Prevalence, population structure, distribution of serotypes, pilus islands and resistance genes among erythromycin-resistant colonizing and invasive Streptococcus agalactiae isolates recovered from pregnant and non-pregnant women in Isfahan, Iran

Hossein Fazeli,Saba Jalalifar,Tahereh Motallebirad,Ataollah Ghahiri,Bahram Nasr Esfahani,Dariush Shokri,Sharareh Moghim

doi:10.1186/s12866-021-02186-2

Hossein Fazeli, Saba Jalalifar + Show 5 more

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https://doi.org/10.1186/s12866-021-02186-2

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Journal: BMC Microbiology	Publication Date: May 4, 2021
Citations: 12	License type: open-access

Affiliation: Isfahan University of Medical Sciences

Abstract

BackgroundThe information on antibiotic resistance and molecular features of Group B Streptococcus (GBS) are essential for epidemiological purposes as well as vaccine development. Therefore, we aimed to assess the antimicrobial resistance profiles and molecular characteristics of GBS isolates in Isfahan, Iran. A total number of 72 colonizing and invasive GBS were collected from pregnant and non-pregnant women. The GBS isolates were analyzed for resistance profiles, capsular genotyping, and detection of PI-1, PI-2a, PI-2b, hvgA, ermB, ermTR, lnuB and, mefA genes. Besides, erythromycin-resistant strains were subjected to multilocus sequence typing (MLST).ResultsThe prevalence of colonizing and invasive GBS were 11 and 0.05%, respectively. The frequency of capsular serotypes was as follows: III (26.3%), Ia (20.83%), Ib and V (each 15.2%), IV (9.7%), II (8.3%), VII (2.7%), and VI (1.3%). Overall frequencies of PIs were as follows: PI-1, 37.5%, PI-1 + PI-2a, 30.5%, PI-1 + PI-2b, 29.1% and PI-2b, 2.7%. Two maternal colonizing GBS (2.6%) were hvgA positive and were belonged to ST-17/CPS-III/PI-1 + PI-2b lineage. Among 30(41.6%) erythromycin resistant GBS, 21 isolates (70%) harbored ermB gene, followed by ermTR (23.3%) and mefA (10%). One clindamycin-resistant isolate harbored the lnuB gene. MLST analysis revealed the following five clonal complexes (CCs) and nine STs: (CC-19/ST-335, ST-19, and ST-197), (CC-12/ST-43, ST-12), (CC-23/ST-163, ST-23), (CC-17/ST-17) and (CC-4/ST-16).ConclusionThe study shows an alarmingly high prevalence of erythromycin-resistant GBS in Iran. In addition, we report dissemination of ST-335/CPS-III clone associated with tetracycline and erythromycin resistance in our region. The distribution of capsular and pilus genotypes varies between invasive and colonizing GBS that could be helpful for vaccine development.

Highlights

Group B Streptococcus (GBS, Streptococcus agalactiae), is regarded as one of the major causes of neonatal sepsis, pneumonia, and meningitis
We found two strains belonging to Clonal Complex (CC)-17/ Sequence Type (ST)-17/ capsular polysaccharide (CPS) III/ pilus island (PI)-1+ PI-2b/ hvgA+ clone from two colonized mothers
This study provided the first information on the population structure and genetic diversity of erythromycinresistant colonizing and invasive GBS strains among adults in Iran

Summary

Introduction

Group B Streptococcus (GBS, Streptococcus agalactiae), is regarded as one of the major causes of neonatal sepsis, pneumonia, and meningitis. This bacterium is increasingly associated with invasive infections in men and non-pregnant women and elderly patients with diabetes mellitus, cancer, renal dialysis, and other significant underlying diseases [1, 2]. The incidence of neonatal early-onset GBS infections has decreased since the use of intrapartum antibiotic prophylaxis (IAP) in GBS-colonized pregnant women [3, 4]. The GBS isolates were analyzed for resistance profiles, capsular genotyping, and detection of PI-1, PI-2a, PI-2b, hvgA, ermB, ermTR, lnuB and, mefA genes. Erythromycin-resistant strains were subjected to multilocus sequence typing (MLST)

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