Detection And Correlation With Capsular Polysaccharide Of Biofilm From S. Aureus Inducing Bovine Mastitis

Bovine mastitis caused by Staphylococcus aureus (S. aureus) is one of the frequently-occurring diseases causing great economic losses in dairy cow breeding industry. The formation of biofilm is an important factor facilitating S. aureus infections and stronger drug resistance. In this study, we used 758 milk samples with more than 500,000 somatic cells for each sample, collected separately from cattle of livestock farms in Beijing, Baoding, Hohhot, Baotou, Erdos, Hulunbuir and Bayannur regions in China, to separate and identify the pathogenic bacteria. Then we used the pathogenic bacteria firstly identified as the staphylococcus to do the further identification using API-Staph, by which we can pick out S. aureus strains to do the qualitative and quantitative experimentation on the formation of biofilm. The drug resistance of S. aureus biofilm producers and biofilm non-producers was analyzed by Kirby-Bauer (K-B) method and polyclonal antibody of S. aureus CP8 was prepared. In this study, the relationship between biofilm and capsular polysaccharide was also discussed preliminary.The results showed that 378 bacterial strains were isolated firstly, including 10.95% E.coli isolates (n=83),2.51% Streptococcus isolates (n=19),36.41% Staphylococcus isolates (n=276) and 27.57% S. aureus isolates (n=209). Meanwhile, 51.67% S. aureus strains were biofilm producers (n=108), and the staining results showed that strong biofilm formation occurred in 16.67%(n=18), moderate biofilm formation occurred in 31.48%(n=34) and weak biofilm formation occurred in 51.85% (n=56). The results showed that 12 kinds of drug have inhibitory effect on S. aureus.S. aureus biofilm producers and biofilm non-producers was slightly different sensitivity to different kinds of drugs. The biofilm positive strains were resistant to penicillin, erythromycin, tetracycline and gentamicin., the resistance of S. aureus biofilm producers to penicillin and erythromycin is more serious, drug resistance rates were 47.37% and 31.58% respectively. Phagocytosis results showed that compared with the control group, sterilization ability of whole blood of CP8-BSA immune group showed significant difference; whole blood of CP8-BSA immune group did not showed significant difference with sterilization ability of different 4 S. aureus which can produce strong,moderate,weak biofilm or did not produce any biofilm. The study proved that there are no cross immunity between S. aureus biofilm and capsular polysaccharide.