**3.3 Device-related infections**

*Bacterial Biofilms*

*3.2.2 Cystic fibrosis with chronic lung infections*

tory failure and death in cystic fibrosis (CF) patients [49].

tion leading to disease development in patients with COPD [51].

fied recently in patients with bronchiectasis to form biofilms [54].

*3.2.3 Chronic obstructive pulmonary disease (COPD)*

*3.2.4 Non-cystic fibrosis bronchiectasis*

*and Streptococcus pneumonia* [55].

*3.2.6 Diffuse pan-bronchiolitis*

A major difficulty in this type of infection is contamination of lower respiratory secretions with the normal oropharyngeal flora, particularly as members of the normal flora (e.g. *Haemophilus influenzae*, *Staphylococcus aureus*, *Streptococcus pneumonia* and *Moraxella catarrhalis*) are common lung pathogens in CF [46, 47]. The incidence of bacterial lung infections in CF is high because the mucoid polysaccharidic material that accumulates on the respiratory epithelium due to the fact that impaired mucociliary removal in the bronchi of such patients favors biofilm formation. The capacity of *Pseudomonas aeruginosa* to form biofilms is believed to be the primary reason for its survival in the CF lung, despite a high inflammatory response and intensive antibiotic treatment [48]. Chronic airway infections cause an increase deterioration of lung tissue, a decline in pulmonary function and, finally, respira-

The role of biofilms in patients with COPD has not been directly validated but has been hypothesized considering the evidence showing that the respiratory tracts of these patients are frequently colonized by pathogens. Murphy and Kirkham [50] have recently confirmed that biofilms do play a role in COPD where they identified major outer membrane proteins of Non-typeable *H. influenzae* during its growth as a biofilm. Even if direct proof of biofilm formation *in vivo* is lacking, biofilms may reasonably be considered to be involved in the vicious cycle of infection/inflamma-

In bronchiectasis not due to cystic fibrosis, infections result in changes in the muscular and elastic components of the bronchial wall, which become distorted and expanded. Airways gradually become unable to clear mucus, leading to serious lung infections, which in turn cause more damage to the bronchi [52]. Recently biofilm formation has been demonstrated *in vivo* and is assumed to play a significant role in the pathophysiological cascade of the disease [53]. Bacterial biofilm formation by *Pseudomonas aeruginosa* or *Klebsiella pneumoniae* is common in bronchiectasis and could be an essential factor that makes infections in bronchiectasis obstinate. Other pathogens such as *Prevotella sp*., *Veillonella sp*. and *Neisseria sp*. have also been identi-

Prolonged bacterial bronchitis may be caused by chronic infections of the respiratory tract. In children especially, the condition appears to be secondary to impaired mucociliary removal that produces an environment favorable for bacteria to become established, usually in the form of biofilms. The most commonly involved bacteria include *Haemophilus influenzae* (30–70%), *Moraxella catarrhalis* 

Diffuse pan-bronchiolitis (DPB) is an unusual inflammatory lung disease of unknown etiology found in adult Japanese patients. With this disease, chronic

**118**

*3.2.5 Bronchitis*

In device-related infections such as ventilator-associated pneumonia (VAP), biofilms result in microbial persistence and reduced response to treatment. Biofilm formation within the first 24 h after intubation has been reported in 95% of endotracheal tubes [57]. Pathogens in both endotracheal tube biofilm and secretions accrued within the airways/endotracheal tubes in 56 to 70% of patients with VAP have been reported. *Pseudomonas aeruginosa* and *Acinetobacter baumannii* are the most common bacteria that colonize these devices [57].

## **3.4 Biofilm forming organisms associated with respiratory tract infections**

This section presents the role of biofilms in respiratory tract infections, with specific emphasis on the biofilms formed by *Pseudomonas*, *Staphylococcus*, and *Haemophilus*, the primary pathogens associated with respiratory tract infections [58] although additional important pathogens, including *Streptococcus pneumoniae*, *Bordetella* and *Mycobacterium* species do play a role [59].
