**2. Uropathogenic strains of** *E. coli* **are associated with male infertility**

Among the different pathogenic strains of *E. coli,* the uropathogenic strains are mainly associ‐ ated with urinary tract infections (UTI). The pathogenic *E. coli* is classified according to the O antigens. Some of these have been associated with uropathogenic *E. coli* (UPEC) being the serotypes O1, O2, O4, O6, O7, O8, O16, O18, O25, and O75 preferentially associated with these strains [14]. Similarly, the most frequently O antigens associated among the serotypes isolated from patients with prostatitis are O1, O2, O4, O16, O18, O22, O25 and O75 serotypes [15], which coincide with *E. coli* strains isolated in cases of infections to the urinary tract. Regarding to the strains isolated from semen of infertile men, the described prevalent antigens are O1, O2, O4 and O6 [16]. These data indicate that the *E. coli* that infects the male reproductive tract is uropathogenic strain, which is not surprising considering the proximity of the urinary and reproductive tracts.
