Group B Streptococcus In Women Research Articles

Detection of group B Streptococcus (GBS) in pregnant women by SYBR Green real-time PCR

Objectives: Application of SYBR Green real-time PCR and bacterial isolation methods to detect Streptococcus agalactiae (GBS) carriage in women at 35-37 weeks’ gestation. Patients and Method: Use of SYBR Green real-time PCR and bacterial isolation methods to detect GBS in 116 women at 35 - 37 weeks’ gestation. Results: The rate of carrier of GBS in women at 35 - 37 weeks gestation was 9.5% (11 pregnant women), in which real-time PCR method was positive in all positive GBS women, while bacterial culture method was positive at 6% (7 pregnant women). These methods (culture and real-time PCR) had substantial agreement with the value of Kappa is 0,77. Checking for the targeted sequence amplification of real-time PCR by the curve of melting temperature and agarose electrophoresis of amplified product, the real-time PCR product was correctly targeted at the expected genetic sequence. Conclusion: SYBR Green real-time PCR method for detecting GBS in pregnant women is useful, low-cost and easy for performing. Therefore, it is suitable for detecting GBS in diagnostic laboratories where real-time PCRs are available. Key words: Streptococcus agalactiae (GBS), real-time PCR, pregnant woman

Comparison of Culture and PCR Methods for Diagnosis of Group B <i>Streptococcus</i> in Women

Group B Streptococcus (GBS), as a risk factor for newborns, is one of the most important causes of meningitis and septicaemia in newborns, intrauterine infections in women and colonization in the vaginal region in late gestation. We evaluate GBS prevalence and infection among pregnant women through culture and PCR methods, and then compare these methods. To this end, vaginal and urine swabs were separately collected from 246 women at the Women’s Hospital of Sari, Iran. Next, the samples were enriched in selective culture media Todd–Hewitt broth for 24 h at 37°C, recognized using blood agar media, and finally were amplified STREP gene by PCR technique. The indicated that the frequency of GBS in samples collected from urine and vaginal cultures and PCR method was positive. In addition, no significant relationship was found among the positive results of culture, maternal age, gestational age, a history of abortion and infection. With regard to the cultivation method as a standard technique, the sensitivity of PCR test was 100% and specificity was 96%. Moreover, it was found that the colonization rate of GBS in women was significant in Sari. Therefore, PCR is recommended as a reliable and rapid method for detection of GBS.

CRISPR: A Useful Genetic Feature to Follow Vaginal Carriage of Group B Streptococcus.

Clustered regularly interspaced short palindromic repeats (CRISPR) and Cas (CRISPR-associated proteins) play a critical role in adaptive immunity against mobile genetic elements, especially phages, through their ability to acquire novel spacer sequences. Polarized spacer acquisition results in spacer polymorphism and temporal organization of CRISPR loci, making them attractive epidemiological markers. Group B Streptococcus (GBS), a genital commensal for 10 to 30% of healthy women and a major neonatal pathogen, possesses a ubiquitous and functional CRISPR1 locus. Our aim was to assess the CRISPR1 locus as an epidemiological marker to follow vaginal carriage of GBS in women. This study also allowed us to observe the evolution of the CRISPR1 locus in response to probable phage infection occurring in vivo. We followed carriage of GBS among 100 women over an 11-year period, with a median duration of approximately 2 years. The CRISPR1 locus was highly conserved over time. The isolates that show the same CRISPR1 genotype were collected from 83% of women. There was an agreement between CRISPR genotyping and other typing methods [MLVA (multilocus variable number of tandem repeat Analysis) and MLST (multilocus sequence typing)] for 94% of the cases. The CRISPR1 locus of the isolates from 18 women showed modifications, four of which acquired polarized spacer, highlighting the in vivo functionality of the system. The novel spacer of one isolate had sequence similarity with phage, suggesting that phage infection occurred during carriage. These findings improve our understanding of CRISPR-Cas evolution in GBS and provide a glimpse of host-phage dynamics in vivo.

Synergistic Effect Between Two Bacteriocin-like Inhibitory Substances Produced by Lactobacilli Strains with Inhibitory Activity for Streptococcus agalactiae

Group B streptococci (GBS) are bacterial species that colonize the vagina in pregnant women and as such may cause serious infections in neonates that passed through the birth channel. The objective of this work was to study the inhibitory activities produced by each bacteriocin-like inhibitory substance (BLIS) of Lactobacillus rhamnosus L60 and Lactobacillus fermentum L23, and the effects of the combined BLIS-es of these lactobacilli on GBS. The interactions between the BLIS-es were assessed by qualitative and quantitative methods on agar plates. The minimum inhibitory concentrations (MICs) and fractional inhibitory concentrations (FICs) were determined by a modification of the broth microdilution and checkerboard methods, respectively. Antibiotic susceptibilities of all S. agalactiae strains were assayed and the results of these tests were evaluated for statistical significance. A 7.5% of GBS isolates were recovered from 760 pregnant women and 91% of those strains were susceptible to each BLIS produced by L. fermentum, L. rhamnosus, and also to a mixture of them. The comparisons among the BLIS-es showed statistically significant differences, with a combination of the BLIS-es from the two Lactobacillus species being better than the BLIS of each one alone (P < 0.05) as GBS growth inhibitors. Synergistic activities between the BLIS-es were found on 100% of susceptible GBS strains, MICs ranges of BLIS of L23 and L60 were 80-160 and 160-320 UA ml(-1), respectively. By the checkerboard method, the BLIS-es combination showed synergistic effect on all sensitive strains tested, with values of FICs ranging from 0.131 to 0.218. The BLIS-es produced by these lactobacilli of vaginal origin were able to inhibit S. agalactiae isolates. The results indicate that these strains may have probiotic potential for the control of GBS in women and may consequently prevent GBS infections in newborns.

Development of a Rapid PCR Assay for Screening of Maternal Colonization by Group B Streptococcus and Neonatal Invasive Escherichia coli during Labor

Objective: Group B Streptococcus (GBS) and Escherichiacoli(E. coli) are the leading causes of early-onset neonatal disease (EOD). Intrapartum antibiotic prophylaxis of GBS-colonized women decreases vertical transmission and EOD due to GBS. Nevertheless, no intervention has been developed to reduce the risk of EOD related to E. coli. Timely and accurate identification of colonized mothers is necessary to implement preventive strategies against neonatal sepsis. To screen for colonization during labor, we developed a real-time PCR assay for the simultaneous detection of GBS and neonatal invasive strains of E. coli. Study Design: Specific DNA targets for GBS are publicly available. For neonatal invasive E. coli, we analyzed candidate DNA targets by DNA hybridization on microarrays of invasive strains isolated from neonatal E. coli sepsis or meningitis (K1 and not K1 ‘invasive’ serotypes). Specificity of DNA probes was tested against a panel of bacteria and by simulating clinical conditions (spiking vaginal samples from pregnant women). Then, the characteristics of the selected probes were evaluated in a pilot study including 200 women in labor. Results: Prevalence of rectovaginal GBS and of vaginal and cervical E. coliserotype K1 colonization were 16.0, 3.5 and 3.5% by culture and 27, 10 and 8.5% by PCR, respectively. The prevalence of other invasive E. coli in the vagina and in the cervix, detected by PCR, was around 10%. Compared to the culture, considered as the gold standard, the sensitivities of the PCRs for the GBS and E. coli K1 were 97 and 71%, respectively. Specificities were 86 and 92%, respectively. Specificity is difficult to interpret, as a false-positive PCR result may in fact be a false-negative result of the culture. The turnaround time needed for PCR analysis was 2.5 h, compared to a minimum of 48 h for the culture. Conclusion: Our rapid PCR is reliable in detecting GBS in women in labor. Optimization of the PCR for invasive E. coli is needed before its implementation in clinical practice. More efforts to fight against main causes of neonatal sepsis need to be undertaken to prevent this terrible medical complication.

Real-Time PCR Assay Provides Reliable Assessment of Intrapartum Carriage of Group B Streptococcus

The objective of this study was to determine the reliability of the real-time PCR assay for determining the group B Streptococcus (GBS) status of women in labor. In this prospective study we compared the results of culture and PCR testing of vaginal and rectal samples collected by nursing staff when women were in labor. Patients' charts were also reviewed to obtain relevant information about pregnancy risk factors. Our results demonstrated a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 90.5%, 96.1%, 86.4%, and 97.4%, respectively, for rapid PCR. Of the 196 women evaluated, 29 (14.8%) presented with unknown GBS status, 11 (37.9%) of whom received unnecessary intrapartum antibiotics. The rapid real-time PCR test was robust and was able to reliably detect the presence of GBS in women in labor within 1 h of specimen submission to the laboratory. We recommend that the rapid PCR test be targeted to women who present in labor with unknown GBS status. In cases where the laboratory does not offer 24-h availability of testing, sample collection followed by PCR testing the next morning is still valuable and provides reliable results 24 to 48 h faster than culture and will aid appropriate decision-making regarding continuing or stopping antibiotics for neonates of women with unknown GBS status.

Low carriage rate of group B streptococcus in pregnant women in Maputo, Mozambique

The prevalence of group B streptococcus (GBS) carriage varies strongly with geographical region. A study was done to determine the prevalence of GBS in women in Maputo, Mozambique. The method used was a rectovaginal swab which was taken from women between 35 and 37 weeks of pregnancy who visited the clinic for antenatal consultation. GBS was cultured from 2 out of 113 samples, yielding a prevalence of 1.8% (95% Cl: 0.0-4.0). In conclusion, the prevalence of GBS carriage among pregnant women in Maputo, Mozambique was low.

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 …

Detection and identification of group B streptococci by use of pigment production.

Pigment production by group B streptococci (GBS) is a useful test for identification of the organisms. The test is positive in 99.5% of beta-haemolytic strains. No false-positives are noted. Non-haemolytic strains do not produce pigment. Islam's media less agar can be used as a one-step broth detector of GBS in mixed cultures. This may have application for the detection of GBS in women in labour. When used as an identification system for GBS, serum-starch broth can be further modified by reduction of serum and starch concentrations by at least 80%.