The slideset is an overview on lessons learnt from maternal colonization epidemiology studies focused on: - Association of maternal recto-vaginal GBS colonization and invasive GBS disease - Correlate of protection against GBS colonization in pregnant women The slideset underlines, moreover, the potential of GBS vaccine protecting against colonization: - Could protect term and preterm (with early vaccination) newborns independent of antibody transfer. - Protecting against maternal complications, including GBS associated chorioamnionitis and stillbirths.

1. Shabir A Madhi & Guarav Kwatra
University of Witwatersrand
Medical Research Council: Respiratory and Meningeal
Pathogens Research Unit,
DST/NRF SARCHI Chair: Vaccine Preventable Diseases

2. » Association of maternal recto-vaginal GBS colonization and
invasive GBS disease.
» Correlate of protection against GBS colonization in pregnant
women.

3. Maternal risks factors for EOD:
1. GBS bacteriuria during pregnancy.
2. Intrapartum maternal fever
3. Prolonged rupture of membranes
(>18 Hours).
4. Premterm labor and birth.
5. Previous sibling with invasive GBS
disease.
Images adapted from: http://www.medicinenet.com/stages_of_pregnancy_pictures_slideshow/article.htm

4. GBS colonized mother
Non-colonized
newborn
50%
Colonized
newborn
50%
Asymptomatic
98%
Early-onset sepsis,
pneumonia, meningitis
2%
Diagram source: http://www.cdc.gov/groupbstrep/clinicians/neonatal-providers.html#slidesets
Cutland C et al. Lancet 2009; 374:1909-16; Cutland C et al. Pediatrics 2012; 130:e581-90;
Madhi SA et al. Vaccine; 2013: ; 315: D52-57
N=5099; 20.9% vaginal
colonization1,2
57% newborns
colonized2
Number cases EOD: 2.0 per 1000 live births
(2% of colonized)1-3

5. Kwatra G et al. Lancet Infect Dis; 2016 (In press)

6. Kwatra G et al. Lancet Infect Dis; 2016 (In press)

7. 0
0.5
1
1.5
2
2.5
0
5
10
15
20
25
Africa Americas Eastern
Mediteranean
Europe South East Asia Western Pacific
IncidenceEOD
(per1000livebirths)
Prevalenceofcolonization
WHO Region
Kwatra G et al. Lancet Infect Dis, 2016 (In press);
Edmond KM et al. Lancet; 2012; 379: 547-56.
* Expected incidence EOD

8. » Screening for GBS colonization 34-37 weeks GA, coupled with intra-partum
antibiotic prophylaxis.
» Implementation of risk-based strategy for intrapartum antibiotic
prophylaxis.
» Differences in serotype (including strain virulence) associated with
colonization and virulence (invasive potential) thereof between region.
» Ethnic/genetic differences in susceptibility to colonization and invasive
disease.
» Differences in maternal anti-capsular antibody levels and transplacental
transfer to their newborns.
» Biases in case detection, due to differences in health care access.

9. » Association of maternal recto-vaginal GBS colonization and
invasive GBS disease.
» Correlate of protection against GBS colonization in pregnant
women.

10. » 13/14 studies cross-sectional, measured maternal colonization
and antibody levels at delivery or during pregnancy.
» 11/14 studies reported higher serotype-specific capsular antibody
levels in GBS recto/vaginal colonized compared to uncolonized
women.
» 2/2 studies in newborns without invasive disease also reported
higher serotype-specific capsular antibody levels in GBS
skin/mucosal colonized compared to uncolonized babies.
» One study indicated that urogenital acquisition of GBS associated
with capsular response.
Dangor Z et al. Exp Rev Vaccines; 2015
(and maternal colonization)

11. » GBS-TT serotype III, DBRCT: 650 USA non-pregnant Women
» GBS-TT vaccination associated with longer time to acquire
first serotype III GBS-positive swab (vaginal colonization
efficacy 36% (p=0.044) and rectum 43% (p=0.015).
» Greater proportion of women in GBS negative group had
persistently negative cultures (p=0.046).
 Association of host natural immune mediators and dynamics of GBS
colonization during pregnancy remains unclear.
Hiller et al; 47th IDSA Annual Meeting, Oct 2009; Abstract: 186

12. 1
 To evaluate the association between humoral or cellular
immune response and GBS recto-vaginal colonization in
pregnant women, in relation to GBS recto-vaginal
acquisition or loss from 20 to 37+ weeks of gestational age.
Inclusion criteria:
 HIV negative pregnant women at 20-25 weeks of gestation
Exclusion criteria:
 Antibiotic usage in the previous two weeks
 Known or suspected condition contraindicating a vaginal examination
Sample Size: 661

13. Pregnant
women,
n=661
Procedure (Gestation age)
20-25 weeks
(Visit-1)
26-30 wks
(Visit-2)
31-35 wks
(Visit-3)
37+ wks
(Visit-4)
Vaginal and rectal
swab
Clotted blood
 Capsular antibody (Ia, Ib, III, V)
 OPA (Ia, III)
Heparinized blood
 CMI
Kwatra et al Clin Micro Infect; April 2015; Kwatra G et al. J Infect Dis; 2016
1. Serum: Serotype Ia, III and V capsular IgG antibody (Luminex assay) and OPA for
serotypes Ia and III
2. Heparinised blood: Capsular specific Elispot assays (interferon gamma) for GBS
serotype Ia, III and V.
3. Vaginal and Rectal swabs was used to detect GBS colonization.

14. • Prevalence GBS colonization at enrolment, visit-2, visit-3 and visit-4 was
33.0% , 32.7%, 28.7% and 28.4%, respectively.
• Of 507, who completed all visits, 50% (252) colonized at least once.
• 28% (70/252) “persistently colonized” (i.e. from V1 to V4)
• 39% (99/252) “cleared colonization”
• Serotype-specific new acquisitions of those not colonized at enrolment
(V1):
• Serotype Ia: 9.6% (52/541),
• Serotype III: 7.0% (39/560)
• Serotype V: 2.8% (17/603)
Kwatra G et al. PlosOne; 2014, 9(6): e98778

15. 7,5
5,2
6,1
9,2
6,9
8,6
6,2
0
2
4
6
8
10
12
Ia Ib II III IV V IX
MedianDurationofColonization-
weeks(95%CI)
Serotype
P=0.026
Kwatra G et al. PlosOne; 2014, 9(6): e98778

16. Serotype Visit-1 (20-25 wks GA) Visit-4 (37+ wks GA)
Serum
IgG
Colonized
GMC (95% CI)
Not-colonized
GMC (95% CI)
p-value Colonized
GMC (95% CI)
Not colonized
GMC (95% CI)
p-value
Ia 0.71
(0.40, 1.27);
n=71c
0.36
(0.28, 0.45);
n=436
0.025 1.52
(0.80, 2.89);
n=50
0.43
(0.12, 0.45);
n=457
<0.001
III 0.51
(0.33, 0.79);
n=56
0.30
(0.26, 0.35);
n=451
0.018 0.47
(0.30,0.76);
n=52
0.30
(0.26, 0.35);
n=455
0.060
V 1.02
(0.52, 2.00);
n=15
0.72
(0.65, 0.82);
n=492
0.31 1.07
(0.66, 1.75);
n=18
0.83
(0.74, 0.92);
n=489
0.372
OPA GMOPT
(95% CI)
GMOPT (95% CI) Not done
Ia 19
(12, 32);
n=71
13
(10, 15);
n=436
0.081
III
178
(88, 359);
n=56
111
(89, 138);
n=451
0.166

17. » 1. Not colonized at enrolment:
 New acquisition episode: Acquisition of GBS serotype not
present at enrolment.
 Non-colonized: Remained free of colonization by specific-
serotype throughout.
» 2. Colonized at enrolment
 Persistently-colonized: Remained colonized throughout by
specific serotype.
 Cleared colonization group: Colonized by specific serotype at
visit-1 in whom colonization was cleared by visit-4.

18. Capsular antibody OPA Titers
ST Ia
ST V
ST III
ST III
ST Ia
Kwatra G et al Clin Micro Infect; April 2015
New acquisition:
Non-colonized:

19.  Capsular antibody threshold ≥5 ug/ml for ST-Ia (aOR:0.37) and ≥3 ug/ml for ST-III
(aOR: 0.11) associated with lower odds of acquisition of homotypic serotype.
 Serotype specific OPA titers ≥8 associated lower odds of serotype Ia (aOR 0.29) and
III (aOR: 0.33) acquisition; with even lower odds at higher OPA titers (≥1:32: aOR 0.05
[Ia] and 0.23 [III]).
Kwatra G et al Clin Micro Infect; April 2015
Neither serotype-specific antibody or OPA associated with clearance of existing
colonization.
Serotype New-acquisition Non-colonized p-value a
GMC (95% CI) GMC (95% CI)
Ia 0.28 (0.17, 0.47); n=52 0.35 (0.27, 0.44); n=387 0.529
III 0.17 (0.11, 0.26); n=39 0.33 (0.28, 0.38); n=414 0.009
V 0.42 (0.26, 0.65); n=17 0.75 (0.66, 0.84); n=471 0.057
OPA GMOPTg (95% CI) GMOPT (95% CI)
Ia 5 (4, 6); n=52 14 (11, 17); n=387 <0.001
III 20 (11, 36); n=39 132 (105, 164); n=414 <0.001

20. ELISpot positivity was higher among the cleared colonization group then
persistently-colonized group
An ELISpot response was considered as positive if the number of antigen-specific
spots was ≥7 SFU/106 PBMC and at least double the number of spots in the
negative control well.
0,0%
10,0%
20,0%
30,0%
40,0%
50,0%
Ia III V
Elispotpositivity
Serotype
Cleared colonization Persistently colonized
44.2% (19/43)
19.0% (4/21)
44.4%(8/18)
7.4% (2/27)
22.9% (2/9)
0% (0/2)
p=0.06
p=0.008
p=1.0
Kwatra G et al. J Infect Dis; 2016 (In press)
Presence of serotype-specific cellular immunity associated partially with
clearance of existing colonization but did not reduce risk of GBS acquisition.

21. Probability of clearance GBS serotype Ia and serotype III colonization at varying
SFU/106 PBMC’s using a Bayesian model
Probability of losing colonization with ≥7 SFU/106
Serotype Ia: 82%
Serotype III: 50%

22.  ?Reasons for regional disconnect between maternal GBS colonization
prevalence and early-onset invasive disease.
 Recto-vaginal GBS colonization during latter half of pregnancy
dynamic.
 Duration of colonization differ by serotype and range from 5.2-9.2
weeks.
 High new-acquisition rate. ?Is recent acquisition more likely to cause
invasive disease and stillbirths.
 “Early” vaccination which induce sufficient antibody (especially OPA)
could reduce risk of GBS acquisition during latter stages of pregnancy.
Potential of GBS vaccine protecting against colonization:
 Could protect term and preterm (with early vaccination) newborns
independent of antibody transfer.
 Protecting against maternal complications, including GBS associated
chorioamnionitis and stillbirths.