Application of the French guidelines for preventing neonatal group B streptococcal disease in a university hospital

This study evaluated the application of the French guidelines for prevention of neonatal group B streptococcus (GBS) infections. The prevalence of GBS vaginal carriage by pregnant women during the study period was 6%. Less than 50% of pregnant women testing positive for GBS were treated with at least two doses of antibiotics during labour, and most received only one dose or no antibiotics. In addition, several neonates were colonised or infected by GBS although their mothers were GBS-negative. These results are consistent with vaginal screening having a poor sensitivity, as suggested by the low prevalence of GBS carriage.     

Serotypes and clinical manifestations of invasive group B streptococcal infections in western Sweden 1998–2001

This study monitored the serotypes of Streptococcus agalactiae (group B streptococcus; GBS) isolated from invasive infections in western Sweden and investigated possible relationships between serotype, age and clinical manifestations. Invasive GBS isolates were collected prospectively during 1998-2001 at six laboratories, covering two counties with a population of 1.8 million, and were serotyped by coagglutination. Clinical data were obtained from hospital notes. In total, 161 invasive strains (50 from neonates and infants aged < 3 months, and 111 from adults) were serotyped. The commonest serotypes from neonates and infants were serotypes III (60%), V (22%) and Ia (10%), and from adults were serotypes V (42%) and III (25%). Serotype V had doubled in frequency among both children and adults compared to a previous study from the same area in 1988-1997. Most (80%) of the adults had an underlying medical condition. No relationship was found between serotype and clinical manifestations. However, the study demonstrated the importance of active surveillance of GBS serotypes and the difficulties of formulating a multivalent polysaccharide conjugate vaccine against GBS.     

Prevention of perinatal group B streptococcal infections: A review with an Indian perspective

Group B Streptococcus (GBS) is an important cause of maternal and neonatal morbidity and mortality in many parts of the world. Asymptomatic colonisation of the vagina and rectum with Group B streptococci is common in pregnancy. Maternal colonisation of GBS can vary depending on ethnicity and geographical distribution. Vertical transmission of this organism from mother to foetus may lead to neonatal GBS disease. Intra-partum use of antibiotics in these women has led to a decrease in the rate of early onset but not late onset GBS disease. Identification of women with GBS is the key factor in the prevention of perinatal GBS disease. There are different screening strategies available to identify women at risk of perinatal GBS disease. Clinicians continue to face the challenge of choosing between preventive strategies to reduce the impact of perinatal GBS disease. Controversy exists regarding the ideal preventive strategy. In India, the mortality and morbidity associated with the GBS disease remains largely a under-recognised problem. This comprehensive review summarises the salient features of GBS disease and discusses the epidemiology, risk factors, screening strategies, intra-partum antibiotic prophylaxis with an Indian perspective and how it compares with the Western nations.     

Carriage of group B Streptococcus in pregnant women and newborns: a 2-year study at Perugia General Hospital

Objective: To study the prevalence of group B Streptococcus (GBS) colonization in pregnant women and their newborns at Perugia General Hospital.
Method: The number of mother-child pairs examined was 2300. Vaginal swabs were collected from the mothers at delivery, and auricular and pharyngeal swabs and gastric aspirate from the newborns at birth. Maternal risk factors for GBS disease, including premature delivery, intrapartum fever, prolonged rupture of membranes and multiple births, were evaluated.
Results: Maternal and neonatal colonization rates were 11.3% and 4.6%, respectively. GBS was isolated in 41.5% of the neonates born to colonized mothers and in 0.1% of those born to non-colonized mothers. No significant difference was observed in vertical transmission rates in the presence or absence of maternal risk factors. The external auditory canal was the most frequent (93.5%) and heavily colonized body site. Type Ib was the most common serotype among GBS isolates from mothers and babies. C surface protein was not detected in serotype V and VIII isolates, but was frequent in all other serotypes. Early-onset disease was observed in 0.4/1000 live births.
Conclusions: The prevalence of maternal and neonatal colonization at Perugia General Hospital was similar to that obtained in other studies performed in Italy. The external auditory canal was confirmed as the most reliable body site to be sampled for the detection of neonates exposed to maternal GBS colonization.     

Group B streptococcal soft tissue infections in non-pregnant adults

Skin and soft tissue infections are the most common presentations of invasive Streptococcus agalactiae infections. This study reviewed 71 patients in a medical centre in southern Taiwan with S. agalactiae soft tissue infections. The mortality rate was 7%, and 11% of patients lost their extremities following extensive tissue necrosis. Critical illness and the presence of cutaneous ulceration heralded a fatal prognosis. Risk-factors for amputation of limbs included advanced age, cutaneous ulceration and polymicrobial infection. It was concluded that invasive S. agalactiae soft tissue infections, as with infections caused by Streptococcus pyogenes, can also lead to substantial morbidity and mortality in non-pregnant adults.     

Modified Granada Agar Medium for the detection of group B streptococcus carriage in pregnant women

Objectives   To improve the detection rate of group B streptococci (GBS) in pregnant women, aiming at the prevention of early-onset septicemia in the newborn.
Methods   The yield from culturing two sites, vaginal and anorectal, on a Modified Granada Medium (MGM) was compared with our standard approach of culturing a vaginal swab on blood agar (BA).
Results   Samples were processed from 430 consecutive pregnant women. GBS was isolated from the vagina in 11.6% with BA, and in 13.7% with MGM. In 17.0% of anorectal samples, GBS was identified with MGM. The combination of both sites and media had a yield of 20.0%. MGM identified all but six (2%) of 310 GBS strains after aerobic incubation, with use of a cover slide, and missed only three strains (1%) after anaerobic incubation.
Conclusions   Separate culture of vaginal and anorectal samples using the same MGM agar plate resulted in an increase in detection rate for GBS of 76% as compared to BA alone. The technique is simple and results are available after overnight incubation. MGM was confirmed as a specific medium for the identification of GBS, with a sensitivity of 98–99%.     

In vitro systems for investigating group B streptococcal: host cell and extracellular matrix interactions

Streptococcus agalactiae or group B streptococci (GBS) are gram-positive diplococci and are the leading bacterial cause of pneumoniae, sepsis, and meningitis in neonates. Neonatal GBS infections may occur prior to or during birth. GBS have been cultured from the chorioamnionic membrane of pregnant women and have therefore been associated with chorioamnionitis and premature labor. A potential route for GBS to establish infection of a neonate would be to penetrate the placental membrane of colonized pregnant women. In our laboratory, we have constructed in vitro systems to emulate certain events during the colonization and invasion of host epithelial cell tissues by GBS. By utilizing techniques to grow primary cultures of both chorion cells and amnion cells isolated from human C-section placentas, we have established a relevant model to investigate certain aspects of GBS adherence and invasion into the placental membrane. To identify relevant molecules required for GBS to colonize the multiple tissues it encounters during an infection, we have applied a variety of biochemical approaches with host cell membrane preparations as well as purified extracellular matrix proteins. These techniques are enabling us to further characterize the pathogenic mechanisms utilized by GBS.     

Spontaneous gas-forming bacterial myonecrosis caused by group B streptococci and peptostreptococci

Summary We present the case of a patient who spontaneously developed a severe gas-forming infection involving the voluntary muscles of both thighs. The organisms responsible were group B -haemolytic streptococci together with peptostreptococci. Following surgical and medical treatment, the patient fully recovered. No predisposing factors, in particular no disease causing immunocompromise, could be identified.Abbreviation IU/1 international units/liter Dedicated to Professor Dr. med. M. Eggstein on the occasion of his 65th birthday     

Serotypes and clinical manifestations of group B streptococcal infections in western Sweden

Objectives   To study the serotype distributions of group B streptococci (GBS) isolated from blood and cerebrospinal fluid and from the genital tract of pregnant women and to investigate any possible relation between serotype, age and clinical manifestation.
Methods   Invasive strains were collected from 1988 to 1997 and genital strains from 1995 to 1996. Strains of GBS were serotyped with coagglutination. Clinical data were obtained from hospital notes.
Results   A total of 144 invasive strains, 78 from neonates and infants and 66 from adults, were serotyped. The most common isolates from neonates and infants were types III (62%), Ia (18%), and V (9%). The most common isolates from adults were types III (29%), Ib (23%), V (21%) and II (15%). A majority of the adults (94%) had an underlying medical condition. The most common serotypes of the 114 strains isolated from the genital tract of pregnant women were types III (32%), V (22%), Ia (13%), Ib (13%) and II (11%).
Conclusions   Serotype III was the single most frequent GBS isolate from infants and adults. Serotype V, which appeared first in 1992, was the third most frequent isolate. A vaccine containing five GBS capsular polysaccharides appears to be appropriate for the Swedish population.     

Improved methods for typing nontypeable isolates of group B streptococci

Group B streptococci (GBS) are classified by capsular polysaccharide (CPS) type and by cell surface-expressed proteins (c and R). Isolates lacking detectable CPS are considered nontypeable (NT) although they frequently express surface proteins. Immunological and genetic methods were used to study 91 NT GBS isolates collected during surveillance studies for invasive disease or colonization in pregnant or non-pregnant women and neonates less than seven days of age. CPS production was upregulated by the addition of glucose and sodium phosphate to Todd-Hewitt broth (THB) and cells were extracted using hot HCl or mutanolysin. Extracts were tested with antisera for specific CPS types Ia, Ib, and II - VIII by double immunodiffusion (DD) in agarose. By mutanolysin extraction, 12 (13.2%) of the 91 isolates were typeable. In contrast, only four of these 12 newly typeable isolates tested positive for CPS with the HCl extracts of cells grown in modified THB. DNA was analyzed by pulsed-field gel electrophoresis (PFGE) using SmaI restriction with NT isolates grouped by protein profile to facilitate analysis. PFGE results of the NT isolates were compared to DNA profiles of typeable isolates and were correlated with the DD results. The DNA profiles of the newly typeable isolates were similar to profiles of isolates with corresponding defined CPS type. Of the remaining 78 NT isolates digested by SmaI, 63 (80.8%) had DNA profiles that resembled those of specific types of GBS. These approaches will be useful for classification of NT isolates in continued epidemiological surveillance associated with GBS vaccine trials.     

Comparison of LightCycler PCR and culture for detection of group B streptococci from vaginal swabs

Group B streptococci (GBS) are an important cause of neonatal sepsis and meningitis. New rapid, sensitive and specific methods for detection of GBS in pregnant women are needed in order to provide timely treatment of neonates. The sensitivity, specificity and cost of a LightCycler PCR method was compared with selective culture for the detection of GBS from 400 vaginal swabs. In addition, two DNA extraction methods (simple boiling and automated DNA extraction by Roche MagNA Pure LC) were compared for a subgroup of 100 clinical samples. The sensitivity of the LightCycler PCR assay for the detection of GBS from vaginal swabs was significantly higher than that of culture. There were no culture-positive, LightCycler PCR-negative cases. The efficiencies of the two DNA extraction procedures were not significantly different. The detection of GBS from vaginal swabs by the molecular method (including simple boiling extraction) required the same hands-on time, but the procedure was completed in 1.5 h, compared with c. 48 h for the culture-based approach. Disadvantages of the molecular method are the increased costs (45%) and the absence of antibiogram data. The LightCycler PCR is a promising tool for sensitive, specific and rapid detection of GBS directly from clinical specimens of pregnant women.     

A human IgG 3 is opsonicin vitro against type III group B streptococci

Preparations of IgG 3 isolated by absorption of IgG 1, IgG 2, and IgG 4 from a human iv immunoglobulin with protein A-Sepharose were evaluated for their opsonic activities against type III group B streptococcal (GBS) strains. The resulting preparations were free of IgG 1 and IgG 2 and contained only trace amounts of IgG 4 (<2% of total IgG). These IgG 3 preparations exhibited excellent opsonic activities against type III GBS strains, similar to those of the unfractionated iv immunoglobulin (based on total IgG concentrations in the opsonic assays). In contrast, preparations of IgG 1, 2, and 4 eluted from protein A-Sepharose with 2M acetic acid and 7M urea were significantly less effective in enhancing phagocytosis and killing of type III GBS than IgG 3 preparations or iv immunoglobulin. The reasons for excellent opsonic activity of IgG 3 preparations as well as for decreased opsonic activity of IgG 1, 2, and 4 preparations are not clear. Perhaps alteration of IgG by lower pH and high concentrations of urea may have impaired the functional activity of IgG 1, 2, and 4 preparations. The significant finding of this study is the first demonstration of the excellent opsonic activity of IgG 3, emphasizing the importance of having intact IgG 3 in commercial immunoglobulin preparations used in prophylaxis or treatment of GBS infections.     

Group B Streptococcus (GBS) colonization is dynamic over time,whilst GBS capsular polysaccharides-specific antibody remains stable

Group B Streptococcus (GBS) is a leading cause of adverse pregnancy outcomes due to invasive infection. This study investigated longitudinal variation in GBS rectovaginal colonization, serum and vaginal GBS capsular polysaccharide (CPS)-specific antibody levels. Non-pregnant women were recruited in the UK and were sampled every 2 weeks over a 12-week period. GBS isolates were taken from recto-vaginal swabs and serotyped by polymerase chain reaction. Serum and vaginal immunoglobulin G (IgG) and nasal immunoglobulin A (IgA) specific to CPS were measured by Luminex, and total IgG/A by ELISA. Seventy women were enrolled, of median age 26. Out of the 66 participants who completed at least three visits: 14/47 (29.8%) women that were GBS negative at screening became positive in follow-up visits and 16/19 (84.2%) women who were GBS positive at screening became negative. There was 50% probability of becoming negative 36 days after the first positive swab. The rate of detectable GBS carriage fluctuated over time, although serum, vaginal, and nasal CPS-specific antibody levels remained constant. Levels of CPS-specific antibodies were higher in the serum of individuals colonized with GBS than in non-colonized, but similar in the vaginal and nasal mucosa. We found correlations between antibody levels in serum and the vaginal and nasal mucosa. Our study demonstrates the feasibility of elution methods to retrieve vaginal and nasal antibodies, and the optimization of immunoassays to measure GBS-CPS-specific antibodies. The difference between the dynamics of colonization and antibody response is interesting and further investigation is required for vaccine development.     

Genetic relatedness between group B streptococci originating from bovine mastitis and a human group B streptococcus type V cluster displaying an identical pulsed-field gel electrophoresis pattern

Twenty isolates of group B streptococcus (GBS) were recovered from the milk of cows with bovine mastitis on three farms located in the south and south-east of Brazil between 1987 and 1988. These isolates were characterised by molecular methods and compared with a collection of 103 human GBS isolates from colonised and infected patients in the same region between 1980 and 2003. Some of the bovine isolates shared identical or similar pulsed-field gel electrophoresis (PFGE) patterns with a PFGE clone of human GBS type V. In addition, these bovine and human isolates also possessed the same ribotype. Multilocus sequence typing (MLST) of representative isolates confirmed the genetic relationship between the human and bovine GBS isolates with identical PFGE patterns, which clustered in the same ST-26 clonal complex. These data support the hypothesis that some bovine GBS strains are related closely to human isolates and may infect humans, or vice versa. Further comparative genomic analyses of GBS isolates from bovine and human origins are required to investigate this hypothesis further.     

Chorioamnionitis: from pathogenesis to treatment

Chorioamnionitis refers to inflammation of the amniochorionic membrane, and is a significant cause of maternal and neonatal morbidity. Chorioamnionitis most often occurs as a result of ascending infection, and is commonly associated with premature rupture of the membranes. Chorioamnionitis is generally the result of a polymicrobial infection, with Ureaplasma urealyticum, Mycoplasma hominis and Gramnegative anaerobes being frequent causative organisms. The mainstay of treatment includes antimicrobial agents, antipyretics, expedition of delivery and supportive care. Further research is required to identify mechanistic pathways and early biomarkers that accurately predict women at higher risk of adverse maternal and neonatal outcomes, and that can thus lead to the development of additional treatment and prevention strategies.     

Reduced susceptibility to penicillin of viridans group streptococci in the oral cavity of patients with haematological disease

The occurrence of oral penicillin-resistant viridans group streptococci (VGS) was studied in 50 patients with either newly diagnosed acute leukaemia or autologous peripheral stem cell transplants. One patient was excluded because of Staphylococcus aureus growth in the stem cell harvest. VGS were isolated from the oral cavity of 48 of the remaining 49 patients. Of these 48 patients, 12 (25%) yielded VGS resistant (MIC > 2 mg/L) to penicillin. These 12 patients had a higher frequency of septicaemia (p 0.04) and more days of treatment with trimethoprim-sulphamethoxazole (p 0.04) than patients who harboured susceptible or intermediately resistant VGS (MIC 2 mg/L). There were no other statistically significant differences between the two groups. It is important to be aware of the high level of penicillin resistance in oral VGS in patients with haematological disease, and this parameter should be considered when selecting antibiotic therapy for cases of septicaemia caused by VGS in immunocompromised patients.     

乙肝免疫球蛋白阻断乙肝病毒母婴垂直传播的研究

目的研究乙肝免疫球蛋白应用于孕妇为乙肝病毒携带者对阻断乙肝病毒母婴垂直传播的效果。方法A组123例，于孕28、32、36w分别注射HBIG200u，B组130例仅常规产前检查及监护。结果A组较B组新生儿出生时外周血HB—sAg阳性率显著降低P〈0．05。结论对乙肝病毒携带的孕妇晚期应用HBIG可以显著降低新生儿外周血HBSAg阳性率。