Screening for bacterial pathogens in semen samples from infertile men with and without leukocytospermia

We aimed to study the correlation between leukocyte counts in semen and bacterial pathogens in seminal samples of infertile men, and to establish the minimum leukocyte count associated with significant bacteriospermia. A total of 116 patients who underwent evaluation of fertility were investigated using routine semen analysis according to the guidelines of the WHO and bacterial pathogens analysis by culture and in-house PCR assay. The overall prevalence of bacteriospermia in semen samples was 56.9% independent of the presence of leukocytes. The most common bacterial species detected were Chlamydia trachomatis (41.4%), Ureaplasma urealyticum (15.5%) and Mycoplasma hominis (10.3%). The receiver operating characteristic curve analysis demonstrated that the sensitivity/specificity for detecting bacteria at a cut off level of >or=1 x 10(6) leukocytes per ml (which is the WHO defined level for leukocytospermia) was 20.3%/81.5%. The highest sensitivity/specificity ratio was found in semen samples with a cut-off level of >or=0.275 x 10(6) leukocytes per ml, which is best shown with the odds ratio of 2.47. A significant correlation was found between bacteriospermia and leukocytospermia at the cut-off level of >or=0.275 x 10(6) leukocytes per ml of semen samples (P = 0.032). We proposed that this is a possible new cut-off level to predict the presence of bacteria in semen of infertile men.