Genomic characteristics and antimicrobial resistance of <em>Streptococcus agalactiae</em> isolates causing infections and asymptomatic carriage in Southwest Finland — ASN Events
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  3. Genomic characteristics and antimicrobial resistance of Streptococcus agalactiae isolates causing infections and asymptomatic carriage in Southwest Finland

Genomic characteristics and antimicrobial resistance of Streptococcus agalactiae isolates causing infections and asymptomatic carriage in Southwest Finland (#151)

Natalie Tomnikov 1 2 , Inka Harju 3 , Kaisu Rantakokko-Jalava 3 , Teemu Kallonen 3 , Roosa Rahkonen 1 , Päivi Polo-Kantola 4 5 , Kaarin Mäkikallio 4 5 , Jaana Vuopio 1 6 , Kirsi Gröndahl-Yli-Hannuksela 1 4
  1. Institute of Biomedicine, University of Turku, Turku, Finland
  2. Turku Doctoral Programme of Molecular Medicine (TuDMM), University of Turku, Turku, Finland
  3. Clinical microbiology, Turku University Hospital, Turku, Finland
  4. Department of Obstetrics and Gynaecology, Turku University Hospital, Turku, Finland
  5. Obstetrics and Gynaecology, University of Turku, Turku, Finland
  6. Finnish Institute for Health and Welfare (THL), Helsinki, Finland

Introduction

Streptococcus agalactiae (GBS) commonly colonizes genital and gastrointestinal tract and can cause infections. Aim of this study is to perform comparative analysis of the serotype distribution, antimicrobial resistance and genomic characteristics of GBS isolates from asymptomatic carriage, invasive infections and urinary cultures in Southwest Finland.

Methods

GBS isolates from asymptomatic throat and screening samples (aGBS) collected during a clinical study (2022-2023), bloodstream infections (iGBS) (2018-2022) and urinary cultures (ucGBS) (2023-2024) from Southwest Finland were included. The GBS isolates were serotyped and antimicrobial susceptibility measured for penicillin, clindamycin, vancomycin, erythromycin and tetracycline. A subset of the isolates was selected for Whole Genome Sequencing (WGS). Demographic data (age, gender) was available for iGBS and ucGBS.

Results

456 isolates were analysed (70 aGBS, 168 iGBS and 218 ucGBS). All ten known serotypes were detected. Serotype Ia dominated in aGBS (30%) and ucGBS (27%), V in iGBS (23.8%). Tetracycline resistance was common (total 87%). Erythromycin resistance was significantly more common in iGBS isolates (35%) than in aGBS and ucGBS (13%, p<0.001 and 18%, p<0.001). All isolates were susceptible to penicillin and vancomycin. 70 aGBS, 78 iGBS and 43 ucGBS were sequenced. WGS revealed 35 sequence types (ST) and 9 novel STs belonging to 9 clonal complexes (CC). ST1 was the most prevalent in aGBS (9%) and iGBS (10%), ST144 in ucGBS (4%). CC23 was most often found in aGBS (9%) and ucGBS (5%), CC1 in iGBS (13%).

Conclusion

iGBS differed from aGBS and ucGBS both in antimicrobial susceptibility and genomic characteristics.

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