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

An invasive Haemophilus influenzae serotype b infection in an Anglo-Saxon plague victim

Background

The human pathogen Haemophilus influenzae was the main cause of bacterial meningitis in children and a major cause of worldwide infant mortality before the introduction of a vaccine in the 1980s. Although the occurrence of serotype b (Hib), the most virulent type of H. influenzae, has since decreased, reports of infections with other serotypes and non-typeable strains are on the rise. While non-typeable strains have been studied in-depth, very little is known of the pathogen’s evolutionary history, and no genomes dating prior to 1940 were available.

Results

We describe a Hib genome isolated from a 6-year-old Anglo-Saxon plague victim, from approximately 540 to 550 CE, Edix Hill, England, showing signs of invasive infection on its skeleton. We find that the genome clusters in phylogenetic division II with Hib strain NCTC8468, which also caused invasive disease. While the virulence profile of our genome was distinct, its genomic similarity to NCTC8468 points to mostly clonal evolution of the clade since the 6th century. We also reconstruct a partial Yersinia pestis genome, which is likely identical to a published first plague pandemic genome of Edix Hill.

Conclusions

Our study presents the earliest genomic evidence for H. influenzae, points to the potential presence of larger genomic diversity in the phylogenetic division II serotype b clade in the past, and allows the first insights into the evolutionary history of this major human pathogen. The identification of both plague and Hib opens questions on the effect of plague in immunocompromised individuals already affected by infectious diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-021-02580-z.

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 .

Global population structure of Haemophilus influenzae serotype a (Hia) and emergence of invasive Hia disease: capsule switching or capsule replacement?

The population structure of Hia was examined by interrogation of the H. influenzae MLST website. There were 196 entries of Hia with 55 sequence types (STs) identified (as of September 3, 2020). BURST analysis clustered related STs into four complexes with ST-23, ST-4, ST-21 and ST-62 identified as their ancestral STs. The majority of Hia entries (73.4%) and STs (65.5%) were identified as clonal division I (ST-23 and the ST-4 complexes). Only 43 (21.9%) entries and 14 STs (25.5%) were identified as clonal division II (ST-62 and ST-21 complexes). Current data suggested most invasive Hia belonged to clonal division I and the ST-23 complex while most clonal division II Hia were respiratory isolates with the exception of ST-62 which was common among invasive Hia in the U.S. southwest. Comparison of the capsule bexABCD genes from clonal divisions I and II strains showed sequence diversity with variations following the pattern of clonal divisions. Evidence from the literature and the current study suggests recent emergence of invasive Hia might be related to capsule replacement subsequent to the implementation of the Hib conjugate vaccine and possibly exacerbated by other conjugate vaccines that may have altered the microbial flora of the human respiratory tract.