Group B Streptococcus Antigen Research Articles

Colonization of pregnant women with group B streptococcus: current view at the problem

The relevance of the problem of group B streptococcus (GBS) in obstetric practice casts no doubt. Attracting the close attention of leading experts, introducing new solutions and based on practical experience gained, it is still not possible to prevent all cases of neonatal infections associated with GBS. The review article demonstrates the current view of the problem. According to the literature, African-American race in combination with sexually transmitted infections are predisposing risk factors for GBS colonization. A direct relationship between obesity and the percentage of GBS carriers was revealed. GBS-colonized primigravidas have a 50 % increased chance of detecting the pathogen in subsequent pregnancies. Absolute factors for massive GBS colonization of the birth tract include GBS-associated asymptomatic bacteriuria and a history of GBS-colonized children. It is assumed that such virulence factors as hemolytic pigment and hyaluronidase contribute to the GBS pathogenic potential. The protective function in the immune system is performed by Kaschenko–Gofbauer cells, but their role is ambiguous. Early neonatal GBS infection realized in 90 % of newborns that manifested by sepsis, pneumonia and purulent meningitis. Implemented measures to prevent early neonatal GBS infection have a number of disadvantages. False-negative results of culture screening for GBS antigen at gestational age of 35–37 weeks increase a risk of vertical transmission, whereas false-positive results underlie a reason for prescribing irrational intranatal antibiotic prophylaxis. Moreover, antenatal GBS microbiological screening and antibiotic prophylaxis at birth do not prevent the risks of late-onset neonatal GBS infection.

Diagnostic Performance of Various Methodologies for Group B Streptococcus Screening in Pregnant Woman in China.

Maternal vaginal/rectal colonization of group B streptococcus (GBS) is a main risk for neonatal invasive infection. Efficient determination of GBS colonization in pregnant women is crucial. This study aimed to investigate the prevalence of GBS carriage and evaluate the diagnostic performance of six methodologies for GBS screening conducted in China, including blood agar plate, liquid chromogenic medium, and loop-mediated isothermal amplification (LAMP) without pre-enrichment, chromogenic agar plate with pre-enrichment, and GBS antigen detection without and with pre-enrichment in comparison with the standard reference method (Lim broth-enriched subculture with plating on 5% sheep blood agar). Vaginal/rectal swabs were collected from 1,281 pregnant women at 35–37 weeks of gestation. Of them, 309 were taken in triplicate, one for Lim broth-enriched subculture, one for blood agar plate, and the third for GBS antigen detection (Reagent W); 177 were acquired in duplicate, one for Lim broth-enriched subculture and the other for GBS antigen detection (Reagent H); 502 were obtained in duplicate, one for Lim broth-enriched subculture and the other for liquid chromogenic medium; 158 were collected in duplicate, one for Lim broth-enriched subculture and the other for LAMP; and 135 were inoculated in Lim broth-enriched for GBS antigen detection (Reagent W) and subculture with chromogenic agar plate and 5% blood agar plate. The overall prevalence of GBS carriage was 10.1% (130/1,281, 95% CI: 8.5–12.1%) according to the standard reference method. Compared with the standard reference method, the LAMP had excellent performance of sensitivity (100%, 95%CI: 83.4–100%), specificity (94%, 95%CI: 88.1–97.1%), and Yoden index (0.940); as well as the blood agar plate with sensitivity (81.5%, 95%CI: 61.3–93.0%), specificity (100%, 95%CI: 98.3–100.0%), and Yoden index (0.815). The other four methods were not sufficient to reach the threshold in terms of sensitivity or specificity compared to the standard reference method. Furthermore, for LAMP, results can be obtained within 0.5–1 h, while for blood agar plate, which needed 24–48 h, and further identification was required. Our data suggested that the performance of LAMP was highly comparable to the standard Lim broth-enriched subculture and LAMP is considered as an alternative for fast and accurate GBS screening.

Diagnostic performance of direct latex agglutination, post-enrichment latex agglutination and culture methods in screening of group B streptococci in late pregnancy: a comparative study.

BackgroundGroup B streptococcus (GBS) is one of the main causes of neonatal sepsis.PurposeEvaluation of the diagnostic performance of direct latex agglutination test (DLA), post-enrichment latex agglutination (LA) test, and direct culture on chromogenic media in rapid identification of GBS carrier in pregnant women in comparison with the conventional post-enrichment CDC-recommended culture method and further to estimate GBS carriage prevalence and its antimicrobial susceptibility.MethodsTwo hundred pregnant women at gestational age (35–37 weeks) were enrolled. Three low vaginal swabs were obtained from each participant. One swab was directly inoculated into Strep B Select (SBS) agar. The second swab was inoculated in enrichment Lim broth for immunological antigen detection by post-enrichment latex agglutination (5 h and 24 h) and subculture for bacteriological detection. The third swab was used for immunological detection of GBS antigen by direct latex agglutination. The isolated GBS was subjected to antimicrobial susceptibility testing.ResultsAmong 200 pregnant women, 47 (23.5%) were GBS carriers. Considering post-enrichment subculture on SBS medium as a gold standard, the sensitivities for post-enrichment 5 h and 24 h LA were 66% and 95.7%, respectively. However, direct cultivation of the vaginal swabs on SBS medium and DLA recorded 83% and 4.3%, respectively, for sensitivity. All GBS isolates (100%) were sensitive to penicillin G, ampicillin, ceftriaxone, and vancomycin. In contrast, 21.3% and 12.8% of isolated GBS were resistant to erythromycin and clindamycin, respectively.ConclusionGroup B streptococcal antigen detection by latex agglutination after 5 h enrichment is a reliable, easy, and relatively rapid method for screening of GBS carriage in pregnant woman not in labor. Latex agglutination after 18–24 h enrichment can be used alternative to standard subculture method for screening GBS carriage.

High prevalence of Group B Streptococcus colonization among pregnant women in Amman, Jordan

BackgroundLittle is known of the burden of Group B Streptococcus (GBS) colonization among pregnant women in Jordan. We conducted a pilot study to determine the prevalence of GBS among pregnant women in Amman, Jordan, where GBS testing is not routine. We also explored GBS serotypes and the performance of a rapid GBS antigen diagnostic test.MethodsWe collected vaginal-rectal swabs from women who presented for labor and delivery at Al-Bashir Hospital. Three methods were used to identify GBS: Strep B Rapid Test (Creative Diagnostics), blood agar media (Remel) with confirmed with BBL Streptocard acid latex test (Becton Dickinson), and CHROMagar StrepB (Remel). Results were read by a senior microbiologist. We defined our gold standard for GBS-positive as a positive blood agar culture confirmed by latex agglutination and positive CHROMagar. PCR testing determined serotype information. Demographic and clinical data were also collected.ResultsIn April and May 2015, 200 women were enrolled with a median age of 27 years (IQR: 23–32); 89.0% were Jordanian nationals and 71.9% completed secondary school. Median gestational age was 38 weeks (IQR: 37–40); most women reported prenatal care (median 9 visits; IQR: 8–12). Median parity was 2 births (IQR: 1–3). Pre-pregnancy median BMI was 24.1 (IQR: 21.5–28.0) and 14.5% reported an underlying medical condition. Obstetric complications included gestational hypertension (9.5%), gestational diabetes (6.0%), and UTI (53.5%), of which 84.5% reported treatment. Overall, 39 (19.5%) of women were GBS-positive on blood agar media and CHROMagar, while 67 (33.5%) were positive by rapid test (36% sensitivity, 67% specificity). Serotype information was available for 25 (64%) isolates: III (48%), Ia (24%), II (20%), and V (8%). No demographic or clinical differences were noted between GBS+ and GBS-negative women.ConclusionsNearly one in five women presenting for labor in Jordan was colonized with GBS, with serotype group III as the most common. The rapid GBS antigen diagnostic had low sensitivity and specificity. These results support expanded research in the region, including defining GBS resistance patterns, serotyping information, and risk factors. It also emphasizes the need for routine GBS testing and improved rapid GBS diagnostics for developing world settings.

Coassociation between Group B Streptococcus and Candida albicans Promotes Interactions with Vaginal Epithelium.

Group B Streptococcus (GBS) is a leading cause of neonatal sepsis, pneumonia, and meningitis worldwide. In the majority of cases, GBS is transmitted vertically from mother to neonate, making maternal vaginal colonization a key risk factor for neonatal disease. The fungus Candida albicans is an opportunistic pathogen of the female genitourinary tract and the causative agent of vaginal thrush. Carriage of C. albicans has been shown to be an independent risk factor for vaginal colonization by GBS. However, the nature of interactions between these two microbes is poorly understood. This study provides evidence of a reciprocal, synergistic interplay between GBS and C. albicans that may serve to promote their cocolonization of the vaginal mucosa. GBS strains NEM316 (serotype III) and 515 (serotype Ia) are shown to physically interact with C. albicans, with the bacteria exhibiting tropism for candidal hyphal filaments. This interaction enhances association levels of both microbes with the vaginal epithelial cell line VK2/E6E7. The ability of GBS to coassociate with C. albicans is dependent upon expression of the hypha-specific adhesin Als3. In turn, expression of GBS antigen I/II family adhesins (Bsp polypeptides) facilitates this coassociation and confers upon surrogate Lactococcus lactis the capacity to exhibit enhanced interactions with C. albicans on vaginal epithelium. As genitourinary tract colonization is an essential first step in the pathogenesis of GBS and C. albicans, the coassociation mechanism reported here may have important implications for the risk of disease involving both of these pathogens.

Screening and genotyping of group B streptococcus in pregnant and non-pregnant women in Turkey.

The purpose of this study was to investigate group B streptococcus (GBS) colonization, to compare the methods, to determine the relationship between GBS carriage and risk factors, and to genotype the GBS isolates. Recto-vaginal swab specimens were obtained from 500 women, and a questionnaire was administered to each to assess their risk factors for GBS carriage. A culture, GBS antigen test, and polymerase chain reaction (PCR) were performed on all samples. Antibiotic susceptibility testing was performed, and the clonal relationship was determined by pulsed-field gel electrophoresis (PFGE) on all viable isolates. Of the 500 women, sixty-eight (13.6%) women were GBS carriers, of whom 9.8% were pregnant and 16.5% not. There was a significant difference between GBS carriage and history of premature rupture of membrane (PROM). GBS was isolated from 65 (13%) samples. GBS was positive in 70 (14%) samples by antigen test and in 62 (12.4%) by PCR. Sixty-eight of the 70 positive antigen tests were confirmed by PCR or culture. Fifty-five isolates were resistant to tetracycline, 16 to erythromycin and clindamycin, and 13 to levofloxacin. Thirteen different pulsotypes and 17 sporadic strains were determined by PFGE. GBS carriage rate in non-pregnant women was higher than in pregnant women. The GBS antigen test was more sensitive than culture and PCR. GBS isolates did not originate from a single clone and contained sporadic strains. There was a significant difference between GBS carriage and history of PROM. Epidemiologic data obtained in this study will help future studies.

Recognition of Streptococcus pseudoporcinus Colonization in Women as a Consequence of Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Group B Streptococcus Identification.

During a 14-month period of using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for group B streptococcus (GBS) identification, we recovered 32 (1%) Streptococcus pseudoporcinus isolates from 3,276 GBS screening cultures from female genital sources (25 isolates from pregnant women and 7 from nonpregnant women). An additional two S. pseudoporcinus isolates were identified from a urine culture and a posthysterectomy wound culture. These isolates were found to cross-react with three different GBS antigen agglutination kits, PathoDx (Remel) (93%), Prolex (Pro-Lab Diagnostics) (38%), and Streptex (Remel) (53%). New approaches to bacterial identification in routine clinical microbiology laboratories may affect the prevalence of S. pseudoporcinus.

Limited Diagnostic Value of Routine Screening of Neonates with the Urinary Group B Streptococcal Antigen Tests

A urinary latex test for detection of antigens from group B Streptococcus (GBS) has been used for the diagnosis of invasive GBS disease. However, the value of routine screening of infants with this test has not been determined. All infants admitted to Linkou Chang-Gung Memorial Hospital (Taoyuan, Taiwan) from January 2005 to May 2013 were screened with a urinary GBS antigen test (Wellcogen Strep B). Medical records were retrospectively reviewed to determine the diagnostic value of this test. A total of 14,277 infants were tested and 38 cases had confirmed diagnoses of invasive GBS disease (34 bacteremia, 18 meningitis, 14 both), corresponding to a prevalence of 0.27% among our admitted infants. A total of 106 infants had positive results, but only 26 had confirmed disease. Among infants with confirmed disease, 12 had negative antigen results. These data allowed calculation of the sensitivity (68.4%), specificity (99.4%), positive predictive value (24.5%), and negative predictive value (99.9%). Adjusting for prevalence, the disease probability of a positive test result was 23.6%, and the probability of a negative post-test result was 0.09%. The absolute risk reduction of a negative result was very small (0.18%). Analysis of demographic, clinical, and laboratory parameters indicated that late age of onset (≥7 days-old), presence of seizure, fever, respiratory distress, leukopenia, bandemia, thrombocytopenia, coagulopathy, metabolic acidosis, and elevated levels of C-reactive protein (CRP) were significantly related to the presence of a true positive test result. In our study population, the positive predictive value of the GBS antigen test was poor and the risk reduction of a negative result was weak. These results indicate that routine screening with this test has a limited diagnostic value. However, GBS antigen testing appears to be useful for early detection of disease in infants with certain demographic, clinical, and laboratory risk factors.

A commercial rapid optical immunoassay detects Streptococcus agalactiae from aquatic cultures and clinical specimens

The BioStar STREP B Optical ImmunoAssay (STREP B OIA) (BioStar ® OIA ® Strep B Assay Kit; BioStar Incorporation, Louisville, CO, USA), commonly used for diagnosis of human maternal group B streptococcus (GBS) colonization, was evaluated for its diagnostic and analytical sensitivity and specificity to aquatic animal GBS isolates, cross-reactivity, and diagnosis and recovery of GBS directly from clinically- infected fish swabs. STREP B OIA identified 25 known fish and dolphin GBS isolates. Thirteen non-GBS negative control isolates from fish and other animals were negative, giving 100% analytical specificity and no cross-reactivity. Three groups of 6 Nile tilapia ( Oreochromis niloticus) (mean weight of 40.60 ± 1.70 g) each were inoculated intraperitoneally with either 10 6 colony-forming units (cfu) GBS/fish, 10 6 cfu Streptococcus iniae/fish or 100 μL of tryptic soy broth (TSB) and observed for mortality for 7 days. The nare and brain of all fish were swabbed and subjected to the STREP B OIA for detection of GBS antigen immediately after swabbing (0 h) or 24, 48 and 72 h post-swabbing and compared to conventional culture on trypticase soy agar with 5% sheep blood. The STREP B OIA method demonstrated a diagnostic sensitivity of 75.0% and a diagnostic specificity of 69.2% compared to direct TSA. The percent agreement between OIA and culture was 100%. GBS antigen could be retrieved by OIA following 72-h storage of swabs. These results demonstrate the utility of the STREP B OIA to identify GBS from culture and directly from swabs of clinically- infected fish.

Perinatal Group B Streptococcal Infections and the New Guidelines

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 …

Biodegradable microspheres containing group B Streptococcus vaccine: Immune response in mice

Objective: This study seeks to show the feasibility of producing a group B Streptococcus (GBS) vaccine, which is capable of producing both a local IgA immune response at the mucosal surface where GBS is colonized and a humoral IgG response, which is capable of transplacental passive immunization. Study Design: Inactivated GBS antigen was microencapsulated in poly (D, L-lactic-co-glycolic acid) (PLG) with a water-in-oil-in-water double emulsion technique. Immunostimulatory synthetic oligodeoxynucleotides containing cytidine-phosphate-guanosine (CpG) motifs were coencapsulated as a potent adjuvant. The ICR strain of mouse was used in these studies. Female mice with normal immune systems were immunized with the PLG microparticles containing GBS type III polysaccharide (GBS PS) vaccine and CpG adjuvant (PLG/GBS/CpG) via the oral, vaginal, or nasal routes or by the intramuscular or intraperitoneal routes. Booster doses were administered 4 weeks after the initial immunization. Vaginal washings and blood samples were obtained 3 weeks after the booster dose and examined for both IgG and secretory IgA (sIgA) GBS antibodies with the use of an enzyme-linked immunoabsorbent assay method. Results: PLG/GBS/CpG microparticles elicited a significantly higher GBS antibody response when compared with nonencapsulated GBS antigen or PLG-encapsulated GBS PS vaccine without the addition of the CpG adjuvant. IgG and secretory IgA (sIgA) antibodies to GBS antigen were documented in both the vaginal washings and blood samples. Conclusion: Preliminary findings indicate that this novel PLG/GBS/CpG vaccine elicited both IgA and IgG antibody responses to the GBS PS antigen studied. This antibody response may provide both protection against maternal GBS colonization and passive transplacental immunization for the fetus and neonate. (Am J Obstet Gynecol 2001;185:1174-9.)

Eosinophilic gastroenteritis with rapid progression of blood eosinophilia

A urinary latex test for detection of antigens from group B Streptococcus (GBS) has been used for the diagnosis of invasive GBS disease. However, the value of routine screening of infants with this test has not been determined.All infants admitted to Linkou Chang-Gung Memorial Hospital (Taoyuan, Taiwan) from January 2005 to May 2013 were screened with a urinary GBS antigen test (Wellcogen Strep B). Medical records were retrospectively reviewed to determine the diagnostic value of this test.A total of 14,277 infants were tested and 38 cases had confirmed diagnoses of invasive GBS disease (34 bacteremia, 18 meningitis, 14 both), corresponding to a prevalence of 0.27% among our admitted infants. A total of 106 infants had positive results, but only 26 had confirmed disease. Among infants with confirmed disease, 12 had negative antigen results. These data allowed calculation of the sensitivity (68.4%), specificity (99.4%), positive predictive value (24.5%), and negative predictive value (99.9%). Adjusting for prevalence, the disease probability of a positive test result was 23.6%, and the probability of a negative post-test result was 0.09%. The absolute risk reduction of a negative result was very small (0.18%). Analysis of demographic, clinical, and laboratory parameters indicated that late age of onset (≥7 days-old), presence of seizure, fever, respiratory distress, leukopenia, bandemia, thrombocytopenia, coagulopathy, metabolic acidosis, and elevated levels of C-reactive protein (CRP) were significantly related to the presence of a true positive test result.In our study population, the positive predictive value of the GBS antigen test was poor and the risk reduction of a negative result was weak. These results indicate that routine screening with this test has a limited diagnostic value. However, GBS antigen testing appears to be useful for early detection of disease in infants with certain demographic, clinical, and laboratory risk factors.

Intrapartum antibiotics and early onset neonatal sepsis caused by group B Streptococcus and by other organisms in Australia. Australasian Study Group for Neonatal Infections.

Early onset group B streptococcal (EOGBS) infection, the major neonatal infection in industrialized countries, can be prevented by intrapartum antibiotics, but population studies are lacking. This study aimed to determine the incidence of early onset infections caused by group B Streptococcus (GBS) and other organisms in Australia and to assess intrapartum antibiotic use. Longitudinal, prospective surveillance of neonatal infections in Australian neonatal units from 1991 to 1997. Early onset infection defined as clinical sepsis in first 48 h after birth, with positive cultures of blood or cerebrospinal fluid or positive urine GBS antigen detection. The incidence of EOGBS sepsis fell from 2.0 per 1000 live births (95% confidence interval, 1.4, 2.5) in 1991 to 1993, to 1.3 (1.2, 1.4) in 1993 to 1995, to 0.5 (0.4, 0.7) in 1995 to 1997 (P < 0.0001). The incidence in Aboriginal babies was 5.2 (1.8, 8.6) in 1991 to 1993, 5.1 (3.0, 7.2) in 1993 to 1995 and 1.8 (1.1, 2.5) in 1995 to 1997 (P < 0.05). The incidence of early onset infections caused by organisms other than GBS also fell, from 1.2 per 1000 live births (0.8, 1.7) in 1991 to 1993, to 0.8 (0.7, 0.9) in 1993 to 1995 and 0.5 (0.3, 0.7) in 1995 to 1997 (P < 0.0001). In 1991, 3 of 9 study hospitals had a formal policy on intrapartum antibiotic use, whereas in 1997 all 11 hospitals had a formal policy (P=0.002). A steady fall in EOGBS infections in Australia from 1991 to 1997 has been associated with increasing use of intrapartum antibiotics. Increased antibiotic use is probably causal in the fall in GBS, because the incidence of early onset infections caused by other organisms has also fallen.

Evaluation of suprapubic bladder aspiration for detection of group B streptococcal antigen by latex agglutination in neonatal urine.

Our objective was to determine whether urine collection by suprapubic bladder aspiration (SBA) improves the specificity of the group B streptococcal (GBS) latex agglutination (LA) test by avoiding contamination of urine with GBS from perineal and rectal colonization that can result in a positive LA test in an uninfected infant when the urine is collected by bag. Part 1 consists of a retrospective review of the medical records of 113 infants who had urine collected by SBA for GBS LA testing as part of evaluation for possible sepsis. The sensitivity and specificity of the urine LA test was assessed by comparing it with blood culture results. In part 2, a prospective analysis was performed of 19 newborns who had rectal and vaginal/penile cultures as well as urine by SBA and bag for GBS cultures and LA. Results of LA testing on urine collected by both of these methods were compared with results of urine, perineal, and rectal cultures. In the retrospective review of GBS LA testing performed on 113 consecutive urine specimens collected by SBA from neonates being evaluated for suspected sepsis, the sensitivity and specificity were 67% and 89%, respectively, when compared with blood culture results. Twelve infants who had a positive LA test result but a sterile blood culture (BC-,LA+) were compared with 95 infants with both blood cultures and urine LA tests negative for GBS (BC-, LA-). BC-, LA+ infants were more likely than those with BC-, LA- to have an immature to total neutrophil (I/T) ratio > or = 0.16 at 12 and 24 hours (p = 0.04 and 0.02, respectively). In the prospective study, we found that a positive GBS LA test can be due to perineal contamination and possibly to gastrointestinal absorption of GBS antigen. No false positive LA test results occurred on urine obtained by SBA; however, use of this method failed to detect the one infant with GBS bacteremia. Because of suboptimal sensitivity and specificity, use of the GBS LA test on urine obtained either by SBA or bag cannot be recommended for diagnosis of early onset GBS disease.

Effect of specimen storage, antibiotics, and feminine hygiene products on the detection of Group B Streptococcus by culture and the STREP B OIA test

Agar culture from vaginal swabs is the routine method for diagnosis of maternal Group B Streptococcus (GBS) colonization. Swab specimens are often transported to a clinical laboratory for processing. In these studies, specimen transport was simulated by inoculating swabs with GBS and storing them at selected temperatures and with or without transport medium. The recovery of viable GBS was assessed by agar culture. GBS antigen was detected immunologically with an Optical ImmunoAssay (OIA®) method. Swabs that were stored with transport medium harbored viable but rapidly declining numbers of GBS. In contrast, a strong OIA signal was maintained. Recovery of viable GBS organisms declined more quickly when swabs were stored in the absence of transport medium, whereas detection of GBS antigen remained consistent. Both methods were tested for interference from either antibiotics or feminine hygiene products. These compounds inhibited the detection of GBS by culture but had no detrimental effect on the OIA result.

Sensitivity of intrapartum group B streptococcal screening and in vitro comparison of four rapid antigen tests

Objectives: To evaluate the sensitivity of intrapartum screening for group B streptococcal (GBS) colonization and to compare 4 rapid GBS antigen tests in vitro. Design: Two swabs of the lower vagina of 769 parturients were taken; one swab was cultured, the other was frozen at −70 °C until antigen testing with the Group B Strep Test (Quidel) of the culture positive samples was performed. The Quidel test was then compared with 3 other rapid GBS antigen tests in vitro: Wellcogen Strep B (Wellcome Diagnostics), Slidex méningite Strepto B (bioMérieux) and ICON Strep B (Hybritech). The supernatant of 29 GBS cultures in Todd-Hewitt broth was tested in bacterial concentrations of 10 6, 10 7, and 10 8 Colony-Forming Units (CFU)/ml, respectively. Results: Lower vagina GBS carrier rate was 13.4% ( 103 769 ) and heavy colonization (growth density 3 and 4 on blood agar plates) was found in 5.2% ( 40 769 ). The Group B Strep Test detected 11% ( 11 103 ) of GBS carriers, with a sensitivity for heavy colonization of 25% ( 10 40 ). In vitro none of the tests scored positively with a concentration of 10 6 CFU/ml, while with 10 7 CFU/ml the enzyme immunoassay tests (Quidel, Hybritech) were more sensitive (McNemar test, P < 0.05) than the latex agglutination tests (Wellcome Diagnostics, bioMérieux). Conclusions: Although in vitro the enzyme immunoassay tests are more sensitive than the latex agglutination tests, sensitivity in vivo is too low to recommend the use of rapid antigen tests for general screening.

False-negative urine latex particle agglutination testing in neonates with group B streptococcal bacteremia. A function of improper test implementation?

Although blood cultures remain the most specific indicator of Group B streptococcus (GBS) sepsis, a potentially life-threatening infection in neonates, test results may not be available for 24 to 48 hours. Detection of GBS antigen in the urine by latex particle agglutination (LPA) may speed diagnosis. This study analyzed the sensitivity of the GBS urine LPA assay under clinical conditions. The urine of neonates with early-onset GBS bacteremia was analyzed for GBS antigen over a three-year period at six military medical centers. Overall, 53.5% (38/71) of infants with positive blood cultures had a positive urine LPA test. Only one medical center routinely followed manufacturer's recommendations to concentrate urine specimens before testing. These data suggest that the sensitivity for the urine LPA assay, when performed on unconcentrated urine, is lower than previously reported. Clinicians should insist that the laboratory maximize sensitivity by concentrating urine prior to GBS LPA testing.

Management of asymptomatic, term gestation neonates born to mothers treated with intrapartum antibiotics

Intrapartum antibiotics are frequently administered to parturient women for suspected chorioamnionitis to treat infection in the mother and to prevent or treat infection in the baby. We sent a questionnaire to the 150 United States fellowship program directors in neonatology and pediatric infectious disease, focusing on recommendations for evaluation and therapy of apparently healthy, pretreated, term gestation infants. Eighty-three (55%) of the completed responses were analyzed. Sixteen (19%) respondents do no initial laboratory evaluation but simply observe the baby, 65 (78%) take a complete blood count as well as a platelet count, 59 (71%) obtain blood cultures, 41 (49%) check urine antigen for Group B Streptococcus (GBS) and 23 (28%) perform a lumbar puncture. Only 39% of respondents would begin antibiotic therapy for all pretreated infants. If the evaluation were unremarkable 65 directors would treat for less than or equal to 3 days. If only the urine GBS antigen were positive 47 would treat for greater than or equal to 7 days, while if an elevated immature neutrophil:total neutrophil ratio were the sole abnormality 19 would treat for greater than or equal to 7 days. Forty-four respondents thought that a combination of an elevated immature neutrophil:total neutrophil ratio and a positive urine GBS antigen should always be considered indicative of bacteremia. Given a different scenario, that of a mother treated with intrapartum antibiotics because of a positive cervical culture for GBS and a risk factor (e.g. temperature greater than or equal to 38 degrees C), 58 respondents would begin antibiotics. There is no consensus regarding management of pretreated, healthy appearing, term gestation neonates.

Intravenous Gamma Globulin as Adjunct Therapy for Severe Group B Streptococcal Disease in the Newborn

Group B streptococcal (GBS) disease remains a significant cause of morbidity and mortality among newborns despite aggressive antibiotic and supportive therapy. Recent success with the prophylactic use of intravenous gamma globulin (IVIg) in newborns suggests that use of IVIg may be an additional therapy for infants with severe GBS disease. Eighty-four infants with GBS antigen in serum, urine, and in some cases spinal fluid were identified by a rapid latex agglutination assay. Twenty-four of these infants had both neutropenia and serum GBS antigen titers of 1:10 or greater and had the highest risk of dying from their infection. Before the availability of IVIg, seven of the first 12 of these infants identified with the highest risk factors died (58%). Twelve additional patients with these highest risk factors have been treated with IVIg. Two of these 12 died (17%), p less than 0.01 when compared with the previous highest risk group. In surviving patients in both IVIg-treated and non-IVIg-treated groups, the time for recovery from neutropenia was 2 to 4 days. Our study suggests a possible beneficial effect of IVIg as adjunct therapy in severe GBS disease.

Effect of group B streptococcal type-specific antigen on polymorphonuclear leukocyte function and polymorphonuclear leukocyte-endothelial cell interaction.

Neonatal group B streptococcal pneumonia is a severe disease, often resulting in death. Autopsy findings resemble those of hyaline membrane disease. Numerous organisms may be seen in the alveoli, but few polymorphonuclear leukocytes (PMNs) are found in the areas of bacterial invasion. Aggregated PMNs are often found, however, in the pulmonary capillaries. This study was designed to explore the effect of the group B streptococcal (GBS) type III antigen on PMN chemotaxis and PMN-endothelial cell interactions. Human PMNs were isolated and pretreated with 0.25 to 4 micrograms/ml of GBS type III antigen prior to determining their chemotactic response to the chemoattractants formyl-methionyl-leucyl-phenylalanine, zymosan-activated serum, platelet-activating factor, and leukotriene B4. The GBS antigen caused a concentration-dependent inhibition of formyl-methionyl-leucyl-phenylalanine, zymosan-activated serum, and platelet-activating factor-mediated chemotaxis (% inhibition of 38.1 +/- 4.0, 55.5 +/- 3.3, 46.7 +/- 9.7%, respectively; p less than 0.01). Leukotriene B4-mediated chemotaxis was not significantly depressed (21.2% +/- 7.7 inhibition; NSD). Group B streptococcal antigen also inhibited formyl-methionyl-leucyl-phenylalanine-induced PMN adherence to endothelial cells in a concentration-dependent fashion when incubations were performed in the absence of serum. In contrast, incubation of GBS type III antigen with serum deficient in antibody to GBS resulted in a marked enhancement of PMN attachment to human endothelial cells. No significant enhancement of adherence was sen with the antigen in the presence of serum containing GBS type III antibody. These data suggest that the GBS type III antigen by itself may inhibit the influx of PMNs into the local site of infection in the alveoli.(ABSTRACT TRUNCATED AT 250 WORDS)