Efficacy of Two Antibiotic-Extender Combinations on Mycoplasma bovis in Bovine Semen Production.

Nella Vähänikkilä,Tarja Pohjanvirta,Tiina Autio,Henri Simonen,Sinikka Pelkonen

doi:10.3390/pathogens9100808

Abstract

Mycoplasma bovis is an important bovine pathogen. Artificial insemination (AI) using contaminated semen can introduce the agent into a naïve herd. Antibiotics, most often gentamycin, tylosin, lincomycin, spectinomycin (GTLS) combination are added to semen extender to prevent transmission of pathogenic bacteria and mycoplasmas. In a commercial AI straw production system with industrial scale procedures, we analyzed the mycoplasmacidal efficacy of GTLS and ofloxacin on M. bovis ATCC and wild type strain isolated from commercial AI straws. The strains were spiked at two concentrations (106 and 103 CFU/mL) into semen. Viable M. bovis in frozen semen straws was detected by enrichment culture and real-time PCR. We also compared different protocols to extract M. bovis DNA from spiked semen. None of the antibiotic protocols had any effect on the viability of either of the M. bovis strains at high spiking concentration. At low concentration, the wild type was inhibited by all other protocols, except low GTLS, whereas the ATCC strain was inhibited only by high GTLS. The InstaGene™ matrix was the most effective method to extract M. bovis DNA from semen. When there is a low M. bovis contamination level in semen, GTLS used at high concentrations, in accordance with Certified Semen Services requirements, is more efficient than GTLS used at concentrations stated in the OIE Terrestrial Code.

Highlights

Mycoplasma bovis is a major bovine pathogen causing substantial economic losses and has a debilitating effect on animal welfare
At a low spiking concentration, the ATCC strain was more resistant than the wild type strain to different antibiotics
The only protocol inhibiting the growth of the ATCC strain was the high GTLS 500/100/300/600 μg/mL supplement added in the semen lab to the extender

Summary

Introduction

Mycoplasma bovis is a major bovine pathogen causing substantial economic losses and has a debilitating effect on animal welfare. M. bovis causes a variety of diseases including mastitis, pneumonia, arthritis, otitis media, and genital infections [1]. Efforts to develop efficacious vaccines have not been successful [2]. Once established in a cattle farm, M. bovis can be difficult to eradicate [3]. It is of paramount importance to prevent the introduction of the agent into naïve herds. One M. bovis transmission route into a herd is artificial insemination (AI) [4]. We reported on how contaminated semen used in AI, introduced M. bovis infection into closed naïve dairy herds [5]

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