Severe meningoencephalitis secondary to calvarial invasion of <i>Lagenidium giganteum</i> forma <i>caninum</i> in a dog

Abstract

Background: The oomycete Lagenidium giganteum forma caninum is an uncommon cause of severe dermal and subcutaneous infections in dogs with possible vascular invasion and other fatal sequelae. Infection within the central nervous system of affected dogs has not been previously reported.Case Description: A 6-year-old spayed female mixed-breed dog was evaluated at a referral institution with a 2-month history of suspected fungal infection in the region of the right mandibular lymph node that was refractory to surgical resection and empiric medical therapy. Physical examination identified a 6-cm fluctuant subcutaneous mass caudoventral to the ramus of the right mandible and a second firm mass in the region of the right caudal maxilla. Lesional punch biopsies were submitted for fungal culture and polymerase chain reaction (PCR), which subsequentlyidentified L. giganteum forma caninum infection. Initial treatment consisted of anti-inflammatory doses of prednisone and hyperbaric oxygen therapy. Four weeks following initial evaluation, the patient was presented with progressive neurological signs consistent with a forebrain lesion. Magnetic resonance imaging revealed soft-tissue, contrastenhancing lesions ventral to the calvarium adjacent to the site of original surgical resection and throughout the brain. Humane euthanasia was elected, and postmortem examination was consistent with the extension of local disease from the right masseter muscle into the right ventral calvarium. Postmortem DNA sequencing confirmed the identity of the organism as L. giganteum forma caninum.Conclusion: This is the first reported case of intracranial lagenidiosis in the dog. PCR distinguished this species from other Lagenidium species and from oomycetes of other genera, such as Pythium insidiosum and Paralagenidium karlingii. Regional extension of cutaneous lagenidiosis should therefore be considered in cases with concurrent or spontaneous neurologic disease.&#x0D; Keywords: Hyperbaric oxygen therapy, Lagenidium giganteum forma caninum, Neurologic disease, Oomycete.

Geographic distribution of Pythium insidiosum infections in the United States

“…These pathogenic oomycetes cannot reliably be distinguished from P insidiosum in histopathological preparations. [25][26][27][28] Based on reports of pythiosis cases in the US in several species and this study, the southern states, particularly Alabama, Florida, Louisiana, Mississippi, and Texas, are heavy endemic areas of P insidiosum, with sporadic cases in adjoining states. 1,4,6,12,[14][15][16][17][18][19][20][21][22][23]25,28,29 However, based on the cases diagnosed in our laboratories, the distribution of the disease within each state did not always involve the entire state.…”

“…[25][26][27][28] Based on reports of pythiosis cases in the US in several species and this study, the southern states, particularly Alabama, Florida, Louisiana, Mississippi, and Texas, are heavy endemic areas of P insidiosum, with sporadic cases in adjoining states. 1,4,6,12,[14][15][16][17][18][19][20][21][22][23]25,28,29 However, based on the cases diagnosed in our laboratories, the distribution of the disease within each state did not always involve the entire state. Texas is a prime example since no cases were diagnosed west of longitude 100°W, where the state is considerably more arid.…”

“…It is important to mention 2 additional emerging mammalian oomycetes, Lagenidium giganteum and Paralagenidium spp. [25][26][27][28] These pathogens also infect the skin and intestinal tract of affected dogs where eosinophilic granulomas developed, thus mimicking the clinical features of pythiosis, potentially delaying accurate diagnosis. These pathogenic oomycetes cannot reliably be distinguished from P insidiosum in histopathological preparations.…”

Cutaneous Lagenidium deciduum infection in a patient with relapsed acute myeloid leukemia

“…In a subsequent case report, a dog presented with a mandibular mass secondary to Lagenidium giganteum forma caninum infection . Despite surgical resection, itraconazole, prednisone and hyperbaric oxygen therapy, the mass invaded the calvaria and caused severe meningoencephalitis [ 20 ].…”

Hyperbaric Oxygen Therapy in Systemic Inflammatory Response Syndrome

“…By promoting the release of VEGF, HBOT increases capillary permeability and endothelial NO synthase, and has antioxidant and endothelial integrity control properties, which are essential for treatment of sepsis or multiorgan failure predisposition situations with tissue ischemia involvement [25]. This was pointed out by Shmalberg et al (2020) [26], when describing the case of a dog with Lagenidium giganteum, which caused diffuse inflammation, vascular thrombosis, and secondary ischemia in several parts of the brain.…”