Haemophilus influenzae is a common opportunistic pathogen that is often isolated from the upper and lower respiratory tracts [
1,
2]. The widespread vaccination of
Haemophilus influenzae B conjugate vaccine in the domestic pediatric population has made
nontypeable Haemophilus influenzae (NTHi) the main pathogenic bacteria causing respiratory tract infections in children [
3]. NTHi colonizes the human nasopharynx, but is an important pathogen in middle ear infection (otitis media) in children [
4] and exacerbations in bacterial bronchitis, chronic obstructive pulmonary disease, and bronchiectasis [
5,
6], as well as community-acquired pneumonia, in adults [
7]. Frequency of disease caused by NTHi is increasing annually, exacerbated by both the absence of an NTHi vaccine and emerging antibiotic resistance [
8]. In the process of pulmonary infection, adhesion to pulmonary epithelial cells is the first step of pulmonary infection [
6,
9,
10], which directly affects its pathogenic ability. Many studies have been conducted on cell adhesion and related factors in otitis media and adult chronic obstructive pulmonary disease [
5,
6,
11], but there are few studies on the adhesion of epithelial cells in children with pulmonary infections, such as pneumonia, bronchiectasis, persistent bacterial bronchitis, and chronic suppurative lung disease. In this study,
Haemophilus influenzae isolates were selected from the nasopharynx of healthy children and from the sputum or bronchoalveolar lavage fluids of hospitalized children. The adhesive abilities of these isolates to A549 cells were compared in vitro, to explore the mechanism of
Haemophilus influenzae infection in the progress of pediatric pulmonary infections.