Distribution of serotypes, antimicrobial resistance and virulence genes among Streptococcus agalactiae isolated from bovine in China

Background: Bovine mastitis, a global disease that is responsible for large economic losses each year due to lower milkyield and reduced milk quality. In some countries, especially in China, Streptococcus agalactiae has become one of themost frequently detected pathogen. Antibiotic treatment and vaccine immunization are important strategies for the controlof infectious diseases. The main objective of the present study was to evaluate distribution of bovine mastitis pathogensand antimicrobial resistance of S. agalactiae, and contribute to the treatment of bovine mastitis.Materials, Methods & Results: Clinical mastitis samples (n= 1,122) were collected from 27 dairy farms located in 15different provinces of China during 2012-2018. The pathogens were identified by 16S rDNA method. Antimicrobial susceptibility was assessed by disc diffusion method. Molecular characteristics was distinguished based on PCR. The resultsshowed that the main pathogens were Streptococcus agalactiae (n= 324, 26.2%), Escherichia coli (n= 287, 23.2%), andStaphylococcus aureus (n= 131, 10.6%). The serotypes of Streptococcus agalactiae were serotype II (53.6%), Ia (44 %)and VII (1.2%), respectively. Streptococcus agalactiae were resistant to kanamycin (93.8%), gentamicin (49.4%), vancomycin (49.4%), tetracycline (35.8%), clindamycin (34.6%) and erythromycin (32.1%). The main resistance genes wereermA (53.1%) and ermB (85.2%). Resistance to erythromycin was attributed to the genes ermA (P < 0.05) and resistanceto tetracycline was attributed to the genes tetK, tetM, tetO (P < 0.01). The virulence genes scpB (81.4%), cyl (100%), glnA(76.6%), cfb (98.8%), hylB (98.8%), scaA (69.1%) were detected in almost all isolates.Discussion: In the present study, Streptococcus agalactiae, Escherichia coli and Staphylococcus aureus were the pathogens isolated most frequently from clinical mastitis. In the case of S. agalactiae, we performed capsular serotyping ofisolates...

Distribution of serotypes, antimicrobial resistance and virulence genes among Streptococcus agalactiae isolated from bovine in China

Background: Bovine mastitis, a global disease that is responsible for large economic losses each year due to lower milkyield and reduced milk quality. In some countries, especially in China, Streptococcus agalactiae has become one of themost frequently detected pathogen. Antibiotic treatment and vaccine immunization are important strategies for the controlof infectious diseases. The main objective of the present study was to evaluate distribution of bovine mastitis pathogensand antimicrobial resistance of S. agalactiae, and contribute to the treatment of bovine mastitis.Materials, Methods & Results: Clinical mastitis samples (n= 1,122) were collected from 27 dairy farms located in 15different provinces of China during 2012-2018. The pathogens were identified by 16S rDNA method. Antimicrobial susceptibility was assessed by disc diffusion method. Molecular characteristics was distinguished based on PCR. The resultsshowed that the main pathogens were Streptococcus agalactiae (n= 324, 26.2%), Escherichia coli (n= 287, 23.2%), andStaphylococcus aureus (n= 131, 10.6%). The serotypes of Streptococcus agalactiae were serotype II (53.6%), Ia (44 %)and VII (1.2%), respectively. Streptococcus agalactiae were resistant to kanamycin (93.8%), gentamicin (49.4%), vancomycin (49.4%), tetracycline (35.8%), clindamycin (34.6%) and erythromycin (32.1%). The main resistance genes wereermA (53.1%) and ermB (85.2%). Resistance to erythromycin was attributed to the genes ermA (P < 0.05) and resistanceto tetracycline was attributed to the genes tetK, tetM, tetO (P < 0.01). The virulence genes scpB (81.4%), cyl (100%), glnA(76.6%), cfb (98.8%), hylB (98.8%), scaA (69.1%) were detected in almost all isolates.Discussion: In the present study, Streptococcus agalactiae, Escherichia coli and Staphylococcus aureus were the pathogens isolated most frequently from clinical mastitis. In the case of S. agalactiae, we performed capsular serotyping ofisolates...(AU)

Immune responses in mice immunized with mastitis multiple vaccines using different adjuvants

Background: Bovine mastitis, a serious disease associated with both high incidence and significant economic losses, posing a major challenge to the global dairy industry. The development of vaccines for protection from new infections by mastitis pathogens is of considerable interest to the milk production industry. Vaccination is a common and easy strategy for the control of infectious diseases, and the adjuvants used in the formulation is a critical factor for vaccine efficacy improvement. The main objective of the present study was to evaluate three different adjuvants for their ability to enhance immune responses of mice that vaccinated with Bovine Mastitis Multiple Vaccine.Materials, Methods & Results: The thymus and spleen index, the phagocytic ability of macrophage and the serum antibody levels of mice were detected after vaccination, respectively. The results showed that the thymus index, spleen index, and the phagocytic ability of macrophage of mice in Aluminum group exhibited a significant higher level (P < 0.05) compared with those in the control groups. The difference of the serum antibody levels was significant (P < 0.05) between experimental groups and control group after vaccination. The serum antibody concentration of mice in FIA group was higher compared with other groups and had a longer duration. The antibody concentration of mice in France 206 oil group can not increase as fast as the antibody concentration of Aluminum group, but it could last a longer time at a high level. In conclusion, multiple vaccines mixed with three different adjuvants (Aluminum, France 206 oil and Freund’s incomplete adjuvant) for bovine mastitis could enhance the immunity of mice and could decrease mortality of mice against challenge. Take all results from this work into consideration, Freund’s incomplete adjuvant (FIA) would be the best candidate as the adjuvant for mastitis multiple vaccines.[...]

Immune responses in mice immunized with mastitis multiple vaccines using different adjuvants

Background: Bovine mastitis, a serious disease associated with both high incidence and significant economic losses, posing a major challenge to the global dairy industry. The development of vaccines for protection from new infections by mastitis pathogens is of considerable interest to the milk production industry. Vaccination is a common and easy strategy for the control of infectious diseases, and the adjuvants used in the formulation is a critical factor for vaccine efficacy improvement. The main objective of the present study was to evaluate three different adjuvants for their ability to enhance immune responses of mice that vaccinated with Bovine Mastitis Multiple Vaccine.Materials, Methods & Results: The thymus and spleen index, the phagocytic ability of macrophage and the serum antibody levels of mice were detected after vaccination, respectively. The results showed that the thymus index, spleen index, and the phagocytic ability of macrophage of mice in Aluminum group exhibited a significant higher level (P < 0.05) compared with those in the control groups. The difference of the serum antibody levels was significant (P < 0.05) between experimental groups and control group after vaccination. The serum antibody concentration of mice in FIA group was higher compared with other groups and had a longer duration. The antibody concentration of mice in France 206 oil group can not increase as fast as the antibody concentration of Aluminum group, but it could last a longer time at a high level. In conclusion, multiple vaccines mixed with three different adjuvants (Aluminum, France 206 oil and Freunds incomplete adjuvant) for bovine mastitis could enhance the immunity of mice and could decrease mortality of mice against challenge. Take all results from this work into consideration, Freunds incomplete adjuvant (FIA) would be the best candidate as the adjuvant for mastitis multiple vaccines.[...](AU)