Selective Intrapartum Chemoprophylaxis Research Articles

Antibioprophylaxie maternelle et infection à bacille Gram négatif chez le nouveau-né

Prevention strategies by maternal antibiotic use have provided undeniable benefits for neonates regarding early neonatal group B streptococcal infections. But at a time where the evolution of resistance of Gram negative bacteria is of particular concern, it is our duty to reassess prevention strategies with a careful evaluation of their potential impact on Gram negative bacteria in the newborn. We conducted a literature review to define the state of the art of antenatal antibiotic prophylaxis and its bacteriological consequences on the newborn. Prevention strategies of early-onset neonatal group B streptococcal disease with selective intrapartum chemoprophylaxis should not be challenged, even at the cost of a small increase of the incidence of late-onset infections with resistant Gram negative bacteria. However, other indications seem more controversial and the type of antibiotics used is not always based on methodologically well-conducted studies. In these indications the prevention strategies should consider not only the immediate expected benefits, but also the long-term ecological impact by using whenever possible narrow-spectrum antibiotics.

New DNA-based PCR approaches for rapid real-time detection and prevention of group B streptococcal infections in newborns and pregnant women.

Group B streptococci (GBS) are an important cause of neonatal sepsis and meningitis, and maternal infection. Although the pathogenesis of GBS infection is not well understood, several virulence factors have been identified. Two prevention strategies have been proposed: chemoprophylaxis and immunoprophylaxis. Implementation of selective intrapartum chemoprophylaxis on the basis of either screening or risk assessment has led to a substantial decrease in the morbidity and mortality of GBS disease in both mothers and infants. Penicillin remains the antibiotic of choice with no reported resistant GBS so far, whereas resistance of 10-20% of GBS to erythromycin and clindamycin has been reported in North America. Chemoprophylaxis based on screening requires optimal detection methods for GBS, which involve selective broth culture of combined vaginal and anal samples. Other conventional methods are useful for rapid identification of heavily colonised women, but are unreliable for the detection of light GBS colonisation because of poor sensitivity. GBS-specific polymerase chain reaction (PCR) assays using real-time PCR coupled with fluorescence-labelling technology offer powerful tools for sensitive and specific, yet rapid (less than 1 h), detection of GBS directly from clinical specimens at the time of delivery. The application of these assays to the current prevention strategies will simplify the prevention practice and rationalise the use of antibiotics. Immunoprophylaxis relies on the development of new vaccines against GBS, and active research is being conducted in this area.

Chemoprophylaxis of early-onset group B streptococcal disease in 1999.

The evolution of the guidelines for selective intrapartum chemoprophylaxis (SIC) of group B streptococcal early-onset disease is reviewed here. To assess the benefits of the risk-based and culture-based strategies for prevention, observational studies since 1996 are summarized. The effect of chorioamnionitis on group B streptococcal early-onset disease, despite SIC, is emphasized. Optimal management remains controversial, and alternative strategies for the selection of women for chemoprophylaxis and for the management of infants are discussed.

COMBINED INTRAPARTUM - POSTPARTUM CHEMOPROPHYLAXIS OF NEONATAL GROUP B STREPTOCOCCAL (GBS) DISEASE: A COMPARISON OF ALGORITHMS AND COST-EFFICACY. † 1305

Two strategies for chemoprophylaxis of neonatal GBS disease have proven efficacy. Selective intrapartum chemoprophylaxis based on prenatal cultures and maternal risk factors (Boyer, Gotoff: NEJM 314:1665, 1986) is effective in high-risk deliveries. It is limited because prenatal cultures obtained at 26-28 weeks have suboptimal predictive value (60-70%) and because 30-50% of cases occur in babies without risk factors. Universal postnatal prophylaxis(Siegel et al: Lancet i: 1426, 1982) has 80% preventive efficacy in uncomplicated deliveries. It may be ineffective against infections established intrapartum in high-risk deliveries. The Centers for Disease Control (MMWR 45[RR-7]:1, 1996) have recently advocated intrapartum chemoprophylaxis for all deliveries in which the mother has either prenatal colonization at 35-36 weeks or perinatal risk factors. As an alternative to the CDC strategy, we recommend a combined approach in which cultures are obtained at 35 weeks and intrapartum chemoprophylaxis is given to colonized women with risk factors (premature labor or prolonged membrane rupture) and to other women with risk factors and unknown colonization status. Postpartum chemoprophylaxis is given to all normal newborns of untreated women with colonization. Febrile women in labor with presumed chorioamnionitis are treated (not prophylaxed) regardless of their colonization status, with cultures obtained prior to initiation of therapy. This combined approach is likely to have equal efficacy (90%) to the CDC strategy. However, it will reduce the predicted number of cases of maternal anaphylaxis from 140 to 40/year (by 70%), and reduce the predicted cost of the program from $250 million to $144 million/year (by 42%).

Combined, selective chemoprophylaxis of early onset neonatal group B streptococcal disease (GBS EOD).

The initial approach to prevention of GBS EOD was selective intrapartum chemoprophylaxis (SIC), limiting the risk of penicillin reactions to a small number of colonized women with risk factors who had a higher probability of delivering infants with established infection at birth with the highest risk of mortality and severe morbidity1, 2. Other clinicians selected women with obstetrical risk factors, but without knowledge of colonization status for SIC3. This strategy would prevent the same number of cases of GBS EOD, but exposes five times the number of women to penicillin reactions. Both strategies ignored infants born to the 80% of pregnant women without risk factors who contribute about 40% of cases of GBS EOD.

Neonatal group B streptococcal infections

Group B streptococci remain a leading cause of life-threatening neonatal infection worldwide. The current estimate of incidence in the United States is 1.8 cases per 1000 live births, with a case-fatality ratio of 10% to 20%. Advances in understanding of the pathogenesis of septic shock and meningitis are yielding new approaches to the treatment of these serious infections. Selective intrapartum chemoprophylaxis with ampicillin has been shown to be both effective and cost effective and is gaining more widespread acceptance as a preventive measure. Conjugate vaccines consisting of type-specific group B streptococci capsular polysaccharides coupled to tetanus toxoid or protein membrane antigens of group B streptococci have been shown to prevent neonatal infection in a mouse model of maternal immunization. Such vaccines are now in trials of safety and immunogenicity in humans.

Effect of Resident Physician Education Regarding Selective Chemoprophylaxis for the Prevention of Early Onset Group B Streptococcal Sepsis: An Outcome Study

Objective: The aim of this study was to evaluate the effect of a voluntary protocol for selective intrapartum chemoprophylaxis on the incidence of early onset group B streptococcal sepsis (GBS EOS). Methods: Cases of GBS EOS were defined as a positive GBS culture from a normally sterile fluid obtained during the first 7 days of life. All cases of GBS EOS at an urban, university-affiliated community hospital were reviewed during 2 time periods. The 2-year period before instituting a resident education program to promote selective chemoprophylaxis (1988–89) was retrospectively reviewed; the 2-year period after the education program was introduced (1990–91) was prospectively recorded. The outcome measure was the incidence of GBS EOS. Results: The rate of GBS EOS was 7/14,335 deliveries (0.05%) before and 9/13,999 (0.064%) after the introduction of the education program (observed difference between proportions 0.016%, 95% confidence interval [CI] for the difference between the proportions –0.071% to 0.04%, P = not significant [NS]). The rate of GBS EOS in preterm infants was 5/1,331 (0.376%) before and 3/1,297 (0.23%) afterward (observed difference between proportions 0.14%, 95% CI –0.28% to 0.56%, P = NS). The incidence of GBS EOS did not decrease during the latter period due to failure of antepartum cultures to predict intrapartum GBS colonization (2 cases); non-compliance with voluntary recommendations to administer chemoprophylaxis (2 cases); failure of chemoprophylaxis or therapy for intraamniotic infection to prevent neonatal infection (3 cases); and occurrence of GBS EOS in infants without risk factors (2 cases). Conclusions: An education program for resident physicians regarding chemoprophylaxis for GBS EOS did not significantly reduce the absolute incidence of disease. Alternative strategies are needed that redress the causes of failure inherent in the current guidelines. Some cases of GBS EOS are not preventable because the parturient does not have risk factors that indicate chemoprophylaxis.

Control of Neonatal Group B Streptococcal Infection

Group B beta-haemolytic streptococcus (GBS) is the leading cause of life-threatening perinatal infection in developed countries. As immunization of women is not yet available, selective intrapartum chemoprophylaxis appears to be the best current strategy for preventing disease. All pregnant women should be screened for GBS at 26 to 28 weeks gestation. During labour, all colonized women with risk factors for invasive GBS neonatal infection should be treated with intravenous penicillin or ampicillin. Risk factors include preterm labour, premature rupture of membranes, intrapartum fever, multiple births, prolonged rupture of membranes, maternal diabetes, previous sibling with invasive GBS disease, and maternal GBS bacteriuria. The latter two categories warrant chemoprophylaxis regardless of maternal colonization status.

Group B streptococcal infections in pregnancy

AbstractGBS is the leading cause of perinatal bacterial infections in the United States. Selective intrapartum chemoprophylaxis can prevent GBS early‐onset neonatal disease and reduce maternal puerperal morbidity. There does not appear to be an effect on late‐onset neonatal disease. Protocols for intrapartum antibiotic chemoprophylaxis based on antepartum cultures, testing at parturition, and clinical risk factors have been summarized.While screening of all pregnant women for GBS is an option, screening and selection methods need further development. A highly reliable rapid screening test for intrapartum detection of light and heavy GBS colonization of the lower genital tract is not yet available.Intrapartum antibiotic chemoprophylaxis of GBS carriers with one or more risk factors substantially reduces the frequency of GBS disease. Benefit may also be obtained from prophylaxis based solely on a knowledge of risk factors if GBS carrier status is unknown. The importance of GBS infection as a perinatal problem and its considerable economic burden justify implementation of chemoprophylactic programs by obstetricians, particularly those who encounter a high proportion of patients with perinatal risk factors in their practices.

Group B Streptococcus

Although antepartum screening for Group B Streptococcus is not ideal, it may be the most practical approach until rapid tests are proven to be useful in this clinical setting. The efficacy has been established for intrapartum chemoprophylaxis with a penicillin antibiotic of patients with a positive antepartum culture. There is evidence that supports the concept for selective intrapartum chemoprophylaxis in some populations. Intrapartum chemoprophylaxis prevents maternal morbidity. Rapid tests for intrapartum diagnosis of Group B streptococcus colonization appear promising, providing results are available in time for therapy to be administered before delivery.

Maternal screening in prevention of neonatal infections: current status and rationale for group B streptococcal screening

Maternal screening—either selective or universal—is an accepted component of a number of strategies for prevention of congenital and perinatal infections. Using the results of maternal screening at prenatal visits and the presence of perinatal risk factors during labour, neonatal group B streptococcal (GBS) early-onset disease can be prevented by selective intrapartum chemoprophylaxis. Possible variations on this strategy may employ semiquantitative tests for GBS colonization at prenatal visits or, possibly, rapid bacterial diagnosis intrapartum. Based on the incidence and economic impact of GBS disease, selective intrapartum chemoprophylaxis appears cost-effective in United States populations, but may not be so in countries with lower incidence rates.

Prevention of early-onset neonatal group B streptococcal disease with selective intrapartum chemoprophylaxis

Abstract Most cases of neonatal group B streptococcal disease with early onset have an intrapartum pathogenesis. Attack rates are increased substantially in infants born to mothers with prenatal group B streptococcal colonization and various perinatal risk factors (premature labor, prolonged membrane rupture, or intrapartum fever). In a randomized controlled trial, we studied the effect of selective intrapartum prophylaxis with ampicillin in 160 such high-risk women. In infants born to mothers who received intravenous ampicillin during labor, as compared with controls who received no treatment, neonatal colonization with group B streptococci was present in 8 of 85 (9 percent) versus 40 of 79 (51 percent; P<0.001), colonization at multiple (≥3) sites was observed in 3 of 85 (4 percent) versus 24 of 79 (30 percent; P<0.001), and bacteremia occurred in none of 85 versus 5 of 79 (6 percent; P = 0.024). The side effects of ampicillin were limited to a single episode of urticaria in a mother who had no history ...

Prevention of neonatal group B streptococcal sepsis by the use of a rapid screening test and selective intrapartum chemoprophylaxis

A randomized 18-month study was conducted to determine the effect of intrapartum chemotherapy in the prevention of neonatal group B streptococcal disease. Twelve hundred seven indigent patients at term were screened weekly for group B streptococci antenatally with a rapid test based on coagglutination methods and at the time of admission in labor, 263 (22%) were confirmed to have colonization, 67 of which had heavy colonization. One hundred thirty-five of these mothers were randomized to a group treated with 1 gm of ampicillin intravenously every 6 hours until delivery. The remaining 128 mothers were not treated. None of the infants born to the treated mothers had colonization with group B streptococci at surface culture sites. Fifty-nine (46%) of the infants born to untreated mothers, including 24 of 30 (80%) from mothers with heavy colonization, had colonization. Ampicillin treatment administered during labor to pregnant patients with heavy colonization significantly reduced vertical transmission of group B streptococci.

1067 SELECTIVE INTRAPARTUM CHEMOPROPHYLAXIS OF EARLYONSET GROUP B STREPTOCOCCAL DISEASE

We examined the effect of selective intrapartum chemoprophylaxis (SIC) on the incidence of group B streptococcal (GBS) early-onset disease in a randomized controlled trial. Parturients were eligible for the study if they had prenatal GBS colonization and either premature labor ( 12 hours). Treated mothers received 2 gm ampicillin IV followed by 1 gm IV Q4H until delivery. Blood cultures were obtained from all study infants at birth and from mothers or older infants if warranted clinically. Of the 175 randomized parturients, 93 received ampicillin and 82 did not. No infant whose mother received SIC had GBS early-onset bacteremia, whereas 5 (6.1%) of the infants whose mothers were not treated were bacteremic (p=0.02). We studied an additional 320 nonrandomized women with the same eligibility criteria. None of the infants born to 76 treated mothers had GBS early-onset bacteremia, whereas 7 of 224 (3.1%) whose mothers were not treated were bacteremic (p=0.13). Four untreated mothers (1 randomized, 3 nonrandomized) developed GBS obstetric sepsis. One infant born to a nonrandomized treated mother developed GBS late-onset sepsis. These results are the first prospective demonstration of the efficacy of SIC to prevent GBS invasive disease.

Selective Intrapartum Chemoprophylaxis of Neonatal Group B Streptococcal Early-Onset Disease. I. Epidemiologic Rationale

Between 1973 and 1981, 61 cases of neonatal group B streptococcal early-onset disease occurred among 32,384 infants born at Michael Reese Hospital and Medical Center, Chicago. Forty-one (67%) of the 61 affected infants were bacteremic at birth, implying intrapartum acquisition of infection. No significant deviations from the overall attack rate of 1.9 per 1,000 live births were associated with maternal demographic factors, but increased attack rates were associated with birth weights of less than or equal to 2.5 kg (7.9 per 1,000), rupture of amniotic membranes greater than 18 hr before birth (7.6 per 1,000), and intrapartum fever (6.5 per 1,000). Forty-five (74%) of the 61 affected infants and 15 (94%) of the 16 with fatal outcome had one or more of these three perinatal risk factors. Based on an intrapartum vaginal carriage rate of 16.7% among parturients with perinatal risk factors, an attack rate of 45.5 per 1,000 was estimated for infants born to colonized high-risk parturients, a subgroup comprising approximately 3% of our obstetric population. These findings provide a compelling epidemiologic rationale for trials of selective intrapartum chemoprophylaxis of neonatal group B streptococcal early-onset disease.