International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease
Gladstone RA., Siira L., Brynildsrud OB., Vestrheim DF., Turner P., Clarke SC., Srifuengfung S., Ford R., Lehmann D., Egorova E., Voropaeva E., Haraldsson G., Kristinsson KG., McGee L., Breiman RF., Bentley SD., Sheppard CL., Fry NK., Corander J., Toropainen M., Steens A., Akpaka PE., Ampofo K., Antonio M., Balaji V., Beall BW., Belabbès H., Benisty R., Bentley SD., Bigogo G., Breiman RF., Brooks AW., Carter PE., Clarke SC., Cornick JE., Corso A., Cristina de Cunto Brandileone M., Cristine Grassi Almeida S., Croucher NJ., Dagan R., Davydov A., Diawara I., Doiphode S., du Plessis M., Egorova E., Elmdaghri N., Köseoglu Eser Ö., Everett DB., Faccone D., Ford R., Gagetti P., Givon-Lavi N., Gladstone RA., Hasanuzzaman M., Hawkins PA., Hryniewicz W., Hulten KG., Ip M., Kapusta A., Kandasamy R., Kastrin T., Keenan J., Klugman KP., Kwambana-Adams B., Law PY., Lees JA., Lehmann D., Leung Ho P., Li Y., Lo SW., Ochoa TJ., Madhi SA., McGee L., Metcalf BJ., Moïsi J., Mucavele Fundação Manhiça H., Ndlangisa KM., Nurse-Lucas M., Nzenze SA., Obaro SK., Paragi M., Pollard AJ., Ravikumar KL., Sadowy E., Saha SK., Sampane-Donkor E., Devi Sekaran S., Shakoor S., Shrestha S., Sigauque B., Skoczynska A., Soo ko K., Tientcheu PE., Titov L., Turner P., Urban Y., Verani J., van Tonder AJ., von Gottberg A.
Background: Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them. Methods: Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating. Results: Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0–2 SNPs) with the common ancestor dated around 2017. Conclusion: The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.