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  Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 38  |  Issue : 3  |  Page : 357-361
 

Group B Streptococcus in Indian pregnant women: Its prevalence and risk factors


1 Department of Clinical Microbiology and Immunology, Sir Ganga Ram Hospital, New Delhi, India
2 Institute of Obstetrics and Gynaecology, Sir Ganga Ram Hospital, New Delhi, India
3 Institute of Neonatology, Sir Ganga Ram Hospital, New Delhi, India

Date of Submission24-Jul-2020
Date of Decision10-Aug-2020
Date of Acceptance11-Aug-2020
Date of Web Publication4-Nov-2020

Correspondence Address:
Dr. Chand Wattal
Department of Clinical Microbiology and Immunology, Sir Ganga Ram Hospital, Rajinder Nagar, New Delhi - 110 060
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijmm.IJMM_20_333

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 ~ Abstract 


Purpose: To study the prevalence of group B streptococci (GBS) in Indian pregnant women and associated risk factors. Methods: Four hundred and fifty pregnant women attending antenatal outpatient/inpatient department between 35-38 weeks of gestation were enrolled in the study. All enrolled subjects were assessed by a predefined proforma for their demographics, socio-economic characteristics, education, toilet habits, obstetric history and clinical outcome. Two cotton swabs each from lower vagina and rectum were collected and plated on selective solid media CHROM agar Strept B (CHROMagarTM) and selective Enrichment Broth LIM RambaQUICK StreptB broth (CHROMagarTM). Presumptive identification of GBS was growth of 1-3 mm grayish white β-hemolytic colonies on BAP or mauve coloured colonies on CHROM agar Strept B. All presumptively identified GBS were confirmed as group B streptococcus by automated identification system-Vitek MS (Bio Merieux). Results: The recto vaginal colonization rate of GBS in this study was observed as 3.3% (n=15). GBS colonization was significantly associated with nulliparous women (p= 0.026) and use of western style toilet (p=0.017). GBS urinary tract infections was also seen more commonly in women with GBS rectovaginal colonization (p=0.002). Conclusion: Due to the low GBS prevalence and no significant association with major risk factors, we recommend to institute universal screening of GBS in pregnant women, instead of risk based screening. Since this was a single centric study with low prevalence of GBS, its applicability may be limited, therefore further larger multi-centric prospective studies are required to understand the true GBS prevalence in Indian society.


Keywords: Group B Streptococci, Indian, pregnant, prevalence, risk factors


How to cite this article:
Goel N, Wattal C, Gujral K, Dhaduk N, Mansukhani C, Garg P. Group B Streptococcus in Indian pregnant women: Its prevalence and risk factors. Indian J Med Microbiol 2020;38:357-61

How to cite this URL:
Goel N, Wattal C, Gujral K, Dhaduk N, Mansukhani C, Garg P. Group B Streptococcus in Indian pregnant women: Its prevalence and risk factors. Indian J Med Microbiol [serial online] 2020 [cited 2020 Nov 28];38:357-61. Available from: https://www.ijmm.org/text.asp?2020/38/3/357/299838





 ~ Introduction Top


Group B Streptococci (GBS) colonisation in pregnant woman is reported to be the leading infectious cause of morbidity and mortality in neonates in many countries.[1] Vertical transmission because of recto-vaginal maternal GBS colonisation is the most important determinant of neonate infection, and there is >25 times increased risk of acquiring this infection in neonates compared to non-colonised women.[1],[2] About 1%–2% of infected neonates ultimately develop early onset GBS infections such as pneumonia and meningitis.[1] Maternal GBS colonisation rate shows high variation across the world ranging from 11.1% to 22.4%, with a mean prevalence of 17.9%.[3] Indian literature, though scarce, also reports a varying but lower prevalence of GBS ranging from 2.3% to 15.0%.[3],[4] Maternal GBS colonisation has also been associated with certain risk factors such as age, parity, education, socioeconomic status and maternal factors (premature rupture of membranes [PROM], low birth weight and puerperal pyrexia), but the literature is conflicting on their true association with GBS colonisation.[1],[3],[4],[5],[6] To decrease the vertical GBS transmission, the Centers for Disease Control and Prevention, USA, has recommended universal screening for GBS at 35–37 weeks of pregnancy and intrapartum antibiotic prophylaxis (IAP) in positive GBS mothers.[1] On the other hand, the Royal College of Obstetricians and Gynaecologists (RCOG) recommends only risk based approach as a more cost effective way of screening of GBS colonisation.[7] Both approaches have advantages as well as its pitfalls in terms of cost, feasibility and sensitivity.[1],[5],[7],[8] There foreoptimal prevention strategies remain unclear. As of now, there are no set protocols for the screening of maternal GBS colonisation or IAP in India. Before formulation of any policy, it is imperative to have sufficient data on GBS prevalence and associated risk factors from India. Since there are only a handful of studies on GBS epidemiology from our region, this study was conducted to study the prevalence and possible risk factors resulting in maternal colonisation of GBS at Sir Gang Ram Hospital, a tertiary care centre at New Delhi.


 ~ Materials and Methods Top


Study area

This was a hospital-based observational cross-sectional study carried out from February 2015 to October 2016 in the department of Clinical Microbiology and Immunology and Institute of Obstetrics and Gynaecology, Sir Ganga Ram Hospital, New Delhi.

Study population

All pregnant women attending antenatal outpatient/inpatient department between 35 and 38 weeks of gestation were eligible to participate in the study. Patients with a history of antibiotic use in the last 2 weeks, history of bleeding or leaking per vaginum or refusal to give consent were excluded from for the study. Four hundred and fifty of 469 pregnant women were recruited for the study.

Study method

All enrolled participants were assessed by a predefined pro forma for their demographics, socio-economic characteristics, education, toilet habits (Indian/western style, wash/wipe), obstetric history and clinical outcome.

Specimen collection and processing

Two cotton swabs each from lower vagina and rectum were collected from the patients and immediately placed in separate Amies transport medium (HiMedia) to maintain the viability of organism.[1],[7] All the swabs were processed for culture within 2 h of collection. First swab from vagina and rectum was directly plated on selective solid media CHROM agar Strept B (CHROMagar) and blood agar (BAP) and 2nd swab from vagina and rectum was inoculated in selective Enrichment Broth LIM RambaQUICKStreptB broth (CHROMagar) and incubated at 35–37° Celsius for 36–48 h. LIM RambaQUICKStrepB method is an enrichment broth, allowing detection of GBS (hemolytic as well as non-hemolytic) while inhibiting the enterococci from the gastrointestinal tract.[1] Following overnight enrichment, the all enrichment broths were sub-cultured on to BAP and further incubated for 16–48 h. Presumptive identification of GBS was growth of 1–3 mm grayish white β-hemolytic colonies on BAP or mauve coloured colonies on CHROM agar Strept B. All presumptively identified GBS were confirmed as Group B Streptococcus by Vitek MS automated identification system (Bio Merieux).

Statistical methods

Statistical testing was conducted with the Statistical Package for the Social Sciences System version SPSS 17.0 (Chicago IL, USA). Descriptive statistics was done for continuous variables, while Chi-square test was used to compare the categorical variables. For all statistical tests, a P < 0.05 was taken to indicate a significant difference.

Ethical consideration

This study was approved by the institutional review board. Each participant was duly counselled and consent taken before enrolling in the study.


 ~ Results Top


In our study, a total of 469 women between 35 and 38 weeks of pregnancy were eligible to participate in the study. Nineteen women had to be excluded as per the pre-defined exclusion criteria (patients with a history of antibiotics use in the last 2 weeks (n = 4), history of bleeding (n = 8) and refusal to give consent (n = 7). Hence, 450 women were finally recruited in the study as per the required sample size. The mean age of the women was 29.18 ± 4.15 years with a range of 18–43 years. Most women were in the age group of 21–30 years (n = 293; 65.1%), and majority of them were Para 1 and above (n = 276; 61.33%).

The recto vaginal colonization rate of GBS in this study was observed as 3.3% (n = 15) [Table 1]. Out of 15 GBS positive samples, 8 (53.33%) were from vagina and 4 (26.66%) were from rectum. Three samples (20%) were positive from both vagina and rectum [Table 2].
Table 1: Prevalence of Group B Streptococci

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Table 2: Group B Streptococci positivity as per the sample site

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GBS culture positivity for the age group <20 years, 21–30 years and 31–40 years was 0%, 3.75% and 2.7%, respectively, and was not statistically significant P = 0.884 [Table 3]. We also could not elicit any significant association between GBS prevalence as with socioeconomic status (P = 0.253), education (P = 0.549) and pregnancy outcome (P = 0.758). However, there was significant association between maternal GBS colonisation and parity (para 1 and above) (P = 0.026) and GBS urinary tract infection (UTI) (P = 0.002). Statistically significant association was also present in relation to toilet habits. GBS colonisation was observed in 5.1% (n = 13) of patients using Western toilet in contrast to 1.0% (n = 2) using Indian toilet (P = 0.017). Further, women using water versus wipes for toilet cleaning were also significantly associated with GBS colonisation [Table 3].
Table 3: Risk factors analysis for Group B Streptococci colonization

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All 15 GBS colonised women were given IAP-Ampicillin-2 g iv loading dose followed by 1 g iv 6 hourly until delivery. On follow up of neonates born to 15 women with GBS colonization, no significant adverse outcome was seen.


 ~ Discussion Top


In our study GBS colonization rate was observed as 3.3%. Our prevalence of GBS rates appears to be lower than the global mean. A meta-analysis of 78 studies from 1997 to 2015 that included 73,791 pregnant women from 37 countries showed overall mean prevalence of 17.9%. Highest maternal GBS colonization was seen in Africa (22.4%) followed by Americas (19.7%), Europe (19.0%) andsouth-east Asia (11.1%).[3] The above data shows that there is great heterogeneity in the prevalence of GBS colonization according to the geography. On reviewing the Indian data, varied prevalence of GBS colonization was also observed from different centres [Table 4]. In a study by Chaudhary et al. from New Delhi on 300 patients, the prevalence of maternal GBS colonisation was found to be 15%.[9] Similarly, a higher presence of GBS (7.6%) was observed in a study during 2012–2013 from Vellore in 305 women, although a comparable prevalence (4.8%) of GBS colonization was noted by Dechen et al. from Sikkim.[4],[10] In contrast, a lower prevalence of maternal GBS colonization was seen by Sharmila et al. (2.30%) from Puducherry.[11] The reason for varying GBS colonisation rate from different regions of India could not be ascertained, but could possibly be explained due to vast diversity in different socioeconomic groups, education, and level of medical and diagnostic facilities in the study population.[1],[3],[4],[5],[6],[12] Therefore, it is important that each center should estimate the GBS colonisation for their area for meaningful formulation of GBS screening policy.
Table 4: Group B Streptococci colonization rates in India

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Many demographic risk factors are shown to be associated with higher prevalence rate of GBS but there are conflicting reports in the literature, both supporting and refuting these relationships.[3],[4],[5],[6],[12] In our study we found parity as a significant risk factor, nulliparous women had a significant relationship with GBS colonization. This is in agreement with the study by Kim et al.,[6] where higher parity was associated with lower prevalence of GBS colonization (P = 0.034), though another study by Ngonzi et al.[13] from Uganda could not elicit the same relationship. On further analyzing our data [Table 3], we did not find any significant correlation between GBS colonisation and demographic risk factors like age, education status and socioeconomic factors, findings similar to many other studies.[5],[6],[13] We also observed that younger women (21–30 years) had higher prevalence of GBS (3.7%, P = 0.884) as compared to older age groups [Table 3]. This finding is consistent with a study from Korea by Kim et al. where younger age (women of <25 years) was associated with significant risk factors for GBS colonization.[6]

We also looked into toilet habits of enrolled subjects. We observed that women using Indian style toilets significantly had lower GBS colonisation (P = 0.017). To the best of our knowledge, this aspect of toilet habits has not been evaluated in the studies reported so far. One reason could be that majority of the data is from Western world where the concept of Indian style toilet is non-existent. Handful studies from India[4],[9],[10],[11] too have not dwelled upon this aspect. Western toilets seat can be contaminated with micro-organisms which can result in the transfer of infections through skin contact, such transfer is unlikely in women using Indian toilets. This interesting aspect cannot be generalized on the basis of this study because of small sample size and requires further validation from large sized sample study.

Expectedly, GBS UTI was significantly associated with rectovaginal colonisation of GBS. GBS bacteriuria in a pregnant woman is a marker of heavy genital tract colonization and is an indication of IAP.[1] Routine screening for UTI and therefore GBS bacteriuria may be recommended as a non-invasive screening method for detection of GBS colonization. Although it has been shown that the treatment of GBS bacteriuria does not ensure elimination of rectovaginal GBS colonisation and IAP would still be necessary in these patients.[1] Association of maternal GBS colonization with adverse pregnancy outcomes like prematurity (<37 weeks), low birth weight, PROM, longer duration of labor, puerperal sepsis or pyrexia has been reported by hosts of studies.[1],[7] In contrast, we found no such association which is in concordance to the findings of study by Ngonzi et al.[13] On detailed neonatal evaluation, none of the neonates born to GBS colonised mothers showed any sign of neonatal sepsisor pneumonia and required neonatal intensive care unit admission. It is a well-recognised fact that IAP prevents early onset GBS which was given to all the 15 mothers in our study.[1],[7]

In conclusion, due to the low GBS prevalence and no significant association with major risk factors, we recommend instituting universal screening of GBS in pregnant women, instead of risk based screening as advised by RCOG. Also it has been reported that up to 19% positive maternal GBS colonization can be seen without the risk factors.[5] Since this was a single centric study with a low prevalence of GBS, its applicability may be limited, therefore further larger multi-centric prospective studies are required to understand the true GBS prevalence in the Indian society.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 ~ References Top

1.
Verani JR, McGee L, Schrag SJ, Division of Bacterial Diseases, national center for immunization and respiratory diseases, centers for disease control and prevention (CDC). Prevention of perinatal Group B streptococcal disease-revised guidelines from CDC, 2010. MMWR Recomm Rep 2010;59:1-36.  Back to cited text no. 1
    
2.
Chen J, Fu J, Du W, Liu X, Rongkavilit C, Huang X, et al. Group B streptococcal colonization in mothers and infants in western China: Prevalences and risk factors. BMC Infect Dis 2018;18:291.  Back to cited text no. 2
    
3.
Kwatra G, Cunnington MC, Merrall E, Adrian PV, Ip M, Klugman KP, et al. Prevalence of maternal colonisation with Group B Streptococcus: A systematic review and meta-analysis. Lancet Infect Dis 2016;16:1076-84.  Back to cited text no. 3
    
4.
Dechen TC, Sumit K, Ranabir P. Correlates of vaginal colonization with Group B Streptococci among pregnant women. J Glob Infect Dis 2010;2:236-41.  Back to cited text no. 4
    
5.
Khalil MR, Uldbjerg N, Thorsen PB, Møller JK. Risk-based approach versus culture-based screening for identification of Group B Streptococci among women in labor. Int J Gynaecol Obstet 2019;144:187-91.  Back to cited text no. 5
    
6.
Kim EJ, Oh KY, Kim MY, Seo YS, Shin JH, Song YR, et al. Risk factors for Group B Streptococcus colonization among pregnant women in Korea. Epidemiol Health 2011;33:e2011010.  Back to cited text no. 6
    
7.
RCOG Green-top Guidelines. Prevention of Early-onset Neonatal Group B Streptococcal Disease. Available from: https://obgyn.onlinelibrary.wiley.com/doi/epdf/10.1111/1471-0528.14821 [Last accessed on 2019 Mar 04].  Back to cited text no. 7
    
8.
Brown AP, Denison FC. Selective or universal screening for GBS in pregnancy (review). Early Hum Dev 2018;126:18-22.  Back to cited text no. 8
    
9.
Chaudhary M, Rench MA, Baker CJ, Singh P, Hans C, Edwards MS. Group B Streptococcal colonization among pregnant Women in Delhi, India. Pediatr Infect Dis J 2017;36:665-9.  Back to cited text no. 9
    
10.
Santhanam S, Jose R, Sahni RD, Thomas N, Beck MM. Prevalence of Group B Streptococcal colonization among pregnant women and neonates in a tertiary hospital in India. J Turk Ger Gynecol Assoc 2017;18:181-4.  Back to cited text no. 10
    
11.
Sharmila V, Joseph NM, Arun Babu T, Chaturvedula L, Sistla S. Genital tract Group B Streptococcal colonization in pregnant women: A South Indian perspective. J Infect Dev Ctries 2011;5:592-5.  Back to cited text no. 11
    
12.
Narava S, Rajaram G, Ramadevi A, Prakash GV, Mackenzie S. Prevention of perinatal Group B Streptococcal infections: A review with an Indian perspective. Indian J Med Microbiol 2014;32:6-12.  Back to cited text no. 12
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13.
Ngonzi J, Bebell LM, Bazira J, Fajardo Y, Nyehangane D, Boum Y, et al. Risk factors for vaginal colonization and relationship between bacterial vaginal colonization and in-hospital outcomes in women with obstructed labor in a Ugandan regional referral Hospital. Int J Microbiol 2018;2018:6579139.  Back to cited text no. 13
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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