Pythium keratitis in South India: Incidence, clinical profile, management, and treatment recommendation

Abstract

Purpose:To study the demographic profile, clinical features, treatment outcome, and ocular morbidity of microbiologically proven Pythium keratitis in South India.Methods:A retrospective analysis of clinical records of microbiologically proven Pythium keratitis at a tertiary eye care referral center in South India from January 2016 to November 2017 was performed. Demographic details, predisposing risk factors, microbiological investigations, clinical course, and visual outcome were analyzed.Results:Seventy-one patients with microbiologically proven Pythium keratitis were identified. The mean age was 44(±18.2) years with an increase in male preponderance and 50% were farmers. Duration of delay at time of presentation to the hospital was a mean of 14(±7.2) days. The visual acuity at baseline ranged from 6/6 to no light perception (median 2.1 logMAR). A combination of 5% natamycin and 1% voriconazole was given to 42% patients, and natamycin alone was given to 39.4% patients. 1% itraconazole eye drops alone was initiated in 7 (10%) patients and 3 among this group responded. Therapeutic keratoplasty (TPK) was performed in 48 (67.6%) patients. None of the primary grafts remained clear after a period of 1 month. Twenty-six eyes (54.2%) had graft reinfection and all these eyes either developed anterior staphyloma (4) or were eviscerated (3) and 13 eyes became phthisical. The remaining 22 patients who had TPK resulted in failed graft. Among these, re-grafts were performed in 6 patients, of which 5 were doing well at the last follow-up.Conclusion:We report a large series of patients with Pythium keratitis. Promoting early and differential diagnosis, awareness of clinicians and specific treatment options are needed for this devastating corneal disease.

Recent update in diagnosis and treatment of human pythiosis

“…Serological tests are not useful because the serum anti-P. insidiosum antibody in patients with Pythium keratitis is usually undetectable (Krajaejun et al, 2006b;Krajaejun et al, 2009;Jindayok et al, 2009). Repeated corneal cultures or combining specimens, including corneal scrapings and corneal buttons, could increase the chance of a positive result (Hasika et al, 2019). In vivo confocal microscopy (IVCM) is an emerging, non-invasive, real-time imaging technique that enables morphological and quantitative analysis of ocular surface microstructure in both health and disease.…”

“…insidiosum inhabits stagnant water and soil, and colonizes aquatic vegetation (Supabandhu et al, 2008;Vanittanakom et al, 2014;Mendoza, Hernandez & Ajello, 1993). Potential risk factors for pythiosis include farming exposure, direct contact with a water resource (i.e., lake, river, lagoon, swamp, or even swimming pool), and a history of travel to endemic countries, such as Thailand (Krajaejun et al, 2006b;Lelievre et al, 2015;Hasika et al, 2019;Appavu, Prajna & Rajapandian, 2019). Inappropriate hygiene of contact lens can pose a risk (Lekhanont et al, 2009;Lelievre et al, 2015;Badenoch et al, 2001;Maeno et al, 2019;Bernheim et al, 2019;Tanhehco et al, 2011;Barequet, Lavinsky & Rosner, 2013;Neufeld et al, 2018;Raghavan et al, 2018), and exposure to dust or some foreign body in their eyes (Bagga et al, 2018;Hasika et al, 2019) predisposes individuals with no agricultural activity to this infection.…”

“…Potential risk factors for pythiosis include farming exposure, direct contact with a water resource (i.e., lake, river, lagoon, swamp, or even swimming pool), and a history of travel to endemic countries, such as Thailand (Krajaejun et al, 2006b;Lelievre et al, 2015;Hasika et al, 2019;Appavu, Prajna & Rajapandian, 2019). Inappropriate hygiene of contact lens can pose a risk (Lekhanont et al, 2009;Lelievre et al, 2015;Badenoch et al, 2001;Maeno et al, 2019;Bernheim et al, 2019;Tanhehco et al, 2011;Barequet, Lavinsky & Rosner, 2013;Neufeld et al, 2018;Raghavan et al, 2018), and exposure to dust or some foreign body in their eyes (Bagga et al, 2018;Hasika et al, 2019) predisposes individuals with no agricultural activity to this infection. The incidence of pythiosis follows a seasonal trend (Hasika et al, 2019;Thanathanee et al, 2013) with outbreaks of Pythium keratitis occurring during the rainy season in Thailand (Thanathanee et al, 2013) and around June to September during monsoon season in South India (Hasika et al, 2019).…”

“…As mentioned earlier (see vascular pythiosis section), P. insidiosum is generally refractory to antifungals, which reflects the failure of medical treatment in majority of cases. However, few cases were resolved with topical 1% itraconazole and only one eye of a patient with bilateral keratitis responded to medical therapy (0.15% amphotericin B, 2% ketoconazole, 1% voriconazole, and oral terbinafine) (Anutarapongpan et al, 2018;Hasika et al, 2019).…”

Identification and Biotyping of Pythium insidiosum Isolated from Urban and Rural Areas of Thailand by Multiplex PCR, DNA Barcode, and Proteomic Analyses

“…Human pythiosis is associated with several hematological disorders (especially thalassemia), in which the underlying mechanism is unknown [1,2,28]. Several case series of human pythiosis (mainly ocular infection) were recently reported from India [29][30][31]. Pythiosis in animals (i.e., horses and dogs) has been mostly diagnosed in other countries, especially Brazil and the United States [3,4,32].…”