Several factors influencing the colonization of group B streptococci--rectum probably the main reservoir

Sexual activity, vaginal symptoms, maternal perineal hygiene behavior, and constipation on ano-vaginal colonization of group B streptococcus in near term pregnancy

BACKGROUND

Maternal Group B Streptococcus (GBS) colonization is influenced by many factors but results are inconsistent. Consideration of antenatal risk factors may help inform decision making on GBS microbiological culture screening where universal screening is not standard of care. We sought to identify independent predictors of GBS colonization at 34-37 weeks gestation incorporating vaginal symptoms, perineal hygiene measures, sexual activity, and a potential novel factor, constipation.

METHODS

In this prospective cross-sectional study, 573 women at 34-37 weeks gestation had an ano-vaginal swab taken and sent for selective culture for GBS. Women were asked about vaginal bleeding, discharge, irritation and candidiasis, antibiotic use during pregnancy, ano-vaginal hygiene practices such as douching and perineal cleansing after toileting, sexual intercourse related activities, and a potential novel factor for GBS carriage, constipation. Maternal basic demographics and obstetric-related characteristics were also collected. Bivariate analyses were performed to identify associates of GBS colonization. All variables with p < 0.05 found on bivariate analysis were then included into a model for multivariable binary logistic regression analysis to identify independent risk factors for GBS colonization.

RESULTS

GBS colonization was found in 235/573 (41.0%) of participants. Twenty six independent variables were considered for bivariate analysis. Eight were found to have p < 0.05. Following adjusted analysis, six independent predictors of GBS colonization were identified: ethnicity, previous neonatal GBS prophylaxis, antenatal vaginal irritation, antibiotic use, recent panty liner use, and frequency of sexual intercourse. Vaginal discharge and perineal cleansing were not associated after adjustment. Recent douching and constipation were not associated on bivariate analysis.

CONCLUSION

The identification of independent predictors of GBS colonization in late pregnancy may inform the woman and care provider in their shared decision making for microbiological screening at 35-38 weeks gestation in locations where universal GBS screening is not standard of care.

ETHICS OVERSIGHT

This study was approved by the Medical Ethics Committee of University Malaya Medical Centre (UMMC) on August 9, 2022, reference number 2022328-11120.

Prevalence of group B streptococcal colonization in the healthy non-pregnant population: a systematic review and meta-analysis

BACKGROUND

Colonization and transmission precede invasive group B streptococcal (GBS) disease. Data on GBS colonization prevalence, detection methods and risk factors for carriage are relevant for vaccine development and to understand GBS pathogenesis.

OBJECTIVES

To evaluate GBS colonization prevalence after the first week of life in the healthy non-pregnant population.

DATA SOURCES

Pubmed/Medline, Embase, Latin American and Caribbean Health Sciences Literature, World Health Organization Library Information System, and Scopus. Search performed 12 January 2021 with search terms related to 'GBS' and 'colonization, epidemiology, prevalence or screening' without restrictions.

STUDY ELIGIBILITY CRITERIA

All studies that reported prevalence of GBS colonization (any site) in the healthy population.

PARTICIPANTS

All individuals (>6 days of age), with no indication of pregnancy, invasive disease or severe underlying immunological co-morbidities.

METHODS

Logit transformation and a random effects model (DerSimonian and Laird) were used to pool colonization estimates. Subgroup analysis and meta-regression on a priori determined subgroups were performed.

RESULTS

We included 98 studies with 43 112 participants. Our search identified 9309 studies of which 8831 were excluded based on title and abstract and 380 after reading the full text. Colonization rates varied considerably between studies (I² = 97%), which could be partly explained by differences in culture methods (R² = 27%), culture sites (R² = 24%), continent (R² = 10%) and participant's age (R² = 6%). Higher prevalence was found with selective culture methods (19%, 95% CI 16%-23% versus non-selective methods 8%, 95% CI 6%-9%; p < 0.0001). Colonization rates were highest in rectum (19%, 95% CI 15%-24%), vagina (14%, 95% CI 12%-17%) and urethra (9%, 95% CI 5%-18%). In participants with negative rectal cultures, 7% (95% CI 5%-9%) had GBS cultured from another niche. Colonization prevalence was lower in children (6 months to 16 years; 3%, 95% CI 2%-5%) compared with adults (16%, 95% CI 14%-20%; p < 0.0001). Using selective culture methods in adults resulted in a prevalence of 26% (95% CI 19%-33%) rectal, 21% (95% CI 17%-25%) vaginal and 9% (95% CI 6%-14%) urethral colonization.

CONCLUSION

The rectum is the most common body site colonized by GBS. The best approach to screen for any GBS colonization is to screen multiple body sites using selective culture methods.

Risk factors for group B streptococcus colonization among pregnant women in Korea

OBJECTIVES

To identify obstetric and maternal factors related to Group B Streptococcus (GBS) colonization in pregnant women in Korea.

METHODS

The study was conducted between the years 2006-2008 in four hospitals, Cheil and Eulji hospital in Seoul, and Motae and Eulji hospital in Daejeon. We recruited 2,644 pregnant women between 35 to 37 weeks of gestation who had visited for antenatal care. Participants completed a questionnaire, and urine, vaginal and rectal specimens were obtained and cultured using selective broth media. After delivery, medical records were reviewed.

RESULTS

GBS colonization was significantly associated with hospital, age group, education, frequency of pregnancy, and premature rupture of membranes (PROM, more than 18 hours). After adjustment for other variables, Cheil hospital (odds ratio [OR], 2.05; 95% confidence interval [CI], 1.20-3.52), and the first pregnancy (OR, 2.32; 95% CI, 1.12-4.81) remained significant. History of vaginitis showed marginal significance (OR, 1.50; 95% CI, 0.98-2.29).

CONCLUSION

To prevent GBS infection of neonates, clinicians should be alert to the potentially higher risk of GBS colonization in pregnant women in their first pregnancy, and women with premature rupture of membranes (PROM) (18 hours+) or who have a history of vaginitis.

[Determinants of group B streptococcus maternal colonization and factors related to its vertical perinatal transmission: case-control study]

OBJECTIVES

To investigate the determinants of Group B streptococcus (GBS) maternal colonization, as well as factors associated with its vertical transmission.

PATIENTS AND METHODS

Case-control study on all singletons pregnancies delivered beyond at least 24 weeks of amenorrhoea in Southern Reunion maternities for which GBS screening was known. Multiple logistic regression analysis using 2004-2007 dataset of South Reunion birth registers.

RESULTS

Out of 17,430 women delivered between 1st January 2004 and 31st December 2007, 2911 (16.7%) carried GBS. In a model adjusted on antenatal care, risk groups for GBS carriage were the women indigenous from another island of the Indian Ocean than Reunion (OR: 1.29, CI95%: 1.05-1.57) and obese women (body mass index ≥ 30, OR: 1.19, CI95%: 1.03-1.18). Protective factors included birthplace in mainland France (OR: 0.82, CI95%: 0.69-0.97) and underweight (OR: 0.81; CI95%: 0.69-0. 95). In a model controlling for a composite obstetrical variable delineating the protective roles of C-section and antibioprophylaxis as well as the putative role of meconium-stained fluids (thin, thick or fetid), all previously found in our setting, three key factors were independently associated with GBS vertical mother-to-child transmission: obesity (OR: 1.48, CI95%: 1.05-2.09), fetal tachycardia (OR: 4.92, CI95%: 2.79-8.68) and late preterm birth (35 to 36 wks, OR: 2.14, CI95%: 1.32-3.45).

CONCLUSION

These findings strengthen the putative roles of corpulence and ethnicity in GBS acquisition previously found in the United States, while confirming an authentic role of obesity in its vertical transmission, independently of other classical cofactors lighted by our study.

Group B streptococci colonization in pregnant women: risk factors and evaluation of the vaginal flora

OBJECTIVE

To determine the prevalence of group B streptococci (GBS) in our population, and to assess the association between risk factors and vaginal flora with maternal rectovaginal colonization.

METHOD

Samples were obtained from 405 patients between 35 and 37 weeks of gestation. Swabs from the vaginal and perianal regions were cultured in Todd Hewitt and subcultured in blood agar. Colonies suggestive of GBS were submitted to catalase and CAMP test. The vaginal flora was evaluated on Gram stain vaginal smears. Socio-demographic and obstetric data were obtained by designed form. Considering maternal GBS colonization as the response variable, a logistic regression model was fitted by the stepwise method with quantitative and qualitative explanatory variables.

RESULTS

The prevalence of GBS colonization was 25.4%. The most frequent vaginal flora abnormalities were cytolytic vaginosis (11.3%), followed by bacterial vaginosis (10.9%), candidosis (8.2%) and intermediate vaginal flora II (8.1%). Logistic regression analysis revealed that maternal age, number of sexual intercourse/week, occurrence of previous spontaneous abortion, presence of candidosis and cytolytic vaginosis were associated with streptococcal colonization.

CONCLUSION

The prevalence of GBS is high in pregnant women and is associated with sexual intercourse frequency, previous spontaneous abortion and the presence of candidosis or cytolytic vaginosis.

Group B Streptococcus carriers among HIV-1 infected pregnant women: Prevalence and risk factors

OBJECTIVE

The objective was to determine the frequency and risk factors of anogenital colonization by Streptococcus agalactiae (GBS) in pregnant women infected with human immunodeficiency virus type 1 (HIV-1).

STUDY DESIGN

A prospective study was conducted on 207 pregnant women divided into two groups: HIV group (n=101) and a control group consisting of HIV-uninfected pregnant women (n=106) to assess regional colonization by GBS. Anal and vaginal swabs were collected and cultured in Todd-Hewitt broth, followed by a confirmatory test. For a control group with an anticipated proportion based on literature research of 10-30% and alpha=0.05, a sample size of 100 would have a power of 80% to detect a difference of 15% or greater with a study group. The mothers were studied in terms of frequency of anogenital colonization by GBS, maternal epidemiological data, and TCD4 lymphocyte counts. The results were analyzed using the chi(2)-test, Fisher's exact test and the Student's t-test, with the level of significance set at p<0.05.

RESULTS

Twenty (19.8%) HIV-1-infected pregnant women were found to be colonized by GBS at between 35 and 37 weeks' gestation. In the control group, the prevalence of GBS was 14.1%.

CONCLUSION

No significant increase in GBS colonization was observed in HIV-1-infected pregnant women. Maternal colonization of GBS in HIV-infected pregnant women was not found to be associated with their immunological status. Sexual contact does not seem to be the principal way of transmitting GBS.

Clinical safety-in-use study of a new tampon design

Objective: To confirm the safety of a new experimental Tampax^® tampon and applicator compared with that of a currently marketed Tampax^® tampon and applicator using comprehensive gynecological and microbiological assessments.

Methods: A 2-month, single-blind, randomized, crossover study was conducted in which each subject served as her own control. Safety was evaluated by comparing potential product-related irritation (using colposcopic examination and subject diary data), assessment of vaginal discharge, vaginal pH, and effects on selected microorganisms (yeast, Escherichia coli ,Staphylococcus aureus and group B streptococci) obtained by vaginal swab cultures after normal menstrual use in the experimental and control groups.

Results: In total, 110 women completed the study. There were no significant differences between the groups that used either the experimental or control tampon with regard to prevalence or mean cell density for the selected microorganisms. No differences were observed in the incidence or severity of erythema, in abrasion or ulceration of the cervix, vagina, introitus, vulva or perineum, or in mean vaginal pH and discharge assessments. There were equivalent low incidences of reported symptoms such as discomfort during insertion, wear or removal, and a similar low incidence of burning, stinging or itching during use of either the control or experimental tampon. There was a more favorable overall product rating for the experimental tampon (p = 0.003).

Conclusions: This approach provides a combination of gynecological, microbiological and self-reported (diary recall) methodologies in order to assess tampon safety during use more thoroughly than has previously been reported, and it supports a comparable safety profile for the experimental tampon and a currently marketed tampon.

Maternal carriage and neonatal colonisation of group B streptococci in labour are uncommon in Turkey

Group B streptococcus infection is an important cause of neonatal morbidity and mortality. We studied 114 women and their newborns to determine the relationship between maternal carriage and neonatal group B streptococcal colonisation. Rectal, cervical and vaginal swabs were taken at delivery. Within a few minutes of birth, swab specimens were also taken from throat, ear, umbilicus, conjunctiva and skin of the newborns. Group B streptococcus was isolated in 10 (8.7%) of the 114 pregnant women studied and in five (4.3%) of the 114 newborns. Vertical transmission rate was found to be 50%. Neonatal group B streptococcus colonisation has not reached a high level in Turkey, and consequently does not warrant intrapartum screening at the moment.

Significance of group B streptococci in urine cultures from males and non-pregnant females

Over a 2-year period, 1% of 24,000 urine cultures with possible relevant bacteria from males and non-pregnant females greater than or equal to 15 years of age were found to harbour group B streptococci (GBS) in quantities greater than or equal to 10(5) colony forming units (cfu)/ml; a further 0.9% harboured GBS in quantities greater than or equal to 10(4) but less than 10(5) cfu/ml. Patients with GBS in urine were evenly distributed by age. Those with greater than or equal to 10(5) cfu GBS/ml in voided urine more frequently had true bacteriuria (i.e. bacteria in the urine bladder) than did patients with less amounts (p = 0.01) as determined by suprapubic aspiration of 23 patients. One third (3/9) of the aspirated patients with greater than or equal to 10(5) cfu GBS/ml in simultaneously voided urine, had contaminated urine only and no true bacteriuria. The acute symptoms and clinical conditions of 128 patients with greater than or equal to 10(5) cfu GBS/ml urine were studied by matching 128 patients with negative urine cultures (less than 10(2) cfu/ml) and 128 patients with comparable quantity of Escherichia coli. The incidence of acute lower urinary tract symptoms in patients with GBS was greater than that in patients with negative urine cultures (p less than 0.01), and the same as that in patients with E. coli. The incidence of fever was lower in patients with GBS than in those with E. coli (p less than 0.01). The incidence of urinary tract abnormalities was greatest in patients with GBS in urine. No GBS serotype seems to have particular affinity to the urinary tract.

Evaluation of culture methods for isolation of group B streptococci

Attempts were made to isolate group B streptococci (GBS) from 382 urethral and 140 rectal specimens by overnight incubation in three variants of Todd Hewitt broth, followed by subculture on human blood agar plates. All three broths prepared contained 5% sheep blood, but one contained no antibiotics (THB), while the other two contained gentamicin and nalidixic acid at concentrations of 0.8 microgram/ml and 1.5 micrograms/ml (THBL), and 8 micrograms/ml and 15 micrograms/ml (THBH), respectively. THBL gave the highest isolation frequency both for urethral and rectal specimens. While THBH was superior to THB for isolating GBS in rectal specimens, for urethral samples they were equally effective. Direct plating of 154 specimens on blood agar was less effective than was enrichment in any of the three broths followed by plating on blood agar.

Faecal carriage of group B streptococci

A study of 1,138 primarily healthy subjects of various ages and sex was conducted to determine the faecal isolation rate of group B streptococci. Five percent of 284 neonates (less than or equal to 5 days old) and 4% of 267 healthy children (1-15 years old) were found to be faecal carriers. Adults were more frequently faecal carriers than children, group B streptococci being isolated in 15% of 361 adults and 11% of 226 pregnant patients. The isolation rate was independent of sex at all ages. Although group B streptococci were found more frequently in rectal than in faecal specimens from pregnant women (p less than or equal to 0.001), the isolation rate for faecal specimens could be increased by using a more selective broth. Forty-four percent of strains isolated from faeces of 105 subjects belonged to serotype III, 27% to type Ia, 15% to type Ib, 11% to type II and 3% were nontypeable. The same serotype of group B streptococci was usually present at different sites in each subject.

Group B streptococci at delivery: high count in urine increases risk for neonatal colonization

Of 858 pregnant women studied in matched rectal, urethral and urine cultured specimens, 186 (22%) were found to be colonized by group B streptococci (GBS). GBS were detected significantly more often in rectal specimens (159) than in urethral specimens (108) or in urine specimens (64). This is supporting evidence for the gastrointestinal tract as the main habitat of GBS. Of 1786 women whose urine was sampled at delivery, GBS were isolated from 128 (7%), in 22 of whom (1% of the total) GBS were present in quantities greater than or equal to 10(4) colony forming units (cfu)/ml urine. Neonates born to women with greater than or equal to 10(4) cfu GBS/ml urine were apparently at greater risk for neonatal infection, as they were more commonly and more heavily colonized than were the newborns of women with lower quantities of GBS in urine, or if positive urethral or rectal specimens were considered. The incidence of preterm delivery or obstetric infection was not higher among women in whom GBS were isolated in specimens from any of the 3 sites; foetal distress was more common among their children, but not neonatal respiratory or infectious diseases of which the incidence was low and difficult to assess statistically.