Presence of multidrug resistant and toxin producing S. aureus in dairy farms pose a major risk to public health. Therefore, this study highlighted the importance of developing an efficient control program to inhibit the transmission of S. aureus, particularly multidrug resistant strains to humans.

Since lactoferrin is acute phase protein and has an exceptional role in defense mechanism of mammary gland, it is considered a candidate gene for mastitis susceptibility in dairy cattle. In this study, blood samples were collected for DNA extraction from fifty Holstein dairy cows in the third lactation season reared under Egyptian conditions assigned into three groups mastitis (n=15), subclinical mastitis (n=20) and healthy (n=15) based on California mastitis test. Moreover biochemical markers for inflammation were determined to detect severity. PCR amplification of a segment of 6th intron of lactoferrin gene yielded a fragment of 301-bp in all animals under study. For revealing polymorphism, DNA sequencing was done for PCR products of lactoferrin gene (301-bp) in only five healthy (resistant) and five affected animals. Results indicated that, association between biochemical data and affections. The PCR-DNA sequencing genetic assessment identified twelve SNPs in the bovine lactoferrin gene and there was association between these identified SNPs and mastitis susceptibility, where ten nucleotide sequence variations for one of the healthy animals were obtained with A166T, T185A, T200C, G230C, A239G, T251G, A254C, A272C, T273C and A296G SNPs (submitted to GenBank with accession number gb|KT159457|. On the other hand, two nucleotide sequence variations for two of the affected animals were obtained with A100G and T275A SNPs. Consequently, the identified SNPs in the bovine lactoferrin gene can be used as marker-assisted selection (MAS) to predict, improve mastitis resistance and minimize incidence of mastitis infection in Holstein dairy cows.

No abstract

To study the prevalence of Coagulase-negative Staphylococci in clinical and subclinical mastitis in dairy cows. Design: Case-control study. Animals: 415 lactating Holstein cows. Procedures: A total of 896 quarter milk samples were collected aseptically from 415 dairy cows for bacteriological examination (mastitic cows, n=50; healthy cows, n=174). Identification of different bacterial isolates followed by antibiotic sensitivity test for Coagulase-negative Staphylococci (CNS) was carried out, using disc-diffusion method against 13 different antibiotics . Results: 224 out of 415 cows (54%) were proven to be mastitic (12% clinical mastitis, 42 % subclinical mastitis). Coagulase-negative Staphylococci were the prevalent isolate (32%). CNS was recorded in 25.7 % of clinical cases and 34% of subclinical mastitis. The antibiogram of CNS isolates against 13 different antibiotics revealed high level of resistance to ampicillin (85%) and oxacillin (85%). However, they were less resistant to vancomycin (5%). The other antibiotics showed variable levels of resistance ranging from 40-75%. Conclusion and clinical relevance:Coagulase-negative Staphylococci were the most common bacteria isolated from mastitic cases. Multi-drug resistance was observed among CNS with high resistance to ampicillin and penicillin, so the use of such B-lactam antibiotics should be restricted specially if there were suspected cases of Coagulasenegative Staphylococci.

No abstract