Experimental infection of goats with pVAPN-harboring Rhodococcus equi causes latent infection in the lymph nodes

Rhodococcus equi has recently been identified in various animals, including ruminants. Several studies have highlighted the emergence of pVAPN-harboring strains, isolated from multiple abscesses, in the liver and lungs of ruminants. Epidemiological evidence strongly suggests that pVAPN-harboring strains are pathogenic in ruminants. This study aims to replicate the disease in goats through experimental infection. Intravenous administration of the pVAPN-harboring strain (Yokkaichi), pVAPA-harboring strain (ATCC33701), and pVAPN-cured strain (Yokkaichi_P-), each at 1.0 × 107 CFU/head, was conducted in 24-month-old goats (n = 1 per group). During the observation period, goats treated with Yokkaichi or ATCC33701 exhibited transient increases in body temperature and white blood cell count, alongside a decrease in body weight from the administration day. Conversely, goats treated with Yokkaichi_P- displayed no significant changes in these values. The Yokkaichi-treated goat demonstrated a >10-fold increase in anti-VapN antibody titers from 11 to 14 days postadministration, whereas the other two goats exhibited no variation in anti-VapA and VapN antibody titers. Pathological autopsy analysis of organs harvested 28 days postadministration revealed no characteristic lesions on gross examination. However, the inoculated strain (vapN-positive R. equi) was exclusively recovered from the tracheobronchial lymph node in the Yokkaichi-treated goat. Immunohistochemistry detected a VapN-positive reaction in the tracheobronchial lymph node, confirming latent infection despite the absence of dramatic suppurative lesions seen in ruminants. Overall, this study highlights the latent infection in lymph nodes induced by the pVAPN-harboring strain, despite the absence of overt pathological manifestations.

Antimicrobial Residue Accumulation Contributes to Higher Levels of Rhodococcus equi Carrying Resistance Genes in the Environment of Horse-Breeding Farms

Antimicrobial residues excreted in the environment following antimicrobial treatment enhance resistant microbial communities in the environment and have long-term effects on the selection and maintenance of antimicrobial resistance genes (AMRGs). In this study, we focused on understanding the impact of antimicrobial use on antimicrobial residue pollution and antimicrobial resistance (AMR) in the environment of horse-breeding farms. Rhodococcus equi is an ideal microbe to study these associations because it lives naturally in the soil, exchanges AMRGs with other bacteria in the environment, and can cause disease in animals and humans. The environment is the main source of R. equi infections in foals; therefore, higher levels of multidrug-resistant (MDR) R. equi in the environment contribute to clinical infections with MDR R. equi. We found that macrolide residues in the environment of horse-breeding farms and the use of thoracic ultrasonographic screening (TUS) for early detection of subclinically affected foals with R. equi infections were strongly associated with the presence of R. equi carrying AMRGs in the soil. Our findings indicate that the use of TUS contributed to historically higher antimicrobial use in foals, leading to the accumulation of antimicrobial residues in the environment and enhancing MDR R. equi.

Development of monoclonal antibodies against Rhodococcus equi virulence-associated protein N and their application to pathological diagnosis

IMPORTANCE

Rhodococcus equi can cause infection in ruminants, and its pathogenicity is suggested to be associated with VapN. Despite its wide distribution, no immunological diagnostic method has been developed for VapN-producing R. equi. Against this background, we attempted to develop monoclonal antibodies targeting VapN and assess their application in immunostaining. In the study, mice were immunized with recombinant VapN, and cell fusion and cloning by limiting dilution permitted the generation of three antibody-producing hybridomas. The utility of the antibodies produced from the hybridomas in immunostaining was demonstrated using an infected mouse model, and the antibodies were further applied to previously reported cases of R. equi infection in goats and cattle. Although the 4H4 antibody induced the strongest reactions, the reactivity of two other antibodies was improved by antigen retrieval. Our monoclonal antibodies will be utilized to support the definitive diagnosis of suspected R. equi infection, including cases that were previously missed.

Assessment of rSodC, rPknG, rNanH, and rSpaC as Antigens for Diagnostic Tools Against Caseous Lymphadenitis

Corynebacterium pseudotuberculosis is a bacillus that causes caseous lymphadenitis in small ruminants, leading to great losses to rural producers; thus, an efficient diagnosis is necessary for using disease control measures. This study aimed to evaluate the antigenic potential of four C. pseudotuberculosis recombinant proteins (rSodC, rPknG, rNanH, and rSpaC) against sera of goat and sheep experimentally infected with one of three different C. pseudotuberculosis strains. Goats were infected with CAP76 or CAP21 strain (n = 10), sheep with VD57 strain (n = 6), and a group of not-infected animals (goats and sheep) were kept as a healthy control (healthy n = 12). Sera were collected at 0, 14, 60, 90, 180, or 190 days after inoculation for antigenicity testing using Western blotting and enzyme-linked immunosorbent assay (ELISA) techniques. Cross-reactivity tests with recombinant proteins were performed in goat serum experimentally vaccinated with Nocardia sp. or Rhodococcus equi bacterin. The rSodC protein showed discriminatory antigenic reactivity with a statistically significant difference against three different C. pseudotuberculosis strains evaluated in goats and sheep samples, while rPknG showed statistical significance only against two C. pseudotuberculosis strains evaluated in goats. rSodC was proved to be a strong candidate as a tool for diagnosis of C. pseudotuberculosis infection, once it was able to recognize antibodies against all strains evaluated in goats and sheep.

Fatal Infection in an Alpaca (Vicugna pacos) Caused by Pathogenic Rhodococcus equi

Simple Summary

Serious consequences of septicemic bacterial infections include the formation of purulent and pyogranulomatous inflammation resulting in abscesses in inner organs. Different bacteria are known to cause these infections in livestock. In this study, we report in detail on a case of a fatal Rhodococcus (R.) equi infection in an alpaca (Vicugna pacos), to our knowledge, for the first time. R. equi is a member of the actinomycetes, a bacterial group known to contain several pathogenic bacteria. R. equi primarily affects equine foals and other domestic animals, but also humans, which renders this bacterium a zoonotic agent. The rhodococcal infection of the alpaca reported herein caused septicemia, resulting in emaciation and severe lesions in the lungs and heart. The onset of infection was presumably caused by aspiration pneumonia, resulting in abscesses exclusively in the lungs. The R. equi isolate proved to be pathogenic, based on the virulence gene vapA encoding the virulence-associated protein A. Antibiotic susceptibility testing revealed a susceptibility to doxycycline, erythromycin, gentamycin, neomycin, rifampicin, trimethoprim/sulfamethoxazole, tetracycline and vancomycin. This report of an R. equi infection in an alpaca makes clear that we still have knowledge gaps about bacterial infectious diseases in alpacas and potential zoonotic impacts. Therefore, the determination of pathogenic, zoonotic bacteria in alpacas is essential for treatment and preventive measures with respect to sustaining the health, welfare and productivity of this camelid species.

Abstract

Rhodococcus (R.) equi is a pathogen primarily known for infections in equine foals, but is also present in numerous livestock species including New World camelids. Moreover, R. equi is considered an emerging zoonotic pathogen. In this report, we describe in detail a fatal rhodococcal infection in an alpaca (Vicugna pacos), to our best knowledge, for the first time. The alpaca died due to a septicemic course of an R. equi infection resulting in emaciation and severe lesions including pyogranulomas in the lungs and pericardial effusion. The onset of the infection was presumably caused by aspiration pneumonia. R. equi could be isolated from the pyogranulomas in the lung and unequivocally identified by MALDI-TOF MS analysis and partial sequencing of the 16S rRNA gene, the 16S-23S internal transcribed spacer (ITS) region and the rpoB gene. The isolate proved to possess the vapA gene in accordance with tested isolates originating from the lungs of infected horses. The R. equi isolates revealed low minimal inhibitory concentrations (MIC values) for doxycycline, erythromycin, gentamycin, neomycin, rifampicin, trimethoprim/sulfamethoxazole, tetracycline and vancomycin in antibiotic susceptibility testing. Investigations on the cause of bacterial, especially fatal, septicemic infections in alpacas are essential for adequately addressing the requirements for health and welfare issues of this New World camelid species. Furthermore, the zoonotic potential of R. equi has to be considered with regard to the One Health approach.

Genomic Characteristics Revealed Plasmid-Mediated Pathogenicity and Ubiquitous Rifamycin Resistance of Rhodococcus equi

Rhodococcus equi is a zoonotic pathogen that can cause fatal disease in patients who are immunocompromised. At present, the epidemiology and pathogenic mechanisms of R. equi infection are not clear. This study characterized the genomes of 53 R. equi strains from different sources. Pan-genome analysis showed that all R. equi strains contained 11481 pan genes, including 3690 core genes and 602 ~ 1079 accessory genes. Functional annotation of pan genome focused on the genes related to basic lifestyle, such as the storage and expression of metabolic and genetic information. Phylogenetic analysis based on pan-genome showed that the R. equi strains were clustered into six clades, which was not directly related to the isolation location and host source. Also, a total of 84 virulence genes were predicted in 53 R. equi strains. These virulence factors can be divided into 20 categories related to substance metabolism, secreted protein and immune escape. Meanwhile, six antibiotic resistance genes (RbpA, tetA (33), erm (46), sul1, qacEdelta 1 and aadA9) were detected, and all strains carried RbpA related to rifamycin resistance. In addition, 28 plasmids were found in the 53 R. equi strains, belonging to Type-A (n = 14), Type-B (n = 8) and Type-N (n = 6), respectively. The genetic structures of the same type of plasmid were highly similar. In conclusion, R. equi strains show different genomic characteristics, virulence-related genes, potential drug resistance and virulence plasmid structures, which may be conducive to the evolution of its pathogenesis.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): antimicrobial-resistant Rhodococcus equi in horses

Rhodococcus equi (R. equi) was identified among the most relevant antimicrobial-resistant (AMR) bacteria in the EU for horses in a previous scientific opinion. Thus, it has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on its eligibility to be listed, Annex IV for its categorisation according to disease prevention and control rules as in Article 9 and Article 8 for listing animal species related to the bacterium. The assessment has been performed following a methodology previously published. The outcome is the median of the probability ranges provided by the experts, which indicates whether each criterion is fulfilled (lower bound ≥ 66%) or not (upper bound ≤ 33%), or whether there is uncertainty about fulfilment. Reasoning points are reported for criteria with uncertain outcome. According to the assessment here performed, it is uncertain whether AMR R. equi can be considered eligible to be listed for Union intervention according to Article 5 of the AHL (10-66% probability). According to the criteria in Annex IV, for the purpose of categorisation related to the level of prevention and control as in Article 9 of the AHL, the AHAW Panel concluded that the bacterium does not meet the criteria in Sections 1 and 2 (Categories A and B; 5-10% and 10-33% probability of meeting the criteria, respectively), and the AHAW Panel is uncertain whether it meets the criteria in Sections 3, 4 and 5 (Categories C, D and E; 10-66% probability of meeting the criteria in all three categories). The animal species to be listed for AMR R. equi according to Article 8 criteria are mainly horses and other species belonging to the Perissodactyla and Artiodactyla orders.

Isolation of Rhodococcus equi from the gastrointestinal contents of earthworms (family Megascolecidae)

Rhodococcus equi was isolated from the gastrointestinal contents of earthworms (family Megascolecidae) and their surrounding soil collected from pastures of two horse-breeding farms in Aomori Prefecture, outdoor pig pens, forest in Towada campus, orange groves and forest where wild boars (Sus scrofa) are established in Tanabe, Wakayama Prefecture. The number of R. equi in the lower gastrointestinal contents of 23 earthworms collected from our campus was significantly larger than that of the upper gastrointestinal content. The mean numbers of R. equi from the gastrointestinal contents of earthworms collected from the various places were 2·3-fold to 39·7-fold more than those of the surrounding soil samples. In all, 1771 isolates from the earthworms and 489 isolates from the soil samples were tested for the presence of vapA and vapB genes using polymerase chain reaction. At the horse-breeding farm N, 9 of the 109 isolates (8·3%) from the earthworms and 7 of the 106 isolates (6·6%) from the soil samples were positive for the vapA gene. At the University's forest, one of the 250 isolates (0·4%) from the gastrointestinal contents of the earthworm was positive for the vapB gene. These results revealed that R. equi can be found in significant quantities in the gastrointestinal contents of earthworms, suggesting that they act as an accumulator of R. equi in the soil environment and as a source or reservoir of animal infection.

Cellulitis-related Rhodococcus equi in a cat harboring VAPA-type plasmid pattern

Rhodococcus equi is a well-known intracellular facultative bacterium that is opportunistic in nature, and a contagious disease-causing agent of pyogranulomatous infections in humans and multihost animals. Feline rhodococcosis is an uncommon or unnoticed clinical condition, in which the organism is usually refractory to conventional antimicrobial therapy. The pathogenicity of the agent is intimately associated with plasmid-governed infectivity, which is attributed to the presence of plasmid-encoded virulence-associated proteins (Vap). Three host-adapted virulence plasmid types (VAPs) have been distinguished to date: pVAPA, pVAPB, and pVAPN, whose infections are related to equine, pig, and bovine or caprine origin, respectively, while humans are infected by all three VAP types. Most virulence studies with R. equi plasmid types in animals involve livestock species. Conversely, data on the pathogenicity and human relevance of the virulence plasmid profile of R. equi isolated from cats remains unclear. This report describes a case of cellulitis-related R. equi that harbors the pVAPA-type in a cat with cutaneous lesion. Long-term therapy of the cat using marbofloxacin, a broad-spectrum third-generation fluoroquinolone, resulted effectiveness. pVAPA is a host-adapted virulent type that has been associated predominantly with pulmonary foal infections. Our cat had a history of contact with other cats, livestock (including horses), and farm environment that could have favored the transmission of the pathogen. Besides no clear evidence of cat-to-humans transmission of the pathogen, the identification of R. equi harboring pVAPA-type in a cat with cutaneous abscessed lesion represent relevance in human health because this virulent type has been described in people worldwide with clinical rhodococcal disorders.

Rhodococcus equi-Occurrence in Goats and Clinical Case Report

Background: Rhodococcus equi infection is commonly known in equine medicine to cause frequently fatal rhodococcosis. Infections in other species and people are also reported. Clinical manifestation in goats is relatively similar to horses and humans, but data regarding bacterium prevalence are scarce. Thus, the study aimed to estimate the occurrence of R. equi in goats. Methods: During post mortem examination, submandibular, mediastinal, and mesenteric lymph nodes were collected. Standard methods were used for bacteria isolation and identification. Results: A total of 134 goats were examined, and 272 lymph node samples were collected. R. equi was isolated from four animals. All four isolates carried the choE gene, and one also had traA and pVAPN plasmid genes. Conclusions: To the authors’ best knowledge, this is the first report of R. equi occurrence and genetic diversity in goats. The results may help create a model for treating rhodococcosis in other animal species and assessing the role of meat contamination as a potential source of human infection. This research should be considered a pilot study for further application of the goat as a model of R. equi infection in horses and humans.

Uptake and replication in Acanthamoeba castellanii of a virulent (pVAPA-positive) strain of Rhodococcus equi and its isogenic, plasmid-cured strain

Rhodococcus equi is a soil saprophytic bacterium and intracellular pathogen that causes pneumonia in foals. Strains of R. equi that are virulent in foals contain a plasmid that encodes a virulence-associated protein A (VapA) necessary for replication in macrophages. Because other intracellular pathogens survive and replicate inside amoebae, we postulated that the VapA-bearing plasmid (pVAPA) confers a survival advantage for R. equi against environmental predators like amoebae. To test this hypothesis, we compared phagocytosis by and survival in Acanthamoeba castellanii of isogenic strains of pVAPA-positive and pVAPA-negative R. equi. Phagocytosis of the pVAPA-negative strain by A. castellanii was significantly (P < 0.0001) greater than the pVAPA-positive strain. Intracellular replication of the pVAPA-positive strain in A. castellanii was significantly (P < 0.0001) greater than the pVAPA-negative strain during both 48 h and 9 days. These results indicate that the presence of the VapA plasmid reduces uptake and aids replication of R. equi in A. castellanii.

Research Relevant Background Lesions and Conditions: Ferrets, Dogs, Swine, Sheep, and Goats

Animal models provide a valuable tool and resource for biomedical researchers as they investigate biological processes, disease pathogenesis, novel therapies, and toxicologic studies. Interpretation of animal model data requires knowledge not only of the processes/diseases being studied but also awareness of spontaneous conditions and background lesions in the model that can influence or even confound the study results. Species, breed/stock, sex, age, anatomy, physiology, diseases (noninfectious and infectious), and neoplastic processes are model features that can impact the results as well as study interpretation. Here, we review these features in several common laboratory animal species, including ferret, dog (beagle), pig, sheep, and goats.

Reinvestigation of the virulence of Rhodococcus equi isolates from patients with and without AIDS

Rhodococcus equi emerged as a zoonotic pathogen of human immunodeficiency virus-infected patients over the last three decades. Two virulence plasmid types of R. equi, pVAPA and pVAPB associated with equine and porcine isolates, have been recognized, and more recently, pVAPN, a novel host-associated virulence plasmid in R. equi, was found in bovine and caprine isolates. We reinvestigated 39 previously reported isolates of R. equi from patients with and without acquired immunodeficiency syndrome (AIDS) by detecting vapA, vapB and vapN using PCR and plasmid profiling. After excluding one isolate that could not be cultured from frozen storage, eight isolates carried a virulence plasmid encoding vapA (pVAPA), 10 carried a virulence plasmid encoding vapB (pVAPB), seven carried a virulence plasmid encoding vapN (pVAPN) and 13 were negative for those genes. Of the 29 isolates from patients with AIDS, 7, 10 and 5 harboured pVAPA, pVAPB and pVAPN respectively. Among nine isolates from patients without AIDS, one and two harboured pVAPA and pVAPN respectively. This study demonstrated that pVAPN-positive R. equi existed in human isolates before 1994 and reaffirmed that equine-associated pVAPA-positive, porcine-associated pVAPB-positive and bovine- or caprine-associated pVAPN-positive R. equi are widely spread globally. Because domestic animals might be major sources of human infection, further research is needed to reveal the prevalence of pVAPN-positive R. equi infection in cattle and goats.

Microbiological assessment of sheep lymph nodes with lymphadenitis found during post-mortem examination of slaughtered sheep: implications for veterinary-sanitary meat control

Background

Microbiological examination of lesions found in slaughtered animals during meat inspection is an important part of public health protection as such lesions may be due to zoonotic agents that can be transmitted by meat. Examination of inflamed lymph nodes also plays a particular important role, as lymphadenitis may reflect a more widespread infection. Such lesions in sheep are mainly caused by pyogenic bacteria but also mycobacteria are occasionally found. Meat inspection data from 2017 to 2018 from southern Poland, especially from the Małopolska region, indicate that purulent or caseous lymphadenitis involving the mediastinal and tracheobronchial lymph nodes (MTLNs) is a common finding. The primary aim of the current study was to determine the aetiology of these lesions. Furthermore, it was investigated how presence of lesions was correlated with age and grazing strategy of affected sheep.

Results

Post-mortem examination revealed purulent or caseous lymphadenitis in the MTLNs of 49 out of 284 animals (17.3%). Subsequent microbiological examination revealed the presence of Corynebacterium pseudotuberculosis (34.7%), Streptococcus dysgalactiae subsp. equisimilis (34.7%), Staphylococcus aureus (8.2%), Enterococcus spp. (2.0%), Trueperella pyogenes (2.0%), and β-haemolytic strains of Escherichia coli (2.0%). Mycobacterium spp. and Rhodococcus equi were not detected. In older sheep, the probability of the presence of purulent or caseous lymphadenitis was higher than in younger, and the risk was increasing by 1.5% with each month of life. Sheep grazing locally had 4.5-times greater risk of having purulent or caseous lymphadenitis than individuals summer grazing in the mountains.

Conclusion

The most common aetiological agents of purulent or caseous lymphadenitis in the MTLNs of sheep in the Małopolska region were C. pseudotuberculosis and S. dysgalactiae subsp. equisimilis. Particular attention during post-mortem examination should be paid to the carcasses of older sheep and sheep grazing on permanent pastures, as they seem more prone to develop purulent or caseous lymphadenitis.

Serological epidemiological surveillance for vapN-harboring Rhodococcus equi infection in goats

Rhodococcus equi causes suppurative pneumonia in foals aged 1-3 months; moreover, it has emerged as a pathogenic cause of zoonotic diseases. After the initial report of the ruminant-pathogenic factor VapN encoded by the novel virulence plasmid pVAPN, several reports have described ruminant infections caused by vapN-harboring R. equi. Herein, we conducted a serological epidemiological surveillance in goats at a breeding farm (Farm A) and characterized the vapN-harboring R. equi isolates from this farm. First, we established a simple screening enzyme-linked immunosorbent assay (ELISA) using recombinant glutathione S-transferase-tagged VapN as an immobilized antigen. This method revealed that the VapN antibody titers were elevated in 12 of 42 goats. Subsequently, we attempted to isolate R. equi from the goat feces and soil of Farm A. choE⁺/vapN⁺R. equi was isolated from the feces of Goat No. 27 and a soil sample near the shed. The pulsed-field gel electrophoresis (PFGE) patterns of five vapN-harboring R. equi strains isolated from Farm A in 2013 and 2019 were investigated and found to be the same except for the strain (OKI2019F1). However, no difference was observed in VapN expression and growth in macrophages among these vapN-harboring R. equi isolates. Our results revealed that some goats had histories of vapN-harboring R. equi infections, and two genomic types of vapN-harboring R. equi were found in isolates from Farm A. Ruminant-specific (pVAPN-carrying) R. equi might be an unrecognized pathogen in Japan and further studies are required to determine its prevalence and distribution.

Histoplasmosis and multicentric lymphoma in a Nubian goat

Following treatment for pneumonia, a 1-y-old female Nubian goat was presented because of a persistent fever for 3 mo and peripheral lymphadenopathy for 1 mo. Cytology and histology of the superficial cervical and prefemoral lymph nodes demonstrated a moderate-to-marked "left-shifted" lymphoid population, suggestive of lymphoma, and extremely rare extracellular, 2-4 µm, oval, basophilic yeast, consistent with Histoplasma capsulatum. On immunohistochemistry, >95% of the lymphocytes demonstrated positive cytoplasmic and membranous immunoreactivity for CD3. Histoplasma spp. urine antigen and serum antibody testing were positive and negative, respectively. Panfungal PCR and sequencing of DNA extracted from scrolls of formalin-fixed, paraffin-embedded tissue yielded matches to H. capsulatum with 99-100% identity. Given the poor prognosis and persistent pyrexia, the animal was euthanized. Postmortem examination confirmed concurrent multicentric, intermediate-size, T-cell, lymphoblastic lymphoma and histoplasmosis; lesions consistent with intestinal coccidiosis and suspected pulmonary Rhodococcus equi were also noted. Although dimorphic fungi have been described previously in goats, lesions of Histoplasma spp. had not been documented in this species, to our knowledge. Given the low disease burden, it is suspected that the lymphoma was primary, leading to an immunocompromised state and development of secondary, opportunistic infections.

Ulcerative, granulomatous glossitis and enteritis caused by Rhodococcus equi in a heifer

Rhodococcus equi infection in horses is common and is characterized by pyogranulomatous pneumonia and ulcerative enterocolitis. R. equi clinical disease in cattle, however, is rare and typically manifests as granulomatous lymphadenitis discovered in the abattoir. A 19-mo-old female Santa Gertrudis had a history of intermittent inappetence and weight loss for a 3-mo period before euthanasia. Gross and histologic examination revealed severe, chronic, ulcerative, and granulomatous inflammation in the tongue, pharynx, and small intestine. Also, the heifer had severe, granulomatous pharyngeal and mesenteric lymphadenitis. Bacterial cultures from the ileum, tongue, and liver yielded numerous-to-moderate numbers of R. equi. PCR analysis of the isolate detected the linear virulence plasmid vapN, which is often identified in bovine isolates (traA- and vapN-positive). The bacteria also lack the circular plasmids vapA and vapB that are associated with virulence in horses and swine, respectively. We report herein an atypical and unusual clinical presentation of R. equi infection in cattle, which has zoonotic potential.

Pyogranulomatous enteritis and mesenteric lymphadenitis in an adult llama caused by Rhodococcus equi carrying virulence-associated protein A gene

We report herein Rhodococcus equi infection in an 11-y-old, male llama with a history of diarrhea and endoparasitism. Postmortem examination revealed granulomatous and ulcerative enteritis, pyogranulomatous mesenteric lymphadenitis, fibrinosuppurative peritonitis, and granulomatous hepatitis. Intralesional macrophages were laden with gram-positive cocci. Bacteriology identified R. equi, and cultures tested positive for R. equi choE and vapA genes by PCR. This case expands the reported spectrum of lesions associated with R. equi infections in llamas from pyogranulomatous bronchopneumonia and peripheral lymphadenitis to pyogranulomatous mesenteric lymphadenitis and enteritis. We also link a R. equi that is carrying the virulent-associated protein gene VapA to clinical disease in New World camelids.

A case report on disseminated Rhodococcus equi infection in a Japanese black heifer

Rhodococcus equi was isolated from the granulomatous lesions of the lung, kidney, liver, and hepatic, mesenteric, and abomasum lymph nodes of a Japanese black heifer. R. equi isolates were analyzed by polymerase chain reaction for virulence-associated protein genes. The vapN gene was detected in all the isolates examined. This is the first report in which vapN-positive R. equi was isolated from cattle in Japan.