Characteristics of the maternal vaginal aerobic flora and the influence of
chorioamnionitis on preterm delivery and newborn early infection.
Aira Peri¹ , Kadri Matt², Tartu University Women`s Clinic¹ ²
INTRODUCTION: Premature delivery is still a major medical problem as about 50% of
cases are presumably due to infection. Potential pathogens arise largely from the ascending
route of the genital tract and from the endogenous vaginal flora, causing chorioamnionitis.
Organisms which induce chorioamnionitis and newborns infections mostly belong to group B
streptococci (GBS), E. Coli, Klebsiella spp, while respiratory tract organisms like
Haemophilus influenzae, Streptococcus pneumoniae occur more rarely. Consequent morbidity
involves maternal sepsis, post-partum endometritis and neonatal sepsis. The incidence of
preterm deliveries is 7-8% in Estonia.
OBJECTIVE: The purpose of the study was to explore the vaginal aerobic flora and the
influence of infection on preterm deliveries in Tartu University Women`s Clinic in 20032004.
METHODS: Descriptive retrospective analysis.
STUDY DESIGN: There were 4264 deliveries in Tartu University Women`s Clinic during
the two-year period. Of them 312 (7.3%) were preterm deliveries. After exclusion of
multiple pregnancies, fetal malformations and antenatal fetal death cases, in which
pathogenetic mechanisms were other than infection, there were 250 preterm delivery cases to
be studied (22-37 weeks of gestation).
Although in general in good clinical practice, in the case of all spontaneous preterm
deliveries, bacteriological analyses are taken from the cervix and vagina, only 68
bacteriological samples were taken from the cervix , 50 from the vagina and 58 from placental
surface during two years.
In 120 cases bacteriological samples were taken from the preterm newborn`s blood.
Table 1. Preterm deliveries by gestational age.
2003Total %
Gestational age in weeks 2004
8
3.2
22-26
29
11.6
26-30
66
26.4
30-34
147
58.8
34-37
250
100
Total
RESULTS:
 Acute chorioamnionitis was diagnosed in 34 cases (13.6%) (Table 2).
 There were 15 cases(40.5 %) of chorioamnionitis before the 30th week of gestation
(Table 2).
 Most of the bacteriological samples taken from the cervix and the vagina were
negative ( Table 3).
 110 (44%) of the spontaneous preterm deliveries were complicated with premature
prelabour rupture of the membranes (PPROM).
 Of the 34 cases of chorioamnionitis PPROM occurred in 25 cases .
 There was no difference in bacteriologically isolated pathogens between the cases
with and without PPROM (Table5).
 Two preterm deliveries with GBS isolated from the cervix resulted in perinatal death.





( Table 6).
In 1 case with maternal GBS colonisation the newborn had congenital sepsis, but the
pathogen isolated from the newborn`s blood was Haemophilus influenzae( Table 6).
In most cases of congenital neonatal sepsis cases bacteriological cultures from the
mother had been negative, or the samples had not been taken ( Table 6).
In 8 of 20 congenital sepsis cases pathogens were isolated from the newborn`s
blood (E. Coli, Citrobacter, Klebsiella pneumoniae, Enterococcus faecalis, αhemolytical Streptococcus, Haemophilus influenzae, CONS, Streptococcus
epidermidis).
Mother and newborn need not share the same pathogens.
In many clinical complication cases the bacteriological sample is negative owing to
method related difficulties ( Tab. 4; 6).
Table 2. Relationship between acute chorioamnionitis and gestational age.
Age group
22-26
26-30
30-34
34-37
Total
Acute
chorioamnionitis
5
10
8
11
34
Proportion (%)
of patients
with
chorioamninitis
62
34.5
12.1
7.5
13.6
Table 3. Relationship between gestational age and presence of pathogens in the cervix and
the vagina before threatened or during preterm delivery.
Gestational age
22-26
26-30
30-34
34-37
Total
E. coli
5
1
6
GBS
1
1
1
5
8
Other
aerobic
Candida pathogens
albicans
*
1
1
1
1
7
4
9
6
Number
of Number of
negative investigated
samples samples
5
7
17
19
29
37
38
55
89
118
*other aerobic pathogens (Klebsiella pneumoniae, Staphylococcus pneumoniae,
Citrobacter kreundii; Streptococcus pyogenes, Enterobacter cloacae, Streptococcus
pyogenes)
Table 4. Relationship between presence of placental surface pathogens and number of acute
chorioamnionitis cases.
Bacteriological
pathogens from
placental surface
Number of acute
Number of
chorioamnionitis
positive samples cases
E. coli
9
4
GBS
3
1
Candida albicans
1
Other aerobic
pathogens
6
2
Sample negative
39
11
Sample was not taken
192
16
Total
250
34
Table 5.Relationship between PPROM and presence of pathogens in the cervix and vagina
before threatened or during preterm delivery.
PPROM
No
Yes
Total
E. Coli
Candida
albicans
GBS
3
3
6
4
4
8
Other aerobic
organism
4
5
9
2
4
6
Negative
38
51
89
Total
number of
investigated
patients
140
110
250
Table 6. Relationship between presence of pathogens isolated from the mother`s cervix
during pregnancy and preterm newborn`s perinatal infection.
Organism
from cervix
Perinatal
death
Infectio Without
Cong. Cong.
sepsis pneum. Omphalitis Conjunct. nonspec. infection Nosocom. Total
E. coli
2
GBS
Candida
albicans
Other aerobic
pathogens
Sample
negative
Sample was
not taken
2
Total
1
2
1
1
4
1
6
6
2
4
2
8
1
7
4
2
26
2
52
4
10
3
32
10
9
108
6
182
8
20
4
41
14
11
144
8
250
Table 7. Relationship between gestational age and preterm newborn´s perinatal infection.
Gestational Perinatal
age
death
Infectio Without
Cong. Cong.
sepsis pneum. Omphalitis Conjunct. nonspec. infection Nosocom. Total
22-26
1
5
1
26-30
2
4
1
30-34
2
10
34-38
3
1
Total
8
20
1
8
3
1
2
10
6
29
17
2
1
33
1
66
2
21
11
8
100
1
147
4
41
14
11
144
8
250
Conclusions:
1. The number of performed bacteriological investigations is too small for making
reliable general conclusions.
2. In most congenital sepsis cases the mother´s bacteriological culture had been
negative, or samples had not been taken.
3. GBS colonisation can be associated with early-gestation preterm delivery, perinatal
death and congenital sepsis, although GBS need not be detected in the newborn´s
blood.
4. In clinical infection cases with a negative bacteriological result it can be assumed that
the method of bacterial investigation is insensitive or inadequate.
5. Further randomised trials with more sensitive methods of bacterial investigation
should be conducted in order to reduce the incidence of preterm deliveries and
newborn early infection.
Literature:
1. S. M. Garland, F.N Chuileannain, C.Satze, R. Robins-Browne . Mechanisms,
organisms and markers of infection in pregnancy. Journal of Reproductive
Immunology 57, 2002;169-183
2. R. L ,Goldenberg, J.C. Hault ,W.W Andrews. Mechanism of Disease:Intrauterine
Infection and Preterm Delivery. The New England Yournal of Medicine.Vol 342 2002
May; 1500-1507
3. Tucker JM, Goldberg RL, Davis RO, Copper RL; Winkler CL Hautch JC. Etiologies
of preterm birth in an indigent population: is prevention a logical
expectation?ObstetrGynecol 1991; 77:343-7
4. Kimberlin DF, Hautch JC, Owen J, Bottoms SF, Iams JD, Mercer BM, Thom EA,
Moawad AH, Van Dorsten JP, Thurnau GR. Indicated versus spontaneous preterm
delivery.Am J Obstetr Gynecol 1999; 180(3pt1):683-9
5. Gilles R.G Monif; David A. Baher Infectious Disease in Obstetrics and Gynecology
2004:451-461