Antibiotic improve treatment outcome as the combined effect of both antibiotics is better than their individual effect. Methicillin-resistant Staphylococcus aureus infections may be treated with a combination therapy of fusidic acid and rifampicin. Antibiotics used in combination may also be antagonistic and the combined effects of the two antibiotics may be less than if the individual antibiotic was given as part of a monotherapy. For example, chloramphenicol and tetracyclines are antagonists to penicillins and aminoglycosides. However, this can vary depending on the species of bacteria. In general, combinations of a bacteriostatic antibiotic and bactericidal antibiotic are antagonistic. Antibiotics are commonly classified
Antibiotic natural products for the identification of new members of the 'antibiotic-ome' (defined as natural products with antibiotic activity), and their application in antibacterial drug discovery in the genomics era. Phytochemicals are the active biological component of plants and some phytochemicals including tannins, alkaloids, terpenoids, and flavonoids possess antimicrobial activity. Some antioxidant dietary supplements also contain phytochemicals (polyphenols), such as grape seed extract, and demonstrate "in vitro" anti-bacterial properties. Phytochemicals are able to inhibit peptidoglycan synthesis, damage microbial membrane structures, modify bacterial membrane surface hydrophobicity and also modulate quorum sensing. With increasing antibiotic resistance in recent years, the potential of new