**2. Defining causes and history of cystic fibrosis**

Cystic fibrosis is a multisystem genetic disease that affects children and young adults [11]. It is caused by mutations in CFTR gene leading to defective or insufficient amounts of functional CFTR protein and causes abnormalities in chloride (Cl), bicarbonate (HCO3), and sodium (Na) transport across cell membranes with serious consequences on multiple organs. The CF lung disease is characterized by infection and inflammation with eventual bronchiectasis and eventual respiratory failure causing death in over 90% of CF patients [3].

Cystic fibrosis is an autosomal recessively inherited disorder caused by the presence of one of more than 1500 possible mutations in CFTR gene with an occurrence of the clinical disease being 1 in 2500 live births. This mutation leads to the nonfunction or loss of function of CFTR (a cyclic AMP-regulated chloride ion channel) leading to defective chloride ion transport through epithelial cell surfaces [12].

Since its first description in 1938, study of the genetics, pathophysiology, and clinical manifestation of the disease has led to the creation of new therapies and significantly improved quality of life and survival [2].

In CF, the biology and treatment strategies are important to understand for several reasons. Firstly, it is the most common cause of chronic respiratory failure in children and adults. Secondly, CF is a common reason for the dysfunction of pancreatic exocrine in children and adults. Thirdly, the majority also develop pansinusitis. Other potential consequences of CF include diabetes, liver disease, bone disease, and infertility [3].

Advances in research of CF have given a roadmap for the understanding of pathophysiology studies and treatment stages for other severe airway diseases, including chronic obstructive pulmonary disease, non-CF bronchiectasis, and asthma [11].

Survival of individuals with CF has improved significantly over the last half century from a median age of survival of 5 years in the 1970s to 40 years of age as of 2011. There are different reasons for improvement in clinical outcomes including the intense use of antibiotic therapy, advancement in chest physiotherapy, nutritional support, specialized CF units, and introduction of CFTR modulators; however, the majority of CF deaths still occurred in young adult especially in the ages between 21 and 30 years as a consequence of respiratory failure [13]. Recent research also suggests that even asymptomatic genetic carriers for CF may be at risk for subclinical physiological derangements, which can be exacerbated by external stresses and other environmental triggers [14, 15].

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survival in CF [21–23].

*Recent Approach in Microbial Pathogen Complications in Patients with Cystic Fibrosis*

Airways of patients with CF are usually infected with various microorganisms. In infected airways of CF patients, microhabitats can develop owing to local differences in the inflammatory reaction between the different focal areas of infection and also as a result of the competing activities of the many co-colonizing microbial populations [16]. Several bacterial strains are major causes of mortality and mor-

Chronic infection is a characteristic of CF airway disease. So, conditions in the airways of patients with CF are conducive to forming colonization by different microorganisms such as bacterial, fungal, and viral pathogens. Molecular identification of microorganisms has emphasized and recorded the polymicrobial nature of microbial infections in the CF airway microenvironment. Additionally, changes in airway of CF physiology through the loss of CFTR functionality lead to a variety of immune dysfunctions that permit microbial pathogen colonization and microbial

The prognosis of patients with the hereditary disease CF is substantially dependent on chronic respiratory infection and inflammation [17]. CF lungs are often colonized or infected with a complex microbial species, mainly composed of bacteria, provoking acute and chronic infections [18]. Airway infection accounts for 90% of the morbidity and mortality observed in CF patients. These chronic infections are typically associated with a few bacterial pathogens such as *Pseudomonas* 

*aeruginosa*, *Staphylococcus aureus*, and *Burkholderia cepacia* complex [19].

High morbidity and mortality rates in cystic fibrosis patients are secondary to recurrent respiratory infections, which, when associated with this obstructive lung disease, lead to respiratory insufficiency, the main cause of death in these

CF lung disease is characterized by progressive colonization of respiratory tract

Bacterial and fungal infections are hallmarks of CF lung disease. In the era of long-term inhaled antibiotics and increasing CF patient survival, new "emerging" pathogens are detected in CF airways, yet their pathophysiological impact remains largely controversial and incompletely defined. As a consequence to chronic microbial triggers, innate immune cells, particularly neutrophils, are continuously recruited into CF airways where they combat pathogens but also lead to tissue injury through the release of oxidants and proteases. The coordinated interplay between host immune cell activation and pathogens is essential for the outcome of CF lung disease. A better understanding of this phenomena may enhance the

infection by different bacterial strains leading to polymicrobial biofilms. Also, the emergence of nontuberculous mycobacteria (NTM) infections has caused additional challenges to patient management due to their multiresistance nature to antibiotics [20]. These are compounded by the impairment of mucociliary clearance and the inability to mobilize thick secretions within the airways. These result in mucus impaction, microorganism colonization, recurrent infections, persistent inflammation and death from respiratory failure. With improvement in CF prognosis, new challenges emerge, including the management of fungal colonization and

**3.2 Host-microbe interactions with CF lung infection**

**3. Microbial complications in patients with cystic fibrosis**

bidity and have therefore been studied intensely [12].

**3.1 Microbial infection in patients with cystic fibrosis**

*DOI: http://dx.doi.org/10.5772/intechopen.91635*

persistence [7].

patients [5, 14].

infection [1].

*Recent Approach in Microbial Pathogen Complications in Patients with Cystic Fibrosis DOI: http://dx.doi.org/10.5772/intechopen.91635*
