In vitro capsule or biofilm formation of Streptococcus uberis and bacteriological cure of bovine mastitis.

Objective: The relationship between the detected virulence factors biofilm and capsule formation of isolates of clinical mastitis in dairy cows and the bacteriological cure rate after antibiotic therapy was investigated in order to better understand the importance of these virulence factors for the bacteriological cure rate.

Material And Methods: A total of 111 clinical mastitis (CM) cases were collected, in which was bacteriologically detected. All mastitis cases were treated in accordance with the approval conditions of the antibiotic udder tubes used. Individual cow information including age, number of lactations, current lactation mastitis and antimicrobial treatment received was recorded. The microtiter plate test was used to detect biofilm formation and Anthony capsule staining was used to detect capsular capacity. Statistical analyses were performed to characterize the correlation between virulence factors and bacteriological cure (BC) rate.

Results: 30.5% (n=29) of the isolates of bacteriologically cured cases and 34.5% (n=10) of the isolates of bacteriologically non-cured mastitis cases were found to have the ability to produce capsules . 70.7% (n=58) of the isolates from bacteriologically cured mastitis cases had the ability to produce biofilm , whereas 58.6% (n=17) of the isolates of non-cured mastitis cases showed ability in producing biofilm. No correlation was found between the ability of to form capsules and biofilms and the BC rate after antibiotic treatment of bovine mastitis.

Conclusion(s): The present work has shown that the investigated virulence factors are not associated with the BC after antibiotic therapy. Further studies on the role of virulence factors are needed to complete the missing knowledge on the difficulties in curing mastitis.

Clinical Relevance: This study is of great clinical relevance since it enhances the understanding of the occurrence of BC in mastitis cases. The investigated virulence factors are often addressed as possible reasons for therapy failure, although respective scientific studies are missing.