Molecular studies of immunological enzyme clumping factor B for the inhibition of Staphylococcus aureus with essential oils of Nigella sativa.

Essential oils from black cumin seeds (Nigella sativa) have largely been used in the manufacturing of nutraceuticals and functional food products due to the presence of a wide variety of bioactive compounds. However, their applications in the pharmaceutical sector have recently attracted interest and started blooming. The present research elucidates the in silico and in vitro efficacies of active leads from essential oil of N sativa against the human pathogenic bacterium Staphylococcus aureus. Biofilm development has become an inevitable situation in the health care sector. Lowering the efficacies of antimicrobial drugs is one of the vital ramifications that resulted in the emergence of multidrug resistance. Clumping factor B (clfB) of S aureus plays a key role in the human immune functions during pathogenesis. Through STRING analysis, the interacting protein partners of clfB were found to regulate biofilm pathway. Therefore, eight ligands from essential oil are docked with the critical clfB protein, which revealed p-cymene, thymoquinone and carvacrol as the robust ligands with highest binding affinity. Therefore, antibiofilm potential of N sativa essential oil at in vitro states was evaluated against S aureus. Further, real time PCR analysis showed that the expression of clfB and intercellular adhesion gene (icaA and icaD) was significantly altered upon treatment with essential oil. Altogether, the findings confirmed the antibiofilm efficacy of N sativa essential oil against S aureus. Hence, the essential oil from N. sativa was envisaged to be promising candidate to treat S aureus biofilm mediated infection.

Annexin A2-Mediated Internalization of Staphylococcus aureus into Bovine Mammary Epithelial Cells Requires Its Interaction with Clumping Factor B.

BACKGROUND: Staphylococcus aureus is a leading cause of contagious mastitis in dairy cattle. Internalization of S. aureus by bovine mammary gland epithelial cells is thought to be responsible for persistent and chronic intramammary infection, but the underlying mechanisms are not fully understood. METHODS: In the present study, we evaluated the role of Annexin A2 (AnxA2), a membrane-binding protein, in S. aureus invasion into bovine mammary epithelial cell line (MAC-T). In vitro binding assays were performed to co-immunoprecipitate the binding proteins of AnxA2 in the lysates of S. aureus. RESULTS: AnxA2 mediated the internalization but not adherence of S. aureus. Engagement of AnxA2 stimulated an integrin-linked protein kinase (ILK)/p38 MAPK cascade to induce S. aureus invasion. One of the AnxA2-precipitated proteins was identified as S. aureus clumping factor B (ClfB) through use of mass spectrometry. Direct binding of ClfB to AnxA2 was further confirmed by using a pull-down assay. Pre-incubation with recombinant ClfB protein enhanced S. aureus internalization, an effect that was specially blocked by anti-AnxA2 antibody. CONCLUSION: Our results demonstrate that binding of ClfB to AnxA2 has a function in promoting S. aureus internalization. Targeting the interaction of ClfB and AnxA2 may confer protection against S. aureus mastitis.

The Clumping factor B gene typing in discriminating the strains of nosocomial-acquired methicillin-resistant Staphylococcus aureus / 中华流行病学杂志

Objective To evaluate the clfB typing method in discriminating the ST239 methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients under nosocomial infection in Tianjin first central hospital so as to access the clinical risk factors and outcomes of the MRSA nosocomial infection from ICU and non-ICU departments.Methods Forty-two stains of MRSA with known SCCmec type were chosen in both ICU (n=35) and non-ICU (n=7) wards,from 2006 to 2012,of which MLST genotype was ST239.Clinical risk factors and rates on drug resistant to MRSA were counted,respectively.Results All the isolates of MRSA belonged to the same lineage 3 and 6 heplotypes,based on clfB variable-number random repeats typing.Thirty-five isolates from ICU belonged to 6 heplotypes,among which clfB3-52,3-52E,3-50,3-52C,3-50A and 3-50E were accouted for 42.9％,37.1％,8.6％,5.7％,2.9％ and 2.9％,respectively.Seven isolates from non-ICU belonged to 3 heplotypes,in which 3-52,3-52E and 3-50 were accouted for 42.8％,28.6％,28.6％,respectively.When clfB typing was combined with SCCmec typing in use,results showed that the index of discrimination as 0.767,better than clfB (ID=0.688) or SCCmec (ID=0.303) used alone.SCCmec Ⅲ-clfB3-52E seemed as the major clone among the 10 heplotypes of clfB/SCCmec typing,which was accounted for 40.4％.There were significant differences on the length of hospitalization (P＜0.005) and the duration of antibiotics use (P＜0.05) between ICU and non-ICU.Conclusion The clfB typing method which was based on variable-numbers of tandom repeats showed powerful ability of resolution.It could also be combined with MLST and SCCmec typing to be used in local epidemiological investigations.