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Serotype Distribution of Streptococcus pneumoniae Isolates Causing Invasive and Non-Invasive Infections Using Whole-Genome Sequencing in Ethiopia

Authors Sharew B, Moges F, Yismaw G, Mihret A, Abebe W, Fentaw S, Tessema B

Received 25 November 2020

Accepted for publication 18 February 2021

Published 2 March 2021 Volume 2021:14 Pages 787—794


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 5

Editor who approved publication: Professor Suresh Antony

Bekele Sharew,1,2 Feleke Moges,1 Gizachew Yismaw,1 Adane Mihret,3 Wondiwossen Abebe,1 Surafal Fentaw,4 Belay Tessema1

1Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia; 2Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia; 3Armauer Hansen Research Institute, Addis Ababa, Ethiopia; 4Ethiopian Public Health Institute, Addis Ababa, Ethiopia

Correspondence: Bekele Sharew
Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, P.O. Box 45, Gondar, Ethiopia
Tel +251 911 165431
Email [email protected]

Background: In Ethiopia, pneumococcal conjugate vaccine 10 (PCV10) was introduced in 2011 in the national vaccination program. This study was aimed to assess serotype distribution of invasive and non-invasive Streptococcus pneumoniae isolates using whole-genome sequencing.
Methods: A hospital-based prospective study was conducted from 2018 to 2019 at Addis Ababa and Amhara region referral hospitals, from all patients. Clinical Samples were collected and initially cultured onto 5% sheep blood agar at 37°C in a 5% CO2 atmosphere. Sequencing was done using the Illumina NextSeq 500 and SeroBA was used to predict serotypes from whole-genome sequencing raw data.
Results: Of the 57 S. pneumoniae isolates, there were 32 circulating serotypes. The most common serotypes were 15A/B/C (n=5, 8.8%), 6A (n=4, 7.0%), 10A/F (n=4, 7.0%), 23A (n=4, 7.0%) and 7C (n=3, 5.3%). The serotype coverage of PCV10 and PCV13 were 12.3% and 26.3% respectively. The most common invasive serotypes were 15A/B/C (n=5, 8.8%) and 6A (n=4, 7.0%), and non-invasive serotypes were 23A (n=4, 7.0%) and 10A/F (n=3, 5.3%). The most prevalent serotype obtained from PCV10 eligible children was 3 (n=2, 3.5%). The prevalent serotype obtained from PCV10 non-eligible patients were type 23A (n=4, 7%) and type 6A (n=3, 5.2%). The most common serotypes among children ≤ 18 years old were 10A/F, 7C, 35A/B, 16F, 19A, 3 and 38. However, the proportions of some non-vaccine serotypes (11A/B and 15A/B/C) were higher in adult patients.
Conclusion: In this study a shift in the distribution of non-vaccinated S. pneumoniae serotypes increases in the population, and PCV10 serotype coverage was reduced as compared to PCV13. Therefore, it is important to continue monitoring serotype changes among all patients in addition to assessing the impact and effectiveness brought by vaccines and provides a foundation for prevention strategies and vaccine policies.

Keywords: Streptococcus pneumoniae, serotypes, whole-genome sequencing

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