Das vaginale und uterine Mikrobiom während des Puerperiums bei Milchkühen

Uterine infections in dairy cows are a common problem in the puerperal phase, with considerable relevance for farm profitability and animal welfare. Postpartum injuries, a weakened immune system, a negative energy balance, broken anatomical barriers and microbial imbalances may contribute to this multifactorial disease process. In recent years, research into the microbiomes of different body regions and species has come to the fore, and for good reason. An undisturbed mucosal microbial community of the genital tract may protect against infections, just as disturbance of microbiomes may be associated with disease. This study aimed to investigate the microbial community of the vagina and uterus and to further deepen our understanding of its complex composition in order to optimise therapies and develop preventive measures. For this purpose, 50 dairy cows from one farm were clinically-gynaecologically examined at six time points (days 2, 4, 6, 14, 21 ± 1 and 41 ± 1) during the puerperium. At the first four time points, samples were collected from the vagina and uterus using swabs. All samples were microbiologically cultured and isolates were identified by MALDI-TOF MS. The clinical results showed high incidences of pathological puerperium (58.7%) in the study farm, coupled with a lack of puerperal management. The results of the microbiological investigation confirmed known uterine pathogens such as Fusobacterium spp. and Bacteroides spp. Recently discussed species such as Helcococcus spp. and Porphyromonas spp. also showed a - partly significant - increased occurrence in sick animals. On the other hand, the results of the present study raise doubts about the role of the much-discussed uterine pathogens such as Escherichia coli and Trueperella pyogenes in the etiopathogenesis of uterine infections. However, Clostridium perfringens could only be detected in diseased animals, which pushes the species into the foreground as a uterine pathogen. Therefore, this species was tested in a second study of this research project, for the production of toxins (alpha, beta, epsilon) and for toxin genes (cpa, cpb1, cpb2 and iap) as well as for antimicrobial resistance by using microdilution. Three of 21 isolates produced the alpha toxin, cpa could be detected in all isolates, the cpb1 gene in two isolates and the cpb2 gene in one isolate. Antimicrobial resistance was found against the commonly used antibiotics penicillin and ampicillin, and phenotypic resistance to clindamycin and metronidazole was also detected. Based on the epidemiological findings as well as the phenotypic and genotypic characterisation, Clostridium perfringens can be incriminated as a uterine pathogen, but further investigations are necessary to allow conclusive statements. Looking at the results of the microbiome analyses with the opposite intention, namely directed towards the detection of protective bacteria, the genus Staphylococcus spp. proved to be significantly less frequent in the cows with a pathological puerperium and this already on day 2 post partum, i.e. before most cows developed clinical symptoms. This indicates an antagonistic interaction with potential uterine pathogens and qualifies this genus for further investigation regarding protective properties. In general, consistent puerperal management, consisting of body temperature measurement and vaginoscopy, should be implemented to curb the still high incidences of puerperal disorders. Potential uterine pathogens identified in this study, as well as potential protective bacteria, should be subject to further studies to promote the health of the reproductive tract of our dairy cows.