AUTHOR=Zhang Tingrui , Niu Guoyi , Boonyayatra Sukolrat , Pichpol Duangporn 

TITLE=Antimicrobial Resistance Profiles and Genes in Streptococcus uberis Associated With Bovine Mastitis in Thailand

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.705338

DOI=10.3389/fvets.2021.705338

ISSN=2297-1769

ABSTRACT=<p><italic>Streptococcus uberis</italic> is recognized as an environmental mastitis pathogen in dairy cattle. The varied success rate of antibiotic treatment for <italic>S. uberis</italic> intramammary infection may be associated with the antimicrobial resistance (AMR) of these bacteria. This observational study aimed to analyze 228 <italic>S. uberis</italic> strains associated with bovine mastitis in northern Thailand from 2010 to 2017. AMR and AMR genes were determined by the minimum inhibitory concentration (MIC) using a microdilution method and polymerase chain reaction, respectively. The majority of <italic>S. uberis</italic> strains were resistant to tetracycline (187/228, 82.02%), followed by ceftiofur (44/228, 19.30%), and erythromycin (19/228, 8.33%). The MIC50 and MIC90 of ceftiofur in 2017 were 2–4-fold higher than those in 2010 (<italic>P</italic> &lt; 0.01). Resistance to tetracycline and ceftiofur significantly increased between 2010 and 2017 (<italic>P</italic> &lt; 0.05). The most common gene detected in <italic>S. uberis</italic> was <italic>tetM</italic> (199/228, 87.28%), followed by <italic>ermB</italic> (151/228, 66.23 %) and <italic>blaZ</italic> (15/228, 6.58 %). The association between tetracycline resistance and <italic>tetM</italic> detection was statistically significant (<italic>P</italic> &lt; 0.01). The detection rates of <italic>tetM</italic> significantly increased, while the detection rates of <italic>tetO</italic> and <italic>ermB</italic> significantly decreased during 2010–2017. AMR monitoring for bovine mastitis pathogens, especially <italic>S. uberis</italic>, is necessary to understand the trend of AMR among mastitis pathogens, which can help create an AMR stewardship program for dairy farms in Thailand.</p>