The Protective Lactobacillus System
Role of lactobacilli
The human vagina possesses a bio-system which
under normal conditions provides a balance between physiologic
lactobacilli and pathogenic bacterial flora, and so ensures a
good protection against the spreading of pathogens, including
their ascension to the uterine cavity. The importance of
lactobacilli for the normal vaginal milieu was first described by
In an article of particular interest to us,
Gregor Reid 
describes the role of lactobacilli in urogenital tract
The following main functions of lactobacilli are
known (Fig. 1):
1. They produce acids, mainly lactic acid.
2. They produce hydrogene peroxide
(H2O2), which releases oxygen and has a
disinfecting effect. These factors, combined with
3. Bacteriocines inhibit the growth of pathogens
which are always present in the vagina.
4. They produce biosurfactants, which cover the
surface of the vaginal wall, thereby inhibiting the adhesion of
5. They produce coaggregation molecules which block the spread
Fig. 1: Protective vaginal bio-system
Please click on the miniature picture.
Not every lactobacillus strain produces all the
factors mentioned above. That’s the reason why some strains are
more effective against specific infections than others. For
instance, women with H2O2-producing
lactobacilli have a lower risk of suffering from Bacterial
Vaginosis, than women whose lactobacilli don’t produce
H2O2 [Hillier et. al 1992a]. Unfortunately, there are also some
microorganisms, the growth of which is not or only marginally inhibited
by lactobacilli (e.g. Streptococci and Candida).
However, we can assume that lactobacilli are the
main regulating factor of the vaginal milieu. Vaginal pH
measurement gives us insight – like peering through a keyhole –
into this protective bio-system. Vaginal pH measurement was
already used by Döderlein, in order to distinguish pathological
from normal vaginal fluid [Döderlein 1892].
Importance of pH measurement
The importance of Lactobacilli and measurement of
vaginal pH is illustrated for instance by the following
al.  found out, that the risk of premature rupture of
the membranes before 37+0 gestational weeks (gw) is three times
higher when the vaginal pH is repeatedly above 4.5, compared to
pregnant patients with pH ≤ 4.5.
From a retrospective evaluation carried out by one
of our co-workers it reveals that: The earlier in pregnancy the
examined children were born, the more frequently the mothers had
an increased vaginal pH, when admitted to hospital. All 15
mothers (100%) of children with a gestational age lower than 32+0
gw had increased pH values, as far as prematures between 32+0 gw
and 36+6 gw were concerned, the rate was still about 60%; when
born mature only 43.5 % were affected [Schumacher 1999]. It follows, that
ascending infections very frequently play a role concerning very
early prematurity, and that in many of these cases threatening
prematurity can be detected by measurement of increased pH
In a prospective study, Hengst et. al  was able to show the
practical importance of measuring the vaginal pH, which we
recommend in routine prenatal care for the prevention of
prematurity. In a cohort of pregnant women with so far normal
course of pregnancy, who had an increased pH values of
> 4.5 and who had received no therapy for acidification,
the number of prematures amounted to 15.1%. On the other hand,
the number was only 2.0% when an acidifying therapy with L.
acidophilus preparations had been applied.
In another earlier evaluation, we also found
results concerning how many pregnant patients had normal vaginal
pH values and how many had pathological (≥ 4.7). In 67% of
all the 695 evaluated cases, normal pH values were present; in
33%, the values were increased twice or more, and 7% of these
were permanently increased [Saling et al. 1995].
It is of particular interest to examine the
success rate in normalizing the pH, in cases with increased
vaginal pH values, by using L. acidophilus therapy. Success was
achieved in 83% of 75 such patients, and this is really an
unexpectedly good result. The therapy was carried out for
5 ± 3 days to achieve this success [Saling et al. 1995].
Normal flora – disturbed milieu – infection
According to some published data, we assume that
the main reason for the good results of our Prematurity-Prevention-Program is not
the early detection of existing infections, but the early
detection of their precursors, namely disturbances of the vaginal
et al. [1992b] diagnosed an intermediate pattern between
normal flora and Bacterial Vaginosis – see also Schröder  – in 16% of
the pregnant women examined, while 22% of the women suffered from
Bacterial Vaginosis, and 61% had a normal flora. Of the women
with such a transitional stage in the 2nd trimester, in the 3rd
trimester in about 1/3 the findings were the same, in about 1/3
the findings were normal, and about 1/3 developed a Bacterial
Hay et al.
 found in a study an increased risk for loss of
pregnancy, when just an intermediate pattern was present.
et al.  reported, that an increasing pH value during
the course of pregnancy leads to an increased risk of
prematurity, even when the pH value stays within the normal
In the literature, there are controversial results
concerning the success of treatment of Bacterial Vaginosis, and
its effects on pregnancy outcome. However, there may have been
little success, when screening, diagnose, and treatment took
place rather late in the course of pregnancy, or when the
diagnosis was incorrect, and there was probably a so-called
“Aerobic Vaginitis” (which is associated with aerobic
microorganisms, mainly group B streptococci and E. coli) rather
than a Bacterial Vaginosis [Donders et al. 2002].
We assume, that the main reason for those
different results is the following:
Up to now no studies have been published, where
vaginal acidity was checked by pH-measurement so early in
pregnancy, and at such short intervals (allowing early
treatment), like is the case for the pregnant women, who
participate in our Self-Care-Program.
We have first results which indicate, that already
disturbances of the vaginal milieu can be detected by
pH-measurement at regular intervals, before Bacterial Vaginosis
develops [Saling/Schreiber 2005]. In 24 pregnant
patients, who visited their doctor because they had themselves
measured an increased vaginal pH value, 33 diagnoses were
46% of the patients were told, that they only had
a disturbance of the vaginal milieu, and not yet a Bacterial
A Bacterial Vaginosis was diagnosed only in
Candida were diagnosed in 33%, Chlamydia in 8%,
and other bacteria in 8%, too.
Although we received these data from the patients,
and not directly from their physicians – and thus they should be
interpreted with caution – there is no reason to question the
results on principle.
Self-Care-Program for pregnant women to prevent