Fulminant Haemophilus Influenzae Type a Infection in a 4-year-old with Previously Undiagnosed Asplenic Heterotaxy

Report of Haemophilus Influenzae serotype a intracranial infections in older children

Introduction

Haemophilus influenzae (Hi) is subdivided into typeable (a-f) and non-typeable groups. Hi serotype b (Hib) has historically been one of the important pathogens responsible for invasive infection. However, after widespread Hib vaccination, the emergence of other Hi serotypes, specifically Hi serotype a (Hia), was noted during the last few decades, mostly in children younger than 5 years of age.

Case presentation

We present two cases of severe intracranial infections with detected Hia in patients > 5 years of age within a short time frame and within the same geographic area.

Conclusion

Epidemiological studies and surveillance on Hia-related illnesses in all age groups worldwide are needed to better understand the clinical and epidemiological characteristics of Hia. This can establish a platform to develop a candidate vaccine against Hia that might protect children of all ages.

Haemophilus influenzaenon-type b Invasive Disease in Children ≤ 5 yearsof age: A Case Report and Review of Literature.. [DOI: 10.14293/s2199-1006.1.sor-.ppwt6cv.v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background:

Haemophilus influenzae type b (Hib) was the leading cause of invasive disease in children <5 years of age before the introduction of Hib conjugate vaccines. Invasive disease due to non-type H. influenzae has been increasingly reported.

Aims:

To describe a case of invasive non-type b Haemophilus influenzae and review the literature.

Case and Methods:

We describe a case of a 4-month-old male presented with fever and lethargy, subsequently diagnosed with bacteremia and meningitis due to Haemophilus influenzae type a (Hia). His clinical course was complicated by subdural empyema (figure 1) and seizures with complete recovery following surgical drainage and prolonged antibiotic therapy. We searched PubMed and Embase from 2010 to 2020 for case reports of non-type b Hi invasive disease in children ≤ 5 years.

Results:

Out of 138 articles screened, 17 were selected for review. 31 individual cases were summarized with 25% reported in the US. Calculated mean age was 1.5 years (range 0-5 years). Most common presentation was bacteremia (80%, 25) and meningitis (55%, 17). Most cases caused by Hia (52%, 16). About 29% (9) has underlying combordities, and additional 13% (4) were later diagnosed with immunodeficiency condition. Subdural collection and seizures occurred separately in 16% (5) Majority of patients recovered, and 3 (10%) died.

Conclusion:

Non-type b Hi invasive disease can lead to high morbidity and mortality in children. Epidemiologic surveillance and serotyping are crucial to monitor changing epidemiology of Hi invasive disease. Inclusion of non-type b strains in the Hib conjugate vaccine may be necessary to protect against H. influenzae invasive disease .

Two cases of type-a Haemophilus influenzae meningitis within the same week in the same hospital are phylogenetically unrelated but recently exchanged capsule genes

Haemophilus influenzae causes common and sometimes severe adult and pediatric disease including chronic obstructive respiratory disease, otitis media and infections of the central nervous system. Serotype b strains, with a b-type capsule, have been the historical cause of invasive disease, and the introduction of a serotype b-specific vaccine has led to their decline. However, unencapsulated or non-b-type H. influenzae infections are not prevented by the vaccine and appear to be increasing in frequency. Here we report two pediatric cases of severe central nervous system H. influenzae infection presenting to the same hospital in San Diego, California during the same week in January 2016. Due to good vaccine coverage in this part of the world, H. influenzae cases are normally rare and seeing two cases in the same week was unexpected. We thus suspected a recent transmission chain, and possible local outbreak. To test this hypothesis, we isolated and sequenced whole genomes from each patient and placed them in a phylogenetic tree spanning the known diversity of H. influenzae. Surprisingly, we found that the two isolates (SD2016_1 and SD2016_2) belonged to distantly related lineages, suggesting two independent transmission events and ruling out a local outbreak. Despite being distantly related, the two isolates belong to two different lineages that have exchanged capsule loci in the recent past. Therefore, as in other bacterial pathogens, capsule switching by horizontal gene transfer may be an important evolutionary mechanism of vaccine evasion in H. influenzae.

Case report of congenital asplenia presenting with Haemophilus influenzae type a (Hia) sepsis: an emerging pediatric infection in Minnesota

Background

In the pre-vaccine era, invasive disease with Haemophilus influenzae, type b (Hib) commonly presented with osteoarticular involvement. Haemophilus influenzae, type a (Hia) sepsis is a rare but emerging problem in recent years. Here, we report a case of sepsis with concomitant osteoarthritis due to Hia that was the presenting infectious disease manifestation of isolated asplenia in a young child. This unique observation adds to our understanding of sepsis and asplenia in children.

Case presentation

A five-year-old girl developed acute Hia bacteremia and sepsis. The patient developed arthritis shortly after onset of septic shock. Arthrocentesis was culture-negative, but given the difficulty differentiating between septic and reactive arthritis, prolonged antibiotic administration was provided for presumed osteoarticular infection, and the patient had an uneventful recovery. The finding of Howell-Jolly bodies on blood smear at the time of presentation prompted an evaluation that revealed isolated congenital asplenia. Evaluation for known genetic causes of asplenia was unrevealing. Investigation by the Minnesota Department of Health revealed an emergence of Hia infections over the past 5 years, particularly in children with an American Indian background.

Conclusions

Hia is an important pathogen in the differential diagnosis of invasive bacterial infections in children and shares overlap in clinical presentation and pathogenesis with Hib. Invasive Hia disease can be a presenting manifestation of asplenia in children. Hia is an emerging pathogen in American Indian children.