**4. Staphylococcal infection and male infertility**

native gene encoding a penicillin-binding protein (PBP2a) that has significantly lower affinity for β-lactams [11]. In addition to MRSA, the vancomycin-intermediate/resistant *S. aureus* (VISA/VRSA) strain has also been reported in staphylococcal infection, particularly in some

Barring the role of a few bacteria such as *Chlamydia* whose impact on fertility has been well established, the significance of other bacteria in infertility is controversial. An epidemiological research revealed that the prevalence of bacterial vaginosis (BV) as 70.34% among infertile women. Previously, the categories of organisms with the potential to cause bacterial infection in female reproductive system have involved *Gardnerella vaginalis*, *Mobiluncus* sp., *Bacteroide* sp., *Prevotella* sp., and *Mycoplasma* sp. [12]. In general, Gram-positive bacteria were significantly higher in number than the Gram-negative bacteria. Series of epidemiological studies have revealed that *Staphylococcus* is among the top bacterium detected from reproductive organs and is closely related with infertility. For example, Momoh et al. [13] reported a prevalence rate of 38.7% *S. aureus* from high vaginal swab and endocervical swabs and a prevalence of 75% from semen cultures of infertile couples. Another investigation identified *S. aureus* as the most prevalent vaginal pathogen (57.33%) among local infertile women, followed by *Escheri‐*

Parallel to the situation in females, abnormal presence of *Staphylococcus* sp. has been increas‐ ingly evidenced in the genitourinary system of male patients with fertile problem. In a study of a total of 140 sperm samples collected from the University of Benin Teaching Hospital, *S. aureus* (28.3%) and *S. saprohyticus* (13.0%) were the most common pathogens found and have negative effects on sperm motility and morphology [15]. The commonest bacteria isolated from 160 men attending infertility clinics in South-eastern Nigeria were *Proteus* sp., *S. aureus*, and *E. coli*, and most of the detected strains were resistant to antibiotics assessed[16]. Besides the *S. aureus*, other staphylococci are also commonly found in infertile male patients. *S. epidermi‐ dis* was found to be one of the most common bacteria in 295 infertile males at the Hospital Juárez de México, and the bacteria profoundly affected the sperm motility, pH, morphology,

In healthy women of child-bearing age, the protective mucosa in the vagina is populated with microflora typically dominated by lactobacilli, and their dominance over pathogenic anae‐ robes is positively associated with vaginal health. Thanks to the biological antagonism provided by a healthy vaginal microbiota, opportunistic microorganisms are in very low numbers in normal vagina. It is proven that lactobacilli provide a constant acidic pH value and maintain the appropriate concentration of hydrogen peroxide in the genital environment. While under the condition of BV, the concentration of lactobacilli reduces but of some pathogenic bacteria, especially anaerobes or microaerophiles, increase [18]. BV represents the most common vaginal syndrome that affects fertile, premenopausal, and pregnant women, with an incidence rate ranging from 20% to 50% [19, 20]. BV is not caused by one specific

**3. Epidemiology of genitourinary staphylococcal infection**

cases of enterococcal infection.

162 Genital Infections and Infertility

*chia coli* (25.33%) [14].

and viscosity [17].

Urogenital tract infections in males are one of the significant etiological factors in infertility. The infection of bacteria such as *Staphylococcus* sp. has been detected at the male reproductive tract. Staphylococcal infection in male reproductive organs and accessory glands may exert detrimental effect on sperm activity. Previous studies indicated that staphylococci not only affect the sperm activity but also impact the secretory capacity of the epididymis, seminal vesicles, and prostate [26]. In fact, staphylococci have been identified as one of the most common strains that can be detected in the male reproductive system. However, the percen‐ tages of males that get infected with staphylococci vary with the different isolation methods and procedures used in different studies. It has been demonstrated that *S. aureus* infection significantly interferes with semen quality and activity. It deteriorates the volume of semen and the concentration of sperm as well as the motility, morphology, and vitality of sperm. Therefore, a causative relationship may exist between staphylococcal infection and male infertility. A previous study reported a 20.6% infection of *S. aureus*in the semen samples from males with fertility problems. More importantly, *S. aureus* infection was found to be closely related to poor semen quality and reduced sperm motility [27]. Also, an investigation by a Poland group associated *S. aureus* infection with abnormal semen parameters or other surogenital tract infection [28].

Besides these prospective studies, several *in vitro* studies also support the effect of *Staphylo‐ coccus* on sperm activity and its relation with infertility. It was revealed that infection of the normal human ejaculated spermatozoa with *S. haemolyticus* profoundly impacted the archi‐ tecture and integrity of the sperm plasma membrane. Bacterial infection serves as a contribu‐ ting factor for severe injury of sperm membrane stability and mitochondrial activity with potential consequences of male fertility [29]. In addition, exposure of ejaculated spermatozoa to *S. haemolyticus* was found to trigger a simultaneous decrease in the percentage of sperm with normal ΔΨm and an increase in the proportion of sperm with Annexin V staining, indicative of apoptotic cells. The data suggested a determinant role of staphylococcal infection in sperm fate [30]. Despite the above findings, the role for staphylococci in male infertility has remained somewhat controversial. A previous study showed that, although *Staphylococcus* sp. was the most common bacteria isolated in 299 asymptomatic men undergoing fertility evaluation, the bacterial counts were not correlated with semen parameters [31].

In an effort to understand the mechanism whereby staphylococci modulate sperm activity, investigators currently identified some of the key molecules that have profound effect on sperm activity. Kaur and Prabha *et al.* firstly identified sperm agglutinating factor (SAF). Based on the observation that *S. aureus* can adhere to the sperm head as well as sperm tail and agglutinate mouse spermatozoa, the group finally isolated a protein with a molecular weight of approximately 57 kDa from *S. aureus* and implicated the protein in control of sperm motility and survival. Moreover, SAF potentially affects various sperm parameters such as Mg2+ dependent ATPase activity, acrosome status, and apoptosis. In support of this, a profound morphological alteration occurs in the spermatozoa upon binding with SAF, as detected with scanning electron microscopy. Also, SAF has a spermicidal effect at high concentrations and may have the potential to function as active ingredient of a vaginal contraceptive. Further studies indicate that the interaction of SAF with spermatozoa is receptor mediated, and the receptor has been isolated and purified from human spermatozoa. This sperm surface receptor component showed homology to glutamate decarboxylase and major histocompatibility complex (MHC) class I molecule [32]. Intriguingly, the receptor was shown to be able to counteract the detrimental effects of SAF on sperm parameters and alleviate SAF-induced infertility in mice [33]. In addition, Prabha *et al.* isolated the SAF from an *E. coli* strain. This kind of SAF also leads to sperm agglutination, the compromised Mg2+-dependent ATPase activity, and spermatozoa apoptosis.

In 2009, another protein with sperm regulatory effect, named sperm immobilization factor (SIF), was identified from *S. aureus*. SIF is a protein with the molecular weight of approximately 20 kDa. Similar to SAF, SIF causes multiple defects in the head, midpiece, neck, and tail region of human spermatozoa [34]. It can completely inhibit Mg2+ ATPase activity of spermatozoa at the concentration of 100 μg/ml and reduce calcium ionophore–induced acrosome reaction. The interaction between SIF and spermatozoa is also ligand-receptor dependent. The analysis by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) showed that the receptor shares sequence similarity with MHC class II antigen. Interestingly, SIF has been found to impede motile bacteria, in addition to sperm, such as *E. coli*, *Pseudomonas aeruginosa*, and *Proteus mirabilis*. The molecular mimicry of SIF receptor has been confirmed between spermatozoa and bacteria [35].

In addition to the effector molecules mentioned above, some novel mechanisms responsible for the staphylococcal regulation of sperm have now been discovered. A recent study on the semen of 589 infertile males indicated that other virulence genes in *S. aureus*, such as hlg (33.3%), scn (23.3%), cna (20%), hlb (20%), and clfA (18.3%), were possibly responsible for spermatozoal immobilization [36]. Berktas et al. raised another point of view that, rather than the direct interaction between bacteria and sperm, the alteration in genital microenvironment or ver-consumption of energy by high dose of bacterium led to the loss of sperm motility [37].
