Infectious diseases are the second major cause of death worldwide and the third leading cause of death in developed countries. In the US, bacteria are the most common cause of infection-related mortality. The total world-wide market for anti-bacterials exceeded US$26 billion in 2004.

Rates of bacterial resistance are rapidly rising, particularly in hospitals, where antibiotics are heavily used. Existing antibiotics are no longer effective in all cases and treatment options for certain microorganisms have become scarce. Antibacterials are the only class of therapeutic in which drugs of last-resort have become first-line therapy.

The ability of bacteria to readily evade any form of established therapy remains a constant in antimicrobial treatment and pathogens that are resistant to one or more antibiotics are emerging and spreading worldwide. The treatment for these and other emerging infections must be the development and use of novel antibiotic therapies.

Acute bacterial infections such as methicillin resistant Staphylococcus aureas (MRSA) account for over half the infections in intensive care units in the US alone, with an estimated 300,000 people contracting the infection each year and resulting in 12,000 deaths.

Chronic bacterial infections such as Helicobacter pylori are also well established as critical healthcare issues. Helicobacter pylori is present in approximately 50% of the human population and over 60% of the Japanese population. It is recognised to cause a spectrum of diseases in humans, including gastritis, ulcer disease, gastric cancer, and gastric lymphoma and is prevalent in both adults and children.

The approved treatments for H. pylori-related disease are combinations of two or more antimicrobial agents in conjunction with acid suppression. The therapies are aggressive and unable to be used in children. Poor patient compliance with treatment and the presence of resistant organisms are thought to be the most important factors contributing to a low cure rate in the population.

Studies in Japan have shown increasing metronidazole and clarithromycin resistance among H. pylori isolates from Japanese adults and children. The high rate of clarithromycin resistance suggests that the effectiveness of clarithromycin-based anti-H. pylori therapies may soon be compromised in Japan and elsewhere.

Recent studies in Europe show the alarming emergence of strains with triple resistance to amoxicillin, metronidazole and clarithromycin.