Pseudomembranous laryngotracheobronchitis due to coinfection with human bocavirus 1 and Mycoplasma pneumoniae: a case report

Abstract

Pseudomembranous laryngotracheobronchitis is rarely reported yet potentially life-threatening infectious cause of airway obstruction in children. The causative organisms of this condition are often considered to promote bacterial superinfection following viral infection. We report a case of pseudomembranous laryngotracheobronchitis in a patient caused by human bocavirus 1 and Mycoplasma pneumoniae (M. pneumoniae). A 2-year-old child was admitted to our hospital presenting with cough, hoarseness, and labored breathing. Computed tomography of the chest revealed atelectasis of the right middle lobe of the lung with bronchostenosis and occlusion. Laryngeal edema, pseudomembrane formation and ulceration of the trachea were found during bronchoscopy. Chronic inflammation of the mucosa and local cellulose exudation with acute and chronic inflammatory cell infiltration were confirmed by hematoxylin-eosin staining. Human bocavirus 1 and M. pneumoniae were detected in the bronchoalveolar lavage fluid by next-generation sequencing. The patient tested positive for IgM antibodies against M. pneumoniae. Bronchoscopy was performed three times to clear the secretions in the airway, and azithromycin, ceftriaxone, methylprednisolone, budesonide inhalation, and ambroxol were administered as treatment. The patient's condition improved and she was discharged 21 days after admission. Clinicians should be aware of the potential involvement of human bocavirus 1 and M. pneumoniae in pseudomembranous laryngotracheobronchitis for accurate diagnosis and timely antibiotic administration, and to lower mortality and morbidity rates.

Keywords: Case report; Mycoplasma pneumoniae (M. pneumoniae); human bocavirus; next-generation sequencing; pseudomembranous laryngotracheobronchitis.

Figure 1

Chest radiograph and computed tomography. (A) No obvious abnormalities on chest radiograph at the local hospital. (B) The initial segment of the bronchus of the middle lobe of the right lung is almost completely obstructed with an endobronchial low-density shadow. (C) Obvious stenosis of the bronchus in the middle lobe of the right lung. (D) Obstruction of the middle lobe bronchus of the right lung leading to atelectasis of the middle lobe of the right lung. (E) Shadow in the lower right lung field obscuring the right heart border.

Figure 2

Bronchoscopy and hematoxylin-eosin staining of the pseudomembrane. (A) Pseudomembrane in the trachea on day 4 post admission. (B) Ulcer in the right main bronchus on day 4 post admission. (C) Day 4 post admission: chronic inflammation of the mucous membrane and local cellulose exudation with infiltration of acute and chronic inflammatory cells, with the focal area covered with squamous epithelium. Extensive necrotic tissue with neutrophil infiltration and bacterial overgrowth can be seen. (D) Pseudomembrane in the trachea on day 11 post admission. (E) Day 11 post admission: chronic inflammation of the mucous membrane, hyperplasia of granulation tissue under the squamous epithelium with hyperemia, hemorrhage, and infiltration of inflammatory cells, with cellulose exudate on the surface. (F) The pseudomembrane in the trachea is significantly reduced on day 18 post admission.

Figure 3

Timeline of the case, including clinical presentations, tests, and treatments.