Environmental Streptococcus uberis Associated with Clinical Mastitis in Dairy Cows: Virulence Traits, Antimicrobial and Biocide Resistance, and Epidemiological Typing

SIMPLE SUMMARY: Mastitis remains one of dairy cattle’s most perplexing and expensive diseases. This study is the first to look into the virulence traits, antimicrobial and biocide resistance, and epidemiological typing of Streptococcus uberis (S. uberis) isolated from bovine clinical mastitis in dairy farms of diverse hygienic interventions in Egypt. The overall S. uberis infection rate was 20.59%; all were multidrug-resistant (MDR). The sua gene was the most frequent virulence gene (42.02%), followed by pauA (40.57%), cfu (21.73%), skc (20.28%), and opp (11.59%). The erm(B) gene serves as the predominant antimicrobial-resistant gene (75.36%), followed by fexA (52.63%) and tet(M), blaZ, and aac(6′)aph(2″) genes (46.38% each). Of note, 79.71% of S. uberis isolates carried qac genes; among them, 55 (79.71%), 54 (78.26%), and 13 (18.84%) harbored qacED1, qacC/D, and qacA/B genes, respectively. Restriction fragment length polymorphism–polymerase chain reaction (RFLP–PCR) indicated that all analyzed isolates were S. uberis type I by their unique RFLP pattern. This study shows a significant variation in the occurrence of virulent S. uberis in dairy cows with clinical mastitis regarding the prospective hygienic concerns. Furthermore, MDR coupled with the existence of biocide resistance genes indicates the importance of S. uberis surveillance and the prudent use of antimicrobials in veterinary clinical medicine to avoid the dissemination of antimicrobial resistance. ABSTRACT: Mastitis remains a serious problem for dairy animals. The misappropriation of antimicrobial agents helps accelerate resistance, which poses a serious challenge in controlling environmental S. uberis infection. Here, we study the virulence attributes, antimicrobial and biocide resistance, and epidemiological typing of S. uberis recovered from bovine clinical mastitis in dairy farms of diverse hygienic interventions in Egypt. The overall S. uberis infection rate was 20.59%; all were multidrug-resistant (MDR). The sua gene was the most frequent virulence gene (42.02%), followed by pauA (40.57%), cfu (21.73%), skc (20.28%), and opp (11.59%). The erm(B) gene served as the predominant antimicrobial-resistant gene (75.36%), followed by fexA (52.63%) and tet(M), blaZ, and aac(6′)aph(2″) genes (46.38% each). Of note, 79.71%, 78.26%, and 18.84% of S. uberis isolates harbored qacED1, qacC/D, and qacA/B genes, respectively. All analyzed isolates were S. uberis type I by their unique RFLP–PCR pattern. In conclusion, the sustained presence of pauA and sua genes throughout the investigated farms contributes to a better understanding of the bacterium’s pathogenicity. Furthermore, MDR coupled with the existence of biocide resistance genes indicates the importance of S. uberis surveillance and the prudent use of antimicrobials in veterinary clinical medicine to avoid the dissemination of antimicrobial resistance.