title: Mechanism of sperm immobilization by Escherichia coli.
abstract: OBJECTIVE
  To explore the influence of Escherichia coli on the motility of human spermatozoa and its possible mechanism.
  
  
  METHODS
  Highly motile preparations of spermatozoa from normozoospermic patients were coincubated with Escherichia coli for 4 hours. At 1, 2 and 4 hours of incubation, sperm motility was determined. The factor responsible for sperm immobilization without agglutination was isolated and purified from filtrates.
  
  
  RESULTS
  This report confirms the immobilization of spermatozoa by E. coli and demonstrates sperm immobilization factor (SIF) excreted by E. coli. Further this factor was purified by ammonium sulfate precipitation, gel permeation chromatography, and ion-exchange chromatography. Purified SIF (56 kDa) caused instant immobilization without agglutination of human spermatozoa at 800 microg/mL and death at 2.1 mg/mL. Spermatozoa incubated with SIF revealed multiple and profound alterations involving all superficial structures of spermatozoa as observed by scanning electron microscopy.
  
  
  CONCLUSIONS
  In conclusion, these results have shown immobilization of spermatozoa by E. coli and demonstrate a factor (SIF) produced and secreted by E. coli which causes variable structural damage as probable morphological correlates of immobilization.
authors.affiliation: Department of Microbiology, Panjab University, Chandigarh-160014, India. satishvijay11@yahoo.com
authors.forename: Vijay
authors.initials: V
authors.lastname: Prabha
authors.forename: Ravneet
authors.initials: R
authors.lastname: Sandhu
authors.forename: Siftjit
authors.initials: S
authors.lastname: Kaur
authors.forename: Kiranjeet
authors.initials: K
authors.lastname: Kaur
authors.forename: Abha
authors.initials: A
authors.lastname: Sarwal
authors.forename: Ravimohan S
authors.initials: RS
authors.lastname: Mavuduru
authors.forename: Shravan Kumar
authors.initials: SK
authors.lastname: Singh