Streptococcal Colonization Research Articles

Group B Streptococcal Colonisation among Antenatal Women from a Tertiary Care Centre, Northern Kerala: A Cross-sectional Study

Introduction: Group B Streptococcus (GBS) is the leading cause of neonatal sepsis all over the world. Maternal colonisation of GBS in vaginal and anorectal area poses risk for subsequent invasive disease. The prevalence of maternal colonisation varies with geographical, biological and socio-economical factors. Current recommendations consider maternal screening and antibiotic therapy to prevent GBS neonatal disease with a potential of alteration of infant gut flora. Aim: To find out the prevalence, outcome and antimicrobial susceptibility pattern of the GBS colonisation in antenatal women. Materials and Methods: A hospital-based descriptive crosssectional study was conducted in Government Medical College, Kozhikode, Kerala, India, during December 2017 to May 2019 including 300 antenatal women of 35-37 weeks gestational age. Vaginal and rectal swabs were taken and were subjected to microbiological examination and culture. Data analysis was done by Statistical Package for the Social Sciences (SPSS) version 16.0. The Chi-square test and Fisher’s exact test were used wherever applicable and p-value <0.05 is considered significant. Results: Among the 300 antenatal women, 8 (2.7%) were colonised with GBS. Higher rate of colonisation was observed in women of 21-25 years, higher parity, rural dwelling and in women with poor glycaemic control. All the colonised women received antibiotic prophylaxis with intravenous ampicillin. None of the colonised women or the neonates born to them developed any invasive GBS infection. Antibiotic susceptibility testing showed that all the isolates were sensitive to penicillin, ampicillin and vancomycin but only 62.5% of the isolates were susceptible to clindamycin and 37.5% of the isolates were susceptible to erythromycin. Conclusion: The prevalence of GBS colonisation is low in Asian countries, compared to the data from western countries. Evidence based usage of narrow spectrum antibiotics should be considered. Further studies regarding prevalence, antibiotic susceptibility pattern, cost benefit analysis of the antibiotic usage and its effect on neonatal gut flora etc, including a wider population, is a need of the hour in the setting of emergence of resistance.

Evaluation of PCR technique as a rapid screening method for detection of group B streptococci colonization in pregnant women

Evaluation of PCR technique as a rapid screening method for detection of group B streptococci colonization in pregnant women

Group B Streptococcal Infection in Jeddah, Saudi Arabia: Maternal Colonization and Neonatal Infection

The existence of Group B Streptococcus (GBS) in the rectovaginal area during pregnancy and labor is linked to disease and even death in neonates. However, the extent of GBS colonization in pregnant women in Saudi Arabia has not been fully established. The goal of this study was to ascertain the prevalence of Group B Streptococcus (GBS) colonization in pregnant women in Saudi Arabia, where GBS screening is not routinely conducted. This retrospective study involved 1201 Saudi women at ≥28 weeks

A Retrospective National Study on Colonization Rate and Antimicrobial Susceptibility of Streptococcus agalactiae in Pregnant Korean Women, 2018-2020.

PurposeThe prevalence of Group B Streptococcus (GBS) colonization in pregnant Korean women is increasing; however, nationwide studies are lacking. Therefore, we aimed to analyze regional colonization rates and antimicrobial susceptibility for GBS in pregnant Korean women through a nationwide survey.Materials and MethodsFrom January 2018 to December 2020, data from the Seoul Clinical Laboratories on vaginal swab cultures were retrospectively analyzed to detect maternal GBS carriers. Each swab specimen was inoculated onto a 5% blood agar plate and incubated at 35℃–37℃ in a 5% CO2 incubator for 24 h. GBS isolates were identified using a Microflex MALDI Biotyper. Antimicrobial susceptibility tests were performed using the Vitek 2 automated system.ResultsThe overall nationwide GBS colonization rate in pregnant Korean women was found to be 10.6% (3578/33721). The maternal GBS colonization rates ranged from 10.5%–10.8% over the 3-year study period. The GBS colonization rates by province, in descending order, were as follows: Jeolla-do, 13.2%; Gangwon-do, 12.0%; Chungcheong-do, 11.8%; Gyeonggi-do, 11.3%; Seoul, 10.2%; and Gyeongsang-do, 9.6%. During the study period, the resistance rates against chloramphenicol, levofloxacin, clindamycin, erythromycin, and tetracycline were 2.6%–2.7%, 18.2%–19.6%, 33.4%–35.7%, 35.6%–36.8%, and 50.5%–53.3%, respectively.ConclusionIn pregnant Korean women, GBS colonization rates were in the range of 9.6%–13.2%, with Gyeongsang-do being the lowest and Jeolla-do the highest. The resistance rate against clindamycin was high (33.4%–35.7%). GBS colonization rates during pregnancy should be studied nationwide according to the Centers for Disease Control and Prevention-recommended guidelines with periodic antimicrobial resistance monitoring.

Association of upper airway bacterial microbiota and asthma: systematic review.

Individual studies have suggested that upper airway dysbiosis may be associated with asthma or its severity. We aimed to systematically review studies that evaluated upper airway bacterial microbiota in relation to asthma, compared to nonasthmatic controls. Searches used MEDLINE, Embase, and Web of Science Core Collection. Eligible studies included association between asthma and upper airway dysbiosis; assessment of composition and diversity of upper airway microbiota using 16S rRNA or metagenomic sequencing; upper airway samples from nose, nasopharynx, oropharynx or hypopharynx. Study quality was assessed and rated using the Newcastle-Ottawa scale. A total of 249 publications were identified; 17 in the final analysis (13 childhood asthma and 4 adult asthma). Microbiome richness was measured in 6 studies, species diversity in 12, and bacterial composition in 17. The quality of evidence was good and fair. The alpha-diversity was found to be higher in younger children with wheezing and asthma, while it was lower when asthmatic children had rhinitis or mite sensitization. In children, Proteobacteria and Firmicutes were higher in asthmatics compared to controls (7 studies), and Moraxella, Streptococcus, and Haemophilus were predominant in the bacterial community. In pooled analysis, nasal Streptococcus colonization was associated with the presence of wheezing at age 5 (p = 0.04). In adult patients with asthma, the abundance of Proteobacteria was elevated in the upper respiratory tract (3 studies). Nasal colonization of Corynebacterium was lower in asthmatics (2 studies). This study demonstrates the potential relationships between asthma and specific bacterial colonization in the upper airway in adult and children with asthma.

Prevalence of Group B Streptococcus Colonization among Pregnant Women and Feto-Maternal Outcomes in a Tertiary Health Institution, North-Western Nigeria

Background: Group B Streptococcus (GBS) infection is a major cause of bacterial infections in the peri-natal period. These include amnionitis, urinary tract infections and endometritis. At birth, 50-60% of the neonates born to colonized mothers have positive cultures taken from mucus membranes and the skin. Aim: The aim of this study is to determine prevalence of GBS colonization and compare the maternal and perinatal outcomes among GBS positive and GBS negative women within 7 days postpartum. Methodology: This was a longitudinal study among pregnant women between 35-37 weeks gestation attending antenatal clinic at Usman Danfodiyo University Teaching Hospital, Sokoto. Vaginal and rectal swabs were taken from the participants and cultured for growth of Group B Streptococcus within 24 hours. The participants were followed up to 7 days post-delivery with their newborns to determine the maternal and early neonatal outcomes. Results: One hundred and eighty five (185) women were recruited and 159 (85.9%) participants were available for follow-up to determining feto-maternal outcomes. Among the participants, 3.8% (7) had GBS vaginal colonization. There was no single case of early neonatal infection, intensive neonatal resuscitation nor neonatal mortality among both GBS positive and GBS negative women. Conclusion: It has been found that the prevalence of maternal GBS colonization during pregnancy was low and neither GBS colonization nor GBS non-colonization was associated with poor maternal or poor fetal outcomes.

The association of Group B Streptococcus colonization with cerclage and suture material

Changes in the vaginal environment have been shown to affect rates of Group B Streptococcus (GBS) colonization. It is possible that cerclage, a foreign body, alters the vaginal environment and changes susceptibility to GBS. Our objective was to compare GBS colonization rates in women with and without transvaginal cerclage, as well as among women with a cerclage using Mersilene versus Prolene suture.

Vaginal Group B Streptococcal Colonization Not Associated With Chorioamnionitis In Laboring Patients

Multiple studies have reported increased rates of chorioamnionitis associated with group B streptococcal (GBS) colonization. We sought to estimate the risk of chorioamnionitis associated with GBS positive status in term laboring patients. This is a retrospective cohort study of term (≥37 weeks), singleton pregnancies who labored at our tertiary care center from 2005 to 2018. The primary outcome of chorioamnionitis was defined as maternal intrapartum fever (single oral temperature of >39°C or 38–38.9°C for 30 minutes) and one or more of the following: maternal leukocytosis, purulent cervical drainage, or fetal tachycardia. The primary exposure was GBS colonization in the medical record. Cox proportional hazard regression was used to model the effect of GBS on the risk of chorioamnionitis while adjusting for number of cervical exams, epidural use, meconium, smoking, parity, BMI, duration of rupture, labor induction and cesarean section. 19,688 individuals met inclusion criteria and 981 (5%) patients met criteria for clinical chorioamnionitis. Of the subjects diagnosed with chorioamnionitis, 188 (19.2%) were GBS positive compared to 25.2% in those not diagnosed with infection (p < 0.001). GBS colonization was not associated with an increased rate of chorioamnionitis after adjusting for potential confounders (hazard ratio [HR] 0.6, 95% confidence interval [CI] 0.5-0.7; p= < 0.001). GBS colonization rates were higher among patients undergoing unplanned cesarean delivery (Vaginal: 12.0% vs Cesarean: 13.4%, p=0.01). Meconium rates were similar between the two groups (GBS positive: 19.0% vs GBS negative: 19.4%, p=0.06). In contrast to previous reports, GBS colonization in laboring patient did not increase the risk of chorioamnionitis. Individuals with positive GBS status should not be counseled on increased risk of chorioamnionitis.

Prevalence and Risk Factors of Group B Streptococcus Colonization in Pregnant Women: A Pilot Study in Palestine.

Background Maternal Streptococcus agalactiae (Group B Streptococcus (GBS)) colonization is an important cause of complications in mothers and neonates during gestation and after delivery. The data regarding GBS colonization among pregnant women in Palestine is scarce. The aim of this study is to determine the prevalence of GBS colonization, its associated risk factors, and the antibiotic sensitivity patterns in Nablus, West Bank, Palestine. Methods A cross-sectional, single center study conducted at Rafidia Governmental Hospital in Nablus, West Bank, Palestine. Samples were collected between November 2019 and January 2020. Vaginal swabs from 200 pregnant women (≥35 weeks of gestation) attending the labor and delivery department were plated directly on CHROMagarTM StrepB (CHROM agar, France) and placed in an incubator at 35–37°C. After 24 and 48 hours, the plates were checked for growth and classified into three categories: growth of GBS with mauve colonies on chromogenic media, no growth, or other growth. The identification of the mauve colonies was confirmed by the CAMP test. Identified GBS isolates were tested for susceptibility to vancomycin, ampicillin, clindamycin, cefotaxime, erythromycin, and levofloxacin using the disc diffusion method. Clinical and demographic information were collected using a questionnaire. Result The overall prevalence of GBS colonization was 12%. The median age of the study population was 27 years. GBS colonization was significantly associated with age (p=0.013), history of previous preterm delivery (p=0.013), and parity (p=0.015). No association was noted with smoking, previous abortion, previous history of fetal demise, vaginitis, or urinary tract infection. Resistance to ampicillin, vancomycin, cefotaxime, erythromycin, clindamycin, and levofloxacin was found to be 91.7%, 54.2%, 45.8%, 29.2%, 25%, and 8.3%, respectively. Conclusion The prevalence of vaginal GBS in this study was 12% from Nablus, West Bank. Further research is needed to determine the GBS serotypes common in West Bank and the burden they cause on the health system. Moreover, this study also highlights the need to establish a screening program suited to a developing country with low control on the antibiotic's prescription protocols.

Group B Streptococcus vaginal colonization in pregnant women living with HIV infection: prevalence and antibiotic susceptibility at HIV referral centers in Lagos, Nigeria

Objectives Group B Streptococcus (GBS) colonization of the genital tract is often asymptomatic yet associated with increased risks of maternal and neonatal morbidity especially amongst women living with HIV infection. The objectives of this study were to determine the prevalence of GBS colonization of the genital tract in women living with HIV infection and antibiotic susceptibility of GBS in the genital tract. Method This cross-sectional study recruited 244 pregnant women (122 women living with HIV infection and 122 HIV-uninfected women) between 35 and 37 weeks of gestation. GBS colonization was determined by collecting lower vaginal and anal swabs at recruitment. Swabs were cultured in Todd Hewitt’s broth and confirmed by Christie, Atkins, and Munch-Peterson (CAMP) test. Most recent CD4 count and viral load estimates were retrieved from the women’s records. Maternal and neonatal outcomes and antibiotic susceptibility were assessed. Statistical analysis was performed at 95% confidence interval at a statistical significance of p < .005 Results The prevalence of GBS colonization of the genital tract in all participants was 3.3%; GBS was isolated in 4 (3.3%) of 122 pregnant women living with HIV. No woman with a GBS-colonized genital tract developed puerperal sepsis and no neonatal infection occurred in neonates born to GBS-positive women, irrespective of HIV infection status. In women living with HIV, GBS isolate was resistant to Ampicillin (100%), Ceftriaxone (100%), Vancomycin (100%), yet partially sensitive to Ciprofloxacin (50%). Conclusion Pregnant women living with HIV do not have an increased risk of genital GBS colonization. Vaginal GBS colonization was not associated with an adverse perinatal outcome. Antibiotic use for GBS colonization should be based on sensitivity pattern and not empiric.

Group B Streptococcal Colonization in African Countries: Prevalence, Capsular Serotypes, and Molecular Sequence Types.

Streptococcus agalactiae or group B streptococcus (GBS) is a commensal of the gastrointestinal and genitourinary tracts of healthy women and an important cause of neonatal invasive infections worldwide. Transmission of bacteria to the newborn occurs at birth and can be prevented by intrapartum antibiotic prophylaxis. However, this not available in resource limited settings in Africa, which carries a particular high burden of disease. Serotype based vaccines are in development and present a suitable alternative to prevent neonatal infections. To be able to assess vaccine efficacy, knowledge and surveillance of GBS epidemiological data are required. This review summarizes investigations about the serotype distribution and the multi-locus sequence types (MLST) found in different African countries. While most serotypes and MLST data are comparable to findings from other continents, some specific differences exist. Serotype V is predominant among colonizing maternal strains in many different African countries. Serotypes that are rarely detected in western industrialized nations, such as serotypes VI, VII and IX, are prevalent in studies from Ghana and Egypt. Moreover, some specific MLST sequence types that seem to be more or less unique to Africa have been detected. However, overall, the data confirm that a hexavalent vaccine can provide broad coverage for the African continent and that a protein vaccine could represent a promising alternative.

Evaluation of the Revogene® GBS DS assay performance for the intrapartum screening of group B streptococcus in comparison with intrapartum culture

Prevention of perinatal Group B Streptococcus (GBS) transmission is crucial in our effort to prevent Early-onset GBS disease. Here, we established the performance of the Revogene GBS DS assay for the detection of group B streptococcus on intrapartum vaginal samples in a laboratory environment using a prospective noninterventional study design. Intrapartum vaginal swabs were enriched using a selective culture method which served as study reference method. Overall, 119 patients were enrolled with an antenatal and intrapartum Group B Streptococcus colonization prevalence of 12.9% and 11.8%, respectively. Compared to intrapartum culture, the Revogene GBS DS assay had a sensitivity of 92.9% and a specificity of 99.1%, while the antenatal culture displayed a sensitivity 78.6% of and specificity of 96.2%. The Revogene GBS DS assay displayed an acceptable performance according to the European Group B Streptococcus consensus recommendations. Complementary studies in clinical practice are needed to confirm these findings.

Tea extracts inhibit the attachment of streptococci to oral/dental substrata by reducing hydrogen bonding energies

Previous work in the authors’ lab demonstrated that tea extracts significantly suppressed streptococcal colonization of abiotic substrata by coating the bacterial cell surfaces with tea components. In this study, the physico-chemical mechanisms by which the tea coating inhibits cellular attachment are demonstrated. The changes in the cell surface physico-chemical properties of streptococci, induced by tea extracts, were measured. Using these results, surface interaction energies were calculated between streptococcal cells and hard surfaces (glass, stainless steel, hydroxyapatite and titanium) within the cellular attachment system exploiting the extended Derjaguin-Landau-Verwey-Overbeek theory. The net energy outcomes were compared with experiment results of attachment assays to validate the predictability of the model. The results showed that the tea extracts inhibited the attachment of the bacteria by 11.1%–91.5%, and reduced the interaction energy by 15.4%–94.9%. It was also demonstrated that the abilities of the bacteria to attach to hard surfaces correlated well with their net interaction energies. The predominant interaction in the systems was found to be hydrogen bonding. In conclusion, tea extracts suppress streptococcal attachment to hard substrata by limiting the formation of hydrogen bonds.

Group B Streptococci Vaginal-Recto Colonization, Vertical Transmission to Newborns, Antimicrobial Susceptibility Profile and Associated Factors in Selected Health Facilities of Bahir Dar City: A Cross-Sectional Study.

BackgroundGroup B streptococci (GBS) is an important pathogen involved in stillbirths, neonatal deaths and neurological defects, and the occurrence of multi-drug resistance (MDR) is an alarming issue. This study determined the prevalence of GBS colonization in pregnant women and newborns, the proportion of vertical transmission, antimicrobial susceptibility profiles of isolates, and the factors associated with colonization and vertical transmission.MethodsA cross-sectional study was conducted from March 1, 2021 to June 30, 2021, at selected health facilities of Bahir Dar city. Vaginal-recto swabs from 292 pregnant women and pooled ear, nasal and umbilical swabs from 292 newborns were collected. GBS were identified following standard microbiological protocols. Antimicrobial susceptibility testing was performed using modified Kirby–Bauer disk diffusion method and interpreted by the accepted 2020 CLSI M100 guidelines. Logistic regression analysis was computed.ResultsOverall, 54 (18.5%) of pregnant women and 22 (7.5%) of newborns had GBS colonization. The proportion of GBS vertical transmission was 22 (40.7%). Group B Streptococcus isolates scored susceptibility to penicillin, ampicillin and vancomycin with 88.9%, 90.7%, and 96.3% for pregnant women and 86.4%, 90.9% and 95.9% for newborns, respectively. A high percentage of non-susceptibility was found for clindamycin and erythromycin with 33.3% and 25.9% for pregnant women and 31.8% and 22.7% from newborns, respectively. Besides, 19 (35.2%) GBS from pregnant women and 8 (36.4%) from newborns were MDR. Group B streptococci colonization was significantly associated with delivery before 37th week of gestation (AOR=2.77, 95% CI 1.14–6.68) and history of stillbirth (AOR=3.13, 95% CI 1.13–8.70).ConclusionPregnant women vaginal-recto GBS colonization and transmission to newborns connected with MDR are a matter of concerns. Although non-susceptible GBS isolates are obtained, penicillin and vancomycin are relatively effective. The use of clindamycin, erythromycin and ceftriaxone should be guided by antimicrobial susceptibility testing. Genetic analysis is recommended to exactly identify the epidemiology of GBS strains, vertical transmission and antimicrobial resistance at the country level.

Antibiotics at delivery: do the benefits outweigh the risks?

Antibiotics administered just before delivery or during the intrapartum period is common globally and recommendations for increased use continue to expand. Before the introduction of maternal screening and treatment for Group B Streptococcus (GBS) colonization to prevent neonatal GBS sepsis in the 1990's, maternal antibiotic treatment at delivery was used rarely, usually for confirmed maternal infections. With maternal screening for GBS, including a 20-25% positivity rate in the United States (US), antibiotic use at delivery increased substantially.(1) Antibiotics at delivery were subsequently recommended for women with prolonged membrane rupture and preterm labor. Recommendations expanded further with evidence that antibiotics reduced post-partum maternal infections associated with cesarean delivery.(2) And now, following a trial in The Gambia that suggested reduced maternal and neonatal infections, several large trials in low- and middle-income countries (LMICs) are evaluating whether widespread azithromycin treatment, not only for women undergoing cesarean delivery, but among all pregnant women, reduces maternal and neonatal morbidity and mortality.(3).

Probiotic interventions to reduce antepartum Group B streptococcus colonization: A systematic review and meta-analysis

ObjectiveTo systematically review and meta-analyse studies of the efficacy of probiotics to reduce antenatal Group B Streptococcus (GBS) colonisation. ParticipantsAntenatal participants with known positive GBS colonisation or unknown GBS status. InterventionProbiotic interventions containing species of Lactobacillus or Streptococcus. DesignSystematic review and meta-analysis. Measurements and findingsThe systematic review included 10 studies. Five articles contained in vitro studies of probiotic interventions to determine antagonistic activity against GBS. Six clinical trials of probiotics to reduce antenatal GBS were systematically reviewed and meta-analysed. The meta-analysis revealed that the use of an antenatal probiotic decreased the probability of a positive GBS result by 44% (OR = 0.56, 95% CI = 8.7%, 194.1%, p = 0.02) (n = 709). However, only one clinical trial of 10 had a low risk of bias. Key conclusionsThe probiotic interventions subjected to in vitro testing showed antagonistic activity against GBS through the mechanisms of acidification, immune modulation, and adhesion. The findings of the meta-analysis of the clinical trials revealed that probiotics are a moderately effective intervention to reduce antenatal GBS colonisation. More well-controlled trials with diverse participants and with better elucidation of variables influencing GBS colonisation rates are needed. Implications for practiceProbiotic interventions appear to be a safe and effective primary prevention strategy for antenatal GBS colonisation. Application of this low-risk intervention needs more study but may reduce the need for intrapartum antibiotic prophylaxis in countries or regions where antenatal GBS screening is used. Midwives can be instrumental in conducting and supporting larger well-controlled clinical trials.

Incremental risk of clinical chorioamnionitis associated with cervical examination

Clinical chorioamnionitis is associated with significant maternal and neonatal morbidity, yet there is no clear evidence on the association between cervical examinations and infection. We sought to assess the association between the number of cervical examinations performed during term labor management and the risk of clinical chorioamnionitis. This is a retrospective cohort study of term (≥37 weeks of gestation), singleton pregnancies who labored at our tertiary care center from 2014 to 2018. The primary outcome of clinical chorioamnionitis was defined as maternal intrapartum fever (single oral temperature of >39°C or 38°C-38.9°C for 30 minutes) and 1 or more of the following: maternal leukocytosis, purulent cervical drainage, or fetal tachycardia. The primary exposure was the number of digital cervical exams documented in the medical record. Log-binomial regression was used to model the effect of cervical examinations on the risk of clinical chorioamnionitis while adjusting for potential confounders. A total of 20,029 individuals met the inclusion criteria and 1028 (5%) patients experienced clinical chorioamnionitis. The number of cervical exams was associated with increased risk of developing infection after adjusting for potential confounders. Individuals with ≥8 cervical exams had 1.7 times the risk of developing clinical chorioamnionitis compared with those with 1 to 3 exams. Prolonged rupture time, nulliparity, Black race, Medicaid insurance, higher gestational age, and higher body mass index were associated with increased risk of clinical chorioamnionitis, whereas smoking and group B Streptococcus colonization were associated with a lower risk. Our study found that the number of cervical exams performed during labor is an independent risk factor for developing clinical chorioamnionitis. Unnecessary cervical exams should be avoided during labor management at term.

Prevalence and Factors Associated with Maternal Group B Streptococcus Colonization in Madagascar and Senegal.

Maternal group B Streptococcus (GBS) colonization is a major risk factor for neonatal GBS infection. However, data on GBS are scarce in low- and middle-income countries. Using sociodemographic data and vaginal swabs collected from an international cohort of mothers and newborns, this study aimed to estimate the prevalence of GBS colonization among pregnant women in Madagascar (n = 1,603) and Senegal (n = 616). The prevalence was 5.0% (95% CI, 3.9-6.1) and 16.1% (95% CI, 13.1-19.0) in Madagascar and Senegal, respectively. No factors among sociodemographic characteristics, living conditions, and obstetric history were found to be associated independently with GBS colonization in both countries. This community-based study provides one of the first estimates of maternal GBS colonization among pregnant women from Madagascar and Senegal.

Bacterial composition of subgingival plaque in crowded and noncrowded teeth

Patients with dental crowding, even with good oral hygiene, may show increased bacterial presence in the crowded area. This study aimed to determine the microbial composition of subgingival plaque in crowded and noncrowded dental regions. Forty dental students with anterior dental crowding, who were aware of correct brushing techniques and oral hygiene, were enrolled in this study. After orthodontic records were taken and the periodontal examination was performed, subgingival plaque samples were collected from the crowded (experimental) and noncrowded regions (control) of each patient. Colony counting was performed for Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), and streptococcus species. The mean amount of Aa and Pg colonies was significantly higher in crowded areas (P<0.0001), but there was no significant difference between streptococcus species colonization and crowding. Aa and Pg colonization had a significant direct relation with the amount of crowding. (P<0.0001). Crowded dental areas, even with good oral hygiene, are more suitable environments for Aa and Pg colonization.

Bacterial and Host Determinants of Group B Streptococcal Vaginal Colonization and Ascending Infection in Pregnancy.

Group B streptococcus (GBS) is a gram-positive bacteria that asymptomatically colonizes the vaginal tract. However, during pregnancy maternal GBS colonization greatly predisposes the mother and baby to a wide range of adverse outcomes, including preterm birth (PTB), stillbirth, and neonatal infection. Although many mechanisms involved in GBS pathogenesis are partially elucidated, there is currently no approved GBS vaccine. The development of a safe and effective vaccine that can be administered during or prior to pregnancy remains a principal objective in the field, because current antibiotic-based therapeutic strategies do not eliminate all cases of invasive GBS infections. Herein, we review our understanding of GBS disease pathogenesis at the maternal-fetal interface with a focus on the bacterial virulence factors and host defenses that modulate the outcome of infection. We follow GBS along its path from an asymptomatic colonizer of the vagina to an invasive pathogen at the maternal-fetal interface, noting factors critical for vaginal colonization, ascending infection, and vertical transmission to the fetus. Finally, at each stage of infection we emphasize important host-pathogen interactions, which, if targeted therapeutically, may help to reduce the global burden of GBS.