TREATMENT AND OUTCOME OF HORSES WITH CUTANEOUS PYTHIOSIS, AND META-ANALYSIS OF SIMILAR REPORTS
Pythiosis is reported to be one of the most life-threatening infections of people and animals in tropical, subtropical and temperate areas worldwide. Infection can result from ingesting zoospores of Pythium insidiosum organism or from contact with water contaminated with zoospores. The ingestion of zoospores may result in enteric pythiosis, whereas cutaneous contact with zoospores/oomycete may result in cutaneous pythiosis. Here, we report 10 horses with pythiosis introduced to our clinic. These horses were treated by excision of the lesion and application of an antifungal cream to the resulting wound. Also, we performed a meta-analysis of 214 horses, in 18 reports, affected with cutaneous pythiosis and analysed the influence of the horse’s sex, age, lesion site, and treatment on outcome. Treatment of horses in these 18 reports varied from surgical excision, topical, regional or systemic administration of an antifungal drug, immunization, or a combination of treatments. Horses with the most successful outcome were those treated by excision of the lesion coupled with systemic or topical administration of an antifungal drug. Horses treated by immunization responded the poorest.
Key words: pythiosis; skin lesions; equine; surgery; Pythium insidiosum
Chaffin, M.K., S. James, and W.C. McMullan, Cutaneous pythiosis in the horse. Veterinary Clinics of North America: Equine Practice, 1995. 11(1): p. 91â€“103.
Mendoza, L., L. Ajello, and M. McGinnis, Infections caused by the oomycetous pathogen Pythium insidiosum. Infecciones causadas por el patÃ³geno oomiceto Pythium insidiosum. Journal de Mycologie Medicale., 1996. 6(4): p. 151â€“64.
Mendoza, L. and A.A. Alfaro, Equine pythiosis in Costa Rica: report of 39 cases. My-copathologia, 1986. 94(2): p. 123â€“29.
dos Santos, C.E.P., et al., Epidemiological Survey of Equine Pythiosis in the Brazilian Pan-tanal and Nearby Areas: Results of 76 Cases. Journal of Equine Veterinary Science, 2014. 34(2): p. 270â€“4.
Hendrix, J.W., Sterol induction of repro-duction and stimulation of growth of Pythium and Phytophthora. Science, 1964. 144(3621): p.1028â€“9.
Cavalheiro, A.S., et al., In vitro activity of terbinafine associated to amphotericin B, fluvastatin, rifampicin, metronidazole and ibu-profen against Pythium insidiosum. Veterinary microbiology, 2009. 137(3-4): p. 408â€“11.
Pereira, D.I.B., et al., Caspofungin in vitro and in vivo activity against Brazilian Pythium insidiosum strains isolated from animals. Jour-nal of Antimicrobial Chemotherapy, 2007. 60(5): p. 1168â€“71.
McMullan, W.C., et al., Amphotericin B for the treatment of localized subcutaneous phycomycosis in the horse. J Am Vet Med As-soc, 1977. 170(11): p. 1293â€“8.
Chitasombat, M.N., et al., Clinicopatho-logical features and outcomes of pythiosis. Int J Infect Dis, 2018. 71: p. 33â€“41.
Reanpang, T., et al., Vascular Pythiosis of the Lower Extremity in Northern Thailand: Ten Years' Experience. Int J Low Extrem Wounds, 2015. 14(3): p. 245â€“50.
Miller, R.I., et al., Complications associ-ated with immunotherapy of equine phycomy-cosis. J Am Vet Med Assoc, 1983. 182(11): p. 1227â€“9.
Santos, C.E., et al., Does immunotherapy protect equines from reinfection by the oomy-cete Pythium insidiosum? Clin Vaccine Immu-nol, 2011. 18(8): p. 1397â€“9.
White, S.D., et al., Cutaneous pythiosis in a nontravelled California horse. Vet Derma-tol, 2008. 19(6): p. 391â€“4.
Sekhon, A.S., A.A. Padhye, and A.K. Garg, In vitro sensitivity of Penicillium marnef-fei and Pythium insidiosum to various antifun-gal agents. European Journal of Epidemiology, 1992. 8(3): p. 427â€“32.
Madoui, M.A., et al., Sterol metabolism in the oomycete Aphanomyces euteiches, a legume root pathogen. New Phytologist, 2009. 183(2): p. 291â€“300.
Pereira, D.I.B., et al., Comparison be-tween immunotherapy and caspofungin as agents to treat experimental pythiosis in rabbits. Journal de Mycologie MÃ©dicale, 2008. 18(3): p. 129â€“33.
Brown, T.A., A.M. Grooters, and G.L. Hosgood, In vitro susceptibility of Pythium in-sidiosum and a Lagenidium sp to itraconazole, posaconazole, voriconazole, terbinafine, caspo-fungin, and mefenoxam. American journal of veterinary research, 2008. 69(11): p. 1463â€“8.
Argenta, J.S., et al., In vitro and in vivo susceptibility of two-drug and three-drug com-binations of terbinafine, itraconazole, caspo-fungin, ibuprofen and fluvastatin against Pythi-um insidiosum. Veterinary Microbiology, 2012. 157(1): p. 137â€“42.
Valente, J.S., et al., In vitro activity of antifungals in combination with essential oils against the oomycete Pythium insidiosum. J Appl Microbiol, 2016. 121(4): p. 998â€“1003.
Araujo, M.J., S.M. Bosco, and J.M. Sforcin, Pythium insidiosum: inhibitory effects of propolis and geopropolis on hyphal growth. Braz J Microbiol, 2016. 47(4): p. 863-â€“9.
Zanette, R., et al., In vitro susceptibility of Pythium insidiosum to garlic extract. African Journal of Microbiology Research, 2011. 5(29): p. 5316â€“8.
Zanette, R.A., et al., Iron chelation thera-py as a treatment for Pythium insidiosum in an animal model. J Antimicrob Chemother, 2013. 68(5): p. 1144â€“7.
Zanette, R.A., et al., Micafungin alone and in combination therapy with deferasirox against Pythium insidiosum. J Mycol Med, 2015. 25(1): p. 91â€“4.
Loreto, E.S., et al., In vitro susceptibility of Pythium insidiosum to macrolides and tetra-cycline antibiotics. Antimicrob Agents Chemother, 2011. 55(7): p. 3588â€“90.
Rawn, C.D. and J.L. Van Etten, Mecha-nism of antibacterial antibiotic sensitivity in Pythium ultimum. Microbiology, 1978. 108(1): p. 133â€“9.
Mahl, D.L., et al., In vitro susceptibility of Pythium insidiosum isolates to aminoglyco-side antibiotics and tigecycline. Antimicrob Agents Chemother, 2012. 56(7): p. 4021â€“3.
Mosbah, E., et al., Diagnosis and Surgical Management of Pythiosis in Draft Horses: Re-port of 33 Cases in Egypt. Journal of Equine Veterinary Science, 2012. 32(3): p. 164â€“9.
Chaffin, M.K., J. Schumacher, and N. Hooper, Multicentric cutaneous pythiosis in a foal. J Am Vet Med Assoc, 1992. 201(2): p. 310â€“2.
Doria, R.G., et al., Treatment of pythiosis in equine limbs using intravenous regional per-fusion of amphotericin B. Vet Surg, 2012. 41(6): p. 759â€“65.
Doria, R.G., et al., Evaluation of intrave-nous regional perfusion with amphotericin B and dimethylsulfoxide to treat horses for pythi-osis of a limb. BMC Vet Res, 2015. 11: p. 152.
Reis, J.L., et al., Disseminated pythiosis in three horses. Veterinary Microbiology, 2003. 96(3): p. 289â€“5.
Sedrish, S., et al., Adjunctive use of a neodymium: yttrium-aluminum garnet laser for treatment of pythiosis granulomas in two hors-es. Journal of the American Veterinary Medical Association, 1997. 211(4): p. 464â€“5.
Pier, A., et al., Prominent animal my-coses from various regions of the world. Sabouraudia, 2000. 38(Supplement_1): p. 47â€“58.
Mendoza, L. and J.C. Newton, Immu-nology and immunotherapy of the infections caused by Pythium insidiosum. Medical Mycol-ogy, 2005. 43(6): p. 477â€“86.
Triscott, J.A., D. Weedon, and E. Caba-na, Human subcutaneous pythiosis. Journal of Cutaneous Pathology, 1993. 20(3): p. 267â€“71.
Shenep, J.L., et al., Successful medical therapy for deeply invasive facial infection due to Pythium insidiosum in a child. Clinical infec-tious diseases, 1998. 27(6): p. 1388â€“93.
Grooters, A.M., Pythiosis, lagenidiosis, and zygomycosis in small animals. Veterinary Clinics: Small Animal Practice, 2003. 33(4): p. 695-720.
Cavalheiro, A.S., et al., In vitro activity of terbinafine combined with caspofungin and azoles against Pythium insidiosum. Antimicro-bial agents and chemotherapy, 2009. 53(5): p. 2136â€“8.
Worster, A.A., et al., Pythiosis with bone lesions in a pregnant mare. Journal of the Amer-ican Veterinary Medical Association, 2000. 216(11): p. 1795â€“8.
Gaastra, W., et al., Pythium insidiosum: an overview. Vet Microbiol, 2010. 146(1-2): p. 1â€“16.
Allison, N. and J.P. Gillis, Enteric pythi-osis in a horse. J Am Vet Med Assoc, 1990. 196(3): p. 462â€“4.
Purcell, K.L., et al., Jejunal obstruction ca-used by a Pythium insidiosum granuloma in a mare. J Am Vet Med Assoc, 1994. 205(2): p. 337â€“9.
Tonpitak, W., et al., First confirmed case of nasal pythiosis in a horse in Thailand. JMM Case Rep, 2018. 5(1): p. e005136.