Streptococcus equi subsp. zooepidemicus isolates from equine infectious endometritis belong to a distinct genetic group

Streptococcus equi subsp. zooepidemicus is the pathogen most commonly isolated from the uterus of mares. S. zooepidemicus is an opportunistic pathogen and part of the resident flora in the caudal reproductive tract. The aim of this study was to investigate whether a genotypically distinct subpopulation of S. zooepidemicus is associated with endometritis in the mare, by genotyping and comparing uterine S. zooepidemicus strains with isolates from the vagina and clitoral fossa. Mares with (n = 18) or without (n = 11) clinical symptoms of endometritis were included. Uterine samples were obtained using a guarded endometrial biopsy punch, whereas a swab was used to recover samples from the cranial vagina and the clitoral fossa. If S. zooepidemicus was present, up to three colonies were selected from each anatomical location (max. 9 isolates per mare). Bacterial isolates were characterized by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). S. zooepidemicus was isolated from the endometrium of 12 mares. A total of 88 isolates were analyzed by PFGE: 31 from the endometrium, 26 from the cranial vagina and 31 isolates from the clitoral fossa. For MLST 21 isolates were chosen. Results demonstrated a higher genetic similarity of the isolates obtained from infectious endometritis compared to isolates obtained from the caudal reproductive tract. In conclusion, we demonstrate for the first time that a genetically distinct group of S. zooepidemicus is associated with infectious endometritis in the mare.     

猪链球菌2型与马链球菌兽疫亚种生物学特性的初步比较

1998年从病死猪分离了数株链球菌 ,其中 2株编号为 980 1,980 2。经鉴定 ,980 1株为猪链球菌 2型 ,980 2株为马链球菌兽疫亚种。 980 1株系从暴发流行地区的病猪中分离 ,同时在该流行地区还发生畜禽从业人员感染相同血清型的链球菌而死亡的病例 ;980 2株系从散发病猪中分离。临床有共同点 ,又有各自特点。病理变化均呈现典型的败血症变化 ,但肝、脾、肺等病变上有一些差别 ,而染色镜检基本一致。对兔均敏感 ,对小白鼠和猪的敏感性有所不同。 980 1株菌落灰色 ,中心浑浊 ,直径 0 5mm ,α溶血 ,有草绿色色素沉着 ;980 2株菌落湿润 ,半透明 ,直径 1 5～ 2mm ,β溶血。 980 1株对氧哌嗪青霉素、头孢他啶、氨苄青霉素最敏感 ;980 2株对氧哌嗪青霉素、复方磺胺、头孢哌酮、呋喃妥因最敏感     

Determination of intraspecies variations of the V2 region of the 16S rRNA gene of Streptococcus equi subsp. zooepidemicus

The 16S rRNA gene of 39 S. equi subsp. zooepidemicus strains and two S. equi subsp. equi strains was amplified by polymerase chain reaction and subsequently digested with the restriction enzyme Hinc II. A restriction profile with two fragments with sizes of 1250 bp and 200 bp could be observed for both S. equi subsp. equi strains and for 30 of the 39 S. equi subsp. zooepidemicus strains indicating a sequence variation within the V2 region of the 16S rRNA gene of the remaining nine S. equi subsp. zooepidemicus isolates. A segment of the 16S rRNA gene including the hypervariable V2 region of 11 S. equi subsp. zooepidemicus and two S. equi subsp. equi could be amplified by PCR and sequenced. The sequence of the V2 region of eight S. equi subsp. zooepidemicus strains appeared to be identical or almost identical to the sequence of the two S. equi subsp. equi strains. The sequence of the remaining three S equi subsp. zooepidemicus strains differed significantly from the sequence of S. equi subsp. equi. These differences allowed a division of S. equi subsp. zooepidemicus strains into two 16S rRNA types and might possibly have consequences for the taxonomic position of these phenotypically indistinguishable strains of one subspecies. A molecular typing could additionally be performed by amplification of the gene encoding the 16S-23S rRNA spacer region. A single amplicon of the spacer gene of 1100 bp could be observed for one S. equi subsp. zooepidemicus, an amplicon of 950 bp for two S. equi subsp. equi strains and 10 S. equi subsp. zooepidemicus strains, a amplicon of 780 bp for 27 S. equi subsp. zooepidemicus strains and a single amplicon of 600 bp for one S. equi subsp. zooepidemicus strain. The variations of the V2 region of the 16S rRNA gene and the size variations of the 16S-23S rRNA spacer gene were not related to each other. Both variations could be used for molecular typing of this species, possibly useful in epidemiological aspects.     

Diagnostic testing patterns for Streptococcus equi subsp. equi in Ontario horses during the years 2008 to 2018

This retrospective study describes testing patterns and the incidence of Streptococcus equi subsp. equi in Ontario to assess the utility of laboratory data for surveillance purposes. Laboratory records for equine infectious disease test submissions were extracted from the Animal Health Laboratory (AHL) at the University of Guelph for the years 2008 to 2018. Yearly and seasonal trends in S. equi testing and the proportion of tests that returned positive results were assessed. The number of samples submitted for S. equi testing decreased over the 11-year period (odds ratio = 0.96, 95% confidence interval: 0.92 to 0.999; P = 0.04). A generalized linear model identified a significant seasonal effect for animals recognized as clinically ill, with the highest test positivity noted in the winter. Although this study identified important trends in the incidence of S. equi in Ontario, the variability in information accompanying test submissions made the data challenging to interpret, highlighting the need for more complete diagnostic submission data for S. equi.     

Plasma vitamin C concentration is not related to the incidence of ketosis in dairy cows during the early lactation period

Many animals including cattle can synthesize vitamin C from glucose. The objective of this study was to investigate plasma vitamin C concentration in ketotic cows during the early lactation period because glucose supply for vitamin C synthesis might be limited in these cows. We measured plasma beta-hydroxybutyrate (BHBA) concentration in 118 cows within 2 months after parturition. Subclinical/clinical ketosis was quantitatively determined using a plasma BHBA threshold of 1,200 microM. Plasma glucose concentration was lower in the ketotic cows than in the control cows but plasma vitamin C concentration did not differ between the control and the ketotic cows. Then we measured plasma vitamin C, BHBA and glucose levels in 7 cows during the periparturient period. Plasma BHBA increased and plasma glucose decreased after parturition but plasma vitamin C did not change. These results indicate that plasma vitamin C is not related to the incidence of ketosis in the early lactation period. We suggest that ketotic cows have the ability to produce vitamin C to meet its requirement in the early lactation period although glucose supply is not sufficient for milk production. Vitamin C synthesis is possibly given a high metabolic-priority for glucose in lactating cows.