Defense factors of vaginal lactobacilli.
OBJECTIVE
To determine the antagonistic relationship between vaginal lactobacilli and endogenous vaginal microflora.


METHODS
Twenty-two Lactobacillus strains were studied for the production of lactic acid, hydrogen peroxide, and bacteriocin.


RESULTS
Under standardized growth conditions, most strains increased their biomass by more than 4 times. Lactobacillus species grew best at a pH > or = 4.5, and growth was retarded at a pH < 4.5. Lactic acid levels were 0.68 to 2.518 mg/mL and were not related to the number of cells or the pH of media. The pH of the media was caused by the secretion of lactic and other organic acids. Approximately 80% of the strains produced H(2)O(2) and were graded as 2+ in one third of the strains and 1+ in others. No statistical correlation was found between H(2)O(2) lactic acid and bacteriocin production. Bacteriocin activity was tested on 4 strains of Gardnerella vaginalis. Approximately 80% of the lactobacilli tested produced bacteriocin that inhibited growth of G vaginalis. Six of the strains did not produce bacteriocin. Thirteen strains produced all 3 defense factors, whereas the others lacked 1 or 2 properties.


CONCLUSIONS
Lactobacillus species grow best at a pH > 4.5. The pH of the media is dependent on the cell mass and on all organic acids produced by Lactobacillus species. Although all species produce organic acids, not all produce H(2)O(2) and bacteriocin. Not all strains of G vaginalis can be inhibited by lactobacilli-producing bacteriocin.
Aroutcheva
A
A
Department of Obstetrics and Gynecology, Rush-Presbyterian, St Luke's Medical Center, Chicago, Illinois, USA.
Gariti
D
D
Simon
M
M
Shott
S
S
Faro
J
J
Simoes
J A
JA
Gurguis
A
A
Faro
S
S
D000328:Adult; D001430:Bacteriocins / Q000096:biosynthesis* / Q000494:pharmacology; D003470:Culture Media; D005260:Female; D006194:Gardnerella vaginalis / Q000187:drug effects / Q000254:growth & development; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000096:biosynthesis*; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism*; D013045:Species Specificity; D014621:Vagina / Q000382:microbiology*
D001430:Bacteriocins; D003470:Culture Media; D019344:Lactic Acid; D006861:Hydrogen Peroxide