Bacteriology and treatment of infections in the upper and lower airways in patients with primary ciliary dyskinesia: adressing the paranasal sinuses.

The respiratory tract is lined with motile cilia that transport respiratory mucus. Primary ciliary dyskinesia (PCD) is a chronic genetic disease caused by mutations in genes responsible for ciliary structure and function. Non-functional airway cilia impair the mucociliary clearance (MCC), causing mucostasis, lung infections and destruction, chronic rhinosinusitis (CRS) and hearing impairment. It is of paramount importance to postpone chronic lung infection mainly with Gram-negative bacteria (GNB) in patients with an impaired MCC. When successful, lung function can be stabilized and quality of life (QoL) improved. In this thesis, we evaluated whether PCD patients can benefit from the experience we have gained from our operative approach towards the paranasal sinuses in cystic fibrosis (CF) patients. In CF, it has been established that bacterial sinusitis can be a focus for initial lung colonization and chronic lung infection. Combined endoscopic sinus surgery (ESS) and adjuvant therapy can eradicate sinus bacteria, reduce pulmonary infections and improve quality of life (QoL).      Currently, approximately 120 patients are diagnosed with PCD in Denmark and all are affiliated with the Danish PCD Centre. Patients included in this thesis were recruited from this cohort. In papers (I, IV), we found that the most frequent sinus pathogen was P. aeruginosa, which was isolated in 12 out of 31 (39%) patients who underwent ESS. In searching for a non-pulmonary infectious focus, we observed simultaneous sinus and lung infec-tions with identical pathogens in two out of three patients. This supports our hypothesis of a bacterial reservoir in the sinuses. Next (II), we examined the bacterial flora associated with acute and chronic pulmonary infections in PCD. A high prevalence of chronic infections encouraged a search for new treatment regimens, including ESS with adjuvant therapy, to impact the course of infection. We revealed that P. aeruginosa frequently colonizes the airways in PCD and during the 11-year study period a total of 42 out of 107 (39%) patients fulfilled the definition of chronic lung infection at some point. Importantly, 10 out of 12 patients (83%) with chronic lung infection had the same clone type of P. aeruginosa for years, as determined by pulsed field gel-electrophoresis (PFGE), thus substantiating factual chronic airway infection. Further, we found an increase in the prevalence of P. aeruginosa with age and observed a negative association between early PCD diagnosis and prevalence of P. aeruginosa. This indicates a positive effect of early diagnosis and initiation of therapy. In paper (III), we performed whole genome sequencing (WGS) of P. aeruginosa isolated from the same 12 patients who were included in the PFGE analysis in paper II. By sequencing and phenotypically characterizing multiple isolates from the same patients we were able to study the with-in host bacterial evolution for the first time in PCD. The analyses provided detailed insight into how P. aeruginosa evolves in PCD when they are stressed by the host immune system and antibiotics. We verified the persistence of clonal lineages and confirmed that different clone types of P. aeruginosa can establish persistent infections in PCD patients. Further, we showed that P. aeruginosa acclimatizes grad-ually to the PCD airway by accumulating pathoadaptive mutations and phenotypic characteristics similar to those of CF. Such information may provide valuable clinical information, and as an example we identified mutations in genes responsible for the development of antibiotic resistance. Based on our research we conclude that P. aeruginosa is a major pathogen in PCD and that future research should focus on pre-venting or eradicating these bacteria. Implementing ESS with adjuvant therapy to PCD patients (I, IV) significantly ameliorated CRS symptoms. Further, postoperatively patients tended to have fewer positive lower airway cultures and better lung function; approximately one out of four operated patients, in search of an infectious focus, remained free of lung colonization with P. aeruginosa during follow-up for at least six months. Based on these results, it is tempting to speculate that ESS with adjuvant therapy can eradicate sinus bacteria and thereby reduce lung re-colonization from the sinuses. However, further evidence is needed to support this hypothesis, preferably from a multicentre randomized controlled trial.