Comparison between chlorhexidine and povidone-iodine solutions for flushing the preputial cavity on penile mucosa and semen bacterial counts in beef bulls

In males, preputial flushing with antiseptics has been recommended prior to abdominal surgery to reduce the risk of potential source of microorganisms for the surgical wound [1,2], before surgery to prepare bulls as teasers for estrus detection [3], as part of the treatment protocols for injuries of penis and prepuce [4,5], to decrease the bacterial load in the ejaculate to be processed for artificial insemination [[6], [7], [8], [9]], and to reduce or eliminate the quantity of contaminant microorganisms from the penis and prepuce prior to collection of a semen sample for further microbiological culture [[10], [11], [12], [13], [14]].

Inside the prepuce of clinically healthy bulls, more than 750 species of bacteria, most of them non-pathogenic or saprophytic, as well as 154 species of yeasts have been isolated [15,16]. The most frequent bacteria isolated were Streptococcus spp., Staphylococcus spp., Micrococcus spp., Escherichia coli, Bacillus spp, Proteus spp., Diphtheroids, and Corynebacterium spp.; the main yeasts isolated were Candida spp., Torulopsis spp., and Rhodotorula spp. [[15], [16], [17], [18]].

A suitable semen sample, non-contaminated and free of impurity, is required for further microbiological culture for a correct diagnosis in cases of inflammation of the bull's internal genital organs, presence of pus in semen, purulent vaginal discharge after natural breeding as well as to rule out specific diseases [13,14]. Three techniques for aseptic semen collection have been reported. The first requires semen collection from the vagina of a female [10]; the second consists of collecting semen using a sterile artificial vagina [11]; and the third consists of collecting semen from previous penis exteriorization, urethra catheterization, and simultaneous massage of the accessory sexual glands [11,12]. The first technique requires a trained bull with adequate libido, mating ability, and a suitable restrained female in estrus in which the prepuce and the vagina have been previously cleaned, flushed first with antiseptics, and then with sterile saline solution. The second technique also requires a bull with adequate libido, mating ability, and trained to be collected with an artificial vagina, a teaser for semen collection, a sterile artificial vagina, at least one assistant for bull and teaser management in an adequate location [11]. The third technique involves tranquilization of the bull, cleaning and asepsis of the penis and prepuce, at least two people, one in charge of exteriorizing and grasping the penis, urethral catheterization, and flushing with sterile saline solution and semen collection, and the other person responsible for the massage of accessory sexual glands per rectum and the root of the penis [11,12]. In practice, most of these aforementioned settings and requirements cannot be entirely satisfied, and a high frequency of contamination of the semen sample can be produced [11,13].

Chlorhexidine and povidone-iodine are the most commonly used antiseptics in human and veterinary medicine [1,19,20]. Chlorhexidine is rapidly bactericidal, with a broad spectrum of activity, low toxicity, and few adverse reactions. Additionally, this activity is minimally affected by the presence of organic debris [21]. Povidone-iodine is also bactericide, with a broad spectrum of activity; however, there are adverse reactions, and it is affected by presence of organic material [1,2].

In the last few years, a new aseptic technique of semen collection in bulls by electroejaculation for microbiological culture under field and clinic conditions was developed and recently reported [13]. At first, many semen samples with reduced or free of microorganisms when collected from clinically healthy bulls previously submitted to antiseptic preputial flushing were obtained [13]. However, this method of semen collection for microbiological culture requires additional improvements. One of these is to establish the level of antiseptic efficacy of two of the most frequent antiseptics, povidone-iodine and chlorhexidine, that were used during the development of this technique. To the best of the authors’ knowledge, no comparative studies about the effect of flushing of the preputial cavity with either chlorhexidine or povidone-iodine solutions on bacterial counts from penile mucosa and semen in bulls are available.

The objectives of the present study were to estimate the number of CFU from penile mucosa and semen, the effect of CHG and POI used to flush the preputial cavity to reduce the bacterial counts from those sites, and compare them.

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