Overcoming antibiotic resistance by studying antibiotic hypersensitivity

Antibiotics have saved millions of lives since their discovery. Antibiotics kill pathogenic bacteria by targeting an essential metabolic process. Pathogenic bacteria can protect themselves from antibiotics by altering or providing a new target that no longer binds the antibiotic, destroying the antibiotic or pumping the antibiotic away from the target. Antibiotic resistance is now a serious problem in treating diseases caused by pathogenic bacteria such that in the EU 25,000 people die annually from untreatable infections. Globally there are 440,000 new cases annually of multidrug resistant tuberculosis resulting in 150,000 deaths. Solutions to the problem of antibiotic resistant bacteria are being sought on several fronts including better control over the use of existing antibiotics, the discovery and development of new antibiotics and antibacterial strategies that do not rely on antibiotics such as phage therapy, bacteriocins, antibacterial peptides and vaccines.
A hitherto underexplored but potentially exciting approach is to use combination therapy in which two or more drugs are used simultaneously and act synergistically to kill antibiotic resistant bacteria. This approach has been used for combating HIV and tuberculosis for some time. However combination therapy need not always involve two antibiotics; one of the drugs used may not itself have anti-microbial activity but potentiates the activity of the antibiotic. A well-known potentiator that has been taken by most people is clavulanic acid, an inhibitor of the enzyme beta-lactamase that destroys beta-lactam antibiotics such as penicillin.
How many potentiator targets are there and how do we find them? There is evidence that there are hundreds of potentiator targets in bacteria of varying efficacy and that might act against different types of antibiotics. This evidence comes from measuring the antibiotic sensitivity in bacteria that have single gene mutations; those mutants with greater sensitivity to an antibiotic compared to a strain with an intact gene (the parent) indicate that the mutated gene or its consequences on metabolic processes is a potentiator target.