The term “nosocomial pneumonia” broadly covers all infections occurring 48 hours or more after hospital admission excluding any infection incubating at the time of admission, and has also been called hospital acquired pneumonia. Intensive care unit (ICU) acquired pneumonia (occurring within 48 hours of admission to the ICU) and ventilator associated pneumonia (occurring within 48 hours of starting mechanical ventilation) are also included in the broader term “nosocomial pneumonia”. The development of nosocomial pneumonia remains a major problem in the ICU with most studies reporting an incidence of between 9% and 45%,1-19 depending on the groups of patients being studied, the definition of nosocomial pneumonia, and the criteria used to diagnose it. It has been shown that nosocomial pneumonia acquired in the ICU markedly increases the length of hospital stay12 ,16 ,20 ,21 and the costs of hospital care.21 ,22 Mortality rates may also be increased,3 ,5 ,7 ,16 ,17 ,19 ,23 although it is not entirely clear whether all deaths from nosocomial pneumonia are directly related to the development of an infection. The so-called “attributable mortality”, defined as the mortality occurring as the direct result of the nosocomial pneumonia, may be especially high whenPseudomonas orAcinetobacter species are involved as pathogens.19

The diagnosis of nosocomial pneumonia is not straightforward, particularly in patients who are critically ill, as routine parameters do not have a high specificity for pneumonia in these patients.24 For example, infiltrates on chest radiographs consistent with pneumonia may be due to many other processes including oedema, atelectasis, and infarction.25 Positive cultures from tracheal aspirates are also non-specific as the upper respiratory tract of most critically ill patients is colonised by potential pulmonary pathogens.26 Alternative diagnostic techniques such as …