Phytochemicals for bacterial resistance--strengths, weaknesses and opportunities

This review covers some of the opportunities which currently exist to exploit plants for their natural products as templates for new antibacterial substances. This is a timely exercise given the continuing and developing problems of bacterial resistance, and in particular multidrug-resistance (MDR). Some of the challenges which are evident with bacterial resistance will be described and the strengths and weaknesses of plant natural products are highlighted. Opportunities to characterise antibacterial compounds from several key taxa are described with activity against methicillin-resistant STAPHYLOCOCCUS AUREUS (MRSA), MDR variants of this species and MYCOBACTERIUM TUBERCULOSIS (MTB). These pathogens continue to cause problems in terms of their eradication and spread and MTB strains which are extremely-drug resistant (XDR) promise to afford an additional challenge for clinicians. The review also covers plant natural products that modulate or modify bacterial resistance. Specific examples include plant-derived efflux pump inhibitors (EPIs) which inhibit bacterial antibiotic efflux mechanisms that are problematic due to their broadness in substrate specificity. A summary on future trends and directions in this fruitful and interesting area is also given.