Any infection not present or incubating at the time of admission into hospital is classified as a nosocomial infection and is often referred to as a hospital acquired infection (HAI). Approximately 1 in 10 patients acquire an infection after admission into hospital of which it has been estimated that 30% or more could be prevented (Gastmeier, 2004).

Urinary tract infection (usually catheter-associated), surgical-site infection, bloodstream infections and pneumonia (usually ventilator-associated) account for more than 80% of all HAIs. The most frequently occurring infections are urinary tract accounting for approximately 35% of HAIs however they are associated with the lowest mortality and cost (see ‘Urinary tract symptoms’). Surgical-site infections account for around 20% and are third in cost whereas bloodstream infections and pneumonia are less common, explaining about 15% each; however these are linked with much higher mortality and costs. While the rates of both urinary tract and surgical-site infections have recently declined slightly, bloodstream infections and methicillin-resistant Staphylococcus aureus (MRSA) infections are rapidly rising. Patients in intensive care units account for 25% of HAI cases with nearly 70% being attributed to micro-organisms that are resistant to one or more antibiotics (Burke, 2003).

Among the factors that promote HAI are underlying diseases and decreased patient immunity, invasive diagnostic and therapeutic techniques, widespread antimicrobial resistance, lack of infection control measures and environmental hygiene (Lazzari et al., 2004). However, the exact extent to which the environment plays a part is largely unknown.