Healthcare Associated Infection (HCAI) is the term used to describe infections acquired by a patient during their stay in hospital or by patients being cared for in community or primary care settings, HCAIs are normally caused by bacteria, the majority of which are harmlessly carried by healthy people. The most common HCAIs are urinary tract infections, chest infections, surgical wound and skin infections and infections of the bloodstream. 

Although not a new problem, HCAIs increasingly represent a significant challenge for all healthcare systems in developed countries. According to Department of Health estimates, around 9% of patients contract an HCAI while in hospital in England. 

Factors behind their increase include advances in medical technology and treatment, which despite their benefits can conversely lead to more vulnerable patients such as the elderly - being exposed to the risk of healthcare associated infections. For example, wider use of invasive procedures means more opportunities for infections to breach the body’s most important defence mechanism – the skin – while treatments used in the management of some serious conditions may result in suppression of the immune system. Financial pressures on healthcare systems to maintain high bed occupancy rates and rapid patient turnover can help compound the problem by facilitating transmission, as do poor standards of hygiene. 

The problem of HCAIs is further magnified by the growing numbers of organisms that have become resistant to antibiotic treatment over the years. A consequence of natural selective pressures, the process has also been greatly accelerated by inappropriate and excessive use of antibiotics. Not only is this reducing the armoury of antibiotics available to treat infections, but it is also making serious infections increasingly more difficult and expensive to treat. Against this background, the need for new agents to combat serious infectious disease has never been greater.