Genomic investigation of a Streptococcus pneumoniae serotype 24F strain causing meningoencephalitis in Hong Kong

Elsevier

Available online 30 November 2021, 151543

International Journal of Medical MicrobiologyAbstract

Pneumococcal conjugate vaccines (PCVs) successfully decreased the incidence of invasive pneumococcal disease in children. However, many countries have reported serotype replacement and a rebound in diseases from non-vaccine serotypes. Here, we report the genomic investigation of a Streptococcus pneumoniae strain M215 that caused severe meningoencephalitis in an infant in 2019. The strain was assigned to serotype 24 F using the bioinfomatic pipeline SeroBA and pneumococcal type specific anti-sera. The strain was resistant to cotrimoxazole from mutations in both folA and folP genes. It was susceptible to penicillin and other non-β-lactam antibiotics. Phylogenetically, it belongs to global pneumococcal sequence cluster (GPSC) 6 and multi-locus sequence type 162. A total of 38 virulence genes were detected in the genome of M215. Upon comparison of the profile of virulence genes, GPSC6 but not non-GPSC6 strains of serotype 24 F and related serotypes were found to possess the major virulence determinant, pilus islet-1, comprising genes encoding sortases (srtB, srtC, srtD), pilus proteins (rrgA, rrgB and rrgC) and one transcriptional regulator (rlrA), which was previously described to be characteristic feature of international clones in the pre-PCV era. In our locality, this represented the first detection of serotype 24 F and GPSC6/ST162 causing serious pneumococcal disease. The emergence of the non-vaccine serotype 24 F GPSC6/ST162 lineage with molecular feature of high virulence is concerning and emphasizes the need for full characterization of strains causing severe disease.

Keywords

pneumococcal conjugate vaccine

epidemiology

invasive pneumococcal disease

cotrimoxazole resistance

© 2021 The Author(s). Published by Elsevier GmbH.

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