Klebsiella oxytoca as a cause of equine abortion--short communication

Metagenomic characterization of the equine endometrial microbiome during anestrus

The equine uterus is highly interrogated during estrus prior to breeding and establishing pregnancy. Many studies in mares have been performed during estrus under the influence of high estrogen concentrations, including the equine estrual microbiome. To date, it is unknown how the uterine microbiome of the mare is influenced by cyclicity; while, the equine vaginal microbiome is stable throughout the estrous cycle. We hypothesized that differences would exist between the equine endometrial microbiome of mares in estrus and anestrus. The aim of this study was two-fold: to characterize the resident endometrial microbiome of healthy mares during anestrus and to compare this with estrus. Double-guarded endometrial swabs were taken from healthy mares during estrus (n = 16) and in the following non-breeding season during anestrus (n = 8). Microbial population was identified using 16S rRNA sequencing. Our results suggest that the equine uterine microbiome in estrus has a low diversity and low richness, while during anestrus, a higher diversity and higher richness were seen compared to estrus. Despite this difference, both the estrus and anestrus endometrial microbiome were dominated by Proteobacteria, Firmicutes, and Bacteroidota. The composition of the microbial community between anestrus and estrus was significantly different. This may be explained by the difference in the composition of the endometrial immune milieu based on the stage of the cycle. Further research investigating the function of the equine endometrial microbiome and dynamics changes within the uterine environment is required.

Metagenomic investigation of potential abortigenic pathogens in foetal tissues from Australian horses

BACKGROUND

Abortion in horses leads to economic and welfare losses to the equine industry. Most cases of equine abortions are sporadic, and the cause is often unknown. This study aimed to detect potential abortigenic pathogens in equine abortion cases in Australia using metagenomic deep sequencing methods.

RESULTS

After sequencing and analysis, a total of 68 and 86 phyla were detected in the material originating from 49 equine abortion samples and 8 samples from normal deliveries, respectively. Most phyla were present in both groups, with the exception of Chlamydiae that were only present in abortion samples. Around 2886 genera were present in the abortion samples and samples from normal deliveries at a cut off value of 0.001% of relative abundance. Significant differences in species diversity between aborted and normal tissues was observed. Several potential abortigenic pathogens were identified at a high level of relative abundance in a number of the abortion cases, including Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Streptococcus equi subspecies zooepidemicus, Pantoea agglomerans, Acinetobacter lwoffii, Acinetobacter calcoaceticus and Chlamydia psittaci.

CONCLUSIONS

This work revealed the presence of several potentially abortigenic pathogens in aborted specimens. No novel potential abortigenic agents were detected. The ability to screen samples for multiple pathogens that may not have been specifically targeted broadens the frontiers of diagnostic potential. The future use of metagenomic approaches for diagnostic purposes is likely to be facilitated by further improvements in deep sequencing technologies.

Diversity of enterobacteria including β-lactamase producing isolates associated with the Spanish slug (Arion vulgaris)

The aim of this study was to determine diversity in members of the family Enterobacteriaceae including the beta-lactamase producing isolates associated with the Spanish slug (Arion vulgaris). 81 isolates, each representing a distinct colonial morphotype, were obtained from fecal samples of Spanish slugs and analyzed. Genetically heterogeneous or similar groups were assessed among the isolates by enterobacterial repetitive intergenic consensus (ERIC)-PCR and further characterized by 16S rDNA sequence analysis. Representative strains were allocated to the genera Citrobacter, Raoultella, Escherichia, Klebsiella, Kluyvera, and Buttiauxella. Fifteen isolates, most closely related to Citrobacter freundii and Escherichia coli, displayed an AmpC phenotype, one E. coli isolate showed an ESBL phenotype. These isolates were phenotypically and genotypically characterized by their antimicrobial resistance pattern. Phylogenetic background and multi-locus sequence typing (MLST) of the E. coli isolates were determined. The multi-drug resistant TEM-1 E. coli positive isolate belongs to the phylogenetic group A and ST10. The CMY-2 positive E. coli isolate belongs to the phylogenetic group D and ST117. Our results show that the common garden slug represents an important potential vector of β-lactamase producing Enterobacteriaceae.