Clinical and Translational Research
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Sep 26, 2020; 8(18): 3988-3998
Published online Sep 26, 2020. doi: 10.12998/wjcc.v8.i18.3988
Streptococcus agalactiae: Identification methods, antimicrobial susceptibility, and resistance genes in pregnant women
Fabrícia Almeida Fernandes Santana, Tais Viana Ledo de Oliveira, Marcelo Barreto de Souza Filho, Lucas Santana Coelho da Silva, Breno Bittencourt de Brito, Fabrício Freire de Melo, Cláudio Lima Souza, Lucas Miranda Marques, Márcio Vasconcelos Oliveira
Fabrícia Almeida Fernandes Santana, Tais Viana Ledo de Oliveira, Breno Bittencourt de Brito, Fabrício Freire de Melo, Cláudio Lima Souza, Lucas Miranda Marques, Márcio Vasconcelos Oliveira, Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Vitória da Conquista 45029-094, Bahia, Brazil
Marcelo Barreto de Souza Filho, Laboratório Oliveira Ltda, LABO, Vitória da Conquista 45020740, Bahia, Brazil
Lucas Santana Coelho da Silva, Lucas Miranda Marques, Campus Soane Nazaré de Andrade, Universidade Estadual de Santa Cruz, Ilhéus 45662900, Bahia, Brazil
Author contributions: All authors equally contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Institutional review board statement: This study was reviewed and approved by the Ethical Committee of Research in Human Beings of the Multidisciplinary institute of Health-Campus Anísio Teixeira from the Federal University of Bahia (IMS-CAT/UFBA) under the protocol number 58104116.8.000.5556.
Informed consent statement: All study participants provided written consent prior to study enrollment.
Conflict-of-interest statement: There is no conflict of interest associated with any of the senior author or other coauthors contributed their efforts in this manuscript.
Data sharing statement: There is no additional data available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Fabrício Freire de Melo, PhD, Postdoc, Professor, Instituto Multidisciplinar em Saúde, Universidade Federal da Bahia, Rua Hormindo Barros, 58, Quadra 17, Lote 58, Vitória da Conquista 45029-094, Bahia, Brazil. freiremelo@yahoo.com.br
Received: April 24, 2020
Peer-review started: April 24, 2020
First decision: April 29, 2020
Revised: July 28, 2020
Accepted: August 22, 2020
Article in press: August 22, 2020
Published online: September 26, 2020
Processing time: 150 Days and 5.8 Hours
Abstract
BACKGROUND

Group B Streptococcus (GBS) is a normal component of the gastrointestinal and genital microbiota in humans and can lead to important infections in newborns.

AIM

To compare GBS isolation and identification methods as well as to assess the antibiotic susceptibility and to identify resistance genes in GBS strains from pregnant women attended in healthcare services from the city of Vitória da Conquista, in Bahia State, Brazil.

METHODS

From January 2017 to February 2018, vaginorectal swabs were obtained from 186 participants and the samples were seeded onto chromogenic agar for GBS before and after inoculation in selective broth. Confirmatory identification using 3 CAMP and latex tests was performed in samples with GBS-suggestive colonies. Then, disk diffusion antibiograms were performed in GBS-positive samples, and the detection of the resistance genes ermB, ermTR, mefA, and linB in the clindamycin and/or erythromycin-resistant samples was carried out.

RESULTS

Thirty-two samples (17.2%) were GBS-positive. The culture in chromogenic agar after sample incubation in selective broth was the most sensitive method (96.9%) for GBS detection. All isolates were susceptible to penicillin, ampicillin, cefotaxime, and vancomycin. Clindamycin resistance was observed in 6 samples (18.8%), while 8 samples (25%) were erythromycin-resistant. All erythromycin and/or clindamycin-resistant GBS strains had negative D-tests. Two strains (25%) presented an M phenotype and 6 isolates (75%) presented a cMLSB phenotype. The ermB gene was identified in 4 samples (44.4%), the mefA gene was also found in 4 samples (44.4%), the ermTR gene was identified in 1 isolate (11.1%), and the linB gene was not found in any isolate.

CONCLUSION

This study evidenced that the screening for SGB can be performed by means of various methods, including chromogenic media, and that the chemoprophylaxis for pregnant women who cannot use penicillin must be susceptibility-guided.

Keywords: Streptococcus agalactiae; Pregnancy; Antimicrobial susceptibility

Core Tip: This study compares available methods for isolation and identification of Group B Streptococcus (GBS) in vaginorectal secretions from pregnant women and reveals the sensitivity profile of the isolated strains as well as evaluates the resistance genes related to the observed bacterial phenotypes. This study included 186 pregnant women and a 17.2% GBS prevalence was identified. Among isolates, 18.8% showed to be resistant to clindamycin while 25% was resistant to erythromycin. In the molecular analysis of the strains, the ermB, mefA, and ermTR were detected, and the linB was not identified.