Ability of Escherichia coli to produce hemolysis leads to a greater pathogenic effect on human sperm

Hemolytic Escherichia coli demonstrated a strain-dependent effect, altering all sperm variables studied, in contrast to nonhemolytic strains, which differentially impair sperm function.

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Rodrigo Boguen, M.Sc., Favian Treulen, M.Sc., Pamela Uribe, M.Sc., Juana V. Villegas, Ph.D.

Volume 103, Issue 5, Pages 1155-1161



To determine the effect on human sperm of Escherichia coli strains separated on the basis of their ability to produce hemolysis.


Experimental study.


University-based laboratory.


Semen samples from healthy donors.


Five million sperm, selected via the swim-up method, were incubated with 3 E. coli concentrations to obtain ratios of sperm to E. coli of 1:2, 1:16, and 1:128. The E. coli strains were: a hemolytic isolated strain (H), a nonhemolytic American Type Culture Collection strain (NH-ATCC), and a nonhemolytic isolated strain (NH-I).

Main Outcome Measure(s):

Aliquots of human sperm were used to measure progressive motility using computer-aided sperm analysis, mitochondrial membrane potential (ΔΨm) with a JC-1 (5,5′,6,6′ tetrachloro-1,1′,3,3′-tetraethylbenzamidazolocarbocyanin iodide) and propidium iodide stain, and intracellular reactive oxygen species (iROS) with a dihydroethidium (DHE) stain. Sperm ΔΨm and iROS were measured by flow cytometry. Sperm vitality was considered the mean of propidium iodide–negative and DHE-negative cells.


Sperm incubated with the H strain in a 1:2 sperm to bacteria ratio demonstrated a significant decrease in motility and ΔΨm, and an increase of iROS. The NH-ATCC strain decreased sperm motility and ΔΨm, but in a ratio of sperm to bacteria of 1:128; it increased iROS at a ratio of 1:16. The NH-I strain did not affect the analyzed sperm functions, even at a 1:128 sperm to bacteria ratio.


Results show a greater pathogenic effect on human sperm of E. coli strains with, versus without, hemolytic capacity.

Read the full text at: http://www.fertstert.org/article/S0015-0282(15)00091-6/fulltext

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

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