Introduction

Pneumonia occurring after admission to hospital is a major contribution to all hospital acquired infections. In a UK Public Health Laboratory Service study of 43 hospitals involving 18,186 patients in 1980, lower respiratory tract infection accounted for 16.8% of all hospital infections (the third most frequent after urinary tract infection at 30.3% and wound infections at 18.9%). In the USA, hospital-acquired pneumonia (HAP) ranks second only to urinary tract infection and accounts for 6 in 1000 hospitalised patients according to the National Nosocomial Infections Study. In addition to substantial patient morbidity and mortality, there are considerable financial burdens on health care. The increasing incidence of HAP is complicated by the emergence of resistant pathogens. This disease poses dynamic challenges for management and prevention.

In this chapter, we review the aetiological highlights, pathogenesis, diagnosis, antimicrobial management and aspects of prevention. Special emphasis is given to the patient who is critically ill since complex pathological events interact to profoundly alter the normal haemodynamic ventilatory and host immune responses. The patient's baseline health status, severity of underlying illness, coupled with invasive intravascular monitoring, mechanical ventilation and possible cytotoxic effects of drug therapy contribute to the increased frequency of nosocomial infection. Hence we will include the particular problems encountered by the patient in this exceptional environment including limitations and discussion of diagnostic techniques and differential diagnosis.