Etiology and pathology of equine placentitis

Maturidade de potros nascidos de éguas com placentite

Objetivou-se descrever a maturidade neonatal através da resposta clínica, comportamental e hematológica de potros nascidos de éguas com placentite. Participaram do estudo seis potros nascidos de éguas submetidas à indução experimental de placentite ascendente através da infusão intracervical de Streptococcus equisubespécie zooepidemicuse tratadas com Sulfa-trimetoprim e Flunixin meglumine. A formação dos grupos neonatais foi realizada de acordo com o grau de viabilidade e sobrevivência até 60 horas: Grupo Não Sobreviventes (n=2); Grupo Debilitados (n=2); Grupo Saudáveis (n=2). Foi considerado o tempo de gestação, período de intervalo inoculação-parto, avaliação comportamental, clínica e hematológica. O Grupo dos potros Saudáveis apresentou maior tempo de gestação (320±2 dias) e maior intervalo inoculação-parto (20,5±2,5 dias). Os Grupos Não Sobreviventes e Debilitados apresentaram atraso para decúbito esternal e reflexo de sucção. Foi observada bradicardia e hipotermia com 48h de vida no Grupo Não Sobreviventes. Os potros do Grupo Não Sobreviventes e Saudáveis apresentaram leucopenia no nascimento com discretas variações até as 48h. Os potros nascidos de éguas com placentite ascendente e tratadas demonstraram evolução clínica e respostas neonatais distintas. Conclui-se que, quanto maior o tempo de manutenção da gestação após a injúria placentária, melhor será a maturação fetal, o que refletirá em viabilidade e melhor capacidade de resposta neonatal.

Streptococcus zooepidemicus and Streptococcus equi evolution: the role of CRISPRs

The host-restricted bacterium Streptococcus equi is the causative agent of equine strangles, the most frequently diagnosed infectious disease of horses worldwide. The disease is characterized by abscessation of the lymph nodes of the head and neck, leading to significant welfare and economic cost. S. equi is believed to have evolved from an ancestral strain of Streptococcus zooepidemicus, an opportunistic pathogen of horses and other animals. Comparison of the genome of S. equi strain 4047 with those of S. zooepidemicus identified examples of gene loss due to mutation and deletion, and gene gain through the acquisition of mobile genetic elements that have probably shaped the pathogenic specialization of S. equi. In particular, deletion of the CRISPR (clustered regularly interspaced short palindromic repeats) locus in the ancestor of S. equi may have predisposed the bacterium to acquire and incorporate new genetic material into its genome. These include four prophages and a novel integrative conjugative element. The virulence cargo carried by these mobile genetic elements is believed to have shaped the ability of S. equi to cause strangles. Further sequencing of S. zooepidemicus has highlighted the diversity of this opportunistic pathogen. Again, CRISPRs are postulated to influence evolution, balancing the need for gene gain over genome stability. Analysis of spacer sequences suggest that these pathogens may be susceptible to a limited range of phages and provide further evidence of cross-species exchange of genetic material among Streptococcus pyogenes, Streptococcus agalactiae and Streptococcus dysgalactiae.

Development of a loop-mediated isothermal amplification method for detecting Streptococcus equi subsp. zooepidemicus and analysis of its use with three simple methods of extracting DNA from equine respiratory tract specimens

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is a dominant pathogenic bacterium in equine pneumonia. We developed a specific loop-mediated isothermal amplification (LAMP) method, which targets the gene encoding sorbitol-6-phosphate 2-dehydrogenase (sorD), for detecting S. zooepidemicus and examined the clinical efficacies of its use in combination with each of 3 DNA extraction methods easily used by veterinary practitioners, namely the Loopamp PURE DNA Extraction Kit, InstaGene Matrix and a conventional boiling method. The LAMP method plus the Loopamp PURE DNA Extraction Kit gave higher rates of positivity than the other combinations in both clinical and spiked samples containing clinically significant concentrations (>1 × 10⁴ CFU/ml) of S. zooepidemicus.

Nasal and cutaneous aspergillosis in a goat

Nasal and cutaneous aspergillosis is reported in an adult goat. The clinical signs were severe respiratory distress due to partial nasal obstruction, bilateral mucopurulent nasal discharge, skin nodules on the ears and dorsal nasal region and focal depigmentation of the ventral commissure of the right nostril. At necropsy examination, sagittal sectioning of the head revealed a yellow irregular mass extending from the nasal vestibule to the frontal portion of the nasal cavity. Microscopically, there was pyogranulomatous rhinitis and dermatitis, with numerous intralesional periodic acid-Schiff-positive fungal hyphae morphologically suggestive of Aspergillus spp. Aspergillus niger was isolated by microbiological examination.

Strangles: taking steps towards eradication

Strangles, caused by the host adapted Lancefield group C bacterium Streptococcus equi sub-species equi (S. equi), is one of the oldest recognised infectious diseases of horses and continues to cause significant welfare and economic cost throughout the world. The ability of S. equi to establish sub-clinical persistent infections primarily in the guttural pouches of convalescent horses has been instrumental to its success. However, the implementation of simple control measures that permit the identification and treatment of persistently infected carriers can prevent further outbreaks of disease at a local level. This review summarises some of the molecular mechanisms exploited by S. equi to cause disease. New qPCR and iELISA diagnostic tests replace culture methodologies as the gold standard for the detection of infected animals. A strategy to maximise the effective application of these tests to direct management methods for the eradication of S. equi infection is presented and the role of preventative vaccines is discussed. In contrast to current understanding, emerging data illustrates the dynamism of the global S. equi population and potential consequences for the effectiveness of currently available vaccines. The ability to use modern vaccines alongside conventional biosecurity and screening procedures will be critical to the large-scale prevention and even eradication of strangles, providing an opportunity to finally break the stranglehold that this disease has on the world's equine industry.

Resposta clínica e metabólica de potros neonatos em relação aos achados histopatológicos da placenta na égua

Avaliaram-se as respostas clínica e metabólica de potros neonatos em relação aos achados histopatológicos da placenta na égua. Foram avaliados dois grupos de éguas da raça Puro Sangue Inglês - um grupo-problema (n=25) e um grupo-controle (n=25), de acordo com os achados da placenta. O exame dos potros constou de avaliação clínica geral, hematologia e bioquímica sérica. O exame histopatológico da placenta apresentou resultado compatível com a apresentação clínica do potro, sendo que a presença de lesões inflamatórias resultou na produção de potros debilitados. A presença de lesões degenerativas não comprometeu o estado clínico do neonato, mas pode ser responsável pela manifestação de distúrbios subclínicos, evidenciados pelo aumento das taxas de AST e GGT. A ureia pareceu ser um indicador de dano renal decorrente de insuficiência placentária em potros neonatos.

Antibiotic susceptibility patterns of Crossiella equi and Amycolatopsis species causing nocardioform placentitis in horses

Nocardioform actinomycetes are significant causes of placentitis and abortions in horses. In the current study, antimicrobial susceptibility patterns of 38 Amycolatopsis spp. and 22 Crossiella equi isolates, the most common nocardioform actinomycetes causing placentitis in horses, were evaluated. Antimicrobial susceptibilities of these isolates were tested by broth microdilution method in a commercial system, which was designed for Nocardia spp., fast-growing Mycobacterium spp., and other aerobic actinomycetes. The minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC90) of the following antibiotics tested for Amycolatopsis spp. were: 4 µg/ml for linezolid, trimethophrim–sulfametaxazole (TMP-SMX), and ciprofloxacin; 8 µg/ml for ceftriaxone, doxycycline, and minocycline; 16 µg/ml for amoxicillin–clavulanic acid, clarithromycin, and imipenem; >16 µg/ml for tobramycin; 32 µg/ml for amikacin and cefepime; and 128 µg/ml for cefoxitin. The MIC90 levels for C. equi were 0.25 µg/ml for doxycycline; ≤1 µg/ml for minocycline; 2 µg/ml for linezolid and TMP-SMX; 4 µg/ml for ciprofloxacin; 8 µg/ml for amoxicillin–clavulanic acid, ceftriaxone, and imipenem; 16 µg/ml for clarithromycin; >16 µg/ml for tobramycin; 32 µg/ml for cefepime; >64 µg/ml for amikacin; and 128 µg/ml for cefoxitin.

Beta-hemolytic Streptococcus spp. from horses: a retrospective study (2000-2010)

The goal of this retrospective study was to have a comprehensive picture of the β-hemolytic streptococci of horses including tissue/organ distributions and susceptibility patterns against specific antimicrobials between January 1, 2000 and December 31, 2010. A total of 2,497 β-hemolytic streptococci were isolated from 2,391 cases, of which Streptococcus equi subsp. zooepidemicus was the most frequent isolate (72.0%). Other species isolated were Streptococcus dysgalactia subsp. equisimilis (21.3%), Streptococcus equi subsp. equi (5.8%), and unidentified β-hemolytic streptococci (0.9%). As expected, S. equi was mostly isolated from lymph node abscesses and the respiratory tract in foals and adult horses. Streptococcus equi subsp. zooepidemicus and S. equisimilis were mostly isolated from placenta, fetal tissues, and genital tract of horses; S. zooepidemicus and S. equisimilis were also recovered in significant numbers from a number of other organs including lung, liver, brain, kidney, and joints, indicating a much broader tissue tropism than S. equi. In addition, more than 1 Streptococcus spp. was recovered in 106 cases, indicating the co-existence of these bacteria in some horses. This data also suggested that S. equisimilis is a major bacterial agent of horses, contrary to present knowledge. Based on Kirby-Bauer antimicrobial susceptibility data, streptococci were found to be generally susceptible to cephalothin, erythromycin, nitrofurantoin, penicillin, and ticarcillin and clavulanate. Resistance to antimicrobials has not developed over the years, except for gentamicin and tetracycline against S. equisimilis.

Infection of an equine placenta with a novel mycobacterial species leading to abortion

A 25-year-old pregnant American Quarter Horse mare presented with a 1-week history of progressively worsening vaginal discharge. Transrectal ultrasound revealed increased thickness of the combined uterus and placenta with evidence of chorioallantoic edema but no placental separation. A thickened amnion was visible on transabdominal ultrasound. Abortion occurred 2 days after presentation despite medical treatment. At necropsy, the chorioallantois had variable but diffuse thickening with focally extensive browning of the chorionic surface in the right horn and adjacent body. There were fluid-filled sacculations on the allantoic surface of the umbilical cord, allantoamnion, and chorioallantois associated with diffuse perivascular fluid microscopically. A nonbranching acid-fast bacterium identified as belonging to the genus Mycobacterium Runyon group IV was isolated from the chorioallantois and uterine fluid. Ziehl-Neelsen stain confirmed the presence of intracellular acid-fast bacilli in trophoblasts of the gravid horn and the cervical star area. The current case is unique in that the mycobacteria did not initiate a significant granulomatous inflammatory response in the chorion unless villar necrosis occurred. Sequence analysis of the 16S ribosomal RNA gene and the rpoβ gene, encoding the β subunit of RNA polymerase, indicated that the strain of mycobacteria isolated in this case belonged to a novel species of rapidly growing mycobacteria and not to an established species. Mycobacteria are an uncommon and sporadic cause of placentitis and abortion, but should be suspected in cases of chronic placentitis that are not restricted to the cervical star area.

Horse species symposium: a novel approach to monitoring pathogen progression during uterine and placental infection in the mare using bioluminescence imaging technology and lux-modified bacteria

Uterine and placental infections are the leading cause of abortion, stillbirth, and preterm delivery in the mare. Whereas uterine and placental infections in women have been studied extensively, a comprehensive examination of the pathogenic processes leading to this unsatisfactory pregnancy outcome in the mare has yet to be completed. Most information in the literature relating to late-term pregnancy loss in mares is based on retrospective studies of clinical cases submitted for necropsy. Here we report the development and application of a novel approach, whereby transgenically modified bacteria transformed with lux genes of Xenorhabdus luminescens or Photorhabdus luminescens origin and biophotonic imaging are utilized to better understand pathogen-induced preterm birth in late-term pregnant mares. This technology uses highly sensitive bioluminescence imaging camera systems to localize and monitor pathogen progression during tissue invasion by measuring the bioluminescent signatures emitted by the lux-modified pathogens. This method has an important advantage in that it allows for the potential tracking of pathogens in vivo in real time and over time, which was hitherto impossible. Although the application of this technology in domestic animals is in its infancy, investigators were successful in identifying the fetal lungs, sinuses, nares, urinary, and gastrointestinal systems as primary tissues for pathogen invasion after experimental infection of pregnant mares with lux-modified Escherichia coli. It is important that pathogens were not detected in other vital organs, such as the liver, brain, and cardiac system. Such precision in localizing sites of pathogen invasion provides potential application for this novel approach in the development of more targeted therapeutic interventions for pathogen-related diseases in the equine and other domestic species.

Detection of Streptococcus dysgalactiae subsp. equisimilis in equine nasopharyngeal swabs by PCR

Streptococcus (S.) dysgalactiae subsp. equisimilis is responsible for severe diseases in humans, including primary bacteraemia, pneumonia, endocarditis, and toxic shock syndrome. Infection in some animal species can also occur, although a few studies have looked into cross-species infectivity. In horses, S. equisimilis is generally considered infrequent or opportunistic, but has recently been isolated from cases of strangles-like disease. Rapid and sensitive diagnostic techniques could enable epidemiological studies and effective investigation of outbreaks involving these bacteria. In this study, PCR protocols previously described in cattle and in humans to detect the species S. dysgalactiae and the subspecies equisimilis were evaluated to detect specific sequences in equine samples. For this purpose, 99 monolateral nasal swabs were collected from horses from stud farms with a history of S. equisimilis infection and were tested blindly by bacteriological isolation and by single and duplex PCR. DNA for PCR was extracted both from the colonies grown on agar media and from enrichment broth aliquots after incubation with nasal swab samples. S. equisimilis was identified by bacteriological isolation in 23 out of 99 swab samples, and PCR assays on these colonies were fully concordant with bacteriological identification (kappa statistic = 1.00). In addition, PCR of the enrichment broth aliquots confirmed the bacteriological results and detected S. equisimilis in 6 samples more than the bacteriological examination (kappa statistic = 0.84). The PCR protocols appeared to be reliable for the rapid identification of S. equisimilis in equine nasal swab samples, and could be useful for microbiological diagnosis.

Identification of three novel superantigen-encoding genes in Streptococcus equi subsp. zooepidemicus, szeF, szeN, and szeP

The acquisition of superantigen-encoding genes by Streptococcus pyogenes has been associated with increased morbidity and mortality in humans, and the gain of four superantigens by Streptococcus equi is linked to the evolution of this host-restricted pathogen from an ancestral strain of the opportunistic pathogen Streptococcus equi subsp. zooepidemicus. A recent study determined that the culture supernatants of several S. equi subsp. zooepidemicus strains possessed mitogenic activity but lacked known superantigen-encoding genes. Here, we report the identification and activities of three novel superantigen-encoding genes. The products of szeF, szeN, and szeP share 59%, 49%, and 34% amino acid sequence identity with SPEH, SPEM, and SPEL, respectively. Recombinant SzeF, SzeN, and SzeP stimulated the proliferation of equine peripheral blood mononuclear cells, and tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) production, in vitro. Although none of these superantigen genes were encoded within functional prophage elements, szeN and szeP were located next to a prophage remnant, suggesting that they were acquired by horizontal transfer. Eighty-one of 165 diverse S. equi subsp. zooepidemicus strains screened, including 7 out of 15 isolates from cases of disease in humans, contained at least one of these new superantigen-encoding genes. The presence of szeN or szeP, but not szeF, was significantly associated with mitogenic activity in the S. equi subsp. zooepidemicus population (P < 0.000001, P < 0.000001, and P = 0.104, respectively). We conclude that horizontal transfer of these novel superantigens from and within the diverse S. equi subsp. zooepidemicus population is likely to have implications for veterinary and human disease.

Continuous monitoring of penicillin G and gentamicin in allantoic fluid of pregnant pony mares by in vivo microdialysis

REASONS FOR PERFORMING STUDY

Most current treatments for placentitis in mares are empirical with few control studies to evaluate their effectiveness.

OBJECTIVE

To monitor drug concentrations in allantoic fluid of pregnant pony mares using in vivo microdialysis and establish if this method would be useful for determining allantoic concentrations of drugs in normal mares and those with placentitis.

METHODS

Five late gestational pony mares had microdialysis probes inserted into the allantoic fluid using transabdominal ultrasound-guided allantocentesis. Single injections of penicillin G (22,000 u/kg), gentamicin (6.6 mg/kg bwt) and flunixin meglumine (1 mg/kg bwt) were administered i.v. and dialysate samples collected continuously for 24 h. In a separate study, drug concentrations were monitored in allantoic fluid of 2 mares with experimental placentitis induced by intracervical inoculation with Streptococcus equi ssp. zooepidemicus. Drug concentrations were measured by high performance liquid chromatography (penicillin G, flunixin meglumine) or enzyme-linked immunosorbent assay (gentamicin).

RESULTS

Penicillin G and gentamicin achieved average peak concentrations of 9.8+/-2.2 and 8.5+/-3.1 microg/ml, respectively, in allantoic fluid of noninfected mares. Pharmacokinetic comparisons indicate that penicillin G persists much longer in allantoic fluid than blood, whereas gentamicin exhibited similar profiles in the 2 compartments. Flunixin meglumine was not detected in allantoic fluid. In infected mares, penicillin G achieved a similar peak concentration in allantoic fluid (11.2 microg/ml) whereas peak gentamicin concentration (3.9 microg/ml) appeared to be reduced relative to drug concentrations in noninfected mares.

CONCLUSIONS

Microdialysis is a useful technique for continuous in vivo monitoring of drugs in equine allantoic fluid. Our results indicate that penicillin G and gentamicin undergo effective placental transfer in pregnant mares and in 2 mares that transplacental drug transfer may be altered selectively if active placental infection is present.

POTENTIAL RELEVANCE

Further studies are needed to evaluate the feasibility of using increased dose intervals for penicillin G and an increased dose rate of gentamicin to effectively combat placental infections in mares.

Streptomyces atriruber sp. nov. and Streptomyces silaceus sp. nov., two novel species of equine origin

Two actinomycete strains, NRRL B-24165(T) and NRRL B-24166(T), isolated from lesions on equine placentas in Kentucky, USA, were analysed using a polyphasic taxonomic approach. On the basis of phylogenetic analysis of 16S rRNA gene sequences, morphological observations and the presence of ll-diaminopimelic acid as the diagnostic diamino acid in whole-cell hydrolysates, the new isolates clearly belonged to the genus Streptomyces. Analyses of the phylogenetic positions of strains NRRL B-24165(T) and NRRL B-24166(T) based on 16S rRNA gene sequences of all recognized species of the genus Streptomyces, as well as evaluation of morphological and physiological characteristics, demonstrated that the new isolates could be differentiated from all recognized species and therefore represented novel species. It is proposed that the new strains represent two novel species for which the names Streptomyces atriruber sp. nov. (type strain NRRL B-24165(T)=DSM 41860(T)=LDDC 6330-99(T)) and Streptomyces silaceus sp. nov. (NRRL B-24166(T)=DSM 41861(T)=LDDC 6638-99(T)) are proposed. The species names are based on the distinctive colours of the substrate mycelium of these strains, dark red and deep orange-yellow, respectively.

Repeated domains of leptospira immunoglobulin-like proteins interact with elastin and tropoelastin

Leptospira spp., the causative agents of leptospirosis, adhere to components of the extracellular matrix, a pivotal role for colonization of host tissues during infection. Previously, we and others have shown that Leptospira immunoglobulin-like proteins (Lig) of Leptospira spp. bind to fibronectin, laminin, collagen, and fibrinogen. In this study, we report that Leptospira can be immobilized by human tropoelastin (HTE) or elastin from different tissues, including lung, skin, and blood vessels, and that Lig proteins can bind to HTE or elastin. Moreover, both elastin and HTE bind to the same LigB immunoglobulin-like domains, including LigBCon4, LigBCen7'-8, LigBCen9, and LigBCen12 as demonstrated by enzyme-linked immunosorbent assay (ELISA) and competition ELISAs. The LigB immunoglobulin-like domain binds to the 17th to 27th exons of HTE (17-27HTE) as determined by ELISA (LigBCon4, K(D) = 0.50 microm; LigBCen7'-8, K(D) = 0.82 microm; LigBCen9, K(D) = 1.54 microm; and LigBCen12, K(D) = 0.73 microm). The interaction of LigBCon4 and 17-27HTE was further confirmed by steady state fluorescence spectroscopy (K(D) = 0.49 microm) and ITC (K(D) = 0.54 microm). Furthermore, the binding was enthalpy-driven and affected by environmental pH, indicating it is a charge-charge interaction. The binding affinity of LigBCon4D341N to 17-27HTE was 4.6-fold less than that of wild type LigBCon4. In summary, we show that Lig proteins of Leptospira spp. interact with elastin and HTE, and we conclude this interaction may contribute to Leptospira adhesion to host tissues during infection.

REVIEW paper: mare reproductive loss syndrome

An epidemic of early fetal loss (EFL), late fetal loss (LFL), fibrinous pericarditis, and unilateral uveitis which occurred during the spring of 2001, are together now known as the mare reproductive loss syndrome (MRLS). A similar epidemic with less intensity was reported during the same period of time from southern Ohio, West Virginia, and Tennessee. The same syndrome with lesser intensity recurred in 2002. The estimated economic loss from the syndrome in 2001 and 2002 together was approximately $500 million. Both EFL and LFL were characterized by the absence of specific clinical signs in aborting mares. Nonhemolytic Streptococcus spp. and Actinobacillus spp. accounted for 65% of the organisms isolated from fetuses submitted for a postmortem during the MRLS period in 2001 and 2002. The pathologic findings in fetoplacental units of LFL included bronchopneumonia and funisitis, and there were no findings in EFL. Epidemiologic studies conducted in 2001 suggested an association between the presences of eastern tent caterpillars (ETC) in pastures with MRLS. Experimental studies in pregnant mares by exposure to ETC, or administration by stomach tube or with feed material, reproduced EFL and LFL. Similar experimental studies in mouse, rats, and goats with ETC were unsuccessful. Currently, 2 hypotheses are proposed for MRLS. One hypothesis proposes that an ETC-related toxin with secondary opportunistic bacterial invasion of the fetus leads to MRLS. The second hypothesis suggests that a breach of gastrointestinal mucosal integrity by hairs of ETC leads to a bacteremia and results in MRLS. In 2004, a similar equine abortion storm was reported from Australia and caterpillar exposure was identified as a risk factor for the abortion. In 2006, the syndrome was observed in Florida and New Jersey.

Development of an unambiguous and discriminatory multilocus sequence typing scheme for the Streptococcus zooepidemicus group

The zoonotic pathogen Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is commonly found harmlessly colonizing the equine nasopharynx. Occasionally, strains can invade host tissues or cross species barriers, and S. zooepidemicus is associated with numerous different diseases in a variety of hosts, including inflammatory airway disease and abortion in horses, pneumonia in dogs and meningitis in humans. A biovar of S. zooepidemicus, Streptococcus equi subsp. equi, is the causative agent of strangles, one of the most important infections of horses worldwide. We report here the development of the first multilocus sequence typing (MLST) scheme for S. zooepidemicus and its exploitation to define the population genetic structure of these related pathogens. A total of 130 unique sequence types were identified from 277 isolates of diverse geographical and temporal origin. Isolates of S. equi shared a recent evolutionary ancestor with isolates of S. zooepidemicus that were significantly associated with cases of uterine infection or abortion in horses (P<0.001). Isolates of S. zooepidemicus from three UK outbreaks of acute fatal haemorrhagic pneumonia in dogs during 1999, 2001 and 2008 were found to be related to isolates from three outbreaks of this disease in the USA during 2005, 1993 and 2006, respectively. Our data provide strong evidence that S. equi evolved from an ancestral S. zooepidemicus strain and that certain related strains of S. zooepidemicus have a greater propensity to infect particular hosts and tissues.

Abortion in a Horse Following Neorickettsia Risticii Infection

A pregnant 18-year-old Quarterhorse mare presented with fever, anorexia, tachycardia, tachypnea, and gastrointestinal hypermotility at day 68 of gestation. Potomac horse fever was diagnosed based on polymerase chain reaction (PCR) analysis of whole blood and a high antibody titer to Neorickettsia risticii. The mare made a rapid clinical recovery following antibiotic therapy, but aborted 98 days later. Necropsy on the aborted fetus revealed lymphohistiocytic colitis, lymphadenitis, myocarditis, and hepatitis. The placenta was grossly and histologically normal. Formalin-fixed lymph node, thymus, liver, and colon taken from the aborted fetus were positive by PCR for N. risticii DNA. Potomac horse fever is a common disease in horses that may result in delayed abortion. The microscopic lesions in the fetus are characteristic, and the diagnosis can be confirmed by PCR on formalin-fixed tissues.

A survey of equine abortion and perinatal foal losses in Hungary during a three-year period (1998-2000)

Cases of equine abortion and perinatal foal losses were investigated in Hungary during a three-year period (1998-2000). Samples from aborted equine fetuses and newborn foals (total n = 96) were examined using bacteriological, virological, pathological, immunohistochemical (IHC), molecular biological and serological methods. The cause of abortion and perinatal foal loss was identified in 67/96 cases (70%); viral infection was found in 22 (23%), viral and bacterial coinfection in 1 (1%), bacterial infection in 23 (24%), protozoan infection in 1 (1%) and fungal infection in 2 cases (2%). Morphological lesions suggestive of infection were recorded in 2 (2%) and non-infectious causes in 16 cases (17%).

High incidence of plant growth-stimulating bacteria associated with the rhizosphere of wheat grown on salinated soil in Uzbekistan

Soil salinization is increasing steadily in many parts of the world and causes major problems for plant productivity. Under these stress conditions, root-associated beneficial bacteria can help improve plant growth and nutrition. In this study, salt-tolerant bacteria from the rhizosphere of Uzbek wheat with potentially beneficial traits were isolated and characterized. Eight strains which initially positively affect the growth of wheat plants in vitro were investigated in detail. All eight strains are salt tolerant and have some of the following plant growth-beneficial properties: production of auxin, HCN, lipase or protease and wheat growth promotion. Using sequencing of part of the 16S rDNA, the eight new isolates were identified as Acinetobacter (two strains), Pseudomonas aeruginosa, Staphylococcus saprophyticus, Bacillus cereus, Enterobacter hormaechei, Pantoae agglomerans and Alcaligenes faecalis. All these strains are potential human pathogens. Possible reasons for why these bacteria present in the rhizosphere and establish there are discussed.

Lentzea kentuckyensis sp. nov., of equine origin

A novel actinomycete, designated strain LDDC 2876-05T, was isolated from an equine placenta during the course of routine diagnostic tests for nocardioform placentitis. In a preliminary study, the strain was observed to be phylogenetically distinct from the generaCrossiellaandAmycolatopsisand probably a member of the genusLentzea.A polyphasic study of strain LDDC 2876-05Tconfirmed its identification as a member ofLentzeaon the basis of its chemotaxonomic and morphological similarity to all of the known species of the genus. Moreover, the strain could be distinguished from other species with validly published names on the basis of its phylogenetic and physiological characteristics and its fatty acid profile. Therefore strain LDDC 2876-05Trepresents a novel species of the genusLentzea, for which the nameLentzea kentuckyensissp. nov. is proposed. The type strain is LDDC 2876-05T(=NRRL B-24416T=DSM 44909T).

Transrectal ultrasonography and plasma progestin profiles identifies feto-placental compromise in mares with experimentally induced placentitis

Transrectal ultrasonography of the caudal uterus and a progestin profile were evaluated for accuracy in identifying mares with feto-placental compromise in a model of placentitis. Twenty-two pregnant ponies were divided into four groups: (1) control mares (n=5); (2) instrumented controls (n=2); (3) instrumented inoculated mares (n=11); (4) inoculated mares (n=4). Mares in Groups 3 and 4 were inoculated with Streptococcus equi subsp. zooepidemicus. Maternal plasma progestins, vulvar discharge, mammary gland development, combined thickness of the uterus and placenta (CTUP) and placental separation were evaluated weekly before instrumentation, inoculation or Day 320 (Groups 1 and 2) and, thereafter, either daily (first three measurements) or several times weekly (last two measurements). Plasma progestin profiles were plotted to identify pattern characteristics. An abbreviated profile was created, consisting of four progestin samples collected at 48-h intervals, with Sample 1 collected the day before inoculation or on Day 285 in controls. Profiles were considered abnormal if Samples 2, 3, or 4 increased or decreased by more than 50% of Sample 1. A CTUP>1.0 cm or placental separation were considered abnormal. Placentitis was confirmed by histology of fetal membranes. Control mares had normal progestin profiles, transrectal ultrasonographic and clinical examinations. Control foals were born after Day 329; six were viable and one died after dystocia. All inoculated mares developed placentitis and foaled before Day 314. Thirteen of 15 foals were not viable. All inoculated mares had abnormal progestin profiles and 13 of the 15 were identified by the abbreviated progestin profile. Transrectal CTUP was affected by gestational age and increased after inoculation (P<0.05). Nine of 15 inoculated mares had a CTUP>1.0 cm by 5-day post-inoculation. By performing both tests, 20 of 22 mares were correctly identified with respect to pregnancy outcome. However, three inoculated mares exhibited minimal clinical signs and likely would not be examined in a clinical setting. These tests were diagnostic for identifying feto-placental compromise in the mare.

Diagnosis and Treatment of Equine Placentitis

Equine placentitis is a complex disease that has devastating consequences for horse owners. Placentitis is a significant cause of foal loss annually. Prompt diagnosis and treatment of the disease are paramount for survival of the affected neonate. This article discusses current information on pathogenesis of the disease as well as diagnostic and therapeutic options.

Classification of Actinobacillus spp isolates from horses involved in mare reproductive loss syndrome

OBJECTIVE

To identify Actinobacillus spp isolates recovered from fetuses and pericardial fluid from horses affected with mare reproductive loss syndrome (MRLS) and determine whether these bacterial species are the same as those isolated from clinically normal horses.

SAMPLE POPULATION

Isolates of actinobacilli recovered from 18 horses with pericarditis and 109 fetuses aborted by mares affected by MRLS. Procedures-Actinobacillus spp isolates were identified to the level of species or subspecies by use of conventional phenotypic tests and biochemical and enzyme test kits. The 16S rRNA gene from selected isolates was amplified, purified, and sequenced. Sequence data were compared with sequence data for actinobacilli in GenBank.

RESULTS

Of the 109 isolates obtained from fetuses, 14 were Actinobacillus equuli subsp equuli, 65 were A equuli subsp haemolyticus, 28 were Bisgaard taxon 10-like bacterium, and 2 were Actinobacillus genomospecies 1. Of the 18 isolates from horses with pericarditis, 4 were A equuli subsp equuli, 13 were A equuli subsp haemolyticus, and 1 was Bisgaard taxon 10-like bacterium. Comparisons with published data and GenBank data revealed that the isolates recovered from horses with MRLS were the same as those isolated from the oral cavity or alimentary tract of healthy horses.

CONCLUSIONS AND CLINICAL RELEVANCE

Actinobacillus spp isolates recovered from fetuses and pericardial fluid samples of horses affected by MRLS in 2001 to 2003 were identical to Actinobacillus spp found in the oral cavity and alimentary tracts of healthy horses.

Nocardioform placentitis with isolation ofAmycolatopsisspp in a Florida-bred mare

CASE DESCRIPTION

A 4-year-old Thoroughbred mare was evaluated because of placental abnormalities and a retained placental remnant.

CLINICAL FINDINGS

Microbial culture of the placenta yielded pure growth of Amycolatopsis spp. Histologic examination of the placenta revealed a focally expanding chorionitis with intralesional gram-positive filamentous bacilli and multifocal allantoic adenomatous hyperplasia on the apposing allantoic surface.

TREATMENT AND OUTCOME

Treatment with lavage and oxytocin resulted in expulsion of the placental remnant within hours of parturition. The mare did not become pregnant again despite multiple breedings. The foal appeared healthy but died of complications during an elective surgical procedure at 7 weeks of age.

CONCLUSIONS AND CLINICAL RELEVANCE

To the author's knowledge, all previously confirmed cases of nocardioform placentitis have been in mares bred in the central Kentucky region. Indications that the pathogen in the mare reported here is a different species than that isolated in Kentucky suggest that this is an emerging disease. Mares with nocardioform placentitis usually do not have the same clinical signs as mares with placentitis resulting from an ascending pathogen.

Detection of equine herpesvirus type 1 using a real-time polymerase chain reaction

Equid herpesvirus 1 (EHV1) is a major disease of equids worldwide causing considerable losses to the horse industry. A variety of techniques, including PCR have been used to diagnose EHV1. Some of these PCRs were used in combination with other techniques such as restriction enzyme analysis (REA) or hybridisation, making them cumbersome for routine diagnostic testing and increasing the chances of cross-contamination. Furthermore, they involve the use of suspected carcinogens such as ethidium bromide and ultraviolet light. In this paper, we describe a real-time PCR, which uses minor groove-binding probe (MGB) technology for the diagnosis of EHV1. This technique does not require post-PCR manipulations thereby reducing the risk of cross-contamination. Most importantly, the technique is specific; it was able to differentiate EHV1 from the closely related member of the Alphaherpesvirinae, equid herpesvirus 4 (EHV4). It was not reactive with common opportunistic pathogens such as Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa and Enterobacter agglomerans often involved in abortion. Similarly, it did not react with equine pathogens such as Streptococcus equi, Streptococcus equisimilis, Streptococcus zooepidemicus, Taylorella equigenitalis and Rhodococcus equi, which also cause abortion. The results obtained with this technique agreed with results from published PCR methods. The assay was sensitive enough to detect EHV1 sequences in paraffin-embedded tissues and clinical samples. When compared to virus isolation, the test was more sensitive. This test will be useful for the routine diagnosis of EHV1 based on its specificity, sensitivity, ease of performance and rapidity.

Pseudomonas aeruginosa from canine otitis externa exhibit a quorum sensing deficiency

Pseudomonas aeruginosa LasB elastase gene (lasB) transcription depends on cell density-dependent quorum-sensing mechanisms of gene activation. Previously, we collected several non-mucoid P. aeruginosa veterinary isolates and showed that the total matrix protease phenotype was similar for isolates regardless of host and site of isolation. In contrast, isolates from chronic canine ear infections (otitis externa) were significantly more likely to exhibit less elastase activity as measured by elastin Congo red than from any other site [Clin. Diag. Lab. Immun. 8 (2001) 632]. In this study, we found that the elastase deficiency phenotype is stable upon passage in broth culture. Transcript amplification analyses indicated that the elastase deficiency appears to be strain-specific, with each isolate exhibiting a unique expression profile relative to strain PAO1. Although a number of strain-specific transcriptional differences were observed, the overall pattern that emerges is a quorum sensing deficiency among canine ear P. aeruginosa isolates.