Effects of antibiotic versus dextrose treatment on microbial populations in metritic cow vaginal discharge

Authors: LECTION, JENNINE - Pennsylvania State University; VAN SYOC, EMILY - Pennsylvania State University; Miles, Asha; BARRAGAN, ADRIAN - Pennsylvania State University; GANDA, ERIKA - Pennsylvania State University

Submitted to: Society of Theriogenology Annual Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/6/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Postpartum metritis has many costs to the dairy producer: decreased milk production, decreased reproductive performance, and veterinarian time/medications. The more commonly isolated bacterial species in metritis cases are E. coli, F. necrophorum, and Prevotella spp. The current treatment strategy involves antibiotics, typically penicillin or a third-generation cephalosporin; however, there is increasing public health concern about judicious use of antibiotics and prevention of drug-resistant pathogens. To evaluate the effects of antibiotic treatment as compared to a non-antibiotic treatment (dextrose) for metritis on the microbiome of the cow’s vagina, we designed a study randomly assigning cows post-metritis diagnosis to either receive a conventional treatment (ceftiofur crystalline free acid; CONV) or an antibiotic-alternative treatment (intrauterine dextrose infusion; DEX). We hypothesized that the clinical cure rate would be similar between the two treatment groups, and therefore, their microbial populations would be similar at the time they were determined to be cured. All cows were enrolled from one dairy farm in central Pennsylvania, and each cow was screened for clinical metritis (CM) at 7+-3 days after parturition using a Metricheck^registered trademark device, with those cows presenting with red-brown fetid watery discharge being diagnosed with CM and therefore, enrolled in the study. The DEX cows received 3 days of intrauterine infusion of a 50% dextrose solution starting on the day of diagnosis, and the CONV cows received two injections of ceftiofur (6.6 mg/Kg of BW; Excede, Zoetis Inc.) one on the day of diagnosis and then 72 hours later. Cows were evaluated for clinical cure rate at 7+-3 and 14+-3 days after diagnosis. Vaginal discharge was collected for a subset of enrolled cows (DEX=13, CONV=14) for 16S rRNA gene sequencing to evaluate changes in the microbiome at each time point (diagnosis, 7+-3, and 14+-3 days after diagnosis). Clinical cure rate between the two treatments groups showed no statistical difference. Alpha diversity (richness of microbes within each sample) did not differ (Welch’s t-test) between the two treatments at any of the three time points or between pre- and post-treatment (last two time points combined). Beta diversity (comparison of microbial communities between cows) based on PERMANOVA analysis did differ at time of diagnosis (P=0.024) and again at the second recheck (P=0.015), but not at the first recheck (P=0.112). When analyzing differential relative abundance through Wald’s test, bacteria of the Prevotella and Fusobacterium genera were more abundant in the vaginal discharge of the CONV group as compared to the DEX group at the time of first recheck, though at the time of diagnosis there was increased relative abundance of Prevotella in the CONV cows and Fusobacterium in the DEX cows. While 16S rRNA analysis does not provide information on the viability of these bacteria, these changes in relative abundance paired with the similar clinical cure rate of the DEX group as compared to the CONV group provides evidence that dextrose may be a low-cost antibiotic alternative treatment for CM in dairy cows.