Absorption of neomycin from the equine uterus: effect of stage of oestrous cycle and volume of vehicle

Plasma concentrations of neomycin were measured following intrauterine infusion of 3.3 mg/kg bodyweight neomycin sulphate. Mares in oestrus absorbed approximately 6 per cent of neomycin infused whereas mares in a luteal phase absorbed 56 per cent. The volume of infusate also affected absorption as increased volume resulted in decreased absorption. The decreased absorption both during oestrus and when large volumes were used was probably due to reflux of antibiotic through the cervix.     

Diagnosis and treatment of equine bacterial endometritis

The diagnosis of equine endometritis should generally begin with a history of reproductive failure followed by demonstration of inflammatory changes in the endometrium. Only then should the results of uterine cultures be considered in establishing an etiological diagnosis.

In therapy, the first consideration should be an attempt to correct the conditions which made the mare susceptible to the disease in the first place. Then advantage should be taken of measures to enhance the mare's natural resistance, perhaps sometimes even allowing her to clear herself of infection without antimicrobial therapy. Finally appropriate antimicrobial therapy should be selected based upon a knowledge of the conditions existing in the uterus and the results of culture and sensitivity.     

Molecular typing and anti-microbial susceptibility of clinical isolates of Streptococcus equi ssp. zooepidemicus from equine bacterial endometritis

The anti-microbial susceptibility and genetic diversity of 65 strains of Streptococcus equi ssp. zooepidemicus (Sez) isolated from mares presenting clinical signs of endometritis was determined by disk agar diffusion and pulsed field gel electrophoresis (PFGE) methods, respectively. Overall, Sez isolates were susceptible to beta-lactams, enrofloxacin, trimethoprim-sulfamethoxazole and gentamicin. These anti-microbials could be recommended as empiric anti-microbial therapy in cases of endometritis caused by Sez. Pulsed field gel electrophoresis typing revealed a great genetic diversity (56 different PFGE macrorestriction profiles) and a low level of genetic relatedness amongst the isolates.     

Inhibition of bacterial endometritis with mannose

Prior research indicates that mannose is capable ofpreventing bacterial adherence to equine endometrial tissues in vitro. The present study was designed to test whether mannose would prevent attachment of pathogenic Escherichia coli (E. coli) to equine endometrium in vivo. Six estrogen-treated anestrous mares received intrauterine infusions of 100 mL E. coli (10⁹ cells) in PBS or E. coli+50 mg mannose/mL PBS. Uterine fluid height and echogenicity were measured at 0,24 and 48 hours following infusion. Intrauterine cultures and endometrial biopsies were obtained at 24 hours post-infusion. Cultures were plated for bacterial growth and identification. Biopsies were prepared for light microscopy and evaluated for bacterial attachment to luminal epithelium. Mares receiving E. coli alone accumulated more intrauterine fluid at 24 hours than the E. coli + mannose treated group. Uterine fluid echogenicity was not different between groups, but did increase at 24 hours. Percent luminal epithelial cells with bacteria attached did not correlate with treatment. Incidence of positive culture at 24 hours was significantly reduced in the mannose-treated group. Preliminary evidence suggests that mannose may be effective in reducing bacterial infection in the equine endometrium.     

Current views on the pathogenesis of bacterial endometritis in mares

Mares with persistent and recurrent endometritis are said to be susceptible to infection; in particular they are unable to resolve the acute endometritis that always follows mating. It is thought, therefore, that these mares have a local immunological defect in the uterus that impedes the elimination of bacteria. Studies on immunoglobulins, opsonins and the functional ability of neutrophils in the uterus of susceptible mares have not confirmed the presence of an impaired immune response. It is concluded that factors involved in the production and drainage of uterine fluid may be important in the aetiology of the condition.     

Inflammatory components in uterine fluid from mares with experimentally induced bacterial endometritis

Exudate and uterine flushings were collected at either 30, 60, 120 or 240 mins after intrauterine infusions of Streptococcus zooepidemicus in genitally normal mares during oestrus. Uteri were also flushed without prior induction of endometritis. Protein concentrations in exudate and flushings increased with time and exudate pH decreased with time; the pH of flushings did not alter. Lysozyme and lactate dehydrogenase were present in flushings from non-infected uteri, but concentrations increased with time after infection. Immunoreactive prostaglandin E2 was undetectable before infection, but concentrations rose after infection. No neutrophils were present in non-infected flushings but, by 30 mins, there were significant (P less than 0.01) neutrophil numbers in exudate and flushings; thereafter numbers increased, particularly in exudate. Acute endometritis resembled acute inflammation at other sites in the horse and a significant response had occurred by 30 mins after experimental infection.     

Absorption of two trimethoprim/sulphonamide combinations from the uterus of pony mares

Plasma drug concentrations were measured after two commercially available potentiated sulphonamides, trimethoprim and sulfadoxine and trimethoprim and sulphadiazine, were infused daily for 2 and 3 days, respectively, into the uteri of pony mares which had been mated before ovulation. Intravenous administration of trimethoprim and sulfadoxine allowed uterine absorption of trimethoprim (23-43%) and sulfadoxine (29-34%) to be calculated. After intra-uterine administration trimethoprim and sulphadiazine were detected in the milk of a lactating mare. In order to maintain plasma concentrations likely to be required for clinical efficacy of both drugs they should be administered every 12 h. However, infusions of both preparations caused endometrial inflammation as assessed by cytological and histological examination and this may have been responsible for the low pregnancy rate.     

Evaluation of progesterone treatment to create a model for equine endometritis.

To investigate a model for equine endometritis, 12 mares with normal reproductive tracts were divided into 2 groups. All mares received progesterone in oil, 250 mg im, daily. At 5 days after initiation of progesterone administration, the uteri were inoculated with 10(6) colony forming units of Pseudomonas aeruginosa. The day of inoculation was designated Day 0. On Day 6, endometrial swab samples yielded P. aeruginosa in 5 mares; samples from the other 7 mares yielded heavy growth of Escherichia coli, Streptococcus zooepidemicus, Klebsiella pneumoniae, Enterobacter spp., Citrobacter diversus, Staphylococcus epidermidis and Streptococcus morbillorum. On Days 6, 7 and 8, Group A mares received intrauterine infusions of 6 g ticarcillin disodium and 0.2 g clavulanate potassium in 100 ml sterile saline. Group B mares received infusions of saline only. The incidence of swab specimens yielding no bacterial growth was significantly higher in Group A than Group B mares on Days 8 and 13 (4/6 vs 0/6). Swab samples from 5 of the 6 mares in Group A yielded growth of fungi on Days 13 and 19. Mares in Group B were then similarly treated with ticarcillin/clavulanate infusions, on Days 19, 20 and 21. The incidence of swab specimens yielding no bacterial growth was 2/6 and 1/6 on Days 21 and 26, respectively; fungi were not recovered from these mares at any time. The incidence of no-growth swabs after antibiotic treatment tended to be higher in Group A and incidence of fungal recovery after antibiotic treatment was significantly higher in Group A.(ABSTRACT TRUNCATED AT 250 WORDS)     

健康水牛与患子宫内膜炎水牛子宫内细菌组成的比较分析

应用16SrDNA克隆文库的方法,分别建立健康和患子宫内膜炎水牛子宫内细菌的16SrDNA克隆文库,并通过序列分析和同源性比对确定细菌的系统发育学地位。结果显示,产后14d水牛子宫内的细菌主要属于梭杆菌门(Fusobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)和变形菌门(Proteobacteria)。患子宫内膜炎组(M组)中有38.89%克隆的属于梭杆菌门(Fusobacteria),序列比对分析表明,这些序列和Fusobacterium necrophorum subsp有最高的的相似度(99%)。另外46.67%的克隆属于拟杆菌门(Bacteroidetes),其中Bacteroides heparinolyticus和Porphyromonas levii在这个门中所占比例最大,分别为55.95%和42.86%,属于厚壁菌门(Firmicutes)和变形菌门(Proteobacteri)的克隆较少,所占比例分别为7.22%和6.67%,但是这2个门中的细菌种类相对丰富。仅仅只有0.56%属于放线菌门(Actinobacteria)。健康组(H组)中,26.56%的克隆属于梭杆菌门(Fusobacteria),并且和Fusobacterium necrophorum subsp的相似度最高(99%),32.81%的克隆属于Firmicutes,这些克隆中的61.9%与Clostridium cadaveris的相似性最高(≧97%),35.94%的克隆属于Bacteroidetes,其中56.52%的序列与Bacteroides heparinolyticus相似性最高(99%)。克隆中属于Proteobacteria的比例较低(4.69%)。结果表明,Fusobacterium necrophorum subsp、Bacteroides heparinolyticus和Porphyromonas levii可能是引起水牛产后子宫内膜炎的主要致病菌。厚壁菌门细菌Clostridium cadaveris,拟杆菌门细菌Porphyromonas somerae、Bacteroides pyogenes可能有利于子宫内膜的恢复。     

Influence of bacterial challenge and long-term progesterone on endometritis of mares

Progress in treatment of endometritis in mares has been impeded by lack of an experimental model. This study tests the hypothesis that exposure of a mare's uterus to bacteria, while being treated with progesterone, will result in a compromised uterine defense after progesterone has been withdrawn. Ten mares were administered progesterone for 8 months and inoculated at the onset of treatment with a 5 x los colony forming units of(CFU) of Streptococcuszooepidemicus into the uterus. Mares were re-inoculated to maintain uterine infection, if necessary. Ten uninoculated mares with normal uteri served as controls. After the end of progesterone treat- ment all mares (treated and controls) experienced a normal estrous cycle and were inoculated with 5 x l0s CFU of Streptococcus zooepidemicus. Results of reproductive evalu- ations performed on days 2, 7 and 12 after bacterial inoculation were similar (P>0.05) for treated and controls. Pregnancy rates for treated and controls were also similar (P>0.05). Thus, the treatment evaluated in this study did not cause an alteration in the mare's ability to resolve endometritis.     

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.