Do mycoplasmas inhibit the human sperm fertilizing ability in vitro?
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Updated: Oct 23, 2026
Fluorimetric Techniques for the Assessment of Sperm Membranes
Published on: November 28, 2018
Abstract:
Although clinical observations have suggested that Ureaplasma urealyticum may be associated with reproductive failure, the role of ureaplasmas in human infertility remains controversial. However, the mechanism whereby ureaplasmas can interfere with the fertilization process is not known. To study possible mechanisms, we used the human sperm-hamster egg fertilization test. Eggs were exposed to the spermatozoa preincubated with Mycoplasma hominis or U. urealyticum (serotype 1-8). U. urealyticum serotype 4 showed greater interference activity on the penetration rate (6.6%) than did the other mycoplasmas, as compared with the control (55%). Furthermore, our data suggest that the inhibition of penetration was not related to a masking of sperm membrane sites, since the mean of adsorbed spermatozoa/egg after preincubation of spermatozoa with mycoplasmas was not significantly different from that of the control. In addition, eggs preincubated with U. urealyticum serotype 4 gave a reduction of the penetration rate by untreated spermatozoa.
Insights
Ureaplasma urealyticum, particularly serotype 4, can interfere with human fertilization. This study investigated the mechanisms behind ureaplasma-induced infertility using a sperm-hamster egg test.
Area of Science:
- Reproductive biology
- Microbiology
- Infectious diseases
Background:
- Clinical observations suggest Ureaplasma urealyticum may cause reproductive failure, but its role in human infertility is debated.
- The specific mechanisms by which ureaplasmas might impact fertilization are not well understood.
Purpose of the Study:
- To investigate the potential interference of Ureaplasma urealyticum and Mycoplasma hominis with human fertilization.
- To elucidate the mechanism of interference using the human sperm-hamster egg fertilization assay.
Main Methods:
- Human spermatozoa were preincubated with Mycoplasma hominis or Ureaplasma urealyticum (serotypes 1-8).
- The effect on sperm penetration rate was assessed using the human sperm-hamster egg fertilization test.
- Spermatozoa adsorption to eggs and the effect of U. urealyticum on unexposed eggs were also evaluated.
Main Results:
- Ureaplasma urealyticum serotype 4 significantly reduced the sperm penetration rate (6.6%) compared to controls (55%).
- Inhibition of penetration was not due to masking of sperm membrane sites, as sperm adsorption to eggs remained unchanged.
- Eggs preincubated with U. urealyticum serotype 4 also showed reduced penetration by untreated spermatozoa.
Conclusions:
- Ureaplasma urealyticum serotype 4 demonstrates significant interference with human fertilization in vitro.
- The mechanism of interference does not appear to involve blocking sperm-egg interaction sites.
- These findings suggest a direct impact of specific ureaplasma serotypes on the fertilization process.
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