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A Case study of Group B Streptococcus Associated with Women in Antepartum Period and their Neonates, Ile Ife South-western Nigeria

Omololu-Aso J*, Oluwatoyin Omololu-Aso O, Toluwalope Akinlolu J, Bukola Grace A and Micheal Tunde A

Department of Microbiology, Obafemi Awolowo University, Ile-Ife, Nigeria

Corresponding Author:
Omololu-Aso J
Department of Microbiology
Obafemi Awolowo University, Ile-Ife, Nigeria
Tel: +2348033770933
E-mail: omololu-aso@oauife.edu.ng

Received Date: March 19, 2017; Accepted Date: November 06, 2017; Published Date: November 11, 2017

Citation: Omololu-Aso J, Omololu-Aso OO, Akinlolu JT, Grace AB, Tunde AM (2017) A Case study of Group B Streptococcus Associated with Women in Antepartum Period and their Neonates, Ile Ife Southwestern Nigeria. Arch Clin Microbiol. Vol.8 No.6:68. doi: 10.4172/1989-8436.100068

Copyright: © 2017 Omololu-Aso J, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

 
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Abstract

Streptococcus agalactiae colonizes the genital and gastrointestinal tract. In pregnancy, vertical transmission of GBS to the new-born can cause neonatal sepsis, pneumonia and meningitis. The aim of this study was to determine the prevalence of GBS in pregnant women in their third trimester, frequency of neonatal colonization and Antibiotics Susceptibility of the isolates recovered at the Obafemi Awolowo University Teaching Hospital Complex (OAUTHC) Ile- Ife, Osun State, Nigeria. Rectum and vaginal swabs were collected from a total number of 24 third trimester pregnant women between 35 - 37 weeks of gestation and their neonate delivered at OAUTHC both at labour ward and labour ward theatre. The samples were cultured in Todd Hewitt Broth and sub cultured on sheep blood agar and Chromogenic Strepto BID agar and incubated at 37ºC for 24 hours. Identification was based on the Gram staining, presence of β-haemolysis and absence of catalase production. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk-diffusion methods. GBS colonization on average was confirmed in 27.8% of pregnant women and their neonate and proportion of GBS isolated from the vagina 6 (30%) as compared to rectum 7(35%), neonates 4 (20%), vaginal and neonate 1(5%), rectum and neonate 1(5%), and both vagina, rectum and neonate1 (5%). All isolates were found susceptible to 40% clindamycin 35% vancomycin, 90% ciprofloxacin 40% erythromycin and 100% resistance to penicillin used. There is need for proper handling of neonates by the health care practitioner and screening of pregnant women attending antenatal care, including known antibiotic Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation susceptibility for an appropriate antepartum antimicrobial prophylaxis can be offered.

Keywords

Antepartum; Neonate; Group B Streptococcus; Maternal morbidity; Postpartum; Antibiotics

Introduction

Group B Streptococcus or Streptococcus agalactiae is one of the leading preventable causes of mortality and morbidity especially in neonate whose mothers are carrier worldwide [1]. Group B Streptococcus (GBS) is a Gram positive Bacterium regarded mainly as pathogen of pregnant or post-partum women and neonates [2].

It is also a significant cause of mortality and morbidity in nonpregnant adult, particularly those with underlying medical condition and in elderly patient such as stroke, renal failure, breast cancer, Diabetes mellitus, cirrhosis, neurological disorder and other liver disease, but with most incidence occurring among neonates [3].

Group B Streptococcus (GBS) is a normal flora or commensal of the genitourinary and gastrointestinal tract of 15%-50% of healthy woman [4]. Neonate can acquire GBS from their mother during the passage through the birth canal or through aspiration of infected amniotic fluid [5]. Vertical acquisition of GBS involving colonization of the skin or mucus membrane occurs in 15-50% new born to GBS colonized mother [6].

In Adult, Group B Streptococcus causes Urinary Tract Infection, osteomyelitis, pneumonia, meningitis, bacteremia, skin and soft tissue infection and Streptococcal Toxic Shock Syndrome [7]. The bacterium also causes high risk of preterm deliveries in pregnant woman [8]. Infections in new-borns occurring within the first week of life are designated Early-onset disease. Late-onset infections occur in infants aged >1 week, with most infections evident during the first 3 months of life (CDC, 2010) Figure 1.

acmicrob-Antibiotics-susceptibility

Figure 1: Antibiotics susceptibility profile of GBS isolates recovered in Ile Ife, South werstern Nigeria.

GBS transmission rate from mothers to neonates through vaginal delivery is approximately 50%, only 1-2% of colonized neonates develop invasive group B streptococcal disease [9]. The rate of early-onset infection has decreased from 1.7 cases per 1,000 live births in 1993 to 0.28 cases per 1,000 live births in the recent years (CDC, 2010). GBS colonization in women varies among age groups depending on study population, sites sampled and method of detection [10]. About 25% of pregnant women (CDC, 2010) and 35% young, non-pregnant woman [11] carry GBS in the rectum or vagina.

GBS continues to be susceptible to penicillin, ampicillin, and first-generation cephalosporins [12]. Under these circumstances, the alternative antibiotic choices have traditionally been erythromycin or clindamycin. However, resistance to these two antibiotics has been remarkably increasing [13]. Because of possible resistance problems with erythromycin and clindamycin, vancomycin is now the initial recommended treatment of GBS infection in patients who are allergic to penicillin [14].

Fluoroquinolones, especially the later generations, are active against GBS infections. Third and four-generation fluoroquinolones have been recommended by many health authorities and international organizations to treat pneumonia caused by GBS [15].

Maternal morbidity is worrisome, we source to determine the Social demographic factors with relative associated GBS colonization, its prevalence rate among pregnant women between 35-37 weeks of gestation period and their neonates, including the antibiotics susceptibility of the isolates recovered. Streptococcus agalactiae was isolated from both the vaginal and rectum of pregnant women between 35-37 weeks of gestation and from the umbilical cord of their newly born neonates delivered at both labour ward and labour ward theatre between June 2016 to February 2017 at the Obafemi Awolowo University Teaching Hospital Complex (OAUTHC), Ile-Ife, Osun State, Nigeria.

Sample Collection

A total of 24 pregnant women samples were collected from each study site. Two sterile swab sticks were used to take two different samples from each patient. Vaginal sampling was carried out by inserting and rotating the sterile swab stick against the vaginal wall at the mid portion of the vault and the swab was carefully withdrawn to prevent contamination with the microflora of the vulva. Another sterile swab stick was inserted 1.5-2.0 cm beyond the anal sphincter and gently rotated to touch the anal crypts and finally sterile swab was used to swab the umbilical cord of the newly born immediately after delivery.

All samples were collected by Midwifery/Gynaecologist and the swab specimens were placed in Stuart transport media and were transported to Department of Microbiology Laboratory of OAU for Laboratory investigation.

Screening for individual isolates

After samples collection under aseptic conditions, the swab sticks were inoculated into selective enrichment broth medium (Todd-Hewitt broth supplemented with 10 μg/ml Colistinand 15 μg/ml Nalidixicacid, Oxoid England) under aseptic condition and were incubated aerobically at 37ᵒC for 24 hours. After 24 hours incubation, broth cultures were observed for growth (Turbidity) and then sub cultured onto 5% sheep Blood Agar and incubated for 18-24 hours at 37ᵒCto increase the recovery rate of GBS. The plates that had no growth were re incubated overnight one more time. Where there were growth, the colonies were examined for their characteristics colonial morphology and beta-haemolysis and non beta-haemolysis were also considered. The suspected colonies were Gram stained (Gram positive) and tested for Catalase (catalase negative).

Bacterial isolation and identification

Rectum and vaginal swabs were collected from the third trimester pregnant women between 35-37 weeks of gestation and their neonate both at labour ward and labour ward theatre. The samples were cultured in Todd Hewitt Broth and sub cultured on sheep blood agar and Chromogenic Strepto B ID agar and incubated at 37ºC for 24 hours. Identification was based on the Gram staining, presence of β-haemolysis and absence of catalase production. A known Staphylococcus aureus was used as positive control and Streptococcus pneumonia was used as a negative control.

Antibiotic susceptibility test

The GBS isolated sensitivity were tested with 5 different classes of antibiotic; vancomycin (5 μg), penicillin (10 μg), erythromycin (15 μg) ciprofloxacin (5 μg), clindamycin (2 μg) Kirby-Bauer disc diffusion method was employed [12]. An inoculum suspension was prepared from a pure culture in a sterile nutrient broth using an inoculation loop. These were incubated overnight. The turbidity of the inoculums were adjusted and compared with 0.5 McFarland standards so as to obtain a confluent growth. Mueller-Hinton media plates were inoculated with a loop-full of the prepared inoculums and streaked by swabbing the surface of the medium rotating the plate through an angle of 60º at each application. Finally, the swab was passed round the edge of the agar surface. The inoculated plates were left for a few minutes at room temperature with the lid closed. This allowed the moisture on the surface to be absorbed into the medium. The antibiotic discs were placed on the inoculated plates using a pair of sterile forceps. Each disc was gently pressed down to ensure even contact with the medium. A control was set up using S. pneumonia which was susceptible to all the antibiotics to be tested. The set up was incubated at 37ºC for 24 hours in 5% CO2. After overnight incubation, the diameter of each zone inhibition (including the diameter of the disc) of each antibiotic was measured and recorded in millimetres. The results were compared with the zone diameter interpretive standards of the Clinical Laboratory Standards Institute CLS.

Results

A total of 72 swabs were taken from 24 pregnant women at 35-37 weeks of gestation and their neonates at OAUTHC, 20 (27.8%) were cultured positive for GBS based on Bergy’s manual Biochemical test and systematic bacteriology. Morphological appearance of all the GBS positive isolates on chromogenic agar and the ability to lyse blood (from 5% sheep blood agar) were observed.

Most isolates were pink or cream in colour, circular in shape, there opacity is either opaque or translucent, entire in edges and have smooth surfaces. Catalase test were carried out on all the isolates to confirm that they were GBS, and all tested catalase negative. The isolates Gram stained and viewed under microscope using immersion oil, also all appeared purple cocci in chains. The isolates were identified based on Bergy’s Manual of systematic Bacteriology.

Discussion, Conclusion and Recommendation

A total of 72 rectal and vaginal swabs were collected from 24 third trimester pregnant women and their neonates’ umbilical cord. The result of the study showed higher prevalence rate of 27.8% Streptococcus agalactiae in this study area therefore confirming GBS colonization among pregnant women and the neonates. The findings agreed with studies of some workers in Tanzania whose reports shown colonization rates among mothers and neonates between 10% - 36% [13]. Consequently, the result is higher than the prevalence rate as described in Nigeria by Onipede in Ile-Ife (11.3%) [14] and Onile in Ibadan (Onile, 1980). The data however, are lower than data reported from Trinidad (32.9%) and Zimbabwe (31.6%) showing country variations [15]. Indicated variations could possibly due to differences in sampling techniques, study sites, populations investigated and the differences in type of culture media and culturing techniques used.

Table 1 summarized the association between GBS status and demographic characteristics of studied participant and the result revealed a higher colonization rate among age group 33 – 36 years (13.89%) which corroborated the report of Onipede where GBS was frequently isolated among older women with age ≥ 30 years (12.79%) against (9.38%) in younger women [16]. These could be due to the fact that pregnant women with age range greater than 30 year were enrolled in the study. Colonization of GBS was higher in pregnant women with purulent vaginal secretion (18.06%) as compare with pregnant women with mild secretion (9.72%).

VARIABLE GBS +VE (%) GBS –Ve (%) Total (%)
AGE(YEARS)      
= 21 1(1.39) 3(4.17) 4(5.56)
22-25.5 1(1.39) 18(25.00) 19(26.39)
25.6-29.1 2(2.78) 12(16.67) 14(19.44)
29.2-32.7
32.8-36.3
6(8.33)
10(13.89)
11(15.28)
8(11.11)
17(23.61)
18(25.00)
TOTAL 20(27.80) 52(72.23) 72(100)
MARITAL STATUS      
Married 20(100) 52(100) 72(100)
Others  (cohabiting) 0(0.00) 0(0.00) 0(0.00)
EXCESSIVE SECRETION      
Mild 7(9.72) 29(55.77) 36(50.00)
Purulent 13(18.06) 23(44.23) 36(50.00)
GBS+VE;
Group B Streptococcus Positive
GBS –VE;
Group B Streptococcus Negative
     

Table 1 Association between GBS status and Demographic Characteristics of Studied participants.

All isolates were found to be 100% resistant to penicillin this is similar to studies performed by onipede in Ile-Ife [17]. All isolates were also found Susceptible to 40% clindamycin, 35% vancomycin, 90% ciprofloxacin, 40%erythromycin used. High level of resistance to Penicillin G which is a first choice of drug for the treatment of GBS could be as result of drug abuse or excessive use of the antibiotic in this part of the country and ease procurement of antibiotics in the country [18-23] Tables 2 and 3.

Sample Code Trimester PROM Antibiotic Prophylaxis Catalase reaction
IV1 3rd NO NO
IB1 3rd NO NO
IR1 3rd NO NO
IV2 3rd NO YES
IB2 3rd NO YES
IV3 3rd NO NO
IR3 3rd NO NO
IB4 3rd NO YES
IR4 3rd NO YES
IB5 3rd NO NO
IB6 3rd NO YES
IB7 3rd NO NO
IB8 3rd NO YES
IV9 3rd NO NO
IV10 3rd NO NO
IV11 3rd NO NO
IR12 3rd NO YES
IR13 3rd NO NO
IR14 3rd NO NO
1R15 3rd NO NO

Table 2 Distribution Analysis for GBS-Infection.

Isolate Code Antibiotic Resisted Antibiotic intermediate Antibiotics susceptible
IV1 PEN, ERY NONE DA, VA, CIP
IB1 PEN, DA, VA CIP ERY
IR1 PEN, ERY NONE DA, VA, CIP
IV2 PEN,VA,CIP NONE DA, ERY
IB2 PEN, VA NONE DA, CIP, ERY
IV3 PEN,DA, VA NONE CIP, ERY
IR3 PEN,DA, VA,ERY NONE CIP
IB4 PEN, DA, VA NONE CIP, ERY
IR4 PEN, VA ERY DA, CIP
IB5 PEN, ERY CIP DA, VA
IB6 PEN,DA,VA,CIP,ERY, NONE NONE
IB7 PEN, DA, VA NONE CIP,ERY
IB8 PEN, ERY NONE DA, VA, CIP
IV9 PEN, DA, VA NONE CIP, ERY
IV10 PEN, DA, ERY CIP VA
IV11 PEN,VA NONE DA,CIP, ERY
IR12 PEN,DA,ERY NONE VA, CIP
IR13 PEN, VA NONE DA,CIP, ERY
IR14 PEN,VA,DA,ERY NONE CIP
IR15 PEN, DA,ERY NONE VA, CIP

Table 3 Multiple Antibiotic Resistannce Pattern of GBS Isolates.

Conclusion

Certain degrees of prevalence of GBS infection among the pregnant women and neonates in this study area was observed and all the isolates recovered were found to be 100% resistant to penicillin happened to be the most widely used antibiotics for treatment of Group B Streptococcal infection. In this findings, ciprofloxacin remains the antibiotic of choice in treatment of Streptococcal infection.

Effective screening for GBS during antenatal care, Proper handling of neonates at postpartum by the health care practitioners with appropriate antepartum antimicrobial prophylaxis should be advocated.

Recommendation

• Women should be educated on GBS infection and the need to improve on personal hygiene.

• All pregnant women at 35 – 37 weeks of gestation should be screened for group B streptococcus Infection.

• Aseptic technique should be ensured in all prenatal caring process

• Since GBS has acquired resistance to several of the commonly used antibiotics, such as penicillin, prevention protocols other than antepartum chemoprophylaxis must be utilized to prevent neonatal disease.

Study Design Limitation

Based on our available procedures and constraint on study population at the centre, the findings may not be translated to be exact outcome of antepartum GBS prevalence rate associated with women in the country. However, the data obtained is of useful findings widely applicable as they will assist in control measures and effective therapeutic approach to GBS in pre-and post- natal stages among women in all part of the world.

References

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