Introduction: Normal vaginal microflora is usually dominated by Lactobacillus species, which play an important role in the maintenance of vaginal health. The dynamism of the vaginal microflora is especially notable as changes that occur during menses. The vaginal micro-environment is dynamic and undergoes changes during the menstrual cycle in women of reproductive age. These changes correlate with the accompanying hormonal changes. Indeed, the vagina is a highly dynamic ecosystem. Studies show that changes occur in the vaginal microflora during the normal menstrual cycle.
The recurrent imbalance that occurs in the equilibrium of vaginal
microflora favors the overgrowth of bacterial vaginosis (BV)-associated
bacteria. The relative depletion of the resident Lactobacilli has been shown to
be most profound at the time of menses, indicating that the vaginal microflora
become less stable during this event. This phenomenon has generally been
attributed to the premenstrual decline in circulating levels of estrogen, which
in turn affects the colonisation strength of the vaginal Lactobacilli, for
example by limiting their capacity for epithelial adherence. The vaginal
Lactobacillus microflora are probably further challenged by the menstrual
flooding of the vagina, which is accompanied by a sharply rising pH, further exacerbating
the unfavorable conditions for epithelial adherence of the Lactobacilli. Under
such conditions, the colonisation resistance offered to BV-associated anaerobes
can easily be overcome. Menses possibly also induces a wash-out of Lactobacilli
through haemagglutination. These mechanisms might explain why BV is less
prevalent in pregnant and postmenopausal women, despite the relative estrogen
deficiency, especially in the latter group. To further demonstrate the
important role that hormones might play in maintaining the balance in the
vaginal ecosystem, a recent longitudinal study found women using hormonal
contraceptives to have less prevalence due to greater remission of BV. The objective of this study was to characterize
and explore the changes in the vaginal microflora during the menstrual cycle of
HIV positive (HIV+) and HIV negative (HIV-) women in a sub-urban population of
Kenya.
Methods: In a longitudinal study of 38 premenopausal women, 20
HIV+ and 18 HIV-, high vaginal swabs were taken for genomic DNA extraction.
Gram stains were prepared at each of the six visits for each woman. Nugent
scores were performed, and quantification of three Lactobacillus spp. (L.
crispatus, L. jensenii and L. iners) and Gardnerella vaginalis and Atopobium
vaginae carried out by real-time or quantitative PCR (qPCR) technique.
Results: Results based on Gram stain category showed a high
concentration of L. iners in the normal vaginal microflora. This increases
during bacterial vaginosis (BV). There were high levels of L. jensenii in half
of the women with BV, while L. Crispatus was absent in BV cases. Concentration
of G. vaginalis increased progressively from normal to BV microflora while A.
vaginae was absent in normal microflora but was detectable in intermediate gram
stain and increased progressively during the BV phase.
Analysis based on HIV status showed a high concentration of L.
iners and G. vaginalis in both the HIV+ and HIV- groups. Condom use was
significantly higher in HIV+ women, but the number of those harbouring the
protective L. crispatus was less than in the HIV- group. The concentration of
L. crispatus was remarkably lower in the HIV+ group. Atopobium vaginae was
present in both groups but L. jensenii was not detectable in the HIV+ women.
Based on the phase of the menstrual cycle, analysis showed a high
concentration of L. iners and G. vaginalis throughout the cycle. Concentration
of L. crispatus increased while concentration of A. vaginae decreased
throughout the menstrual cycle. At the initial phase of the menstrual cycle, L.
jensenii was comparatively low and not detectable thereafter.
Conclusions: The predominant species in normal vaginal microflora
in this Kenyan population of women is L. iners, and which increased during BV.
Both HIV+ and HIV- groups had high concentrations of L. iners and G. vaginalis.
Throughout the menstrual cycle, concentration of L. crispatus increased while
concentration of A. vaginae decreased. At the initial phase of the menstrual
cycle, L. jensenii was comparatively low and not detectable thereafter.
Author
(s) Details
Teresa
N. Kiama
Department of Human Anatomy& Medical Physiology, University of
Nairobi, Kenya.
Mario Vaneechoutte
Laboratory for Bacteriology Research, Faculty of Medicine and Health
Sciences, University of Ghent, Belgium.
Paul M. Mbugua
Department of Human Anatomy& Medical Physiology, University of Nairobi,
Kenya.
Hans Verstraelen
Department of Obstetrics & Gynaecology, Ghent University Hospital,
Belgium.
Benson Estambale
University of Nairobi Institute of Tropical and Infectious Diseases
(UNITID), Kenya.
Marleen Temmerman
Department of Obstetrics & Gynaecology, Ghent University Hospital,
Belgium.
Rita Verhelst
Laboratory for Bacteriology Research, Faculty of Medicine and Health
Sciences, University of Ghent, Belgium.
Please see the book here:- https://doi.org/10.9734/bpi/rpbs/v4/1438
