Neurologic melioidosis in an imported pigtail macaque (Macaca nemestrina)

Burkholderia pseudomallei is the cause of melioidosis in humans and other animals. Disease occurs predominately in Asia and Australia. It is rare in North America, and affected people and animals typically have a history of travel to (in human cases) or importation from (in animal cases) endemic areas. We describe the gross and histopathologic features and the microbiologic, molecular, and immunohistochemical diagnoses of a case of acute meningoencephalomyelitis and focal pneumonia caused by B. pseudomallei infection in a pigtail macaque that was imported from Indonesia to the United States for research purposes. This bacterium has been classified as a Tier 1 overlap select agent and toxin; therefore, recognition of pathologic features, along with accurate and timely confirmatory diagnostic testing, in naturally infected research animals is imperative to protect animals and personnel in the laboratory animal setting.

Bartonella henselae-mediated disease in solid organ transplant recipients: two pediatric cases and a literature review

Bartonella henselae, the etiologic agent of cat-scratch disease, causes a well-defined, self-limited syndrome of fever and regional lymphadenopathy in immunocompetent hosts. In immunocompromised hosts, however, B. henselae can cause severe disseminated disease and pathologic vasoproliferation known as bacillary angiomatosis (BA) or bacillary peliosis. BA was first recognized in patients infected with human immunodeficiency virus. It has become more frequently recognized in solid organ transplant (SOT) recipients, but reports of pediatric cases remain rare. Our review of the literature revealed only one previously reported case of BA in a pediatric SOT recipient. We herein present 2 pediatric cases, one of which is the first reported case of BA in a pediatric cardiac transplant recipient, to our knowledge. In addition, we review and summarize the literature pertaining to all cases of B. henselae-mediated disease in SOT recipients.

A potential role for indoleamine 2,3-dioxygenase (IDO) in Rhodococcus equi infection

Rhodococcus equi is a facultative intracellular bacterial pathogen of foals and immunocompromised humans that infects and proliferates within host macrophages and dendritic cells (DC). Indoleamine 2,3-dioxygenase (IDO), the initial enzyme in the tryptophan catabolism pathway, is upregulated in R. equi infected equine monocyte-derived DC and alveolar macrophages. Tryptophan requirement of R. equi for extracellular and intracellular growth was assessed. Growth of R. equi in minimal media did not require tryptophan and pharmacologic inhibition of IDO had no effect on intracellular proliferation of R. equi in equine alveolar macrophages. To investigate an immune-regulatory role for INDO in R. equi infection, IDO(-/-) (B6.129-(Indotm1Alm)/J) (n=22) and strain matched control (C57BL/6J) (n=20) mice were infected with R. equi by intraperitoneal injection, for 3 and 6 days. There was no difference in bacterial counts in liver or spleen between the two groups. Histological sections of liver and spleen were assigned inflammation scores and RT-PCR for interferon-gamma (IFNγ), tumor necrosis factor-alpha (TNFα), IL-4, IL-6, IL-10, IL-12, IL-23, forkhead box P3 (FoxP3), and transforming growth factor-beta (TGFβ) was performed on liver and spleen. Liver tissue of IDO(-/-) had higher inflammation scores at 6 days post-infection (PI) (P=0.05) and had decreased expression of TGFβ at 3 days PI (P=0.01), and FOXP3 at 3 days (P=0.02) and 6 days (P=0.03) compared to control mice. Immunostaining for FOXP3 showed lower numbers of FOXP3+ regulatory T cells in liver of IDO(-/-) mice 6 days PI. Prolonged inflammation in the liver tissue of IDO(-/-) mice corresponded with lower expression of FOXP3 and TGFβ in that tissue, and also with lower numbers of FOXP3+ regulatory T cells. We conclude that IDO expression by activated macrophages and DC plays a role in dampening the inflammatory response to R. equi infection in mice.

Idiopathic chronic eosinophilic pneumonia in 7 horses

BACKGROUND

Idiopathic chronic eosinophilic pneumonia of horses is incompletely described.

OBJECTIVES

To describe the physical examination, clinicopathologic, histopathologic, and radiographic features and response to corticosteroid treatment of idiopathic chronic eosinophilic pneumonia of horses.

ANIMALS

Seven horses with eosinophilic pneumonia.

METHODS

Retrospective, descriptive study.

RESULTS

Anamnesis, clinical signs, and clinicopathologic and radiologic findings in 7 adult horses with histologically confirmed eosinophilic pneumonia were reviewed. The horses were examined for signs of chronic respiratory disease. The horses ranged in age from 8 to 20 years. Significant findings on physical examination included tachypnea and abnormal respiratory sounds. Thoracic radiography revealed severe diffuse interstitial patterns of increased pulmonary density in all horses. There was a predominance of eosinophils in bronchoalveolar lavage fluid (BALF), and 6 of 7 horses had peripheral blood eosinophilia. Lung biopsies revealed eosinophilic infiltrates in all horses. Dexamethasone was administered to 3 horses and resulted in short-term clinical improvement in all three.

CONCLUSIONS AND CLINICAL IMPORTANCE

A diagnosis of idiopathic eosinophilic pneumonia should be considered in horses with a history of chronic pulmonary disease, diffuse interstitial pattern of increased pulmonary density on thoracic radiographs, and a predominance of eosinophils in BALF. Horses with this condition may show a temporary response to treatment with dexamethasone.

Characterization of histone H3/H4 gene region and phylogenetic affinity of Ichthyophthirius multifiliis based on H4 DNA sequence variation

We sequenced the amino-terminal third of the histone H3 and H4 genes and the intergenic region from Ichthyophthirius multifiliis. Fourteen recombinant clones of 646 bp were sequenced and the level of sequence variation detected among these clones was similar to that reported among closely related species of Tetrahymena and to levels of sequence variation detected within other ciliates. The intergenic region is 417 bp and approximately 92% AT rich, making it the longest and most AT-rich ciliate H3/H4 intergenic region yet identified. Similar to Tetrahymena, the intergenic region of Ichthyophthirius contains two CCAAT regions arranged in a complementary orientation. A neighbor-joining tree was constructed based on nucleotide sequence variation among H4 genes to evaluate evolutionary relationships within and among six classes of Ciliophora. The single shortest neighbor-joining tree depicted a sister-group relationship of Ichthyophthirius with taxa of Tetrahymenina, thereby supporting monophyly of Oligohymenophorea.