PMC8203807_01
Gram-stained smear of the horse's nasal exudate showing numerous intracellular C. ulcerans with lesser amounts of Streptococcus zooepidemicus.
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F1
This was consistent with Gram-stained smears of the nasal specimen (Figure 1) and confirmed the cytological findings, which outlined the presence of active exudative rhinitis with mixed bacteria and no fungal structures. At this point, all antimicrobial treatment ceased, and the patient was discharged upon full clinical recovery a week later (Supplementary Figure 1).
(A) Circular genome diagrams were produced using BLAST Ring Image Generator (BRIG) version 0.95, which uses BLAST to align the genome sequences. The whole genome sequence of LIV-14050 was compared against six other genomes using NCBI's online BLAST tool and visualized using the Artemis Comparison Tool (ACT) version 13.0.16. Areas of the genome present in the ST453 sequences but not present in the other genomes were examined for coding sequences. A total of 24 regions and 29 genes were identified. Only the regions absent in all non-ST543 C. ulcerans genomes are annotated. (B) Minimum spanning tree diagram showing sequence types (STs) of LIV-14050, the six genomes compared in Figure 2A and the additional ST543 isolates previously reported. The size of the circle indicates the number of isolates with that ST in the data set. The colors within the circle indicate species the ST was isolated from: Human (blue); Equine (brown); Feline (orange); and Canine (green). The isolates represented by each ST are indicated by the same color labels next to the corresponding node. The numbers on the connecting edges indicate the number of nonmatching alleles between the two ST nodes.
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F2
The nasal discharge and swelling were confined to the right ventral and middle meatus, where a subsequent endoscopy demonstrated a large diphtheritic-like membrane (Supplementary Figure 2). However, several genomic regions containing annotated coding sequences were found in only LIV-14050 and MRi49, a C. ulcerans isolate retrieved from a diseased horse in Scotland, which displayed 99.91% genomic similarity to LIV-14050 (Figure 2A). Both isolates possessed the same prophage sequence (located in LIV-14050 between 2469058-2506376 bp), shared the highest degree of similarity in virulence factor genes among the C. ulcerans genomes examined, and belonged to the same ST (Figure 2B), i.e., the same clonal lineage.