Synergistic effects of ethnomedicinal plants of Apocynaceae family and antibiotics against clinical isolates of Acinetobacter baumannii

Objective:To investigate the efficacy of 17 ethnomedicinal plants belonging to Apocynaceae family used in combination with 16 conventional antibiotics against non-multidrug resistant-,multidrug resistant(MDR)-.and extensive drug resistant(XDR) Acinetobacter baumannii(A.haumannii).Methods:Antibacterial activity and resistance modifying ability of 272combinations were determined by growth inhibition assays and further confirmed by time-kill assay.Results:Among the combinations of the antibiotics with Apocynaceae ethanol extracts on this pathogen,15(5%) had synergistic effects,23(8%) had partial synergistic effects and 234(86%) had no effects.Synergistic activity was observed mostly when the Apocynaceae extracts were combined with rifampicin or cefazolin.Interestingly.10 out of 17 combinations between the extracts and rifampicin displayed synergistic or partial synergistic behaviors.Holarrhena antidysenterica extract was additionally tested to restore rifampicin activity against clinical isolates of MDR and XDR A.haumannii.With respect to total or partial synergy,70%was XDR A.haumannii isolates and 66%was MDR A.haumannii isolates.Conclusions:Holarrhena antidysenterica extract clearly demonstrated the ability to restore rifampicin activity against both A.haumannii ATCC19606 and clinically isolated A.haumannii.Additional studies examining its active principles as well as nieclianisms of actions such as the effects on efflux pumps and outer membrane permeability alterations are recommended.

Macrophage-Mediated Defensive Mechanisms Involving Zinc Homeostasis in Bacterial Infection

Zinc homeostasis in macrophages is essential for maintaining their antimicrobial functions,and a growing body of evidence indicates that both zinc depletion and excess zinc in myeloid cells decrease bacterial survival.In macrophages,maintaining intracellular and extracellular zinc levels via zinc transporter proteins,including Slc30a and Slc39a family members,plays an important role in the response to immunological signals and infection.Recently,studies have found that macrophages utilize a variety of zinc-modulating mechanisms,thus expanding our knowledge regarding the role that zinc plays in response to bacterial infection.Here,we review recent progress with respect to altered zinc metabolism in macrophages and the consequences with respect to fighting invading pathogens.