Cerebral Candida albicans Infection in Two dogs

Abstract

Background: Candida spp. are pleomorphic fungi that are commensal inhabitants of the oral, gastrointestinal, upper respiratory and urogenital mucosa of mammals. Candida albicans is described as the most important species. This opportunistic pathogen may produce local or systemic infections in dogs. Local infections have been reported in several tissues and systemic infection is rare in dogs with few reports in the literature describing this presentation. The aim of the present study was to report two cases of cerebral Candida albicans infection in dogs in Brazil.Case: Two cases of cerebral Candida albicans infection in dogs that showed nervous signs are described. In both cases, the brain showed marked asymmetry of the telencephalic hemispheres with multifocal to coalescing yellowish or reddish areas and a partial loss of distinction between gray and white matter. In Case 1, the mediastinal, tracheobronchial and mesenteric lymph nodes, as well as the right kidney and adrenal gland, showed altered architecture due to numerous whitish gray nodules. Histological lesions were characterized by granulomatous (case 1) or pyogranulomatous (case 2) necrotizing meningoencephalitis with intralesional fungal organisms. In case 1, similar granulomatous infiltrate with intralesional fungal organisms was also seen in the lymph nodes, kidney and adrenal gland. In case 2, there was evidence consistent with an underlying infection of canine distemper virus. Were observed lymphoplasmocytic interstitial pneumonia, lymphoid rarefaction in lymph nodes, and viral intracytoplasmic inclusion bodies in the epithelial cells of the stomach and vesical urothelium. In these two cases, the fungal organisms displayed three different morphological patterns. The first pattern was characterized by delicate tubular structures with thin parallel walls that were rarely septate and tended to undulate slightly, and measured approximately 4-20 µm (true hyphae). The second pattern was characterized by chains of elongated yeast, separated by constrictions at septal sites, and measured approximately 4-10 µm (pseudohyphae). The other morphological pattern, which was rarely observed, was characterized by round budding yeast cells that measured 3-4 µm in diameter and were often elongated by the germ tube. Sections were also stained using immunohistochemical antibodies against Candida albicans. The fungi revealed strong immunolabelling of the cytoplasm and wall for Candida albicans.Discussion: The diagnosis was based on the histomorphological and immunohistochemical characteristics of the agent, which were consistent with Candida albicans. In these two cases, immunocompromise appeared to have been an important factor in the progression of the infection. In case 1, the dog was senile and treated with corticosteroids, conditions that could effectively limit innate, humoral and cell-mediated immune response to infection. In case 2, the dog displayed cachexia and was infected by canine distemper virus, evidenced by the presence of viral inclusion bodies. The inflammatory reactions in both cases were characteristic of fungal infections, but were distinct due to differences in the infectious process. In case 1, there was a subacute to chronic progression; while in case 2 neutrophilic infiltrate predominated, suggesting an acute progression. The different morphological patterns of the fungi suggested a pleomorphic fungi and the immunohistochemistry allowed us to identify the infectious agent. In conclusion, opportunistic infections caused by Candida albicans should be considered when diagnosing diseases that affect the central nervous system of dogs, particularly in immunosuppressed animals.

Systemic Candidosis in Dogs Associated with Canine Distemper Virus

“…Os relatos de candidose sistêmica são raros em cães e têm sido associados a doenças subjacentes e/ou fatores imunossupressores, incluindo a infecção por parvovírus [12], hiperadrenocorticismo, diabetes mellitus, tratamento prévio com corticosteroides e antibióticos [7,16], mastocitoma mesentérico metastático [10], peritonite secundária a enterotomia [18] e neutropenia induzida por ciclofosfamida [9]. Recentemente foi descrito um caso associado a infecção pelo vírus da cinomose [14], como visto nos 3 casos deste relatório. Esse vírus provoca inibição crônica e profunda com comprometimento das funções imunes celulares e humorais, perda dos linfócitos e leucopenia, que culminam em imunossupressão [11], tornando o animal suscetível às infecções oportunistas [15].…”

“…O envolvimento testicular observado neste caso é uma condição muito rara, relatada apenas em humanos, secundário a procedimentos operatórios na próstata [8]. No caso 3, não foi possível determinar a porta de entrada primária da infecção, mas é provável que o fungo tenha momentaneamente conseguido ultrapassar as barreiras de defesa e posteriormente invadido os vasos sanguíneos com disseminação para o coração, rins e encéfalo [12,14].…”

“…São conhecidas mais de 200 espécies e somente uma pequena parte é considerada patogênica, sendo Candida albicans a espécie mais comumente isolada em infecções disseminadas [6]. As infecções sistêmicas são raras em cães e a maioria dos relatos tem sido associados à imunossupressão [14], e ocasionalmente descritos em animais sadios como patógenos primários [13]. Entretanto, poucos relatos sobre a micose estão disponíveis na literatura.…”

Fungal diseases in dogs and cats in Northeastern Brazil

“…In Brazil, despite the increase in fungal infections in dogs and cats in recent years, there is a scarcity of studies related to the characterization of mycoses in these species (Galiza et al 2014, Castro et al 2017. However, publications have reported the occurrence of mycoses in the Northeastern region, restricted to the description of a few isolated cases (Uchôa et al 2012, Souto et al 2016, Alves et al 2021, 2022, case study compilations (Souto et al 2018, Alves et al 2020a, 2020b, and description of an outbreak (Silva et al 2018). Therefore, the objective of this retrospective study was to determine the occurrence of fungal diseases in dogs and cats in the region and characterize the clinical and anatomopathological findings.…”