AOM - GBS PDF

Summary Document GROUP B STREPTOCOCCUS This summary provides easy access to some of the most essential content of AOM CPG No. 19 – Antepartum, Intrapartum and Postpartum Management of Group B Streptococcus, and is intended for use in...

Summary Document GROUP B STREPTOCOCCUS This summary provides easy access to some of the most essential content of AOM CPG No. 19 – Antepartum, Intrapartum and Postpartum Management of Group B Streptococcus, and is intended for use in conjunction with the full-length Clinical Practice Guideline (CPG). For a complete analysis of the research relevant to the management of group B streptococcus, along with citations, refer to the full CPG. PREVALENCE OF GBS IN BIRTHING PARENTS Estimates suggest that approximately 15% to 40% of pregnant people are colonized with GBS in the vagina and/or rectum, with rates varying by study populations, specimen collection or culturing techniques. (1) In Ontario in 2019, approximately 19% of pregnant people who were screened for GBS between 35 and 37 weeks’ gestation had a positive result. (2) Of pregnant people who did not undergo screening for GBS at 35 to 37 weeks’ gestation, 0.5% had already screened positive for GBS bacteriuria through a urine test. INCIDENCE OF EARLY-ONSET GROUP B STREPTOCOCCUS IN BIRTHING PARENTS Early-onset group B streptococcus (EOGBSD) occurs within the first seven days of life, and incidence rates vary. Before the widespread adoption of prevention strategies such as intrapartum antibiotic prophylaxis (IAP) in the 1980s, the incidence of EOGBSD was estimated at 3/1000 live births. This has dramatically changed over several decades; in Ontario in 2019, there were only 35 cases of EOGBSD in neonates, a rate of 0.23/1000 live births. Understanding GBS prevalence, incidence and complications The following statistics help explain how GBS may impact the neonate: 15% to 40% of pregnant people are GBS positive; 40% to 70% of babies born to GBS-positive pregnant people will be colonized if untreated; 1% to 2% of colonized babies will develop an infection if untreated; (3) 5% of babies who develop an infection will die. (1,4) Using these statistics as a guide, taking an initial group of 50 000 pregnant people: 7500 to 20 000 pregnant people will be colonized with GBS; 3000 to 14 000 babies will be colonized with GBS; 30 to 280 babies will develop an infection if untreated: bacteremia (19 to 232 babies) pneumonia (three to 64 babies) meningitis (two to 35 babies) Two to 14 babies will die.  RISK FACTORS GBS COLONIZATION IN THE BIRTHING PARENT TABLE 1. FACTORS ASSOCIATED WITH GBS COLONIZATION IN THE BIRTHING PARENT Risk factor OR Interpretation Sources Strong predictive factor (OR > 1.75 or < 0.25) Colonization in a previous (OR 5.80, 95% CI 4.18-8.05) Increases likelihood of (5) pregnancy colonization Moderate predictive factor (OR 1.25-1.75 or 0.26-0.75) Pregestational diabetes (OR 1.34, 95% CI 1.09-1.63) Increases likelihood of (6–11) colonization Weak predictive factor (OR < 1.25 and > 0.76) Gestational diabetes (OR 1.17, 95% CI 1.03-1.31) Increases likelihood of (6,9–16) colonization BMI > 25 kg/m2 (OR 1.21, 95% CI 1.11-1.33) Increases likelihood of (17–20) colonization EOGBSD TABLE 2. FACTORS ASSOCIATED WITH THE DEVELOPMENT OF EOGBSD IN NEWBORNS Predictive factor OR Interpretation Sources Strong predictive factor (OR > 1.75 or < 0.25) Previous infant with EOGBSD (OR 27.81, 95% CI 9.08-85.17) Increases likelihood of (12) EOGBSD GBS-positive birthing parent (OR 10.44, 95% CI 3.69-29.56) Increases likelihood of (21–23) EOGBSD Frequent vaginal exams (OR 6.32, 95% CI 2.44-16.40) Increases likelihood of (24) EOGBSD GBS bacteriuria (OR 5.34, 95% CI 2.49-11.46) Increases likelihood of (12,21,25) EOGBSD Chorioamnionitis (OR 4.19, 95% CI 0.71-24.59) May increase likelihood (12,24,26,27) of EOGBSD Intrapartum fever (> 38°C) (OR 3.62, 95% CI 1.71-7.66) Increases likelihood of (12,23–25,28) EOGBSD Membrane sweeping (OR 2.52, 95% CI 1.33-4.78) Increases likelihood of (23) EOGBSD Preterm birth (< 37 weeks) (OR 2.02, 95% CI 1.36-3.01) Increases likelihood of (12,21–24,26,27) EOGBSD Prelabour rupture of (OR 2.02, 95% CI 0.87-4.73) May increase likelihood (12,22–25) membranes (PROM) > 18 hours) of EOGBSD Low birth weight (< 2500 g) (OR 2.01, 95% CI 1.39-2.92) Increases likelihood of (12,21,23,24) EOGBSD Multiple pregnancy (OR 1.98, 95% CI 0.78-5.02) May increase likelihood (12,26,28) of EOGBSD 2: Group B Streptococcus Summary Document EOGBSD IN GBS-NEGATIVE CLIENTS The absolute risk of EOGBSD in the context of a negative prenatal screen is low. However, the majority of cases diagnosed in the context of screening and IAP occur in infants born to pregnant people who screened negative at 35 to 37 weeks’ gestation and who did not receive IAP. ANTEPARTUM PREVENTION OF GBS COLONIZATION PROBIOTICS Seven studies were found that investigated the effect of oral probiotics for the prevention of GBS colonization in the birthing parent at or before birth. (29–35) Meta-analyses of four RCTs show that oral probiotics likely reduce GBS colonization close to delivery and likely have no side effects. Observational literature supports these findings. (34,35) No studies were identified that investigated the effects of dietary sources of probiotics; nor did the available research provide clear guidance on the optimal duration or dosage of probiotics. Recommendation: 1. Midwives may discuss the use of probiotics in the antepartum period with clients as a means of reducing the chances of GBS colonization at birth. [new 2022] Weak recommendation; moderate certainty of evidence This recommendation recognizes the limits of the existing research on probiotics for GBS, as well as existing barriers to access. HOMEOPATHIC AND NATURAL REMEDIES No studies were identified on the use of homeopathic or natural remedies (including but not limited to garlic suppositories, vitamins, echinacea or other remedies) in the antepartum period for the prevention of GBS colonization at birth. VAGINAL-RECTAL CULTURE SCREENING FOR GBS DIAGNOSTIC ACCURACY OF VAGINAL-RECTAL SWABS Twelve observational studies (n = 15 610) (moderate certainty of evidence) were found that compared the sensitivity and specificity of an antepartum GBS culture taken at 35 to 37 weeks’ gestation with an intrapartum GBS culture. (36–47) Results showed that these swabs likely have high specificity (90%) and sensitivity (77%). The concern with these findings is that some pregnant people who have GBS at birth will be missed and therefore will not receive IAP, while a smaller proportion may receive IAP unnecessarily. SELF-SAMPLING WITH A VAGINAL-RECTAL SWAB One observational study (n = 800) (very low certainty of evidence) found that self-collection may capture more positive GBS results than collection by a health-care provider, although we are uncertain of these results due to concerns about the imprecision of the estimate of effect. Other observational studies found the performance of self-collected swabs very similar to that of swabs collected by health professionals. (48–51) Recommendation: 2. Offer all clients screening for GBS at 35 to 37 weeks’ gestation, with a culture done from one swab first to the vagina then the rectum. Clients may be offered instructions on how to do the swab themselves. Strong recommendation; moderate certainty of evidence This recommendation recognizes the evidence on diagnostic accuracy of vaginal-rectal culture screening, as well as variability in client preferences, values and ability regarding self-sampling. 3: Group B Streptococcus Summary Document TIMING OF VAGINAL-RECTAL CULTURE SCREENING FOR GBS One systematic review (moderate certainty of evidence) that investigated the optimal time to perform antepartum GBS culture screening found that: An antepartum culture is most accurate in predicting GBS status at birth when performed at a later gestational age, which allows for a shorter interval between screening and birth. An interval of greater than six weeks between antepartum culture and birth likely reduces the probability of an accurate result. (52) There is no research to guide practice if a client has two or more swabs within five weeks of delivery that indicate different results. Recommendation: 3. Offer re-screening if more than five weeks have elapsed from initial swab and the client has not yet given birth. Strong recommendation; moderate certainty of evidence This recommendation recognizes the evidence to demonstrate that the predictive ability of a swab declines after six weeks. How- ever, there may be practical limitations due to long sampling and processing times, which warrant earlier re-swabbing. FACILITATING DECISION-MAKING WITH CLIENTS Clients are generally willing to be screened for GBS; however, they would benefit from receiving information prior to screening about the process and the implications of a positive result. These practice points outline strategies that may lessen the emotional and psychological impacts of screening positive for GBS. Provide general information about GBS and the meaning of a positive result. Discuss screening options and support informed choice. Prior to GBS s creening If client is self-swabbing, ensure that they have detailed instructions and feel confident about performing the swab Share result and explain its meaning. When delivering a positive If possible, deliver the result in person. result to a client Consider the language you use and how it may affect the client: try using “common” rathen than “normal” and explain the meaning of “positive.” Provide support and reassurance. After the client receives a Allow time to answer any questions. positive result Discuss treatment options and support informed choice. Discuss relevant risk factors for EOGBSD with client. 4: Group B Streptococcus Summary Document  ANTEPARTUM MANAGEMENT OF CLIENTS WITH PENICILLIN ALLERGIES PENICILLIN ALLERGY TESTING Research suggests that immune-mediated allergic responses are rare among people who report unconfirmed penicillin allergies; and up to 95% of those people may have the label removed through testing. (53,54) Allergy tests have been shown to be safe for pregnant people (with or without GBS), with few adverse reactions. (53,55) GBS-positive pregnant people with active, unverified penicillin allergies have higher rates of caesarean section; and they spend significantly more total days in the hospital within six months of delivery compared with GBS-positive pregnant people with no penicillin allergies. (56) Allergy testing increases the likelihood that individuals will receive narrow beta-lactams, specifically penicillin, rather than beta-lactam alternatives in their current pregnancy and in the future. Good practice statement: 4. Midwives should discuss the risks and benefits of penicillin allergy testing with clients who have an unconfirmed penicillin allergy, as early in their pregnancy as possible. [new 2022] Good practice statement This good practice statement recognizes the long-term health benefits of penicillin allergy testing and the importance of appropri- ate antimicrobial use, as well as potential constraints around prompt access to penicillin allergy testing. TESTING GBS ISOLATES There are no direct studies that compare GBS outcomes for those who had testing of GBS isolates. A systematic review shows that most GBS isolates were susceptible to penicillin, ampicillin and vancomycin; and pooled rates of resistance to erythromycin, clindamycin, and tetracycline were 25%, 27% and 73% respectively. (57) Findings in Canada and Ontario are similar. (4,58–60) Good practice statement: 5. Request sensitivity testing for the GBS swab if: Client has a confirmed penicillin allergy; Client reports symptoms consistent with a penicillin allergy and has not been tested to confirm an allergy. Good practice statement This good practice statement recognizes the larger body of evidence on antimicrobial susceptibility of GBS isolates. INTRAPARTUM MANAGEMENT STRATEGIES EFFECTIVENESS OF IAP Two systematic reviews, including 13 RCTs and one cohort study, showed that IAP for birthing parents known to be colonized with GBS likely reduces EOGBS infections, as well as neonatal infections from other bacteria. IAP may also reduce neonatal mortality from EOGBSD and infections caused by bacteria other than GBS, although the results are uncertain. IAP may make little to no difference in the rate of non-GBS neonatal sepsis. (61,62) In discussions with clients, midwives can share evidence on other effects of IAP: In the short term, IAP diminishes beneficial commensals in the newborn’s microbiota; IAP potentially increases antimicrobial resistance; IAP rarely causes anaphylaxis; IAP increases the chances of breast/chest candidiasis and yeast infections; IAP has no significant impact on penicillin allergies or atopic dermatitis in children. 5: Group B Streptococcus Summary Document APPROACHES TO DETERMINING WHO RECEIVES IAP The following approaches have been studied: Culture-screening approach: IAP is given to labouring people who screened positive on a vaginal-rectal culture between 35 and 37 weeks’ gestation, those with GBS bacteriuria and those who previously had an infant with EOGBSD. Four observational studies (very low certainty of evidence) showed that culture screening may reduce rates of neonatal EOGBSD compared with no policy. (63) Risk-factor approach: IAP is given to labouring people with one or more of the following risk factors: gestation < 37 weeks, rupture of membranes ≥ 18h, intrapartum fever ≥ 38°C, GBS bacteriuria in pregnancy, and/or prior infant with GBS disease. Seven observational studies (very low certainty of evidence) showed that the risk-factor approach may reduce rates of neonatal EOGBSD, compared with no policy. (63) Culture-screening and risk-factors approach: IAP is given to labouring people who screened positive on a vaginal-rectal culture between 35 and 37 weeks’ gestation and who also have one or more risk factors. One observational study (very low certainty) showed that the culture-screening and risk-factor approach may reduce the cases of EOGBSD, compared with no policy. (64) Ten observational studies (very low certainty) showed that culture screening may reduce rates of neonatal EOGBSD compared with the risk-factor approach. (63) To help contextualize these research findings, Table 5 models the impact of each IAP approach on important neonatal outcomes, as well as the number of birthing parents needed to treat (NNT) with antibiotics, in order to prevent one case of EOGBSD. No available research provides a direct comparison between the culture-screening approach and the culture-screening and risk-factor approach. Well-designed comparative studies with similar populations and settings are needed to understand the relative efficacy of these two strategies. Without such direct comparisons, it cannot be ascertained that similar results, as presented above, would be found. While the research to date suggests that the incidence of EOGBSD and neonatal mortality is lowest when a culture-screening strategy is used, the culture-screening plus risk-factor approach may serve as a targeted approach to EOGBSD prevention that could result in lower rates of IAP use. TABLE 3. NEONATAL OUTCOMES BY APPROACH TO IAP No approach Risk-factor Culture-screening and Culture-screening approach risk-factor approach approach Cases of EOGBSD 10 per 1000 8.4 per 1000 5.4 per 1000 3.1 per 1000 Neonatal mortality 0.9 per 1000 0.76 per 1000 0.49 per 1000 0.28 per 1000 NNT with IAP – 23 22 63 6: Group B Streptococcus Summary Document  Recommendations: 6. The risks and benefits of the following two approaches to IAP delivery should be discussed with clients as part of their informed choice discussion about GBS: a) Culture-screening approach All clients who receive a GBS-positive swab at 35 to 37 weeks’ gestation, have documented GBS bacteriuria or previously had an infant with GBS should be offered IAP. b) Culture-screening and risk-factor approach All clients who receive a GBS-positive swab at 35 to 37 weeks’ gestation and develop one or more of these intrapartum risk factors should be offered IAP. Intrapartum risk factors include: Preterm labour (>37 weeks) Prolonged rupture of membranes (≥ 18 hours) Maternal fever (≥ 38°C) All clients with documented GBS bacteriuria or who previously had an infant with GBS should be offered IAP. Informed choice discussions should address: The body of evidence for both strategies, including a discussion of the larger body of evidence in support of a culture- screening approach; The SOGC recommendation to use a culture-screening approach; Community standards regarding approaches to determining who receives IAP; Alternatives to penicillin, as well as choice of birthplace considerations for those with penicillin allergies; Client values, preferences and risk tolerance. Strong recommendation; very low certainty of evidence This recommendation acknowledges that both approaches reduce EOGBSD, and it recognizes the larger body of evidence in sup- port of the culture-screening approach. 7. For clients with an unknown GBS status, offer IAP if one or more intrapartum risk factors are present: Preterm labour (< 37 weeks) Prolonged rupture of membranes (≥ 18 hours) Maternal fever (≥ 38°C) Strong recommendation; very low certainty of evidence This recommendation acknowledges the evidence suggesting that administering IAP to those with risk factors, in the absence of known GBS status, is more protective than no policy. INTRAPARTUM MANAGEMENT OF PRELABOUR RUPTURE OF MEM- BRANES (PROM): INDUCTION VS. EXPECTANT MANAGEMENT In a secondary analysis of the TermPROM study, results show that for pregnant people with GBS (n = 270), induction may reduce cases of neonatal infection, compared with expectant management. (65) However, we are very uncertain of these findings due to issues with risk of bias, directness and precision. As well, the data from the TermPROM trial does not address different management approaches based on length of PROM. INTRAPARTUM MANAGEMENT OF PROM: TIMING OF IAP No studies were identified that compared different timing of IAP for GBS-positive pregnant people who experience PROM. In the absence of research, midwives use a variety of approaches to ensure adequate administration of IAP for these clients. Further research is needed to understand optimal timing of IAP for those who experience PROM. 7: Group B Streptococcus Summary Document  Recommendations: 8. Offer a choice between expectant management and immediate medical induction of labour to clients at term who are GBS positive, experience PROM for < 18 hours, and have no other risk factors. Informed choice discussions should include information on: Research gaps regarding the most effective approach to preventing EOGBSD in infants born to GBS carriers who experi- ence term PROM; Guidance from the SOGC on induction for those who experience PROM; Client preferences and values. Strong recommendation; very low certainty of evidence This recommendation recognizes the limited evidence on expectant management and induction of GBS-positive clients who expe- rience PROM < 18 hours, and it recognizes the client as the primary decision-maker. 9. Recommend medical induction of labour to clients who are GBS positive with PROM ≥ 18 hours. IAP should be offered upon start of labour. Strong recommendation; very low certainty of evidence This recommendation recognizes the increased risk of EOGBSD for clients who experience PROM ≥ 18 hours. 10. O  ffer GBS-positive clients with PROM who choose expectant management a range of options for IAP administration, taking into account local resource constraints: a. IAP in active labour b. IAP in the latent phase c. IAP upon initiation of induction of labour Weak recommendation; no direct evidence This recommendation recognizes the lack of evidence on timing of IAP for clients who experience PROM, as well as acknowledging the client as the primary decision-maker. POSTPARTUM MANAGEMENT STRATEGIES: EOGBSD IDENTIFYING EOGBSD None of the GBS prevention strategies available will prevent all cases of EOGBSD. As current incidence patterns demonstrate, EOGBSD can occur in the presence of a negative prenatal screen, in the absence of risk factors or despite administration of IAP. There is no clear distinction between EOGBSD and other early-onset infections in the clinical signs that may present, and non- infectious neonatal disorders may share similar signs. Signs of sepsis include: Respiratory distress Temperature instability Tachycardia Seizures Hypotonia Lethargy Poor peripheral perfusion Hypotension Acidosis As the progression of EOGBSD is very rapid, any neonate with clinical signs suggestive of infection should receive immediate assessment and consultation for treatment. (66) 8: Group B Streptococcus Summary Document ASSESSMENTS FOR EOGBSD How can midwives assess neonates for EOGBSD? Conventional monitoring practices have not been evaluated for their impact on clinical outcomes. However, studies consistently suggest that most cases of EOGBSD occur soon after birth. According to the Canadian Pediatric Society (CPS), 95% of septic infants present within the first 24 hours of life, regardless of antibiotic exposure. (66) The first 24 hours is the most critical period to assess for EOGBSD. Midwives may conduct assessments and monitor the newborn in the home, clinic, birth centre or hospital. They also educate parents on how to take an active role in identifying signs of illness; respond to inquiries from parents about their newborns; give advice by phone; and determine the urgency and necessity of an in-person assessment of the newborn as needed. After discussing concerns with parents, midwives use clinical judgement and consider local community factors to determine whether clinical evaluation of the newborn should occur in the clinic, at home or in hospital. Good practice statements: 11. Midwives should discuss with all clients, regardless of prenatal GBS status: What to expect as normal newborn transition and behaviour in the first 24 hours; How to recognize signs in the newborn that may be indicative of sepsis (including breathing, temperature instability, colour and tone); How to contact the midwife and access urgent care when necessary. Good practice statement This good practice statement recognizes midwives’ strengths in providing health education to clients, and it acknowledges that sepsis may occur in infants born to parents who have tested negative for GBS or received IAP. 12. If a midwife suspects EOGBSD, an assessment should be done promptly. If signs of sepsis are noted upon an in-person exam, they should arrange an immediate consult. Once a consult has been initiated, the midwife should discuss with the client any hospital protocols and care plans ap- plicable to management decisions. Good practice statement This good practice statement recognizes the rapid progression of sepsis, as well as midwives’ ability to identify emerging complica- tions and work interprofessionally to provide safe, excellent client care. POSTPARTUM MANAGEMENT STRATEGIES: CHORIOAMNIONITIS Researchers note a relatively high frequency of maternal fever and chorioamnionitis in cases where neonates develop EOGBSD despite the administration of IAP. Data from risk-factor literature suggests that chorioamnionitis may be strongly predictive of EOGBSD, as is intrapartum fever (>38°C). (12,24,25,28) No studies were identified that compared management strategies of expectant observation vs. routine laboratory testing, including complete blood count (CBC) and/or blood culture, for asymptomatic newborns born to GBS-positive birthing parents who experienced chorioamnionitis. Results from two small observational studies of GBS-negative parents suggest that clinical monitoring of well-appearing asymptomatic newborns exposed to chorioamnionitis, including examination at birth and every four hours in the first 24 hours of life, maintains low rates of laboratory testing and antibiotic use, reduces separation of the parent-infant dyad and results in no adverse events. (67,68) Because the majority of EOGBSD cases tend to present within the first 24 hours, CBC may not be as useful for guiding treatment decisions vs. promptly recognizing clinical signs of sepsis. The latest guidance from CPS (2017) suggests the following approach: 9: Group B Streptococcus Summary Document  Multiple risk factors for sepsis and/or chorioamnionitis: Infants should be investigated and treated using an individualized approach that includes consideration of the severity of risk factors and maternal antibiotic therapy. At minimum, infants should have close observation in hospital for at least 24 h with vital signs every 3 h to 4 h and reassessment before discharge. A CBC done after 4 h of age may be helpful; WBC 4 hours. (72) Results suggest that the risk of EOGBSD and sepsis decreases as the duration of IAP increases; receiving IAP for < 2 hours poses a higher risk to newborns compared with receiving 2-4 hours or > 4 hours. EXPECTANT OBSERVATION VS. LABORATORY TESTING Results from two observational studies (very low certainty of evidence) suggest that serial physical examinations (expectant observation) have a similar ability to detect early-onset sepsis as compared with laboratory testing. Moreover, expectant management appears to reduce the rate of newborn antibiotic use without increasing the risk of suspected sepsis. (75,76) CPS provides the following guidance for the monitoring and assessment of well-appearing newborns (≥ 37 weeks’ gestation) in the context of GBS: GBS positive birthing parent, adequate IAP, no risk factors OR GBS-negative or GBS-unknown status, with one other risk factor and adequate IAP: Infants do not require investigation or treatment for sepsis. They may be discharged home after 24 hours if they remain well, meet other discharge criteria and if parents understand signs of sepsis and when to seek medical care. (Strong recommendation) 10: Group B Streptococcus Summary Document  GBS positive birthing parent, inadequate IAP, no risk factors OR GBS-negative or GBS-unknown status, with one other risk factor and inadequate IAP: Infants should be examined at birth, observed closely in hospital with vital signs every 3 to 4 hours, and reassessed before discharge home. They may be discharged home after 24 hours if they remain well and meet other discharge criteria, providing there is ready access to health care and the parents understand and are able to seek medical care if the infant develops signs of sepsis. Routine investigation or treatment is not required. (Strong recommendation) Multiple risk factors for sepsis and/or chorioamnionitis: Infants should be investigated and treated using an individualized approach that includes consideration of the severity of risk factors and maternal antibiotic therapy. At minimum, infants should have close observation in hospital for at least 24 hours with vital signs every 3 h to four hours and reassessment before discharge. A CBC done after 4 h of age may be helpful; WBC