LEGIONELLA - World Health Organization

Aspiration may occur in patients with immunosuppression or swallowing disorders (e.g. after
an operation on the neck) (Stout & Yu, 1997). Nasogastric tubes have been identified as risk
factors in several studies of nosocomial legionellosis, with microaspiration of contaminated
water presumed to be the mode of entry (Marrie et al., 1991; Blatt et al., 1994; Stout & Yu,
1997).
Patients suffering from Legionnaires’ disease are significantly more likely to have undergone
endotracheal tube placement or to have been intubated for longer than patients with other
types of pneumonia (Muder et al., 1983; Strebel et al., 1988; Kool et al., 1998). However, a
recent study failed to detect colonization of the oesophageal tract by Legionella (Pedro-Botet
et al., 2002).
Wound infection may be caused by direct entry of legionellae into damaged skin, and has
been observed after immersion of a wound in contaminated water (Brabender et al., 1983;
Lowry et al., 1991). However, there is no evidence to support pulmonary disease arising from
wound infection. Although cases of infection have been reported among pregnant women
(which could increase their risk of premature labour), pregnancy is not considered a risk factor
for legionellosis (Roig & Rello, 2003). The most susceptible hosts are immunocompromised
patients, including solid-organ transplant recipients and those receiving corticosteroid treatments
(Arnow et al., 1982; Strebel et al., 1988).
Tables 1.5 and 1.6 identify the risk factors for Legionella infection.
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS