Modified Tectonic Corneoscleral Graft For Management of Devastating Corneoscleral Infections

Purpose To analyze the clinical results and the efficacy of modified tectonic corneoscleral graft (TCG) in patients with devastating corneoscleral infections.Methods Twenty-five eyes from 25 patients who underwent modified TCG were enrolled. The recurrence, best-corrected visual acuity (BCVA), ocular surface stability, postoperative complications and graft survival condition were recorded.Results Among 25 patients, 19 cases were fungal infection and 6 cases were bacterial. The rate of recurrence was 8% with Pythium Insidiosum as a corresponding pathogen. The rate of monocular blindness declined from 100% to 57%. Changes in BCVA from preoperative to postoperative values were significant ( Z=4.22, P＜0.001). The survival of ocular surface stability was 73.6% and 43.9% at 1 and 3 years after surgery, respectively. Within the mean follow-up period of 17.5 ± 8.9 months, 21eyes (84.0%) had a stable ocular surface. The incidence rate of immune rejection was 36%. Corneal epithelial defects occurred in 7 patients and choroidal detachment occurred in 3 patients. No elevation of intraocular pressure was detected.Conclusions The modified TCG is effective in eradicating infection, salvaging the eyeball and saving some useful vision for devastating corneoscleral infections. Regular application of tacrolimus, timely addition of glucocorticoid and good compliance may decrease the postoperative course challenging.

Geographic distribution of Pythium insidiosum infections in the United States

OBJECTIVE To describe the geographic distribution of infections caused by Pythium insidiosum in dogs, horses, and other animal species in the US. ANIMALS For the last 20 years, we have collected data from cases of pythiosis in 1,150 horses, 467 dogs, and other species (59) from various geographic locations in the US. PROCEDURES Due to lost data (from 2006 to 2016), the selected cases include years 2000 to 2005 and 2016 to 2020. The selection of cases was based on infected host clinical features, serum samples demonstrating strong positive anti–P insidiosum IgG titers in serologic assays, and positive results on ≥ 1 of the following diagnostic modalities: microbial culture on 2% Sabouraud dextrose agar, histologic evaluation, PCR assay, and wet mount cytologic evaluation (with potassium hydroxide). RESULTS Most confirmed P insidiosum infections were found in horses and dogs in the southeastern US. Interestingly, in Texas, no cases were found west of longitude 100°W. Few pythiosis cases were diagnosed in west-coast states. Equine cases were more often diagnosed during summer and fall months, but canine cases were more often diagnosed between September and February. Cases in other species were discovered in the same geographic areas as those in dogs and horses. CLINICAL RELEVANCE To our knowledge, this is the first report providing the ecological distribution of P insidiosum infection in affected species in the US. Results of this study illustrated the importance of including P insidiosum in the differential diagnostic scheme of nonhealing skin lesions or intestinal granulomatous masses, particularly in dogs and horses inhabiting or having visited endemic areas.

Pythium insidiosum keratitis reported in China, raising the alertness to this fungus-like infection: a case series

Background The objective of this study is to report typical clinical and laboratory characteristics of three cases of keratitis caused by Pythium insidiosum in China. Case presentation Three Chinese patients of Han nationality diagnosed with Pythium keratitis from 2017 to 2019 were included. One 45-year-old female and one 55-year-old male were exposed to river water, and one 51-year-old female was burned by ash in the eyes. All of them are of Han ethnicity. Upon slit-lamp examination, subepithelial and superficial stromal opacities were observed in a reticular pattern. After conventional treatment with antifungal agents, the clinical status worsened and therapeutic penetrating keratoplasty was performed. Unfortunately, enucleation was performed to remove all infected tissue and relieve pain. Pythium insidiosum was identified in culture and confirmed by internal transcribed spacer ribosomal RNA gene sequencing analysis. Following the systemic and local antibiotic regimens, the patients were cured ultimately and no regression of infection was observed. Conclusions It is significant for ophthalmologists and microbiologist to be alert to this eye-threatening infection, especially in patients who are resistant to antifungal treatments and with water-related exposure.

History and Perspective of Immunotherapy for Pythiosis

The fungus-like microorganism Pythium insidiosum causes pythiosis, a life-threatening infectious disease increasingly reported worldwide. Antimicrobial drugs are ineffective. Radical surgery is an essential treatment. Pythiosis can resume post-surgically. Immunotherapy using P. insidiosum antigens (PIA) has emerged as an alternative treatment. This review aims at providing up-to-date information of the immunotherapeutic PIA, with the focus on its history, preparation, clinical application, outcome, mechanism, and recent advances, in order to promote the proper use and future development of this treatment modality. P. insidiosum crude extract is the primary source of immunotherapeutic antigens. Based on 967 documented human and animal (mainly horses) pythiosis cases, PIA immunotherapy reduced disease morbidity and mortality. Concerning clinical outcomes, 19.4% of PIA-immunized human patients succumbed to vascular pythiosis instead of 41.0% in unimmunized cases. PIA immunotherapy may not provide an advantage in a local P. insidiosum infection of the eye. Both PIA-immunized and unimmunized horses with pythiosis showed a similar survival rate of ~70%; however, demands for surgical intervention were much lesser in the immunized cases (22.8% vs. 75.2%). The proposed PIA action involves switching the non-protective T-helper-2 to protective T-helper-1 mediated immunity. By exploring the available P. insidiosum genome data, synthetic peptides, recombinant proteins, and nucleic acids are potential sources of the immunotherapeutic antigens worth investigating. The PIA therapeutic property needs improvement for a better prognosis of pythiosis patients.

Pythiosis mamaria en una yegua criolla colombiana

Se reporta un caso de una yegua criolla colombiana, color castaño, de 7 años y un peso de 300 Kg, la cual fue atendida por el Servicio Clínico Ambulatorio del área de Clínica Médico-Quirúrgica de Grandes Animales de la Universidad de Córdoba. La anamnesis indica que la yegua presentó un aumento progresivo de tamaño a nivel de la glándula mamaria, con secreción mucopurulenta constante por diferentes orificios, así mismo el propietario reporta que le realizó incisiones para facilitar el drenaje de material desde la glándula mamaría, ya que pensaba que ese aumento consistía en un absceso, de igual forma, informó la aplicación de antibióticos a base de tetraciclinas y antiinflamatorios no esteroidales. Al examen clínico, se determinó la presencia de una lesión granulomatosa que comprometía toda la glándula mamaria, con presencia de varias aberturas en forma de cráter y salida de material fibrinopurulento, a la compresión presento salida de mayor cantidad de secreción, así como masas caseificadas llamadas Kunker. Se decidió realizar mastectomía total como medida de control y alargar la vida útil de la yegua. Durante el procedimiento quirúrgico bajo anestesia general, se evidenció la presencia de abundante tejido granulomatoso, así como la presencia de grandes cantidades de kunkers acumulados en cavitaciones originadas por la invasión del Pythium insidiosum en el tejido granular. Se concluye la importancia de conocer la epidemiología de la Pythiosis, siendo relevante la ubicación de casos clínicos a nivel de glándula mamaria en yeguas criollas colombianas expuestas a factores de riesgo.

Immunological Cross-Reactivity of Proteins Extracted from the Oomycete Pythium insidiosum and the Fungus Basidiobolus ranarum Compromises the Detection Specificity of Immunodiagnostic Assays for Pythiosis

Pythiosis, a life-threatening disease caused by Pythium insidiosum, has been increasingly diagnosed worldwide. A recently developed immunochromatographic test (ICT) enables the rapid diagnosis of pythiosis. During the 3-year clinical implementation of ICT in Thailand, we collected the laboratory reports of 38 animals with suspected pythiosis and detected ICT false-positive results in three horses and a dog with basidiobolomycosis. P. insidiosum and Basidiobolus ranarum cause infections with indistinguishable clinical and microscopic features. This study investigated cross-reactive antibodies by probing P. insidiosum and B. ranarum crude extracts and cell-free synthesized I06 protein (encoded in P. insidiosum genome, not other fungi) against a panel of pythiosis, basidiobolomycosis, rabbit anti-I06 peptide, and control sera by Western blot analyses. ICT false-positive results occurred from the cross-reactivity of anti-B. ranarum antibodies to the 15, 50, 60, and 120 kDa proteins of P. insidiosum, not double infections caused by both pathogens. Notably, ICT could help to screen pythiosis, and the positive test requires confirmation by culture or molecular method. The detection specificity of ICT requires improvement. The crude extract containing multispecies antigens needs replacement with a refined P. insidiosum-specific protein. We proposed that the 55 kDa I06 protein is an excellent candidate for developing a more specific serodiagnostic test for pythiosis.

Prospecting Biomarkers for Diagnostic and Therapeutic Approaches in Pythiosis

Pythiosis, whose etiological agent is the oomycete Pythium insidiosum, is a life-threatening disease that occurs mainly in tropical and subtropical countries, affecting several animal species. It is frequently found in horses in Brazil and humans in Thailand. The disease is difficult to diagnose because the pathogen’s hyphae are often misdiagnosed as mucoromycete fungi in histological sections. Additionally, there is no specific antigen to use for rapid diagnosis, the availability of which could improve the prognosis in different animal species. In this scenario, we investigated which P. insidiosum antigens are recognized by circulating antibodies in horses and humans with pythiosis from Brazil and Thailand, respectively, using 2D immunoblotting followed by mass spectrometry for the identification of antigens. We identified 23 protein spots, 14 recognized by pooled serum from horses and humans. Seven antigens were commonly recognized by both species, such as the heat-shock cognate 70 KDa protein, the heat-shock 70 KDa protein, glucan 1,3-beta-glucosidase, fructose-bisphosphate aldolase, serine/threonine-protein phosphatase, aconitate hydratase, and 14-3-3 protein epsilon. These results demonstrate that there are common antigens recognized by the immune responses of horses and humans, and these antigens may be studied as biomarkers for improving diagnosis and treatment.