Effects of different treatment approaches on microbial populations in the vaginal discharge of cows diagnosed with clinical metritis

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

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/4/2023
Publication Date: 5/26/2023
Citation: Lection, J.M., Van Syoc, E., Miles, A.M., Hamilton, J., Barragan, A., Ganda, E. 2023. Effects of different treatment approaches on microbial populations in the vaginal discharge of cows diagnosed with clinical metritis [abstract]. Penn State 7th Annual Life Sciences Symposium. p. 32.

Interpretive Summary:

Technical Abstract: Clinical metritis (CM) has significant costs to dairy producers, associated with decreased milk production, reduced reproductive performance, and treatments. The current treatment strategy involves systemic antibiotics; however, there is increasing public health concern about judicious antibiotic use and preventing drug-resistant pathogens. The objective of our study was to evaluate the effects of a non-antibiotic treatment vs systemic antibiotic therapy on the microbiome of the vaginal discharge of dairy cows diagnosed with CM at 7±3 DIM (days in milk). We hypothesized that clinical cure rate would be similar between the two treatment groups, and therefore, their microbial populations would be similar. Cows (n=351) were enrolled from a dairy in central Pennsylvania and were screened for CM at 7±3 days DIM using a Metricheck® device. Cows presenting with red-brown watery discharge were diagnosed with CM and eligible for enrollment. Eligible cows were blocked by parity and randomly allocated to one of two treatments starting on the day of diagnosis: 1) Intrauterine dextrose (DEX, n=38): cows received 1 liter of an intrauterine 50% dextrose solution for 3 days, and 2) Systemic ceftiofur (CONV, n=39): cows received two injections of ceftiofur (6.6 mg/Kg of BW; Excede, Zoetis Inc.) 72 hours apart. Cows were evaluated for clinical cure rate at 7 and 14 days post-diagnosis. Vaginal discharge samples were collected using the Metricheck® at enrollment day (study d 0, before treatment), study d 7, and study d 14 for a subset of enrolled cows (DEX=13, CONV=14). Vaginal discharge samples were analyzed for 16S rRNA gene sequencing to evaluate changes in the microbiome between treatments. Clinical cure rate between the two groups showed no significant difference (7 days: CONV = 64.1%, n = 25; DEX = 60.52%, n = 23 and 14 days: CONV = 79%, n= 31; DEX = 82%, n = 31) (d 7 P=0.56, d 14 P=0.69, GLIMMIX procedure of SAS, Cary, NC). Alpha diversity (richness and evenness of microbes within each sample) did not differ (Welch’s t-test) between the treatments at any of the three time points or between pre- and post-treatment. Beta diversity (comparison of microbial communities between cows) based on PERMANOVA analysis did differ between treatment groups at time of diagnosis (P=0.014) and again at study d 14 (P=0.028), but not at study d 7 (P=0.261). Statistical testing (t-test) for differential relative abundance revealed no taxa were significantly increased or decreased between the two treatment groups at any of the three timepoints. Though beta diversity does differ prior to treatment, the microbiome of each group did not differ in any of the results at the time point immediately following treatment which could indicate that each treatment has a similar impact on the microbiome. While 16S rRNA analysis does not provide information on the viability of bacteria, the relative similarity of the microbiome between the two groups immediately following treatment paired with the similar clinical cure rate of the DEX group compared to the CONV group provides evidence that dextrose may be a low-cost antibiotic alternative treatment for CM.