reduce economic losses due to mastitis in the dairy industry. Here, we generated S. aureus-specific bovine IgG antibodies (anti-S. aureus) that directly inhibited bacterial growth in vitro. Inhibition depended on specificity for anti-S. aureus, not the interaction between Protein A and the fragment crystallizable region of the IgG antibodies or bacterial agglutination. An in vitro culture study using S. aureus strain JE2 and its deletion mutant JE2ΔSrtA, which lacks the gene encoding sortase A, revealed that the effect of anti-S. aureus was sortase-A-independent. Sortase A is involved in the synthesis of cell-wall-associated proteins. Thus, other surface molecules, such as membrane proteins, cell surface polysaccharides, or both, may trigger the inhibition of bacterial growth by anti-S. aureus. Together, our findings contribute insights into developing new strategies to further improve the available mastitis vaccine by designing a novel antigen on the surface of S. aureus to induce inhibitory signals that prevent bacterial growth.

Mastitis vaccines in dairy cows: Recent developments and recommendations of application

The objective of this review article was to summarize the most recent clinical field trials that have been published evaluating the use of different types of vaccines against mastitis pathogens in dairy cows. Mastitis is one of the most common and economically important diseases in dairy cows in the world. The disease is considered an important welfare issue facing the dairy industry in addition to the loss of production and premature removal or death of affected cows. Losses are also related to high cost of veterinary medicines and the cost of unsalable milk of treated cows. Mastitis can be caused by either contagious or environmental pathogens both of which are best prevented rather than treated. In addition to the application of best management practices in the parlor during milking, vaccination against common udder pathogens is widely practiced in many dairy farms to prevent or reduce the severity of clinical mastitis. In this review, the most recent clinical field studies that evaluated the use of different types of vaccines in dairy cows are summarized.