Equi Subspecies Zooepidemicus Research Articles

Streptococcus equi Subspecies zooepidemicus Endocarditis and Meningitis in a 62-Year-Old Horse Rider Patient: A Case Report and Literature Review.

The present article presents a case report and literature review concerning the Streptococcus equi subspecies zooepidemicus (SEZ), a rare zoonotic pathogen in humans. The case involves a 62-year-old man with no prior heart disease, presenting with endocarditis, pneumonia, and meningitis following close contact with a horse. The patient underwent urgent aortic valve replacement due to severe valvular damage caused by the infection. Blood and cerebrospinal fluid cultures confirmed the presence of SEZ, and the patient was treated with a combination of antibiotics, followed by a successful step-down to oral therapy using linezolid. A review of 25 additional Streptococcus equi endocarditis cases highlights the rarity of the condition, its association with animal contact, and its tendency to cause multi-site infections, such as pneumonia and meningitis. Early diagnosis, appropriate antibiotic therapy, and, in severe cases, surgical intervention are critical for a favorable outcome. This report emphasizes the importance of recognizing zoonotic infections in at-risk populations and the potential need for public health surveillance in these scenarios.

Isolation and characterization of bacteriophages specific to Streptococcus equi subspecies zooepidemicus and evaluation of efficacy ex vivo.

Streptococcus (S.) equi subspecies (subsp.) zooepidemicus is an important facultative pathogen in horses and can cause severe infections in other species including humans. Facing the post-antibiotic era, novel antimicrobials are needed for fighting bacterial infections. Bacteriophages (phages) are the natural predators of bacteria and discussed as a promising antimicrobial treatment option. The objective of this study was to isolate and characterize S. equi subsp. zooepidemicus-specific phages for the first time and to evaluate their efficacy in vitro and ex vivo. In total, 13 phages with lytic activity were isolated and host ranges were determined. Two phages with broad host ranges and high efficiency of plating (vB_SeqZP_LmqsRe26-2 (lytic activity: 30/37 bacterial isolates) and vB_SeqZP_LmqsRe26-3 (lytic activity: 29/37 bacterial isolates)) and one phage with relatively low efficiency of plating (vB_SeqZP_LmqsRe26-1) were selected for further characterization, including electron microscopy and whole genome sequencing. In in vitro planktonic killing assays at two tested multiplicities of infection (MOI 1 and MOI 10), significant bacterial growth reduction was observed when the phages vB_SeqZP_LmqsRe26-2 and vB_SeqZP_LmqsRe26-3 were added. These phages were subsequently co-incubated with clinical S. equi subsp. zooepidemicus isolates in an equine endometrial explant model but did not achieve bacterial growth reduction at MOI 1 and MOI 10. However, helium ion microscopy revealed presence of particles adherent to the bacteria on the explant after incubation (25 h), suggesting possible phage-bacteria interactions. In conclusion, phages against S. equi subsp. zooepidemicus were successfully isolated and characterized. Promising results were observed in in vitro but no significant reduction was detected in ex vivo experiments, requiring additional investigations. However, after further adaptations (e.g., optimization of MOIs and phage administration or use of phage-antibiotic combination), phages could be a potential antimicrobial tool for future therapeutic use in S. equi subsp. zooepidemicus infections, although the available results do not currently support the therapeutic usage.

Bacterial and host factors involved in zoonotic Streptococcal meningitis

Zoonotic streptococci cause several invasive diseases with high mortality rates, especially meningitis. Numerous studies elucidated the meningitis pathogenesis of zoonotic streptococci, some specific to certain bacterial species. In contrast, others are shared among different bacterial species, involving colonization and invasion of mucosal barriers, survival in the bloodstream, breaching the blood–brain and/or blood–cerebrospinal fluid barrier to access the central nervous system, and triggering inflammation of the meninges. This review focuses on the recent advancements in comprehending the molecular and cellular events of five major zoonotic streptococci responsible for causing meningitis in humans or animals, including Streptococcus agalactiae, Streptococcus equi subspecies zooepidemicus, Streptococcus suis, Streptococcus dysgalactiae, and Streptococcus iniae. The underlying mechanism was summarized into four themes, including 1) bacterial survival in blood, 2) brain microvascular endothelial cell adhesion and invasion, 3) penetration of the blood–brain barrier, and 4) activation of the immune system and inflammatory reaction within the brain. This review may contribute to developing therapeutics to prevent or mitigate injury of streptococcal meningitis and improve risk stratification.

Streptococcus equi subspecies zooepidemicus: an emergent cause of meningoencephalitis in Northeastern Brazil.

This study describes an outbreak of Streptococcus equi subspecies zooepidemicus infections that caused meningoencephalitis and bacteremia related to unpasteurized milk consumption in northeastern Brazil. Epidemiological investigations and a brief literature review were conducted. Strains with possible neurotropism had not been identified in Brazil before these cases; however, in 2023, another case of meningoencephalitis caused by Streptococcus equi sp. zooepidemicus was described, revealing the need to maintain surveillance and highlighting that these neurotropic strains continue to circulate in the environment.

Complete genome sequencing and comparative genomic analysis of three donkey Streptococcus equi subsp. equi isolates.

Streptococcus equi subspecies equi (S. equi) is the causative agent of strangles, which is one of the most common and highly contagious respiratory infectious illnesses in horses. Streptococcus equi (S. equi) is a horse-specific pathogen that originated from the closely related zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). Despite decades of research, the movement of genetic material across host-restricted diseases remains a mystery. Three S. equi donkey isolates (HTP133, HTP232, and HT1112) were recently isolated from a strangles epidemic on donkey farms in China's Xinjiang Province. In this study, we performed a comprehensive comparative analysis of these isolates using whole genome sequencing and compared them to the published genomic sequences of equine strain S. equi 4047 to uncover evidence of genetic events that shaped the evolution of these donkey S. equi isolates' genomes. Whole genome sequencing indicated that both strains were closely related, with comparable gene compositions and a high rate of shared core genomes (1788-2004). Our comparative genomic study indicated that the genome structure is substantially conserved across three donkey strains; however, there are several rearrangements and inversions when compared to the horse isolate S. equi 4047. The virulence factors conveyed by genomic islands and prophages, in particular, played a key role in shaping the pathogenic capacity and genetic diversity of these S. equi strains. Furthermore, we discovered that the HT133 isolate had a strong colonization ability and increased motility; the HT1112 isolates had a significantly higher ability for antimicrobial resistance and biofilm formation, and the HT232 isolate gained pathogenic specialization by acquiring a bacteriophage encoding hyaluronate lyase. In summary, our findings show that genetic exchange across S. equi strains influences the development of the donkey S. equi genome, offering important genetic insights for future epidemiological studies of S. equi infection.

Streptococcus equi subspecies zooepidemicus and endocarditis: first reported case in Tunisia and review of the literature

Streptococcus equi subspecies zooepidemicus (S. equi subsp. zooepidemicus) is a b-haemolytic group C streptococcus known for causing strangles in equine and rarely isolated in human infection. To the best of our knowledge, this is the first reported case of native aortic endocarditis caused by S. equi subsp. zooepidemicus followed by a severe acute ischemic stroke due to systemic embolism. The clinical case reported here is about a previously healthy 70-year-old farmer who was having regular contact with a mule. Also, we give a review of previous reports on S. equi subsp. zooepidemicus-infective endocarditis.

Streptococcus equi subspecies zooepidemicus – a case report of sudden death in a German sow farm

A farm in North-West Germany experienced a high morbidity and mortality in their sow herd. Sows showed fever, lethargy, oedema, mucosal discharge and dyspnoea. Necropsy revealed a severe fibrinous and purulent polyserositis. Haematological and histological examinations confirmed septicaemia. Streptococcus equi subspecies zooepidemicus was isolated in high yields from major organs. Sequence typing of this isolate (21/455) revealed a new sequence type showing a significantly higher proliferation rate in comparison to two other isolates. Other infectious agents (influenza A virus, Porcine Reproductive and Respiratory Syndrome Virus, Porcine Circovirus 2, african swine fever virus, classical swine fever virus, Actinobacillus pleuropneumoniae) were excluded by routine diagnostic examinations. A climate check revealed an insufficient air supply in the area for the gestating sows. This case describes the first disease outbreak in swine due to S. zooepidemicus in Germany.

Genomic characterization of Streptococcus equi subspecies zooepidemicus from a 2021 outbreak in Indiana with increased sow mortality.

This study highlights a Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) strain isolated from an outbreak in Indiana, which resulted in mortality events among a swine herd in 2021. The Indiana outbreak strain was found to be genetically and phylogenetically distant to a strain isolated from the 2019 outbreaks in Ohio and Tennessee, which caused high swine mortality. We also discovered multiple unique genetic features in the Indiana outbreak strain, including distinct S. zooepidemicus genomic islands, and notable S. zooepidemicus virulence genes-many of which could serve as biomarkers for the diagnosis of this strain. These findings provide significant insights into monitoring and potentially preventing severe outbreaks caused by the Indiana outbreak strain in the future.

A Pandora's box in feline medicine: presenting signs and surgical outcomes in 58 previously hoarded cats with chronic otitis media-interna.

The aim of the present study was to report clinical findings, surgical complications and outcomes for previously hoarded cats treated surgically for otitis media-interna (OMI) and to investigate the risk factors for complications and poor outcomes. A retrospective study was conducted of 58 cats from an institutional hoarding environment that underwent ventral bulla osteotomy (VBO). Inappetence was uncommon at presentation (9/58, 16%) compared with pruritus/alopecia (50%), nasopharyngeal signs (45%), otitis externa (OE) (79%) and otitis interna (OI) (ataxia ± head tilt/head excursions) in 40%. Purulent aural discharge occurred in 36% and polyps in 26%. The tympanic bulla wall was moderately or severely thickened radiographically in 38/108 (35%) ears. Cultures were positive for Streptococcus equi subspecies zooepidemicus in 26/48 (54%) cats. Of the 58 cats, 40 (69%) had complications after the first VBO and 19/30 (63%) after the second. Of 101 complications, 56 (55%), from 27/88 (31%) surgeries, were considered serious, including life-threatening perioperative complications in seven, OI in eight, prolonged anorexia in six and worsening of pruritus/alopecia in nine cases. Three cats developed xerostomia (dry mouth) after the second VBO. Pruritus/alopecia, nasopharyngeal signs, OE and purulent aural discharge resolved in a statistically significant proportion of cats but persisted in some. Full resolution of OI was uncommon. OI preoperatively, and surgery performed by a generalist (vs specialist) surgeon, were risk factors for OE at recheck (OI: odds ratio [OR] 4.35; 95% confidence interval [CI] 1.21-15.70; P = 0.02; surgery: OR 3.64; 95% CI 1.03-12.87; P = 0.045). No other prognostic indicators were identified. No variables tested were significantly associated with risk of serious complications or euthanasia. Surgical management of chronic OMI was successful in most cases but was not benign and not always beneficial. The analysis was unable to identify clinically helpful outcome predictors. Optimal management of chronic feline OMI remains a challenge, particularly for animal shelters. Less invasive approaches and chronic medical management require further investigation.

Colic due to dorsally located perirectal abscesses: A retrospective case series of six horses

SummaryPerirectal abscesses have only rarely been reported in horses. This case series describes the clinical signs, diagnosis, treatment and outcome of six horses with this condition. The equids affected were geldings or stallions of various breeds and aged from 4 months to 21 years (median age 10 months). Typical clinical signs included colic with tachycardia, tenesmus, dyschezia and abdominal distension. The diagnosis was obtained by transrectal palpation and ultrasonographic examination in five of six horses and by median laparotomy in one horse. All abscesses were located dorsally to the rectum. Rectal impaction and large colon tympany were common secondary findings. Microbiologic examination of abscess content revealed Streptococcus equi subspecies zooepidemicus in all horses. Abscesses were treated by a combination of medical and surgical approaches. One horse had to be euthanised due to complete obstruction of the pelvis by the abscess. In the other horses (5/6), the disorder was associated with an excellent prognosis. In terms of the total population of horses presenting with colic in the investigated period, the prevalence of cases with perirectal abscesses was 0.4%. Although uncommon, described cases indicate that perirectal abscesses should be considered as differential diagnosis for young and mature horses with colic signs.

Advances in the understanding, detection and management of equine strangles

SummaryStreptococcus equi subspecies equi (S. equi) is the causative organism of the upper respiratory disease of equids, strangles, characterised by pyrexia, lymphadenopathy and mucopurulent nasal discharge. Strangles was first reported over 750 years ago and continues to be of significance in equine populations across the globe. This review discusses how S. equi has adapted, the clinical manifestation of strangles, and how clinicians and caregivers can tackle the disease in the future. S. equi evolved from the commensal, and occasionally opportunistic pathogen, Streptococcus equi subspecies zooepidemicus refining its capabilities as it became host restricted. The success of S. equi can be attributed to its ability to cause both acute and persistent infection, the latter occurring in about 10% of those infected. In this carrier state, S. equi persists in the guttural pouch without causing clinical signs, intermittently shedding into the environment, and encountering naïve animals. Insight into the S. equi genome and lifestyle has led to advances in diagnostic assays and the development of a safe and efficacious recombinant‐fusion vaccine, giving clinicians and caregivers the tools to better combat this infection. Alongside rigorous biosecurity protocols and pragmatic control measures such as screening new arrivals for exposure and carrier status, these new technologies demonstrate that strangles can be an increasingly preventable infection.

Severe Streptococcus equi Subspecies zooepidemicus Outbreak from Unpasteurized Dairy Product Consumption, Italy

During November 2021-May 2022, we identified 37 clinical cases of Streptococcus equi subspecies zooepidemicus infections in central Italy. Epidemiologic investigations and whole-genome sequencing showed unpasteurized fresh dairy products were the outbreak source. Early diagnosis by using sequencing technology prevented the spread of life-threatening S. equi subsp. zooepidemicus infections.

Detection of infectious agents in equine pregnancy loss, stillbirth and neonatal death

Equine abortion, stillbirth and neonatal death cause major economic losses to the equine industry worldwide. Both non-infectious and a wide range of infectious causes have been described. However, the relative contribution of pathogens to equine abortion, stillbirth and neonatal death is poorly documented, since available studies involve only a limited number of pathogens. Therefore, the objectives of the present retrospective monitoring study were to determine the prevalence of infectious agents associated with equine abortion and perinatal mortality in Belgium, and to set up a protocol usable under field conditions using polymerase chain reaction targeting. A real-time simple polymerase chain reaction for eight different abortifacient pathogens was conducted leading to the detection of at least one infectious agent in 37% of 105 analyzed cases. In the diagnosed cases, equine herpesvirus-1 was the most detected pathogen (49%), followed by Streptococcus equi subspecies zooepidemicus (28%), Coxiella burnetii (18%), Leptospira interrogans (3%) and Neospora caninum (3%). None of the analyzed cases was positive for equine viral arteritis, equine herpesvirus-4 and Chlamydophila spp. In this study, PCR targeting is shown to have its value to detect a (co)-infectious cause in equine abortion, stillbirth and neonatal death, especially in field conditions where autolysis and contamination might preclude a full post-mortem examination protocol based on classical microbiological examination.

Susceptibility pattern of bacterial isolates in equine ulcerative keratitis: Implications for empirical treatment at a university teaching hospital in Sydney.

Corneal ulceration is a common ophthalmic condition in horses. It is frequently caused by trauma to the corneal surface, followed by secondary infection by commensal or pathogenic organisms including Streptococcus equi subspecies zooepidemicus, Pseudomonas aeruginosa and Staphylococcus spp. Emerging antimicrobial resistance amongst these organisms has raised the need for appropriate antimicrobial therapy selection, to optimise treatment efficacy while minimising further antimicrobial resistance. Medical records of 38 horses presented at the University Veterinary Teaching Hospital Camden for ulcerative keratitis between 2010 and 2020 were reviewed to identify those with positive bacterial cultures and antimicrobial susceptibility profiles (13/38). Common susceptibility patterns were identified and used to guide the empirical treatment of equine bacterial corneal ulcers. Pseudomonas spp. (64.3%), Streptococcus equi subspecies zooepidemicus (14.3%) and Actinobacillus spp. (14.3%) were most commonly identified. Susceptibility to amikacin, gentamicin and ciprofloxacin was observed in 100%, 66.7% and 85.7% Pseudomonas spp. isolates respectively. Resistance to polymyxin B and neomycin occurred in 85.7% and 71.4% of Pseudomonas spp., respectively. All Streptococcus equi subspecies zooepidemicus organisms in this study were susceptible to ceftiofur, cephalexin, penicillin and ampicillin, while they were all resistant to gentamicin, neomycin, enrofloxacin and marbofloxacin. Predominating in this study, Pseudomonas spp. maintained overall aminoglycoside susceptibility despite some emerging resistance, and good fluoroquinolone susceptibility. High resistance to Polymyxin B could have arisen from its common use as first-line therapy for bacterial corneal ulcers. Although further research is required, these new findings about predominant bacteria in equine corneal ulceration in the Camden region and their antimicrobial susceptibility patterns can be used to guide the empirical treatment of bacterial corneal ulcers in horses.

Rapid application of long-acting ceftiofur can prevent death losses associated with Streptococcus equi subspecies zooepidemicus in pigs

Objective: Introduction of Streptococcus equi subspecies zooepidemicus strains into naive populations results in field mortality rates of 30% to 50% over 5 to 10 days. Because of the rapid disease progression, our goal was to determine whether antibiotic intervention could control S zooepidemicus disease in a group of animals following development of clinical signs. Materials and methods: Thirty-two pigs were challenged with S equi subsp zooepidemicus. Following the development of clinical signs, 16 were treated with long-acting, injectable ceftiofur. Seven unchallenged pigs served as controls. Clinical signs were monitored following challenge and survival was compared between groups. Antibody titers were measured on day 0 and day 30 post challenge. On day 30 post challenge, 3 contact pigs were commingled with 2 treated animals to evaluate S equi subsp zooepidemicus transmission. Results: Ceftiofur treatment eliminated clinical signs in 15 of 16 animals. However, multiple treatments were required to control disease in treated animals (2-3 doses providing 12-18 days of coverage). Antibody titers to S equi subsp zooepidemicus increased in challenged animals treated with ceftiofur, indicating sufficient exposure for immune stimulation. No contact pigs developed clinical signs of S equi subsp zooepidemicus following exposure. Implication: Rapid application of injectable antibiotics is a viable method to reduce losses due to the introduction of S equi subsp zooepidemicus into a naive group of pigs and may help prevent transmission to contact animals following recovery.

Bacterin Vaccination Provides Insufficient Protection Against Streptococcus equi Subspecies zooepidemicus Infection in Pigs.

Streptococcus equi subspecies zooepidemicus (SEZ) is a zoonotic pathogen capable of causing severe disease in many mammalian species. Historically, SEZ has not been a common cause of disease in pigs in North America; however, in 2019, SEZ caused mortality events leading to severe illness and 30–50% mortality in exposed animal groups. Because of the rapid progression of disease, it is important to investigate intervention strategies to prevent disease development. In this study, pigs were divided into four groups: (1) vaccinated with an inactivated SEZ vaccine generated from a highly mucoid 2019 mortality event isolate; (2) vaccinated with an inactivated SEZ vaccine generated from a genetically similar, non-mucoid isolate from a guinea pig; (3) and (4) sham vaccinated. Following boost vaccination, groups 1–3 were challenged with a 2019 mortality event isolate and group 4 were non-challenged controls. Antibody titers were higher for SEZ vaccinated animals than sham vaccinated animals; however, no anamnestic response was observed, and titers were lower than typically seen following the use of inactivated vaccines. Vaccination did not provide protection from disease development or mortality following challenge, which could be associated with the comparatively low antibody titers generated by vaccination. Surviving pigs also remained colonized and transmitted SEZ to naïve contact pigs 3 weeks following challenge, indicating that healthy animals can act as a source of SEZ exposure. Future investigation should evaluate different vaccine formulations, such as increased antigen load or an alternative adjuvant, that could induce a more robust adaptive immune response.

Replication of Streptococcus equi subspecies zooepidemicus infection in swine

Streptococcus equi subspecies zooepidemicus (SEZ) is a commensal bacterium of horses and causes infections in mammalian species, including humans. Historically, virulent strains of SEZ caused high mortality in pigs in China and Indonesia, while disease in the U.S. was infrequent. More recently, high mortality events in sows were attributed to SEZ in North America. The SEZ isolates from these mortality events have high genetic similarity to an isolate from an outbreak in China. Taken together, this may indicate SEZ is an emerging threat to swine health. To generate a disease model and evaluate the susceptibility of healthy, conventionally raised pigs to SEZ, we challenged sows and five-month-old pigs with an isolate from a 2019 mortality event. Pigs were challenged with a genetically similar guinea pig isolate or genetically distinct horse isolate to evaluate comparative virulence. The swine isolate caused severe systemic disease in challenged pigs with 100 % mortality. Disease manifestation in sows was similar to field reports: lethargy/depression, fever, reluctance to rise, and high mortality. The guinea pig isolate also caused severe systemic disease; however, most five-month-old pigs recovered. In contrast, the horse isolate did not cause disease and was readily cleared from the respiratory tract. In conclusion, we were able to replicate disease reported in the field. The results indicate differences in virulence between isolates, with the highest virulence associated with the swine isolate. Additionally, we generated a challenge model that can be used in future research to evaluate virulence factors and disease prevention strategies.

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

BackgroundAbortion 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.ResultsAfter 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.ConclusionsThis 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.

A Novel Real-Time PCR Assay for the Rapid Detection of Virulent Streptococcus equi Subspecies zooepidemicus—An Emerging Pathogen of Swine

Streptococcus equi subspecies zooepidemicus, a zoonotic bacterial pathogen caused a series of outbreaks with high mortality affecting swine herds in multiple locations of the USA and Canada in 2019. Further genetic analysis revealed that this agent clustered with ATCC 35246, a S. zooepidemicus strain associated with high mortality outbreaks in swine herds of China originally reported in 1977. Rapid and accurate diagnosis is absolutely critical for controlling and limiting further spread of this emerging disease of swine. Currently available diagnostic methods including bacteriological examination and PCR assays do not distinguish between the virulent strains and avirulent commensal strains of S. zooepidemicus, which is critical given that this pathogen is a normal inhabitant of the swine respiratory tract. Based on comparative analyses of whole genome sequences of the virulent isolates and avirulent sequences, we identified a region in the SzM gene that is highly conserved and restricted to virulent S. zooepidemicus strains. We developed and validated a novel probe-based real-time PCR targeting the conserved region of SzM. The assay was highly sensitive and specific to the virulent swine isolates of Streptococcus equi subspecies zooepidemicus. No cross reactivity was observed with avirulent S. zooepidemicus isolates as well as other streptococcal species and a panel of porcine respiratory bacterial and viral pathogens. The PCR efficiency of the assay was 96.64 % and was able to detect as little as 20 fg of the bacterial DNA. We then validated the diagnostic sensitivity and specificity of the new PCR assay using a panel of clinical samples (n = 57) and found that the assay has 100% sensitivity and specificity as compared to bacteriological culture method. In summary, the PCR assay will be an extremely valuable tool for the rapid accurate detection of virulent swine S. zooepidemicus isolates and directly from clinical samples.

English

Endometritis has recently become one of the most important infectious diseases in donkey breeding farms in China. However, so far, no research has been conducted to confirm the causative agents. In the present study, one breeding farm was selected as a research model for isolation and identification of causative agents and epidemiological investigation. Streptococcus equi subspecies zooepidemicus was isolated from the uterus of symptomatic and asymptomatic donkeys and identified by PCR and MALDI-TOF MS analysis. On the farm, the infection rate was 57.1%, which indicated that endometritis is a severe problem and needs to pay much attention to donkey breeding farms. Moreover, female donkeys without mating experience were all negative which suggested the transmitting route might be artificial insemination or related handlings. This study will lead to a great understanding of the causative agent and epidemiological characteristics for endometritis in intensive donkey breeding farms