Amy M. Grooters

Pythiosis, lagenidiosis, and zygomycosis in small animals

Pythiosis, lagenidiosis, and zygomycosis affect animals living in temperate, tropical, and subtropical climates, and these diseases are often fatal. Although Pythium insidiosum, Conidiobolus species, and Basidiobolus species have been recognized as pathogens for several years, members of the genus Lagenidium have been identified as a cause of oomycosis in dogs only recently. Pythiosis, lagenidiosis, and zygomycosis share similar clinical and histologic characteristics, making them difficult to distinguish from one another; however, distinguishing between these pathogens is important because of differences in epidemiology, choice and duration of therapy, and prognosis.

Gastrointestinal Pythiosis in 10 Dogs from California

BACKGROUND Pythium insidiosum is an aquatic oomycete that causes severe segmental thickening of the canine gastrointestinal (GI) tract, resulting in weight loss, vomiting, diarrhea, and death. Infection in dogs previously has been observed primarily in the southeastern United States. OBJECTIVE To describe the clinicopathologic and epidemiologic findings associated with GI pythiosis in 10 dogs from California. METHODS Dogs were initially identified on the basis of supportive clinical findings and routine histology. Pythiosis was confirmed in each dog with at least one of the following: immunoblot serology, enzyme-linked immunosorbent assay serology, immunohistochemistry, and culture followed by species-specific polymerase chain reaction, rRNA gene sequencing, or both. RESULTS Between September 2003 and December 2006, GI pythiosis was confirmed in 1 dog from central California and 9 dogs that lived within a 30-mile radius of Davis, CA. Seven of 8 dogs for which environmental data were available had frequent access to flooded rice fields or other water sources. Esophageal lesions were present in 2 of 10 dogs. Common laboratory findings included eosinophilia (7/9), hypoalbuminemia (9/9), and hyperglobulinemia (8/9). Median survival time was 26.5 days (range, 0-122 days), and the disease was ultimately fatal in all 10 dogs. CONCLUSIONS AND CLINICAL IMPORTANCE The geographic distribution of pythiosis has widened in recent years to include the western United States. Factors that may have contributed to this change include altered rice-farming practices and landscape irrigation. Veterinarians in California should be familiar with the clinicopathologic features associated with GI pythiosis to aid in early diagnosis and effective treatment.

Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

The purpose of this study was to evaluate the effects of sample handling, storage, and culture techniques on the isolation of Pythium insidiosum from infected equine tissues. Tissue and kunker samples obtained immediately posteuthanasia from a horse with subcutaneous pythiosis were used to assess the effects of sample type (kunkers vs. tissues), media type (selective vs. nonselective), storage technique, and storage time on P. insidiosum isolation rate. Overall, isolation rates were higher from fresh kunkers (94.6%) and stored kunkers (76.4%) than from fresh tissues (8.3%) or stored tissues (4.6%). Isolation of P. insidiosum also occurred more often on antibiotic-containing media than on nonselective media for both fresh and stored samples. For samples that were stored for 1–3 days prior to culture, P. insidiosum isolation rates were highest for the following techniques: kunkers stored at room temperature and plated on selective media (100%), kunkers stored at 4 C and then plated on either nonselective (91.7%) or selective (95.8%) media, kunkers stored on cold packs and then plated on either nonselective (93.8%) or selective (100%) media, kunkers stored in ampicillin solution and plated on selective media (100%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). For samples stored for 4–5 days, P. insidiosum isolation rates were highest for kunkers stored at 4 C and then plated on either nonselective (81.3%) or selective (87.5%) media, kunkers stored in ampicillin solution and then plated on selective media (87.5%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). Results of this study suggest that optimal isolation rates of P. insidiosum from infected equine tissues are achieved by culturing fresh kunkers on selective media. For samples that cannot be processed immediately, acceptable handling techniques include storage at room temperature for up to 3 days, refrigeration for up to 5 days, shipping on cold packs, and storage in antibiotic solution, each combined with subsequent inoculation on selective media.

Exophiala oligosperma Causing Olecranon Bursitis

ABSTRACT A 62-year-old male with a history of Wegeners granulomatosis and immunosuppressive therapy presented with chronic olecranon bursitis. A black velvety mould with brown septate hyphae and tapered annellides was isolated from a left elbow bursa aspirate and was identified as an Exophiala species. Internal transcribed sequence rRNA sequencing showed the isolate to be identical to Exophiala oligosperma. The patient was successfully treated with aspiration and intrabursal amphotericin B.

Identification of Exophiala mesophila isolated from treated dental unit waterlines.

ABSTRACT Members of the genus Exophiala are often difficult to identify to the species level because of their variable morphological appearances. This paper describes the methods used to identify Exophiala mesophila and provides salient differential features for distinguishing other mesophilic members of the genus.

Granulomatous pneumonia caused by Pythium insidiosum in a central American jaguar, Panthera onca.

A 7-month-old, male jaguar presented with dyspnea and leukocytosis unresponsive to antibiotic therapy. Radiographs revealed unilateral pulmonary consolidation. An exploratory thoracotomy was performed, and the left lung, which contained a large multilobular mass with extensive fibrosis and numerous caseonecrotic foci, was removed. Microscopically, eosinophilic granulomatous inflammation surrounded broad (4.4–8.3 μm) rarely septate hyphae. A diagnosis of Pythium insidiosum infection was confirmed by immunohistochemistry, immunoblot serology, culture, and polymerase chain reaction. Dyspnea recurred despite treatment, and the animal succumbed 3 weeks after surgery. Necropsy findings indicated that death resulted from occlusion of the right main stem bronchus by a fungal granuloma. The oomycete P. insidiosum typically causes granulomatous disease of the skin or gastrointestinal tract in animals and arteritis, keratitis, or cellulitis in humans. Infection is uncommon in felines, and pulmonary involvement is rare. This report details the first case of P. insidiosum infection in an exotic felid and provides the first description of primary pulmonary pythiosis in any species.

Assessment of exposure to Leptospira serovars in veterinary staff and dog owners in contact with infected dogs

OBJECTIVE To assess patterns of seroreactivity to Leptospira serovars in veterinary professional staff and dog owners exposed to dogs with acute leptospirosis and to contrast these patterns in people with those observed in dogs. DESIGN Cross-sectional study. SAMPLE POPULATION Human subjects consisted of 91 people (50 veterinarians, 19 technical staff, 9 administrative personnel, and 13 dog owners) exposed to dogs with leptospirosis. Canine subjects consisted of 52 dogs with naturally occurring leptospirosis admitted to the University of Bern Vetsuisse Faculty Small Animal Clinic in 2007 and 2008. PROCEDURES People were tested for seroreactivity to regionally prevalent Leptospira serovars by use of a complement fixation test. A questionnaire designed to identify risk factors associated with seropositivity was used to collect demographic information from each study participant. Dogs were tested for seroreactivity to Leptospira serovars by use of a microscopic agglutination test. RESULTS On the basis of microscopic agglutination test results, infected dogs were seropositive for antibodies against Leptospira serovars as follows (in descending order): Bratislava (43/52 [83%]), Australis (43/52 [83%]), Grippotyphosa (18/52 [35%]), Pomona (12/52 [23%]), Autumnalis (6/52 [12%]), Icterohemorrhagiae (4/52 [8%]), Tarassovi (2/52 [4%]), and Canicola (1/52 [2%]). All 91 people were seronegative for antibodies against Leptospira serovars. Therefore, statistical evaluation of risk factors and comparison of patterns of seroreactivity to Leptospira serovars between human and canine subjects were limited to theoretical risks. CONCLUSIONS AND CLINICAL RELEVANCE Seroreactivity to Leptospira serovars among veterinary staff adhering to standard hygiene protocols and pet owners exposed to dogs with acute leptospirosis was uncommon.

Successful management of gastrointestinal pythiosis in a dog using itraconazole, terbinafine, and mefenoxam

Medical therapy for pythiosis is hampered by a lack of efficacious drugs. The present report describes a case of canine gastrointestinal pythiosis in which lesions were resolved through the administration of itraconazole, terbinafine, and the agricultural fungicide mefenoxam. No substantial adverse effects occurred in association with administration of the latter compound. Additional studies are needed to evaluate the pharmacokinetics of mefenoxam and to further assess its tolerability and potential efficacy for the treatment of pythiosis in dogs.

Hypercalcemia associated with gastric pythiosis in a dog.

A 20-month-old castrated male Labrador Retriever with a 3-month history of anorexia, weight loss, and vomiting was evaluated. Plasma biochemical abnormalities included marked hyperglobulinemia and hypercalcemia. Serum levels of parathyroid hormone, parathyroid hormone-related protein, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were either low or within reference intervals. Gastric wall thickening and abdominal lymphadenomegaly were observed with abdominal ultrasonography. Cytologic evaluation of a sample obtained via fine-needle aspiration of the gastric wall revealed pyogranulomatous inflammation and numerous poorly stained hyphae. Partial gastrectomy was performed, and a diagnosis of gastric pythiosis was made by immunohistochemical staining of infected gastric tissue, as well as by immunoblot serology. This case demonstrates that diagnostic samples for cytologic evaluation can be obtained by fine-needle aspiration of Pythium insidiosum-infected tissues and that a presumptive diagnosis can be made by examination of a Romanowsky-stained smear. Furthermore, pythiosis should be considered as a differential diagnosis for hypercalcemia, especially in young dogs with inflammatory lesions that have a granulomatous component. The mechanism for the hypercalcemia in this dog was not determined; however, calcium concentrations normalized after surgical resection of the gastric lesion.

Ulcerative Mycosis Caused by Aphanomyces invadans in Channel Catfish, Black Bullhead, and Bluegill from Southeastern Louisiana

Abstract Eight cases of chronic ulcerative mycosis affecting populations of channel catfish Ictalurus punctatus, black bullhead Ameiurus melas, and bluegill Lepomis macrochirus cultured in recreational fishing ponds were submitted to the Louisiana Aquatic Diagnostic Laboratory between April 2000 and January 2002. Diseased clinical specimens presented with multiple foci of skin ulceration, typically overlying more extensive areas of granulomatous myositis that extended to the vertebral column in advanced cases. Lesions were predominated by fields of plump macrophages and multinucleated giant cells surrounding nonseptate, thick-walled hyphae with nonparallel cell walls suggestive of an oomycete. Because deep ulcerative mycoses in other fish species in the western Atlantic (USA), Australia, and Southeast Asia have been attributed to Aphanomyces spp., diagnostic methods were employed to isolate and identify this oomycete along with other potential pathogens. The organism was isolated from sites deep in the mu...