The importance of recognizing protracted bacterial bronchitis in children

Impact of Immune-Inflammatory Microenvironment Alterations on the Bronchial Lumen of Children With Protracted Bacterial Bronchitis

Protracted bacterial bronchitis is a syndrome that is among the most common causes of chronic cough. In order to understand its pathogenetic mechanisms, there is an increasing interest in the study of the immune microenvironment in the bronchial lumen. The aim of this retrospective study is the determination of the types and quantity of the inflammatory cells that infiltrate the bronchial epithelium as well as of the thickness of the basement membrane. Ninety-seven endobronchial biopsies, obtained from 77 children (30 males and 47 females) aged between 5 and 14 years, with chronic (>8 weeks) wet/productive cough, were subjected to hematoxylin and eosin staining. Using an appropriate image analysis and processing software, we determined the types and the quantity of the inflammatory cells that infiltrated the bronchial epithelium, and the thickness of the basement membrane. The metric data were then subjected to extensive statistical analysis. According to our results, females had increased levels of eosinophils (p = 0.021) and lymphocytes (p = 0.044) compared to males. Moreover, we found that membrane thickness was negatively correlated with the number of eosinophils (p < 0.0001), neutrophils (p = 0.023), and lymphocytes (p = 0.024). Finally, the pairwise comparisons of the number of eosinophils, neutrophils, lymphocytes, and other cell types revealed significant (p < 0.05) positive correlations. Protracted bacterial bronchitis activates pulmonary innate immune pathways. Also, it is accompanied by basement membrane thickening, which is a typical characteristic of several respiratory diseases, such as asthma.

An underestimated cause of chronic cough: The Protracted Bacterial Bronchitis

Chronic cough in childhood is associated with a high morbidity and decreased quality of life. Protracted bacterial bronchitis (PBB) seems to be the second most common cause of chronic cough in children under 6 years of age. Its main clinical feature is represented by wet cough that worsens when changing posture and improves after the introduction of antibiotics. Currently, the mainstay of PBB treatment is a 2-week therapy with a high dose of antibiotics, such as co-amoxiclav, to eradicate the infection and restore epithelial integrity. It is very important to contemplate this disease in a child with chronic cough since the misdiagnosis of PBB could lead to complications such as bronchiectasis. Clinicians, however, often do not consider this disease in the differential diagnosis and, consequently, they are inclined to change the antibiotic therapy rather than to extend it or to add steroids. Data sources of this review include PubMed up to December 2016, using the search terms “child,” “chronic cough,” and “protracted bacterial bronchitis.”

Clinical characteristics of protracted bacterial bronchitis in Chinese infants

Protracted bacterial bronchitis (PBB) is the common cause of chronic cough in children worldwide, but its etiology has not been fully recognized in China. We retrospectively investigated a total of 66 hospitalized infants under the age of three years with chronic wet cough enrolled in the Affiliated Children's Hospital of Soochow University from October 2010 to March 2014. All patients underwent bronchoscopy and broncho-alveolar lavage (BAL) samples were processed for microbiological and cytological analysis. Of 66 patients with wet cough, 50 (75.8%) were diagnosed with PBB. In the PBB group, wet cough was accompanied by wheezing (90%). Airway malacia were identified in 22 cases (44%). The clinical manifestations of PBB with airway malacia did not differ from those without malacia. Haemophilus influenzae (47.4%) and Streptococcus pneumoniae (36.8%) were the most commonly identified pathogens. Furthermore, CD3(+) and CD3(+)CD4(+) cells were significantly lower in the PBB group (p < 0.01), while CD19(+), CD16(+)CD56(+) and CD23(+) cells were elevated (p < 0.01) in the PBB group. Our study revealed PBB is an important cause of chronic wet cough in Chinese infants, and that changes of lymphocyte subsets are observed in children with PBB. Airway malacia frequently co-existed with PBB, but did not exacerbate the disease.

[Persistent coughs in children and adolescents]

A persistent cough lasting more than 4-8weeks should lead to a diagnostic workup. A detailed history and a full clinical examination, with a chest X-ray, are essential for initial assessment. Most reported causes of chronic cough in children are post-nasal drip syndrome, cough variant asthma (a spirometry with test of bronchodilator responsiveness should be attempted in children old enough to perform the manoeuvres). GERD is often suspected but a causal relationship is difficult to establish. Protracted bacterial bronchitis, post-infectious cough (B. pertussis, Mycoplasma) and somatoform respiratory disorders (including hyperventilation syndrome) are also common. Signs which are pointers suggesting an underlying respiratory or systemic disease require further investigation: inhaled foreign bodies, cystic fibrosis and chronic lung diseases with bronchiectasis, airway abnormalities, interstitial lung diseases need to be considered. Recent reports of refractory coughs have identified features of a sensory neuropathy disorder, and might explain persistent cough triggers.