In vitro and ex vivo anti-Pythium insidiosum potential of ozonated sunflower oil

This study sought to evaluate the in vitro and ex vivo susceptibility of Pythium insidiosum to ozonized sunflower oil (OSO) and verify the morphological alterations of OSO-exposed hyphae. Susceptibility assays were performed according to the broth microdilution protocol M38-A2/CLSI, and the minimal inhibitory (MIC) and minimal oomicidal (MOC) concentrations were also determined. Non-ozonated sunflower oil (SO) was used as the oil control. Additionally, kunkers from equine pythiosis were exposed to OSO. Damages caused by OSO and SO on P. insidiosum hyphae ultrastructure were verified using scanning electron microscopy. The MIC range for OSO was 7000 to 437.5 mg/mL, and the values for SO were higher, ranging from 56000 to 14000 mg/mL. The MOC was equal to MIC for both oil formulations. The OSO fully inhibited the oomycete growth from kunkers, although there was P. insidiosum growth in the kunker control in 24 h of incubation. The SEM analyses showed that both OSO and SO caused morphological alterations in P. insidiosum hyphae, highlighting the presence of cavitation along the hyphae with loss of continuity of the cell wall, which was more evident in the OSO-treated hyphae. The OSO had the best oomicidal activity, leading us to believe that our findings may support future research containing this formulation to be applied in integrative medicine protocols to control pythiosis in animals and humans.

Melaleuca alternifolia formulations in the treatment of experimental pythiosis

Essential oils (EO) are aromatic compounds from the plant secondary metabolism. Melaleuca alternifolia EO is well known for its medicinal properties and promising use as an antimicrobial agent. Pythiosis is a difficult-to-treat and emerging disease caused by the oomycete Pythium insidiosum. This study evaluated a nanoemulsion formulation of M. alternifolia (NEMA) in topical and intralesional application to treat experimental pythiosis. Dermal toxicity tests were performed on M. alternifolia EO in Wistar rats. Pythiosis was reproduced in rabbits (n = 9) that were divided into groups: group 1 (control), cutaneous lesions with daily topical application of a non-ionizable gel-based formulation and intralesional application of sterile distilled water every 48 h; group 2 (topical formulation), lesions treated daily with topical application of a non-ionizable gel-based formulation containing 5 mg/ml of NEMA; and group 3 (intralesional formulation), lesions treated with NEMA at 5 mg/ml in aqueous solution applied intralesionally/48 h. The animals were treated for 45 days, and the subcutaneous lesion areas were measured every 5 days. M. alternifolia EO showed no dermal toxicity. The lesion areas treated with intralesional NEMA reduced at the end of treatment, differing from groups 1 and 2 (P < 0.05). In the topically treated group, the lesion areas did not differ from the control group, although the number of hyphae significantly reduced (P < 0.05). Under the experimental conditions of this study, the NEMA formulations presented a favorable safety profile. However, further studies are required to evaluate if this safety applies to higher concentrations of NEMA and to validate its use in clinical pythiosis.

Biogenic silver nanoparticles in the treatment of experimental pythiosis Bio-AgNP in pythiosis therapy

Pythiosis is a rapidly progressing disease that can be lethal to affected individuals due to resistance to available therapeutic protocols. The disease affects mammals, with the largest number of reports in horses and humans. The present study investigated the activity of biogenic silver nanoparticles (bioAgNP) in the treatment of experimental pythiosis. The disease was reproduced in nine female 90-day-old New Zealand rabbits. Animals were divided into three groups: group1 (control, n = 3) daily and topically treated with a nonionized gel-based formulation and 1 ml of sterile distilled water intralesion administered every 48 hours; group 2 (n = 3), daily and topically treated with gel-based formulation containing 1 μg/ml bio-AgNP; group 3 (n = 3), treated with 1 ml bio-AgNP in 1 μg/ml aqueous solution intralesion administered every 48 hours. Animals were treated for 45 days, and the area of subcutaneous lesions was measured every 5 days. Results showed that groups 2 and 3 differed from control group (P < .05) in the lesion area, as well as the amount of hyphae within the lesions. It was observed that lesions of treated animals (groups 2 and 3) did not differ from each other, showing that the application route did not influence the regression of lesions. However, it was observed that one animal from group 2 reached clinical cure at 35 days of treatment. This research is pioneer in the application of nanocomposites for the treatment of experimental pythiosis and showed that bio-AgNP can be powerful allies of integrative medicine and can be included in pythiosis therapeutic protocols.

Protein profile of Brazilian Pythium insidiosum isolates

Pythium insidiosum is an important aquatic Oomycota that causes pythiosis in mammals, especially horses, dogs, and humans; these inhabit marshy environments in tropical and subtropical areas. The aim of this study was to determine the protein profile, as well as identify likely immunodominant proteins, of Brazilian P. insidiosum isolates from southern Brazil, an important equine pythiosis endemic area. P. insidiosum isolates (horses, n = 20 and dogs, n = 02) were analyzed by SDS-PAGE and Western blot techniques. Horse, cattle, dog, and rabbit sera of both diseased and healthy animals were used to identify P. insidiosum proteins. SDS-PAGE protein profile detected antigens of molecular weights ranging from 100 to 20 KDa. Dog isolates revealed a protein profile similar to that of horse isolates. Anti-P. insidiosum antibodies in the sera of the four species could recognize proteins of different molecular weights (∼74 KDa to ∼24 KDa), and proteins ∼50-55 KDa and ∼34 KDa were shown to be immunodominant. Furthermore, ∼74 KDa, ∼60 KDa, ∼30 KDa and ∼24 KDa proteins were poorly recognized by host species antibodies. The Brazilian P. insidiosum isolates analyzed showed a similar protein profile; however, further studies are essential for the identification and characterization of proteins expressed by P. insidiosum, and an evaluation of the immunological profile of hosts susceptible to this Oomycota is necessary.

Influence of temperature on in vitro zoosporogenesis of Pythium insidiosum

This study verified the influence of different temperatures on P. insidiosum in vitro zoosporogenesis. P. insidiosum isolates (n = 26) were submitted to zoosporogenesis and incubated at 5°C, 15°C, 20°C and 37°C (1st stage). Grass fragments were evaluated under optical microscopy at 4, 8, and 24 hours of incubation. Afterward, all isolates were incubated at 37°C and assessed at the same periods of time (2nd stage). The development of hyphae, presence of vesicles, zoosporangia and zoospores were checked. Only the presence of short hyphae was observed at 5°C. At 15°C, the hyphae were either under development or elongated and two isolates produced zoospores. When the isolates were submitted to 20°C for 4 hours, the presence of long and mycelial hyphae, vesicles, zoosporangia and zoospores was observed, which also happened at the other periods evaluated. In the second stage, the isolates which were initially at 5°C and 15°C evidenced long developing hyphae with the presence of vesicles, zoosporangia, and zoospores within 4 hours of incubation, and these characteristics were kept at the other evaluated periods. The isolates kept at 37°C showed evident zoosporogenesis in the first 4 hours of evaluation. It was concluded that temperatures of 20°C and 37°C support P. insidiosum zoosporogenesis process. On the other hand, 5°C and 15°C temperatures do not kill the microorganism.