Infection is a common cause of admission to intensive care units (ICUs). In addition, around 30% of patients in ICUs will acquire infection (nosocomial infection) during their admission. The resulting increase in mortality is between 20 and 80% depending on site of infection and organism. The impact on length of stay and costs is substantial [1]. Increasing severity of illness is inevitably associated with more frequent infections.

Certain causes for admission are more commonly associated with infection:

• trauma,

• burns,

• following emergency surgery (particularly intra-abdominal).

Common intensive care interventions also increase nosocomial infections:

• tracheal intubation and ventilation,

• intravascular catheters,

• urinary catheters,

• drugs (sedatives, muscle relaxants, corticosteroids, antibiotics),

• blood transfusion.

Some patients are predisposed to infection:

• elderly,

• malnourished,

• high alcohol intake,

• heavy smoking,

• diabetes,

• neutropenia.

The EPIC study

Although 10-year old, the Early Pseudomonas Infection Control (EPIC) study [2] still gives a useful overview of infection in ICUs.

Causative organisms isolated in the EPIC study

• Enterobacter 34%.

• Staphylococcus aureus 30%, (60% MRSA) — probably now higher, with a greater proportion of MRSA.

• Pseudomonas 29%.

• Staphylococcus epidemidis 19%.

• Candida 17%.

The source of infection is evenly divided between the patients' bacterial flora and exogenous causes.

Site of infection in EPIC study

• All lower respiratory tract 65%.

• Urinary tract 17%.

• Blood 12%.