Haemophilus influenzae is a Gram-negative coccobacillus capable of colonizing and infecting the human respiratory tract.

In the adult population, patients with an abnormality of their mucociliary epithelium and a deficiency in innate or adaptive immunity are particularly exposed.

The Infectious and Tropical Diseases department of Necker-Enfants Malades hospital has noted a recent increase in the number of cases of respiratory infections due to H. influenzae, with a high frequency of early relapses and recurrences despite appropriate treatment.

The research focuses on lower respiratory infections (pneumonia) caused by Haemophilus influenzae in adults, excluding pneumonia acquired under mechanical ventilation linked to Haemophilus influenzae in patients in 13 AP-HP hospitals during 12 months, from 09/01/2022 to 08/31/2023.

Haemophilus influenzae is a Gram-negative coccobacillus capable of colonizing and infecting the human respiratory tract.

In the adult population, patients with an abnormality of their mucociliary epithelium and a deficiency in innate or adaptive immunity are particularly exposed.

The Infectious and Tropical Diseases department of Necker-Enfants Malades hospital has noted a recent increase in the number of cases of respiratory infections due to H. influenzae, with a high frequency of early relapses and recurrences despite appropriate treatment.

The research focuses on lower respiratory infections (pneumonia) caused by Haemophilus influenzae in adults, excluding pneumonia acquired under mechanical ventilation linked to Haemophilus influenzae in patients in 13 AP-HP hospitals during 12 months, from 09/01/2022 to 08/31/2023.

The main objective of the study is to identify factors associated with relapse in hospitalized adult Haemophilus influenzae pneumonia.

Inclusion Criteria:

• Acute respiratory symptoms: cough and/or dyspnea and/or purulent sputum or worsening of the color of the sputum for patients with chronic respiratory pathology, chest pain, desaturation defined by saturation < 95% in ambient air
• Inflammatory syndrome: fever ≥ 38.5°C or CRP ≥ 30 mg/L
• Pulmonary imaging (x-ray or CT scan) compatible with pneumonia
• Good quality respiratory sample (for cytobacteriological examination of sputum (CBES) : leukocytes > 25/mm3 and cells < 10/mm3) positive in culture for H. influenzae at a significant threshold (for CBES ≥ 107 CFU/mL, for "standard" bronchial aspirate ≥ 105 CFU/mL, for protected bronchial aspiration ≥ 103 CFU/mL, for bronchoalveolar lavage ≥ 104 CFU/mL)
• Respiratory antibiotic therapy started by the clinician

Exclusion Criteria:

• Age < 18 years
• Opposition formulated (following receipt of the study information note)
• Legal protection measure (impossibility of collecting non-opposition)
• Ventilator-associated pneumonia (VAP)

Hospitalized patients for a Haemophilus influenzae pneumonia in 14 hospitals of Assistance Publique - Hôpitaux de Paris, between 09/01/2022 to 08/31/2023.