Antimicrobial Activity of Human Seminal Fluid

Abstract

The antibacterial, antifungal and antimycoplasmal activity of human semen was studied. Gram-positive aerobic bacterial species i.e. staphylococci, but not gram-negative aerobic bacteria, were inhibited by seminal fluid in vitro. Neither were anaerobic gram-positive or gram-negative bacteria, nor Candida or Mycoplasma inhibited. Semen of healthy males had a higher antibacterial effect on S. albus than that of patients with symptoms of chronic prostatitis. There was a positive correlation between the antibacterial power of the semen of the patients studied and their content of zinc and magnesium, while no correlation was found with fructose and lysozyme or the number of spermatozoa in any of the groups. A positive correlation was found between the antibacterial capacity and the volume of the ejaculate in the patients but not among the controls. The antibacterial substance(s) was dialysable, ether-extractable, resistant to boiling and partly to storage at room temperature. The addition of EDTA, tranexamic acid and ammonium reineckate to semen did not influence the antibacterial effect, which was, however, slightly inhibited by sodium polyanethol sulphonate. The nature of possible antibacterial substances in semen is discussed.

Seminal fluid of honeybees contains multiple mechanisms to combat infections of the sexually transmitted pathogen Nosema apis

“…Second, we found that the defence response against N. apis also shows a degree of specificity, as our zone of inhibition experiments detected no antimicrobial activity of seminal fluid towards a number of other microorganisms. Such a specific antimicrobial response to a pathogen in the ejaculate has so far only been described for vertebrates [7,9]. Consequently, finding redundancy and specificity of an immune protection in an insect is quite surprising and requires further research to unravel the genetic and biochemical mechanisms that underlie the phenotypic interaction between the honeybee's antimicrobial defence and the N. apis pathogen, using novel approaches such as evolutionary proteomics [39].…”

“…To counter this, males are expected to evolve adaptations to reduce the risk of infecting their mates or offspring and ejaculates are indeed known to contain molecules with antimicrobial activity [5,6]. Host-parasite interactions in reproductive tissues and secretions has received relatively little scientific attention in insects but have been studied in vertebrates [7], where it is suggested that proteins with antimicrobial functions within the ejaculate are of central importance for male fitness because they suppress microbial growth [8,9] and affect sperm motility [10]. Antimicrobial proteins in ejaculates have also been reported in insects [5,6,[11][12][13], and antimicrobial activity of seminal fluid in the bedbug Cimex lectularius reduces sperm mortality in vitro [13,14].…”

The Human Cationic Antimicrobial Protein (hCAP-18) Is Expressed in the Epithelium of Human Epididymis, Is Present in Seminal Plasma at High Concentrations, and Is Attached to Spermatozoa

“…Despite this, the level in seminal plasma was 70-fold higher than that in blood plasma, which may indicate a key role for hCAP-18 in the context of reproduction. It has previously been reported that human seminal plasma has some, but not very strong, antibacterial activity (12). In general, for this family of antimicrobial proteins, the cathelicidins, the N-terminal cathelin segment must be removed to unleash the microbicidal activity of the C-terminal part (13,21).…”

Granulocyte Elastase as a Sensitive Diagnostic Parameter of Silent Male Genital Tract Inflammation*

“…Although these parameters in total support the diagnosis of the silent seminal tract infection, its prediction by a single factor is limited due to various sources of error (Mardh and Colleen -1975;Comhaire et al -1980;Riedel and Semm -1980).…”