Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand

IntroductionStreptococcus agalactiae is a highly contagious pathogen that causes bovine mastitis, leading to significant economic losses. This study aimed to (1) identify and characterize S. agalactiae strains responsible for bovine mastitis by examining their phenotypic and genotypic characteristic...

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Main Authors: Sirirat Wataradee, Sukuma Samngamnim, Thanasak Boonserm, Kittisak Ajariyakhajorn
Format: Article
Language:English
Published: Frontiers Media S.A. 2023-11-01
Series:Frontiers in Veterinary Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fvets.2023.1250436/full
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author Sirirat Wataradee
Sukuma Samngamnim
Thanasak Boonserm
Kittisak Ajariyakhajorn
author_facet Sirirat Wataradee
Sukuma Samngamnim
Thanasak Boonserm
Kittisak Ajariyakhajorn
author_sort Sirirat Wataradee
collection DOAJ
description IntroductionStreptococcus agalactiae is a highly contagious pathogen that causes bovine mastitis, leading to significant economic losses. This study aimed to (1) identify and characterize S. agalactiae strains responsible for bovine mastitis by examining their phenotypic and genotypic characteristics in Thai dairy-intensive farming areas and (2) determine their susceptibility profiles to antimicrobial agents.Material and methodsIn total, 100 S. agalactiae isolates obtained from clinical and subclinical mastitis cases from 13 dairy herds located in the central region of Thailand were examined. To confirm the identity of the bacterial pathogens, conventional microbiological procedures recommended by the National Mastitis Council (NMC) and the VITEK® 2 system were employed.ResultsAll 100 isolates were successfully identified as S. agalactiae using the NMC procedure, whereas 94 isolates were identified as S. agalactiae using the VITEK® 2 system. Finally, the S. agalactiae-specific gene dlt S was identified in all the examined isolates using polymerase chain reaction. Capsular polysaccharide (CPS) typing revealed that all strains belonged to CPS type Ia. Multilocus sequence typing identified 33 selected isolates as sequence type 103. Random amplified polymorphic DNA (RAPD) typing yielded 43 RAPD types, with 6 RAPD clusters identified. These results demonstrated a high level of genetic diversity among S. agalactiae within the studied herds. RAPD analysis suggested that specific S. agalactiae strains could persist in dairy farms for 2–12 months. Furthermore, antimicrobial susceptibility testing was performed using the broth microdilution method. Most strains demonstrated susceptibility to ampicillin, penicillin, penicillin/novobiocin, cephalothin, oxacillin, ceftiofur, and erythromycin.DiscussionThis study revealed the phenotypic and genotypic characteristics of S. agalactiae isolates responsible for bovine mastitis in the central region of Thailand. The rapid identification of S. agalactiae and application of molecular typing methods can provide valuable epidemiological information regarding S. agalactiae causing mastitis in dairy farms. The antimicrobial susceptibility of S. agalactiae indicates that antimicrobial treatment for control and eradication could be a successful protocol. Our findings revealed that a single clonal strain of S. agalactiae affected the 13 studied farms. Further research is needed to explore the feasibility of vaccine development and application.
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spelling doaj.art-c4132c331fcf452d809bda7e481018cc2023-11-13T04:30:06ZengFrontiers Media S.A.Frontiers in Veterinary Science2297-17692023-11-011010.3389/fvets.2023.12504361250436Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of ThailandSirirat WataradeeSukuma SamngamnimThanasak BoonsermKittisak AjariyakhajornIntroductionStreptococcus agalactiae is a highly contagious pathogen that causes bovine mastitis, leading to significant economic losses. This study aimed to (1) identify and characterize S. agalactiae strains responsible for bovine mastitis by examining their phenotypic and genotypic characteristics in Thai dairy-intensive farming areas and (2) determine their susceptibility profiles to antimicrobial agents.Material and methodsIn total, 100 S. agalactiae isolates obtained from clinical and subclinical mastitis cases from 13 dairy herds located in the central region of Thailand were examined. To confirm the identity of the bacterial pathogens, conventional microbiological procedures recommended by the National Mastitis Council (NMC) and the VITEK® 2 system were employed.ResultsAll 100 isolates were successfully identified as S. agalactiae using the NMC procedure, whereas 94 isolates were identified as S. agalactiae using the VITEK® 2 system. Finally, the S. agalactiae-specific gene dlt S was identified in all the examined isolates using polymerase chain reaction. Capsular polysaccharide (CPS) typing revealed that all strains belonged to CPS type Ia. Multilocus sequence typing identified 33 selected isolates as sequence type 103. Random amplified polymorphic DNA (RAPD) typing yielded 43 RAPD types, with 6 RAPD clusters identified. These results demonstrated a high level of genetic diversity among S. agalactiae within the studied herds. RAPD analysis suggested that specific S. agalactiae strains could persist in dairy farms for 2–12 months. Furthermore, antimicrobial susceptibility testing was performed using the broth microdilution method. Most strains demonstrated susceptibility to ampicillin, penicillin, penicillin/novobiocin, cephalothin, oxacillin, ceftiofur, and erythromycin.DiscussionThis study revealed the phenotypic and genotypic characteristics of S. agalactiae isolates responsible for bovine mastitis in the central region of Thailand. The rapid identification of S. agalactiae and application of molecular typing methods can provide valuable epidemiological information regarding S. agalactiae causing mastitis in dairy farms. The antimicrobial susceptibility of S. agalactiae indicates that antimicrobial treatment for control and eradication could be a successful protocol. Our findings revealed that a single clonal strain of S. agalactiae affected the 13 studied farms. Further research is needed to explore the feasibility of vaccine development and application.https://www.frontiersin.org/articles/10.3389/fvets.2023.1250436/fullantimicrobial susceptibilitycapsular polysaccharidemolecular epidemiologymultilocus sequence typingrandom amplified polymorphic DNA
spellingShingle Sirirat Wataradee
Sukuma Samngamnim
Thanasak Boonserm
Kittisak Ajariyakhajorn
Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand
Frontiers in Veterinary Science
antimicrobial susceptibility
capsular polysaccharide
molecular epidemiology
multilocus sequence typing
random amplified polymorphic DNA
title Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand
title_full Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand
title_fullStr Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand
title_full_unstemmed Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand
title_short Genotypic and antimicrobial susceptibility of Streptococcus agalactiae causing bovine mastitis in the central region of Thailand
title_sort genotypic and antimicrobial susceptibility of streptococcus agalactiae causing bovine mastitis in the central region of thailand
topic antimicrobial susceptibility
capsular polysaccharide
molecular epidemiology
multilocus sequence typing
random amplified polymorphic DNA
url https://www.frontiersin.org/articles/10.3389/fvets.2023.1250436/full
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