Polyangiitis overlap syndrome (POS) is a diagnostic term coined by Leavitt and Fauci that characterises patients with overlapping features of more than one vasculitis. Prior case studies of antineutrophil cytoplasmic antibodies (ANCA)-associated POS have only been published in patients with eosinophilic granulomatosis with polyangiitis (EGPA) and granulomatosis with polyangiitis alongside proteinase-3/cytoplasmic (C)-ANCA positivity. We present a case of a 60-year-old woman with dyspnoea, hemoptysis, positive perinuclear-ANCA and renal biopsy demonstrating evidence of microscopic polyangiitis. In addition, our patient also had asthma, mononeuritis multiplex, eosinophilia and migratory pulmonary infiltrates, thus fulfilling the criteria for EGPA. This novel case report suggests that POS is not limited to C-ANCA positivity and has variable presentations.

<P>Introduction: Staph infection, caused by a bacterium known as Staphylococcus aureus, results in a range of diseases from cellulitis to meningitis. Dicoumarol compounds are now emerging as new anti-Staph infection agents as they possess a different chemical structure than compounds used in previous treatments, in order to combat antibiotic-resistant strains. However, it is unclear how such chemical modulations to the dicoumarol backbone structure achieve higher drug performance. </P><P> Methods: The following review analyzed various quantitative structure-activity relationship (QSAR) studies on dicoumarol compounds and compared them against the corresponding minimum inhibitory concentration and binding affinity values. </P><P> Results: Compared to the antimicrobial activity, the dicoumarol derivatives with electron withdrawing substituents, CL, NO2, and CF3 showed an inverse correlation; whereas, the opposite was observed with electron donating compounds such as OH, OMe, and amine groups. Based on the interactions of dicoumarol at the active site, an “aromatic donor-acceptor” relationship was proposed as the method of action for this drug. Furthermore, substituent positioning on the benzene ring was found to exert a greater effect on the binding affinity, speculating that the mechanism of action is two characteristics based, needing, both, the proper aromatic pi-pi interaction for stabilization and direct binding to the OH group in the Tyrosine residue, affected by the steric hindrance. </P><P> Conclusion: This foundational review can enhance productivity sought by the pharmaceutical agency to use combinational chemistry to increase the efficiency to discover new hits in the synthesis of dicoumarol drugs against Staph infection.</P>