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

Norhan K Abd El-Aziz,Hend M El Damaty,Ahmed M Ammar,Waleed El-Kazzaz,Hosam A Saad,Eman Khalifa,Rehab A Abd Elkader

doi:10.3390/ani11071849

Abstract

Simple SummaryMastitis 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.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.

Highlights

Mastitis is a significant concern affecting dairy animals worldwide, causing great losses to breeders and impacting the country’s national income [1,2]
S. uberis isolates were catalase-test-negative, whereas all isolates were positive for sodium hippurate and bileesculin hydrolyses tests
Discussion epidemiological data on S. uberis isolated from lactating cows in Egypt, especially in the Mastitis remains a critical problem for dairy animals, causing drastic losses during lactation seasons

Summary

Introduction

Mastitis is a significant concern affecting dairy animals worldwide, causing great losses to breeders and impacting the country’s national income [1,2]. Environmental streptococci, notably Streptococcus uberis (S. uberis), are among the main contributing agents of mastitis in many countries and have increased their significance for udder health in recent decades [3]. This pathogen is not obligatorily adapted to the udder but is ubiquitous as it is considered an environment-associated straw bedding and pasture pathogen [4].

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