Prevalência, susceptibilidade antimicrobiana e presença de genes de resistência em streptococcus agalactiae isolados de gestantes colonizadas em Hospital Universitário

Abstract

Streptococcus agalactiae (GBS) belongs to Lancefield group B, and is the leading cause of neonatal infectious disease. Anovaginal colonization of pregnant women is the main risk factor for the development of neonatal GBS disease. Beta-lactams are the main therapeutic choice; however, due to the risk of anaphylaxis, in case of hypersensitivity to beta-lactams, other classes of antimicrobials should be used. However, the emergence and prevalence of antimicrobial resistance among S. agalactiae isolates has been observed, especially after the COVID-19 pandemic. The present study aimed to investigate the prevalence of anovaginal colonization, the antimicrobial susceptibility profile, and the presence of resistance genes in Streptococcus agalactiae isolated from pregnant women treated at a university hospital between January 2020 and June 2024. An observational, cross-sectional study was carried out. Colonization and antimicrobial susceptibility data were obtained from the hospital's microbiology records. Throughout the study, isolates obtained by convenience were provided by the hospital for the investigation of resistance determinants. In total, the study obtained 1.323 anovaginal cultures from pregnant women, of which S. agalactiae was found in 11.94%. It should be noted that the prevalence of colonization was higher during the pandemic period. The susceptibility of GBS to penicillin, ampicillin, erythromycin, clindamycin, tetracycline and levofloxacin was obtained. PCR reactions were performed to investigate the following resistance genes: tetM, tetO, ermTR, ermB and mef. All isolates were susceptible to beta-lactams. A significant increase in resistance to erythromycin and levofloxacin was reported post-pandemic. The mef gene was the main cause of resistance to erythromycin, but an increase in the proportion of isolates carrying ermB genes was observed. An increasing trend was also observed for clindamycin in association with the ermB gene. Tetracycline resistance rates were high, and tetM was the predominant gene. Despite the clinical relevance of S. agalactiae, Brazil lacks epidemiological studies on the subject, especially in the Northeast region. Research on this pathogen is relevant to public health and can help promote better surveillance and prevention of neonatal diseases. In addition, due to the emergence of resistant strains of this pathogen worldwide, it is important to monitor resistance rates and their molecular mechanisms, which can contribute to the development of effective strategies for treating the infection.