ADHERENCE OF ESCHERICHIA-COLI TO SPERM - A MANNOSE MEDIATED PHENOMENON LEADING TO AGGLUTINATION OF SPERM AND ESCHERICHIA-COLI

Objective: To investigate the mechanism of adherence between Escherich ia coli and sperm. Design: Experimental study performed with donor spe rm and male genital tract-derived E. coli. Setting: Andrology unit of a university hospital. Patients: None. Interventions: Monitoring of sp erm-E. coli agglutination; addition of sugars to block adherence; elec tron microscopy. Main Outcome Measure: Sperm-E. coli agglutination. Re sults: Escherichia coli readily adhered to and agglutinated sperm. The phenomenon was observed at E. coli to sperm ratios as low as 1:20; ma ximum sperm agglutination involving approximately 90% of spermatozoa w as seen with ratios of 1:5 or higher. By transmission electron microsc opy, E. coli adherence was observed both on sperm heads and tails. Het eroagglutination could be blocked by D-mannose and alpha-methyl-mannop yranoside but not by other sugars. Preincubation of sperm or E. coli w ith mannose resulted in block of agglutination, indicating mannose-bin ding structures both on sperm and E. coli. Conclusions: Adherence of E . coli to sperm is mediated by mannose and mannose-binding structures present on both cell types. Agglutination of sperm by E. coli may be r elevant in male and female infertility.