Group B streptococcus colonization in pregnancy and neonatal outcomes: a three-year monocentric retrospective study during and after the COVID-19 pandemic
Authors: Serra Gregorio , Scalzo Lucia Lo , Giordano Maria , Giuffrè Mario , Trupiano Pietro , Venezia Renato , Corsello Giovanni 
Published: June 2024

Background
Group B Streptococcus (GBS) is a major cause of sepsis and meningitis in newborns. The Centers for Disease Control and Prevention (CDC) recommends to pregnant women, between 35 and 37 weeks of gestation, universal vaginal-rectal screening for GBS colonization, aimed at intrapartum antibiotic prophylaxis (IAP). The latter is the only currently available and highly effective method against GBS neonatal infections. Since the onset of the coronavirus disease 2019 (COVID-19) pandemic, the preventive measures implemented to mitigate the effects of SARS-CoV-2 infection led to the reduction in the access to many health facilities and services, including the obstetric and perinatal ones. The purpose of the present study was to evaluate the prevalence rates of maternal GBS colonization, as well as use and effects of IAP in the newborn, in a population of pregnant women during (years 2020–2021) and after (year 2022) the COVID-19 pandemic, also with the aim to establish possible epidemiological and clinical differences in the two subjects’ groups.
Methods
We retrospectively analyzed the clinical data of pregnant women admitted to, and delivering, at the Gynaecology and Obstetrics Unit, Department of Sciences for Health Promotion and Mother and Child Care, of the University Hospital of Palermo, Italy, from 01.01.2020 to 31.12.2022. For each of them, we recorded pertinent socio-demographic information, clinical data related to pregnancy, delivery and peripartum, and specifically execution and status of vaginal and rectal swab test for GBS detection, along with eventual administration and modality of IAP. The neonatal outcome was investigated in all cases at risk. The data observed during the pandemic (years 2020–2021) were compared with those recorded in the following period (year 2022).
Results
The present analysis involved 2109 pregnant women, in addition to their 2144 newborns. The vaginal-rectal swab for GBS was performed in 1559 (73.92%) individuals. The test resulted positive in 178 cases overall (11.42% of those undergoing the screening). Amongst our whole sample, 298 women had an indication for IAP, and 64 (21.48%) received adequate treatment; for 23 (7.72%) it was inadequate/incomplete, while 211 (70.8%) did not receive IAP. Comparing the pandemic period (years 2020–2021) with the following one (year 2022), a lower incidence (p = 0.009) in the execution of vaginal-rectal swabs for GBS was found (70.38% during vs 75.65% after) in the first two years, while a greater number (although not statistically significant, p = 0.12) of adequate and complete IAP conducted in 2022, than in the previous biennium (26.36 vs 18.62%). During the study time, 13 neonates with early onset disease (EOD), out of 179 (7.3%) born to mothers with risk factors, were observed (the global prevalence on the total of babies delivered in the period under investigation was 6.06‰). 3 among these patients’ mothers performed incomplete IAP, while the others did not receive IAP. Neither cases of neonatal meningitis, nor deaths were observed.
Conclusions
The present study revealed in our Department an increased prevalence of pregnant women screened for, and colonized by GBS, in the last decade. However, a significantly lower frequency of vaginal-rectal swabs performed for GBS, as well as a smaller number of adequate and complete IAP were found in the pandemic biennium (2020–2021) than in the following year (2022). Such data are in accordance with those observed during the pandemic period for other care settings, where significant delays in diagnosis and treatment and increased mortality/morbidity rates, due to the indirect effects of COVID-19, have been described. Although IAP is an easy procedure to implement, however adherence and uniformity in the management protocols are still not optimal. In addition, significant EOD prevalence has been reported among children of mothers carrying risk factors. Therefore, the prophylactic measures adopted to date cannot be considered fully satisfactory, and should be improved. Better skills integration and obstetrical-neonatological collaboration, in addition to new effective preventive tools, like vaccines able to prevent invasive disease, may allow further reduction in morbidity and mortality rates related to GBS perinatal infection.