Clinical features and pathogen distributions of microbiological-based protracted bacterial bronchitis in children of different ages in Northeast China

Clinical characteristics of infants with protracted bacterial bronchitis: an observational cohort study

Background

Infants with protracted bacterial bronchitis (PBB) have been reported in case reports and limited small case series, which is not commonly recognized. The aim of the study is to determine the clinical features and image findings of infants with PBB for early detection and diagnosis.

Methods

Infants with PBB were prospectively enrolled during January 2021 to January 2024 in Guangzhou Women and Children's Medical Center. Clinical data were collected, including clinical manifestations, laboratory parameters, radiological findings, management, and follow-up.

Results

There were 37 patients included (30 boys, 81.08%; 7 girls, 18.92%) with a median onset age of 6 months [interquartile range (IQR), 4-7.5 months]. All patients presented with wet cough (100.00%), 34 presented with persistent wheezing (91.89%). Moraxella bacteria (12/37, 32.43%) and Streptococcus pneumoniae (11/37, 29.73%) were the most often diagnosed pathogens. There were nine patients detected with multiple drug-resistant strains by bronchoalveolar lavage (BAL) cultures (9/32, 28.13%). Uneven inflation was the most common form of chest computed tomography (CT) manifestation (27/37, 72.97%). Under bronchoscopy, thick pale yellow or yellow mucus was attached to the airway in all patients. The use of antibiotics was permitted for all infants with PBB after a definite diagnosis (37/37, 100.00%). The condition can be completely mitigated (34/37, 91.89%), only three patients developed recurrent PBB.

Conclusions

Wheezing was a very common clinical performance in infants with PBB, and the most common pathogens were Moraxella bacteria and Streptococcus pneumoniae. The CT performance of PBB mainly is uneven inflation in infants.

Molecular characteristics and biofilm formation capacity of nontypeable Haemophilus influenza strains isolated from lower respiratory tract in children

With the widespread introduction of the Hib conjugate vaccine, Nontypeable Haemophilus influenzae (NTHi) has emerged as the predominant strain globally. NTHi presents a significant challenge as a causative agent of chronic clinical infections due to its high rates of drug resistance and biofilm formation. While current research on NTHi biofilms in children has primarily focused on upper respiratory diseases, investigations into lower respiratory sources remain limited. In this study, we collected 54 clinical strains of lower respiratory tract origin from children. Molecular information and drug resistance features were obtained through whole gene sequencing and the disk diffusion method, respectively. Additionally, an in vitro biofilm model was established. All clinical strains were identified as NTHi and demonstrated the ability to form biofilms in vitro. Based on scanning electron microscopy and crystal violet staining, the strains were categorized into weak and strong biofilm-forming groups. We explored the correlation between biofilm formation ability and drug resistance patterns, as well as clinical characteristics. Stronger biofilm formation was associated with a longer cough duration and a higher proportion of abnormal lung imaging findings. Frequent intake of β-lactam antibiotics might be associated with strong biofilm formation. While a complementary relationship between biofilm-forming capacity and drug resistance may exist, further comprehensive studies are warranted. This study confirms the in vitro biofilm formation of clinical NTHi strains and establishes correlations with clinical characteristics, offering valuable insights for combating NTHi infections.