Bacterial Meningitis Caused by Haemophilus influenzae Type F Diagnosed Using Next-Generation Sequencing

Excerpt

To the Editor: Haemophilus influenzae type b vaccination was introduced in routine immunization schedule in 2013 in Japan. After that, the incidence of invasive H. influenzae has significantly decreased. On the other hand, the cases of invasive infection caused by non-typable H. influenzae and non-typable b-strains have been observed more frequently [1]. We report a case of H. influenzae type f meningitis and bacteremia in a 10-mo-old boy who was previously healthy and had been fully immunized. He was admitted to our hospital with symptoms suggestive of meningitis and diagnosed as bacterial meningitis by blood and cerebrospinal fluid (CSF) testing. He was treated with antibiotics and improved clinically. The pathogen was determined to be H. influenzae type f using nanopore sequence technology (MinIONFLO-MIN107R ver. 9.5; Oxford Nanopore Technologies, Oxford, UK) and hicap software that aided rapid in silico serotype predictions by reference to H. influenzae genomic sequences [2]. Next-generation sequencing (NGS) has advantages in terms of accuracy compared to slide agglutination tests. Usually, antisera are employed to identify H. influenzae capsular types. However, in silico identification via NGS and hicap may be valuable in clinical practice. The standard slide agglutination tests using specific antibodies are estimated to yield incorrect results at a rate of 17.5% [3]. However, hicap can identify capsular with approximately 98% accuracy [2]. In addition, bacterial culture requires 3 d; NGS is complete within 6 h, affording a rapid diagnosis [4]. Although pathogen identification in children with severe infections is crucial in terms of both initiation of appropriate therapy and prognosis, such identification is often impossible. Under such circumstances, NGS may aid diagnosis. We used NGS to identify and type cultured H. influenzae. Several case reports have used CSF NGS to directly diagnose meningitis [4]. If the use of NGS becomes more common, it could help diagnose invasive infections. …