Pulmonary Paecilomyces lilacinus Infection in a Cat

Case Report: Novel Disseminated Paecilomyces formosus Infection in a Dog

A 2.5-year-old, 25.5 kg, spayed female Australian Shepherd dog had a 2-month history of shifting leg lameness in all limbs, tetraparesis, progressive lethargy, and severe pain. On the physical examination, fever (40.61°C), tachycardia, tachypnea, mild diffuse pelvic limb muscular atrophy, left prescapular and right popliteal lymphadenomegaly were observed. Due to the poor prognosis and difficult pain management, humane euthanasia was elected. Macroscopic and histological findings revealed multifocal to coalescing granulomas with central areas of lytic necrosis within the right femur, left humerus, left scapula, left biceps brachii, right semimembranosus muscle, liver, spleen, and lymph nodes. The necrotic areas contained myriad intralesional, intracellular, and extracellular negatively stained, non-pigmented, septate acute angle branching hyphae with parallel walls measuring 3–6 μm in width with polar bulbous projections measuring 7–13 μm in width. Fresh samples of the liver were submitted for fungal culture. Panfungal PCR targeting the major conserved genes-ITS, TUB, CAL-confirmed Paecilomyces formosus. Paecilomyces spp. are members of anamorphic fungi classified under the phylum Ascomycota. Paecilomycosis is an uncommon fungal infection caused by Paecilomyces spp with a disease reported in humans and animals ranging from superficial to systemic clinical forms affecting both immunocompromised and immunocompetent individuals. In dogs, disseminated paecilomycosis has been reported, but the species of fungi are not always determined. To our knowledge, this is the first case of disseminated paecilomycosis caused by P. formosus infection in a dog.

Interaction of an opportunistic fungus Purpureocillium lilacinum with human macrophages and dendritic cells

INTRODUCTION

Purpureocillium lilacinum is emerging as a causal agent of hyalohyphomycosis that is refractory to antifungal drugs; however, the pathogenic mechanisms underlying P. lilacinum infection are not understood. In this study, we investigated the interaction of P. lilacinum conidia with human macrophages and dendritic cells in vitro.

METHODS

Spores of a P. lilacinum clinical isolate were obtained by chill-heat shock. Mononuclear cells were isolated from eight healthy individuals. Monocytes were separated by cold aggregation and differentiated into macrophages by incubation for 7 to 10 days at 37°C or into dendritic cells by the addition of the cytokines human granulocyte-macrophage colony stimulating factor and interleukin-4. Conidial suspension was added to the human cells at 1:1, 2:1, and 5:1 (conidia:cells) ratios for 1h, 6h, and 24h, and the infection was evaluated by Giemsa staining and light microscopy.

RESULTS

After 1h interaction, P. lilacinum conidia were internalized by human cells and after 6h contact, some conidia became inflated. After 24h interaction, the conidia produced germ tubes and hyphae, leading to the disruption of macrophage and dendritic cell membranes. The infection rate analyzed after 6h incubation of P. lilacinum conidia with cells at 2:1 and 1:1 ratios was 76.5% and 25.5%, respectively, for macrophages and 54.3% and 19.5%, respectively, for cultured dendritic cells.

CONCLUSIONS

P. lilacinum conidia are capable of infecting and destroying both macrophages and dendritic cells, clearly demonstrating the ability of this pathogenic fungus to invade human phagocytic cells.

Antagonistic activity of the fungusPochonia chlamydosporiaon mature and immatureToxocara caniseggs

In vitrotests were performed to evaluate the ability of 6 isolates of the nematophagous fungusPochonia chlamydosporiato infect immature and matureToxocara caniseggs on cellulose dialysis membrane. There was a direct relationship between the number of eggs colonized and the increase in the days of interaction, as well as between the number of eggs colonized and the increase in the concentration of chlamydospores (P<0·05). Immature eggs were more susceptible to infection than mature eggs. The isolate Pc-04 was the most efficient egg parasite until the 7th day, and showed no difference in capacity to infect mature and immature eggs in comparison to Pc-07 at 14 and 21 days of interaction, respectively. Isolate Pc-04 was the most infective on the two evolutionary phases of the eggs at most concentrations, but its ability to infect immature eggs did not differ from that presented by the isolates Pc-07 and Pc-10 at the inoculum level of 5000 chlamydospores. Colonization of infective larvae inside or outside the egg was observed in treatments with the isolates Pc-03, Pc-04, Pc-07 and Pc-10. The isolate Pc-04 ofP. chlamydosporiahas great biological capacity to destroy immature and matureT. caniseggs in laboratory conditions.

Purpureocillium lilacinum as a cause of cavitary pulmonary disease: a new clinical presentation and observations on atypical morphologic characteristics of the isolate

The first case of cavitary pulmonary disease caused by Purpureocillium lilacinum is described. The isolate showed atypical microscopic characteristics similar to Acremonium and Fusarium spp., which necessitated molecular identification by sequencing of multiple conserved loci. The patient responded to voriconazole, reinforcing its therapeutic efficacy for P. lilacinum infections.

Lower respiratory tract infections in cats: reaching beyond empirical therapy

PRACTICAL RELEVANCE

Lower respiratory tract infections (LRTIs) in cats can be due to bacteria, parasites, fungi and viruses. This review details the practical investigation of these infections and highlights specific therapy where possible. The aim is to avoid the all-too-frequent temptation in practice to treat cats with lower respiratory tract signs empirically for feline bronchial disease (FBD)/asthma. This is potentially hazardous as immunosuppressive therapy for FBD/asthma could exacerbate disease due to a LRTI. Empirical treatment of suspected LRTI is also difficult to recommend given the wide range of potential pathogens.

CLINICAL CHALLENGES

Making a clinical ante-mortem diagnosis of LRTI in a cat can be challenging. Consistent historical, clinical, haematological and radiographic abnormalities are often lacking and findings may be non-specific. Astute clinical acumen, thorough investigation and high quality laboratory analysis are usually required for a diagnosis. Bronchoalveolar lavage, if feasible, and tests for lungworm should be routine in cats with lower respiratory tract signs. Lung fine needle aspiration may be useful in cases of diffuse or nodular pulmonary disease. Histopathology is rarely employed in ante-mortem investigations.

EVIDENCE BASE

The authors have reviewed a substantial body of literature to provide information on many of the reported bacterial, parasitic, fungal and viral pathogens, including some that occur in Asia. Attention has been given to specific therapy for each pathogen, with evidence-based comments when there is a deviation from routine recommendations.