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.


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

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