Detección e identificación de <i>Streptococcus agalactiae</i> en gestantes: aspectos relevantes y revisión narrativa de la literatura

After completing this article, readers should be able to: 1. Describe the current literature on surveillance studies and patient outcomes regarding group B Streptococcus (GBS) disease. 2. Discuss the current perinatal GBS prevention guidelines. 3. Describe the limitations of the “limited evaluation” in assessing newborns at risk for GBS disease. 4. Delineate the proposed management of asymptomatic infants at risk for GBS disease, with the goal of decreasing unnecessary testing and avoiding prolonged hospitalization. Group B Streptococcus (GBS), also known as S agalactiae , is an encapsulated gram-positive bacterium that is a common inhabitant of the human gastrointestinal and genitourinary tracts. Despite recent reductions in incidence, it remains the most common cause of neonatal bacterial infections in most developed countries. The most desirable approach suggested to eliminate neonatal GBS infection is the use of GBS vaccines prior to or early in pregnancy. However, until effective GBS vaccines become available, screening pregnant women for GBS colonization and providing intrapartum antibiotic prophylaxis (IAP) will continue to be the mainstay for prevention of GBS infection in neonates, as suggested by the Centers for Disease Control and Prevention (CDC). A 70% decline in the rate of early-onset GBS disease followed the introduction of the first national consensus guidelines in 1996. In 2002, new national guidelines were released based on evidence that the screening-based strategy was superior to a risk factor-based strategy for preventing GBS infections in the neonate. As a result of many obstetricians adopting the screening-based strategy, CDC data from 2004 showed a further decline in the incidence of early-onset GBS infection to 0.34 cases per 1,000 live births. This surpasses the Healthy People 2010 objective of a reduction in the incidence of early-onset disease to 0.5 cases per 1,000 live births for all races. It should be mentioned that different countries may demonstrate different results, but …

BackgroundScreening for maternal anogenital Group B streptococci (GBS) colonization in pregnancy with initiation of intravenous intrapartum antibiotic prophylaxis as indicated has led to a significant reduction in the incidence of neonatal GBS infection. This study aims to evaluate the agreement between vaginal-perianal or vaginal-perineal culture and the more typically used vaginal-rectal culture for screening for maternal anogenital GBS colonization in the third trimester of pregnancy.MethodsEligible English-language studies published until January 2020 were retrieved from Scopus, Web of Science, PubMed, Embase, and ClinicalTrials.gov databases. Studies were compiled that assessed for GBS colonization utilizing vaginal-perianal or vaginal-perineal culture and vaginal-rectal culture during the third trimester of pregnancy. Nonoriginal research articles and studies that did not assess pregnant patients, did not use culture-based screening, or did not compare vaginal-perianal or vaginal-perineal culture with vaginal-rectal culture were excluded. The search identified 559 articles with three prospective cohort studies that met inclusion criteria, including 643 participants. Quality was assessed using the Newcastle–Ottawa Scale, and risk of bias was assessed using the Risk of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool. Patient characteristics and associated pain with specimen collection were abstracted. Meta-analyses of both the raw agreement and the Cohen’s kappa statistic were performed.ResultsWithin the three included studies, the range of GBS detection was 17.6–34.0%, consistent with the anticipated prevalence of GBS colonization reported in earlier publications. For both raw agreement and Cohen’s kappa coefficient, the test for heterogeneity was not significant, indicating low heterogeneity among studies. The pooled estimate of the raw agreement was 0.97 (95%CI 0.95–0.98) and of the Cohen's kappa coefficient was 0.91 (95% CI: 0.87–0.95), indicating (according to the Landis and Koch criteria) an “almost perfect” agreement between the compared clinical tests. In the two studies that assessed procedure-related patient discomfort, vaginal-rectal swabbing caused more discomfort.ConclusionUse of vaginal-perineal culture for assessment of maternal GBS colonization is comparable to the more typically utilized vaginal-rectal culture and is associated with less discomfort.

Guidelines for intrapartum antibiotic prophylaxis appear to have reduced the incidence of early-onset group B streptococcal (GBS) infection, but it still is a major cause of early-onset neonatal sepsis and infectious mortality in newborn infants in the United States. The authors reviewed 92 infants admitted to one of two university-affiliated nurseries in the years 1992 through 2001 at age 7 days or less with culture-proved GBS disease. The mean age at the onset of symptoms was 2.5 hours. Only one infant was diagnosed after death. No intrapartum prophylaxis was given to 68 women, half of whom were known before delivery to have risk factors for early-onset GBS infection. Of 32 infants with clinical risk factors, 22 had a gestational age less than 37 weeks. Less frequent risk factors were ruptured amniotic membranes for 18 hours or longer, intrapartum maternal fever, and previous GBS bacteriuria. In several cases, there was more than one risk factor. Four of 22 women having rectovaginal cultures for GBS were positive, but proper culture medium was not consistently used. Intrapartum prophylaxis was withheld in 18 women who were screen-negative for GBS colonization. Fourteen of 68 infected infants required extracorporeal membrane oxygenation and three infants died. The absence of clinical risk factors or known maternal colonization did not protect these infants. Twenty-four women received what were thought to be adequate doses of antibiotic prophylaxis, most frequently ampicillin. All of these women had risk factors and a majority had multiple risk factors. Five of six studies for maternal rectovaginal colonization were positive. In 15 cases, prophylaxis lasted less than 4 hours. All infants became ill in the first 24 hours of life. Two required extracorporeal membrane oxygenation and one died. These findings suggest that early-onset GBS disease can occur despite appropriate prophylaxis. Possible improvements include a rapid and practical test for GBS colonization, development of effective vaccines, and studies of adjunctive postnatal prophylaxis.

To compare the incidences of early and late-onset neonatal sepsis, including group B streptococcus (GBS) and Escherichia coli (E.coli) before and after implementation of universal screening and intrapartum antibiotics prophylaxis (IAP). Retrospective cohort study. Eight public hospitals and 31 Maternal and Child Health Centres (in Hong Kong. 460 552 women attending routine antenatal service from 2009 to 2020. Universal culture-based GBS screening has been offered to eligible women since 2012. Total births, GBS screening tests, maternal GBS colonisation and neonatal sepsis with positive blood or cerebrospinal fluid were retrieved from clinical and laboratory database. Maternal GBS colonisation rate, early- and late-onset neonatal sepsis (including GBS and E.coli). Of 318 740 women with universal culture-based screening, 63 767 women (20.0%) screened positive. After implementation of GBS screening and IAP, the incidence of early-onset neonatal sepsis decreased (3.25 versus 2.26 per 1000 live births, p < 0.05), including those caused by GBS (1.03 versus 0.26 per 1000 live births, p < 0.05). Segmented regression showed that change in early-onse GBS sepsis incidence after screening was the only significant variable in the outcome trend. There was no significant evidence of increase in incidence of late-onset neonatal sepsis including those caused by GBS. Universal culture-based GBS screening and IAP were associated with reduction in early-onset neonatal sepsis including GBS disease. Although an increase in incidence of late-onset neonatal sepsis including those caused by GBS cannot be totally ruled out, we did not identify significant evidence that this occurred.

Culture-based versus risk-based screening for the prevention of group B streptococcal disease in newborns: A review of national guidelines

Background: Group B streptococcus (GBS) or Streptococcus agalactiae are members of the normal flora of the female genital tract. Maternal colonization has been found to be a major risk factor for invasive GBS disease within 6 days of birth. GBS has become the major cause of bacterial infections in the perinatal period, including bacteremia, amnionitis, endometritis, and urinary tract infection in pregnant women as well as sepsis and meningitis in neonates and young infants. Infection of the new born may be acquired by the intra-amniotic route or directly during passage through the birth canal. This study was undertaken to determine the prevalence of GBS colonization in pregnant women attending the antenatal clinic of Al-Hada Armed Forces Hospital in Western province, Taif, Saudi Arabia. This paper was the first data on incidence of GBS in pregnant women at Western province, Taif, Saudi Arabia. Methods: A total of 2,632 pregnant women were screened for GBS colonization between January and December 2014. Standard microbiological methods were used to isolate and identify GBS from vaginal and anorectal swabs obtained from study subjects. An antimicrobial susceptibility test was performed for all GBS isolates according to the criteria of the Clinical and Laboratory Standards Institute (CLSI) by disk diffusion method. Results: A total of 632 out of 2,632 (24%) pregnant women were colonized by GBS. Statistically significant association was observed for GBS colonization with any of socio-demographic characteristics of the study subjects including age, occupation, number of antenatal clinic visits, and type of gravida. All GBS strains were susceptible to penicillin, ampicillin, vancomycin and gentamicin, erythromycin, tetracycline, ceftriaxone, chloramphenicol, ciprofloxacin, clindamycin, and norfloxacin. Resistance was observed in some strains against clindamycin (0.18%). The data from the present study showed that incidence of GBS in Saudi pregnant women increased rapidly. These results are the first record of the database in Saudi Arabia at western province with high prevalence of GBS in pregnant women. Conclusion: This study showed that prevalence of GBS colonization was 24% among the study subjects. The finding of this study was comparable with findings reported from developed and developing countries. However, further epidemiological investigations should be done in different parts of the country (all provinces) in order to know the actual GBS colonization rate in pregnant women and to consider the use of intrapartum antibiotics prophylaxis for prevention of early onset GBS-neonatal diseases, considering the accelerated demand for reducing neonatal morbidity and mortality due to GBS. J Clin Gynecol Obstet. 2015;4(3):258-264 doi: http://dx.doi.org/10.14740/jcgo341w

A term male is born via scheduled repeat cesarean section to a 28-year-old G2P1 woman following an uncomplicated pregnancy. Serologic test results were unremarkable, including a negative screen for group B Streptococcus (GBS). The infant cries immediately at birth, and his Apgar scores are 9 at both 1 and 5 minutes. He is rooming-in with his mother. At 16 hours of age, he exhibits perioral cyanosis while attempting to breastfeed. Pulse oximetry measures 85% and, therefore, free-flowing supplemental oxygen is delivered by mask, increasing his pulse oximetry reading to 100%. Gradually, he is weaned to room air. On physical examination, his heart rate is 150 beats/min and his respiratory rate is 60 breaths/min while crying. He has no dysmorphisms, appears well, has a lusty cry, and is vigorous. His capillary refill time is 5 seconds, his peripheral pulses are well felt, and his blood pressure is 80/40 mm Hg in the right arm. Results of a complete blood count (CBC) and differential count are unremarkable. Ampicillin and gentamicin are initiated. A laboratory evaluation reveals the diagnosis.A prolonged capillary refill time can be caused hypothermia or shock. The ambient temperature and the infant’s body temperature rule out hypothermia in this case. Hypovolemic shock (hemorrhagic shock) is unlikely because there is no history of overt hemorrhage. Occult hemorrhage, as in fetomaternal transfusion or ruptured spleen or liver, is unlikely because the infant is pink. Distributive shock due to anaphylaxis is not common in neonates, and neurogenic shock due to disruption of sympathetic innervation of the heart typically is seen in traumatic deliveries with spinal cord injuries (eg, difficult breech extraction). Distributive shock also is seen in sepsis, but it appears unlikely in this infant without any risk factors for sepsis, lack of maternal colonization with GBS, and unremarkable findings on CBC. Cardiogenic shock is defined as inadequate tissue perfusion from myocardial dysfunction. Myocardial dysfunction could be due to poor contractility, arrhythmia, or congenital heart disease. The normal liver size, absent third heart sound, lack of crackles (suggestive of pulmonary edema), and normal heart size on chest film for this patient make cardiogenic shock unlikely.Obstructive shock due to tension pneumothorax is unlikely because there is no respiratory distress, and the lack of muffled heart sounds and hepatomegaly make cardiac tamponade unlikely. Although obstructive shock due to duct-dependent pulmonary or systemic circulation is a possibility, patent ductus arteriosus-dependent pulmonary lesions of the heart present with central cyanosis, and the lack of central cyanosis for this infant rules out cyanotic heart diseases. Because the infant’s pulse oximetry is 100% on room air, a hyperoxia test is not considered. Patent ductus arteriosus-dependent systemic circulation (coarctation of aorta, severe aortic stenosis, or hypoplastic left heart syndrome) is a possibility with delayed capillary refill but is ruled out by the well-felt peripheral pulses. Four quadrant blood pressures are normal, which can be seen if the ductus has not closed completely. Therefore, urgent echocardiography is ordered. The ductus rarely closes in the first 24 hours after delivery, but it is possible. Echocardiography reveals a right ventricular pressure of 35 mm Hg plus the right atrial pressure and a tricuspid regurgitation jet. There is no evidence of structural heart disease.A fluid bolus is administered for the possibility of septic shock, despite the lack of supporting evidence, and the infant’s capillary refill time improves. A blood culture is positive for GBS sensitive to penicillin. The white blood cell count becomes abnormal, with the immature-to-total neutrophil ratio well above 0.2. Findings of a cerebrospinal fluid examination are normal. The infant is treated with penicillin for 10 days. The pulmonary hypertension appears to have been either physiologic or resulting from sepsis and may have caused the initial desaturation that brought him to the neonatal intensive care unit. The remainder of his hospital course is uneventful.GBS infection is responsible for 0.4% of sepsis in neonates. This gram-positive bacterium frequently colonizes the genital tracts of women. There are nine serotypes, with type 3 being the most common cause of early-onset neonatal meningitis and most late-onset infections. GBS causes early- (0 to 6 days) and late-onset (7 days to 3 months) sepsis in neonates and can cause bacteremia in adults. Neonatal colonization with GBS during passage through the birth canal in labor can be reduced by identifying maternal colonization through universal screening of pregnant mothers (between 35 and 37 weeks of gestation) and antibiotic prophylaxis of colonized mothers during labor. Intrapartum antibiotic prophylaxis does not delay the onset or severity of early-onset neonatal sepsis.False-negative screening test results can be due to screening more than 5 weeks before delivery, incorrect site of swab collection, use of suboptimal or incorrect transport medium, or use of incorrect microbiologic techniques in the culture of the collected swabs. Colonized women, women who have GBS bacteriuria (surrogate marker for heavy maternal colonization), and women who have had a previous neonate affected with invasive GBS sepsis are offered intrapartum antibiotic prophylaxis irrespective of their colonization status. About 60% of term neonates who have invasive GBS sepsis are born to mothers who have no risk factors for sepsis, as illustrated by this case. Late-onset neonatal sepsis is not influenced by intrapartum antibiotic prophylaxis because it is transmitted horizontally.Strategies to prevent early-onset neonatal sepsis are outlined in the Centers for Disease Control and Prevention (CDC) guidelines on perinatal prevention of GBS disease. Emphasis is placed on evaluating and treating neonates born to mothers who have chorioamnionitis. In the case presented, the mother did not qualify for intrapartum antibiotic prophylaxis as per the current CDC guidelines. The differential diagnosis of shock was considered, but despite the lack of risk factors and a negative GBS screen, the neonate did have GBS sepsis. The mother is a candidate for intrapartum antibiotic prophylaxis in her next pregnancy without GBS screening.Proven GBS sepsis is treated with parenteral penicillin; there is no report of resistance to penicillin to date. The duration of treatment varies from 10 days for septicemia to 14 to 21 days for meningitis.Sepsis and septic shock are the most common causes of shock in clinical practice. GBS sepsis should be considered despite a lack of risk factors for sepsis and negative maternal GBS screening results. (Akshaya J. Vachharajani, Department of Pediatrics, Washington University School of Medicine, St. Louis, Mo.)

Background Maternal colonization with group B Streptococcus (GBS) is a predictor of neonatal sepsis. In Nicaragua, neonatal sepsis is a major cause of hospitalization, but it can be prevented with intrapartum antibiotic prophylaxis. We undertook this study to estimate the pooled prevalence of rectovaginal GBS colonization among pregnant women 35–40-week gestation in Nicaragua, and sensitivity of GBS isolates to various antibiotics. Methods We systematically searched electronic databases of peer-reviewed and unpublished literature using prespecified search terms. We included English- and Spanish-language studies of rectovaginal GBS colonization and/or antibiotic sensitivity of GBS isolates that followed internationally-recognized diagnostic standards, from various sites and years. Two reviewers independently abstracted data and assessed risk of study bias. We then meta-analyzed the pooled prevalence of rectovaginal GBS colonization and antibiotic sensitivity of GBS isolates. We performed subgroup analyses by geographic location, urbanicity, and study risk of bias. Main results Prevalence of rectovaginal GBS colonization from 13 samples in 11 studies was 0.14 (95% CI: 0.09, 0.21). Effect size heterogeneity was identified between coastal (0.12 [95% CI: 0.07, 0.19]) and central study sites (0.23 [95% CI: 0.18, 0.28]), and between predominantly rural (0.06 [95% CI: 0.02, 0.10]) and urban (0.28 [95% CI: 0.19, 0.37]) samples of pregnant women. GBS sensitivity to penicillin, the first-line antibiotic for intrapartum prophylaxis, was 0.89 (95% CI: 0.71, 1.00) based on seven studies. Conclusions Maternal GBS colonization was substantial in some study sites. Most GBS isolates are sensitive to recommended antibiotics, and intrapartum antibiotic prophylaxis may effectively prevent neonatal sepsis in Nicaragua.

Objectives: To determine the prevalence of maternal colonization with group B streptococcus (GBS), and early onset GBS disease (EOGBSD) after implementation of universal screening.Methods: This was a three-year retrospective cohort study on universal antenatal rectovaginal culture-based screening and intrapartum antimicrobial prophylaxis (IAP) to colonized women in the public sector in Hong Kong. Routinely collected data including maternal colonization and EOGBSD were retrieved.Results: Of 113,989 GBS screening performed, 21.8% were positive. The colonization rate was higher in the public hospitals (higher risk) than in the Maternal and Child Health Centers (lower risk) (23.7% vs 18.1%, p < .001), while their false negative rates were not greater than expected. Majority of eligible women opted for screening, and colonized women received IAP. There were 29 cases of EOGBSD with clinical signs and a positive blood or cerebrospinal fluid culture. Compared to clinical risk-based screening, EOGBSD incidence decreased after universal screening (1 vs 0.24 per 1000 births, p < .001). Although EOGBSD occurred at a higher rate in preterm than term infants, 86.7% occurred in the latter, and were associated with a false negative screening result (41.3%), lack of screening (20.7%) or unavailability of a colonization result at labour (13.8%).Conclusions: Maternal GBS colonization rate was higher than previously reported, and varied with different risk populations. EOGBSD reduced after universal screening.

To describe lapses in adherence to group B streptococcus (GBS) prevention guidelines among cases of early-onset GBS disease in term and preterm neonates and to estimate the potential for further reduction in disease burden under current prevention strategies. We reviewed labor and delivery and prenatal records of mothers of neonates with early-onset GBS disease (aged younger than 7 days with GBS isolated from a normally sterile site) identified at population-based surveillance sites in 2008-2009. We interviewed prenatal care providers about GBS screening practices and obtained relevant laboratory records. We evaluated the data for errors in prenatal screening, laboratory methods, communication of results, and intrapartum antibiotic prophylaxis. Using published data on screening sensitivity and intrapartum prophylaxis effectiveness, we estimated the potential reduction in cases under optimal prevention implementation. Among 309 cases, 179 (57.9%) had one or more implementation errors. The most common error type in term and preterm case-patients was prenatal screening (80 of 222 [36.0%]) and intrapartum prophylaxis (46 of 85 [54.1%]), respectively. We estimated that under optimal implementation, cases of early-onset GBS disease could be reduced by 26-59% with the largest benefit from a single intervention coming from improved use of intrapartum prophylaxis (16% decrease). Further reduction of early-onset GBS disease burden is possible under current prevention strategies, particularly with improved implementation of antibiotic prophylaxis. However, even with perfect adherence to recommended practices, the decline in cases may be modest. Therefore, novel prevention approaches such as improved intrapartum assays and vaccines are also needed.

Evaluation of liquid biphasic Granada medium and instant liquid biphasic Granada medium for group B streptococcus detection

Group B streptococci (GBS) may cause life-threatening invasive infections in infants. The incidence of these infections has been increasing during the last decades. The aim of the study was to determine the epidemiology of neonatal GBS infections to be able to implement therapeutic and preventive measures more effectively. A retrospective case study was conducted in Iceland that included all neonates with positive GBS cultures from blood or cerebrospinal fluid during the period 1975 to 2006. Serotyping of all available GBS isolates was performed. A total of 87 children with 89 infections were included in the study. In all, 53 infants had early-onset (EO) GBS infections (occurring <7 days after birth) and 34 had late-onset (LO) infections (occurring on days 7-90). EO infections increased during the first 3 quartiles of the study period but decreased during the last quartile. LO infections increased throughout the entire study period. GBS was cultured from cerebrospinal fluid in 21 patients; 9 with EO and 12 with LO infections. Premature infants comprised 15 with EO and 14 with LO infections. Eight children died of GBS infection, 7 with EO and 1 with LO infections; no correlation with serotypes was found. Serotype III was most common for both EO (34%) and LO infections (62%). The number of GBS infections increased during the study period. The decrease in EO infections in recent years could be attributed to intrapartum antibiotic treatment. The increasing number of LO infections is a concern.

Background: Group B Streptococcus (GBS) is a gram-positive bacterium and a major cause of bacterial infections in the newborns delivered by women whose rectum and vagina were colonized by GBS during pregnancy. Objectives: To study the association between maternal GBS recto-vaginal colonization and neonatal colonization and occurrence of early onset neonatal group B Streptococcal sepsis. Methodology: A prospective cohort study involving 28 mother-infant pairs of GBS positive and 28 negative controls. Results: Of the 196 pregnant women screened for GBS recto-vaginal colonization between 35-37weeks, 31 women were positive giving a prevalence rate of 15.8%. Three (3) cases were later excluded for different reasons, thus only 28 infants delivered to GBS-positive mothers and 28 infants delivered to GBS-negative mothers were followed up for signs and symptoms of sepsis. Of the 28 newborns delivered to GBS colonized mother, 12(43.0%) were colonized with GBS at birth compared to 2 (7.1%) colonized newborns delivered to GBS-negative pregnant women. An association was observed between maternal GBS recto-vaginal colonization and neonatal colonization (P=0.0003, RR: 2.25 CI:(1.45 – 3.49)) with a vertical transmission rate of 43% among the GBS colonized motherinfant pairs. A significant difference was also observed between the birth weights of infants delivered to GBSpositive mothers (3100.00 ± 392.8g) and GBS- negative mothers (3338.4 ± 338.4g) (P=0.018). Low social class was associated with higher GBS colonization rate (P = 0.029). A prevalence rate of 17.9/1000 births of GBS early sepsis was found in this study. Conclusion: Low social class increases the risk of maternal colonization by GBS, and maternal colonization in late third trimester is associated with newborn GBS colonization at birth.

Maternal colonization with group B Streptococcus (GBS) during pregnancy increases the risk of neonatal infection by vertical transmission. However, it remains unclear whether treating all colonized women during labor exposes a large number of their neonates to possible adverse effects without benefit. We performed a meta-analysis to assess the effect of intrapartum antibiotic prophylaxis on neonatal adverse outcomes. We identified studies by searching several English and Chinese electronic databases and reviewing relevant articles. Data were pooled using fixed-effects or random-effects meta-analysis, and for each outcome both risk ratio (RR) and 95% confidence intervals (95% CIs) were calculated. Fourteen studies (2,051 pregnant women and 2,063 neonates) were included, comprising 13 randomized clinical trials and 1 cohort study. Antibiotic prophylaxis is associated with a significant reduced risk of all cause infections (RR = 0.28, 95% CI = 0.18–0.42), GBS infection (RR = 0.24, 95% CI = 0.13–0.44), early-onset GBS infection (RR = 0.24, 95% CI = 0.13–0.45), non-GBS infections (RR = 0.34, 95% CI = 0.20–0.59), and GBS colonization (RR = 0.10, 95% CI = 0.06–0.16). But no significant reduction was observed in late-onset GBS infection, mortality from early-onset GBS infection or from non-GBS infections. Notably, no significant differences were found between ampicillin and penicillin prevention for neonatal adverse outcomes. Our findings suggest that antibiotic prophylaxis is effective in reducing neonatal GBS colonization and infection.

GBS public awareness, advocacy, and prevention—What's working, what's not and why we need a maternal GBS vaccine