Update on antifungal therapy

Feline cutaneous nodular and ocular Cryptococcus neoformans in Belgium

Case summary

An 11-year-old spayed female cat presented with a 6-month history of a progressive nodular skin disease with concurrent, ocular lesions, intermittent vomiting, halitosis and weight loss. The cat had received different topical treatments without success prior to referral to the Dermatology Department of Faculty of Veterinary Medicine, Ghent University. Several fine-needle aspirations of the lesions showed a vast number of macrophages with intra-cytoplasmic inclusions compatible with Cryptococcus species. Histopathological examination revealed pyogranulomatous inflammation with capsulated yeast. Periodic acid–Schiff stain was positive. Latex cryptococcal antigen agglutination test on serum was positive with a titre of >1/524,288. PCR and fungal culture identified Cryptococcus neoformans. The cat was treated with itraconazole 10 mg/kg PO q24h. After 10 months of therapy, there was a complete resolution of the lesions except for a small nodule on the ventral aspect of the tongue.

Relevance and novel information

As far as we are aware, this is the first feline case reported of cutaneous nodular cryptococcosis without nasal involvement in Belgium. Oral itraconazole therapy was well tolerated and appeared to give a good result and prognosis.

Equine Pulmonary Cryptococcosis: A Comparative Literature Review and Evaluation of Fluconazole Monotherapy

Cryptococcus is the most common fungal respiratory pathogen in Australian horses, manifesting primarily as pulmonary granulomas. Disease severity at presentation is dependent on the athletic use of the horse. The diagnosis and estimation of disease severity are centred around clinical findings, cytological evaluation of respiratory tract secretions, diagnostic imaging, and antigen titre testing. Both the lateral flow assay and the latex cryptococcal antigen titre are used, and important similarities and differences between species are discussed. Cryptococcus gattii occurs with greater frequency than Cryptococcus neoformans in equine pulmonic cryptococcosis and can be successfully treated with enteral fluconazole monotherapy, with disease severity determining treatment length.

Successful management of an intracranial phaeohyphomycotic fungal granuloma in a dog

CASE DESCRIPTION

A 12-month-old castrated male Boxer was examined because of signs of acute, progressive intracranial disease.

CLINICAL FINDINGS

Cytologic and histologic findings were consistent with an intracranial fungal granuloma in the right cerebral hemisphere. Fungal culture yielded a Cladophialophora sp.

TREATMENT AND OUTCOME

The granuloma was surgically debulked to remove infected brain tissue and the avascular purulent core. Postoperatively, the patient was treated with fluconazole (2.3 mg/kg [1 mg/lb], PO, q 12 h) for 4 months, followed by voriconazole (3.4 mg/kg [1.5 mg/lb], PO, q 12 h) for a further 10 months. The outcome was considered excellent on the basis of resolution of neurologic signs and a lack of evidence of recurrence of the granuloma during magnetic resonance imaging and CSF analysis 8 months after surgery. Magnetic resonance imaging and CSF analysis 9 weeks after administration of antifungal medications was discontinued (16 months after surgery) confirmed resolution.

CLINICAL RELEVANCE

Intracranial phaeohyphomycosis in small animals is rare and is most commonly associated with Cladophialophora infection. Phaeohyphomycosis frequently causes a focal granuloma, whereas other fungal infections typically cause diffuse meningoencephalitis. In all previous reports of phaeohyphomycosis of the CNS in dogs, treatment has been limited to medical management with conventional antifungal drugs and had failed to prevent death. The present report suggested that combined management of granulomas with surgery and newer triazole medications such as voriconazole may represent a novel strategy that improves the prognosis for this disease.

Terbinafine pharmacokinetics after single dose oral administration in the dog

Terbinafine is an allylamine antifungal prescribed for the treatment of mycoses in humans. It is increasingly being used in veterinary patients. The purpose of this study was to evaluate the pharmacokinetic properties of terbinafine in dogs after a single oral dose. Ten healthy adult dogs were included in the study. A single dose of terbinafine (30-35 mg/kg) was administered orally, and blood samples were periodically collected over a 24 h period during which dogs were monitored for adverse effects. Two of 10 dogs developed transient ocular changes. A high-performance liquid chromatography assay was developed and used to determine plasma terbinafine concentrations. Pharmacokinetic analysis was performed using PK Solutions(®) computer software. Area under the curve (AUC) from time 0 to 24 h was 15.4 μg·h/mL (range 5-27), maximal plasma concentration (C(max) ) was 3.5 μg/mL (range 3-4.9 μg/mL) and time to C(max) (T(max) ) was 3.6 h (range 2-6 h). The time above minimal inhibitory concentration (T > MIC) as well as AUC/MIC was calculated for important invasive fungal pathogens and dermatophytes. The T > MIC was 17-18 h for Blastomyces dermatitidis, Histoplasma capsulatum and dermatophytes (Microsporum spp. and Trichophyton mentagrophytes), while the MIC for Sporothrix schenckii and Coccidioides immitis was exceeded for 9.5-11 h. The AUC/MIC values ranged from 9 to 13 μg h/mL for these fungi. Our results provide evidence supporting the use of terbinafine as an oral therapeutic agent for treating systemic and subcutaneous mycoses in dogs.

Patellar blastomycosis in a dog

A 4-year-old, spayed female, mixed-breed dog was presented for evaluation of chronic left hind-limb lameness. Lytic lesions were observed in the left patella on radiographs of the stifle. A biopsy of the patella led to a histopathological diagnosis of blastomycosis. Surgical debridement followed by a 90-day course of itraconazole and physical rehabilitation resolved the clinical signs and stopped the progression of radiographic lesions. Blastomycosis should be considered as a differential diagnosis for stifle joint lameness with lytic lesions in the patella.

Effect of multiple oral dosing of fluconazole on the pharmacokinetics of cyclosporine in healthy beagles

Fluconazole (Fcz) is successfully used in human organ transplant patients as an antifungal therapy. However, Fcz can increase the cyclosporine (CsA) trough level and lead to CsA nephrotoxicity. In canine renal transplantation, CsA has been used as a major immunosuppressant, and it is important to control its trough level. However, the interaction of Fcz with CsA has not yet been reported in dogs. In this study, the effect of Fcz treatment on the pharmacokinetics of CsA in four healthy beagles was investigated using a four-period crossover design. The treatments included CsA alone (A), CsA + multiple-dose Fcz 50 mg (B), CsA + multiple-dose Fcz 25 mg (C) and CsA + single-dose Fcz 50 mg (D). Blood CsA concentrations were measured at 0.5, 1, 2, 4, 6, 8, 10, 12 and 24 hr after CsA administration. The AUC(0-12) and C(max) values for treatment B were significantly higher than those for the other treatments. In particular, the AUC(0-12) of treatment B was about two times higher than that of treatment A. Fcz administration did not significantly prolong the half-life or mean residence time of CsA. The results of our study show that administration of multiple therapeutic doses of Fcz can significantly increase the CsA blood concentration, which might partially depend upon the Fcz blood concentration. When Fcz is used in CsA-based canine renal transplantation, it may be necessary to adjust the CsA trough level by decreasing the dose.

Visual outcome in a group of dogs with ocular blastomycosis treated with systemic antifungals and systemic corticosteroids

OBJECTIVE

To evaluate the success of the use of systemic corticosteroids and antifungal medications in the treatment of dogs with ocular lesions associated with systemic blastomycosis.

DESIGN

Retrospective study.

ANIMALS STUDIED

Medical records of 25 dogs diagnosed with blastomycosis, via either cytology or histopathology, at the Purdue University Veterinary Teaching Hospital between 1 January 2000 and 1 January 2005, were reviewed.

PROCEDURE

Data collected from the medical records included signalment, presence and progression of ocular lesions, antifungal drugs administered, oral and topical corticosteroid administration, length of follow-up, response to treatment, and visual outcome.

RESULTS

Of the 25 cases reviewed, 12 dogs (19 eyes) with follow-up information were found to have lesions consistent with ocular blastomycosis. Length of follow-up in the 12 cases ranged from 1 month to 31 months with a mean of 9 months. Antifungal therapy for all cases consisted of oral itraconazole (5 mg/kg every 24 h) initially. In seven cases, the antifungal drug administered was changed from itraconazole to oral fluconazole. Two of these also received intravenous amphotericin B, and two received additional treatment with itraconazole. All 12 dogs also received oral prednisone. The dose of oral prednisone utilized ranged from 0.2 mg/kg/day to 1.4 mg/kg/day with a mean of 0.7 mg/kg/day; the duration of oral prednisone administration ranged from 2 weeks to 8.5 months with a mean of 3 months. Topical prednisolone was a component of the treatment of 16 of the 19 eyes. Duration of topical prednisolone treatment ranged from 1 month to 30 months with a mean of 5 months. Lesions not located in the eyes exhibited a positive response to treatment in 11 (92%) of the 12 dogs. Overall, 14/19 (74%) affected eyes were visual at the time of their final recheck. All eyes with mild or moderate lesions and 5/10 (50%) severely affected eyes were visual at their last recorded recheck examination.

CONCLUSIONS

The administration of systemic corticosteroids did not appear to adversely affect the survival rate and might have played a role in preservation of vision in a majority of dogs in this group with ocular blastomycosis.

Management of bilateral uveitis in a Toxoplasma gondii-seropositive cat with histopathologic evidence of fungal panuveitis

A 5‐year‐old, neutered male Domestic Short‐haired cat was referred with a 5‐month history of anterior uveitis and cataract in the right eye. Clinical examination confirmed anterior uveitis and immature cataract in the right eye and chorioretinitis in the left eye. Ocular ultrasound showed a retinal detachment in the right eye. Diagnostic testing revealed elevated serum titers for Toxoplasma gondii. Anterior uveitis in the right eye and chorioretinitis in the left eye progressed, resulting in blindness despite a 21‐day course of clindamycin and aggressive topical medical management of uveitis. The right eye was enucleated and histopathologic evaluation of the globe revealed panuveitis and multiple organisms morphologically consistent with Histoplasma capsulatum. Systemic treatment with itraconazole was initiated. Vision returned after 3 months of treatment and complete resolution of the retinal hemorrhages with formation of a flat chorioretinal scar was noted after 6 months of therapy. Itraconazole was discontinued 7 months after starting therapy, at which time the funduscopic appearance of the chorioretinal scar had remained static for 1 month. The cat has remained visual without evidence of disease progression for 6 months following discontinuation of itraconazole.

Treatment of thoracolumbar spinal cord compression associated withHistoplasma capsulatuminfection in a cat

CASE DESCRIPTION

A 7-year-old domestic shorthair cat with a 2-month history of decreased appetite and weight loss was examined because of paraparesis of 1 week's duration that had progressed to paraplegia 3 days earlier.

CLINICAL FINDINGS

Neurologic examination revealed normo- to hyperreflexia and absence of deep pain sensation in the hind limbs and thoracolumbar spinal hyperesthesia. Neuro-anatomically, the lesion was located within the T3 through L3 spinal cord segments. Biochemical analysis and cytologic examination of CSF revealed no abnormalities. Radiography revealed narrowing of the T11-12 intervertebral disk space and intervertebral foramen suggestive of intervertebral disk disease. Myelography revealed an extradural mass centered at the T12-13 intervertebral disk space with extension over the dorsal surfaces of T11-13 and L1 vertebral bodies.

TREATMENT AND OUTCOME

A right-sided hemilaminectomy was performed over the T11-12, T12-13, and T13-L1 intervertebral disk spaces, and a space-occupying mass was revealed. Aerobic bacterial culture of samples of the mass yielded growth of a yeast organism after a 10-day incubation period; histologically, Histoplasma capsulatum was identified. Treatment with itraconazole was initiated. Nineteen days after surgery, superficial pain sensation and voluntary motor function were evident in both hind limbs. After approximately 3.5 months, the cat was ambulatory with sling assistance and had regained some ability to urinate voluntarily.

CLINICAL RELEVANCE

In cats with myelopathies that have no overt evidence of fungal dissemination, differential diagnoses should include CNS histoplasmosis. Although prognosis associated with fungal infections of the CNS is generally guarded, treatment is warranted and may have a positive outcome.

Systemic infection with Geomyces organisms in a dog with lytic bone lesions

CASE DESCRIPTION

A 5-year-old neutered male mixed-breed dog was evaluated by a veterinarian because of a 4-week history of progressive lethargy and poor appetite; the dog was then examined at a referral hospital.

CLINICAL FINDINGS

Hyperglobulinemia was identified via serum biochemical analyses performed before and after arrival at the hospital. Lysis of sternebrae 1 and 2 and sternal lymphadenopathy were detected radiographically. Fine-needle aspirates were collected from the affected sternebrae and lymph node for cytologic examination; findings were consistent with pyogranulomatous inflammation associated with fungal infiltrates. Geomyces organisms were identified via microbial culture of sternebral aspirates.

TREATMENT AND OUTCOME

Treatment consisted of oral administration of itraconazole. After 6 months, remodeling of the affected sternebrae and resolution of sternebral lysis were evident radiographically. Geomyces organisms and pyogranulomatous infiltrates persisted despite clinical improvement. Treatment with itraconazole was continued for an additional 3 months.

CLINICAL RELEVANCE

Infection with Geomyces organisms is typically localized to the skin and nail beds. In the dog of this report, systemic dissemination of Geomyces organisms resulted in lysis of the first 2 sternebrae. Cytologic examination of fine-needle aspirates and microbial culture of samples of the affected sternebrae were important diagnostic tests for successful identification of the organism. Despite 6 months of itraconazole administration and evidence of clinical improvement, fungal organisms persisted in the dog's affected sternebrae. Practitioners should include Geomyces infection among the differential diagnoses for suspected systemic mycosis and should perform cytologic examination and microbial culture of affected tissue throughout treatment of affected dogs.

Use of Posaconazole in the Management of Invasive Orbital Aspergillosis in a Cat

Orbital infection with Aspergillus fumigatus was diagnosed in a Persian cat that was presented with chronic third eyelid protrusion and exophthalmos. Evidence of nasal, sinus, or disseminated aspergillosis was not detected in this cat. Complete surgical excision of diseased tissues was not possible during orbital exenteration, and infection subsequently extended into the tissues of the oral cavity. Oral therapy with itraconazole and parenteral therapy with amphotericin B were ineffective in resolving the infection. Oral therapy with a novel triazole, posaconazole, was curative.

Fungal Infections of the Central Nervous System in the Dog and Cat

Fungal infections of the central nervous system (CNS) in dogs and cats are uncommon. The purpose of this paper is to review the clinical signs, diagnostic tests, and therapeutic options of fungal infections of the CNS in the dog and cat. Clinical signs are dependent on lesion location and are often multifocal. Extraneural involvement is common. Antemortem diagnosis can be difficult and is definitively made via cytology, biopsy, or culture of an affected organ or cerebrospinal fluid (CSF). Magnetic resonance imaging can support a diagnosis and may assist in therapeutic decisions. Fungal serology can support a diagnosis when direct visualization of the organism is not possible. Long-term azole maintenance therapy is suggested to enhance survival and prevent relapse. Serial cerebrospinal fluid evaluation and magnetic resonance imaging may identify early relapse.

Histoplasmose cutânea em gato: relato de caso

Descreve-se um caso de histoplasmose cutânea em um gato, da raça Siamesa, com três anos de idade. O animal apresentava crescimento de aspecto esponjoso, sangüinolento, com secreção purulenta na região nasal, cuja evolução ocorreu em cerca de dois meses. O exame citológico revelou presença de Histoplasma capsulatum. O animal foi tratado com cetoconazol durante 20 dias, ocorrendo remissão completa dos sintomas.