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Journal Reading Annals Of Clinical Microbiology and Antimicrobials 2011, 10:8
By : Diana Astari
Moderator : Dewi Kartika T.
Day/Date : Wednesday/ October, 19th 2011
Clinical Pathology Department, Faculty Of Medicine Universitas Padjajaran/RSUP Dr.
Hasan Sadikin BandungThe Role Of Acidification In The Inhibition ofNeisseria gonorrhoeae By
Vaginal Lactobacilli During Anaerobic Growth
Michelle A Graver, Jeremy J Wade
BACKGROUND
The majority of healthy women harbor lactobacillli (LB) in the vagina at counts of 107-109
cfu/gm secretions, protect the female genital tract to produce lactic acid. LB may also inhibit
opportunist bacteria through production of bacteriocins, hydrogen peroxide (H2O2) or local
immune response.
In bacterial vaginosis (BV) is replacement of normal vagina LB by a mixed flora of
anaerobic bacteria and may increase susceptibility to infection with sexually-transmitted
pathogens includingNeisseria gonorrhoeae (NG), a facultative anaerobe.
Bacterial interference between LB and NG growing anaerobically in liquid medium has
not been studied. By co-cultivating LB and NG, this study sought to identify the relative
contribution of LB acidification and H2O2production to any inhibition of NG under anaerobic
conditions.
METHODS
Media
A defined medium rendered anaerobic with Oxyrase for Broth (Oxyrase Inc, Ohio,
USA) was used, with ad without MES buffer adjusted to an intial pH 6.5 with 1 M HCl.
Bacterial Strains
The strains studied included three LB : Lactobacillus crispatus (LC), Lactobacillusgasseri (LG), andLactobacillus jensenii (LJ) distinguishable by auxotyping by the method ofCopley & Egglestone. Fusobacterium nucleatum (FN) was included as an indicator of
anaerobiosis.
Preparation Of Inocula
Inocula were prepared from overnight growth on chocolate agar in 5% CO2 at 37C for
NG, from blood agar incubated anaerobically overnight at 37C for FN, and from blood agar
incubated in 5% CO2 at 37C for 48 h for LB (media from Oxoid, Basingstoke, UK).
Monomicrobial Culture
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Monomicrobial growth studies were done to ensure that all bacteria were capable of
growth in medium, to identify any effect of MES buffer on growth, and to confirm
anaerobiosis by growth of the anaerobe FN.
Co-cultivation
Co-cultivation experiments were designed to demostrate whether high concentrations of
LB affect the growth of NG and if the addition of a pH buffer had any influence.
Sampling, Colony Counts And Growth Curves
Capped bijoux were incubated at 37C, and at times 15 h, 20 h and 25 h were examined
and confirmed reduction of inoculation and up to at least 25 h. Colonies were counted using
an aCOLyte colony counter (Don Whitley, UK). To demonstrate growth in the media, and
any effect of MES buffer, growth curves were prepared for the FN, NG and LB with and
without MES, using the median bacterial count at each time point.
RESULTS
The median counts (median log10 cfu/mL) for FN at times 0 and 25 h were 5.27 and 8.2,
respectively, confirming anaerobiosis. All LB and NG grew in media with and without MES
buffer. LB at the high inoculum grew over the first 15 h after inoculation and remained viable
thereafter. The addition of MES had negligible effect on growth.
In co-cultivation experiments, the median log10 cfu/mL inocula for LB and NG were 6.78
and 4.0, respectively. In the absence of MES buffer both LC and LG reduced the pH by > 1
point by 25 h; MES resisted this acidification, with a pH fall of
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used in for bacterial interference studies. This inhibitory actions appears to be primarily due
to acidification rather than H2O2 production demostrated by the correlation between the
degree of inhibition and the acidification capabilities of individual LB, the effects of buffer
and lacks of H2O2production. This study remains possible that a bacteriocin produced at, or
activated by, a lower pH could account. These study suggest that those seeking to select LB
for probiotic use in BV should address the acidification potential of candidate LB
CONCLUSION
During anaerobic growth, inhibition of NG by the vaginal LB tested was primarily due to
acidification, as evidenced by reduced inhibition in the presence of buffer. There was no
evidence of a specific mechanism of inhibition other than acid production, H2O2 was not
produce under these conditions. The acidification potential of vaginal lactobacilli under
anaerobic conditions may be an important characteristic conferring protection against NG
infection.
The Role Of Acidification In The Inhibition ofNeisseria gonorrhoeae By Vaginal
Lactobacilli During Anaerobic Growth
Background:
- Vaginal lactobacilli (LB) protect the female genital tract by producing lactic acid.
- LB inhibit opportunist bacteria through production bacteriocins, H2O2, or local immune response.
- Bacterial vaginosis (BV) is replacement of normal vagina LB by a mixed flora of anaerobic
bacteria and may increase susceptibility to infection with sexually-transmitted pathogens including
Neisseria gonorrhoeae (NG)
By co-cultivating NG in the presence of LB, to identify the relative contributions ofacidificat2ion and H2O2production to any growth inhibition of NG.
Methods :
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Three strains of NG by auxotyping grown in the presence of high concentrations of three vaginal LB
(L. Crispatus, L.gasseri and L.jensenii) in anaerobic liquid medium, wit or without MES buffer.
Fusobacterium nucleatum as an indicator anaerobiosis.
Bacterial counts performed at 15, 20 and 25 h; at 25 h pH and H2O2 concentration
Result:
Growth ofF.nucleatum confirmed anaerobiosis
All bacteria grew in anaerobic liquid medium and addition MES buffer had effect on growth.
L.crispatus and L.gasseri produced acidification and reduction in growth of NG.
L.jensenii produced less acidification and did not inhibit NG.
H2O2 not detected.
Discussion:
LB, normal vaginal flora plays a key role in maintaining vaginal health.
BV characterized by loss of the protective LB flora in the vagina & problem as risk factor infections
gonorrhoeae.
H2O2production is an important protective characteristic of LB comprising in normal vaginal flora.
Antibacterial effect H2O2permit LB to suppress other bacteria and control the vaginal flora.
NG can growth in anaerobic conditions and inhibit by vaginal LB growing.
Inhibitory appears due to acidification rather than H2O2production.
Correlation between the degree inhibition and the acidification individual LB, the effects of buffer,
and lack of H2O2production.
Conclusion :
During anaerobic growth inhibition of NG by LB due to acidification and abrogated by the presence
buffer.
H2O2 not produced
The acidification potential of vaginal lactobacilli under anaerobic conditions may be an
important characteristic conferring protection against NG infection.