Pediatric Haemophilus Infuenza Invasive Disease in a Portuguese Second-Level Hospital: 2010-2018

Introduction: Haemophilus influenza is a nasopharynx colonizer in children, responsible for upper respiratory tract infections and rarely causes invasive disease, namely meningitis, pneumonia, arthritis or bacteremia. Before routine immunization against Haemophilus influenza type b (Hib) was included in National Vaccination Program (NVP) in 1994, this was the main responsible for invasive disease. Afterwards, non-capsulated (NC) strains have been the most frequently implicated.

Methods: Retrospective observational study describing all pediatric cases of invasive Haemophilus influenza disease in a second-level hospital between 2010 and 2018.

Results: Seven cases were identified: three Hib and four NC strains. There were five boys and two girls and a mean age was 18 months (3 m -11 y).

Hib vaccination was complete in all children except for one, who wasn`t vaccinated. Major risk factors were prematurity (2), asthma (1), psychomotor development retardation (1), recurrent acute otitis (1), recent tonsillectomy (1) and IgA deficiency (2). Two vaccine failures occurred, a girl with a recent tonsillectomy and a boy with IgA deficiency.

Diagnosis was confirmed by isolation of Haemophilus from blood (6), cerebrospinal fluid (3) and pleural fluid (1). Clinical presentations were meningitis (4), three of them with septicemia, pneumonia (2) and occult bacteremia (1). Of the Hib infection cases, two presented with meningitis and one with occult bacteremia. One patient with Hib meningitis developed permanent neurosensorial hear loss and ataxia. Three patients were admitted to Intensive Care Unit for a medium of four days.

Third generation cephalosporins (5) and ampicillin (2) were the chosen antibiotics. Ampicillin resistance mediated by beta-lactamases was identified in one patient.

Discussion: Haemophilus influenza invasive disease represents a potential serious condition. Although NC strains are the most prevalent, Hib is still present and responsible for some cases

National epidemiological surveillance is of crucial importance and may help the development of new preventive strategies.