Etiological spectrum of infectious keratitis in the era of MALDI-TOF-MS at a tertiary care hospital

Abstract

Background: Infectious Keratitis (Ik) Is A Potential Vision-Threatening Ocular Infection Caused By A Variety Of Microorganisms. Aim: To Explore Risk Factors And Etiological Agents Associated With Ik. Design: A Prospective Cross-Sectional Study In Which Corneal Scrapings From 120 Suspected Cases Were Evaluated At A Tertiary Health Care Institute From January To December 2019. Methods: Scrapings Were Subjected To Direct Microscopy, Culture, And Identification By Both Conventional Methods And Maldi-Tof-Ms. The Patient's Demographic Data And Predisposing Factors, If Any Were Recorded. Results: The Mean Age Of Patients Was 48.9 Years And Predisposing Factors Were Documented In 46% (55/120) Of Cases. Overall, Infective Etiology Could Be Established In 51% ( N = 61/120) Of Cases. Fungal Growth In 26% ( N = 31/120) Of Cases And Bacterial Growth In 22% ( N = 27/120) Of Cases Was Obtained. Growth Of More Than One Species Of Fungi Or Growth Of Bacteria Along With Fungus Were Observed In 2% ( N = 3/120) Of Cases. Of All The Fungal Isolates Obtained ( N = 34), The Most Common Isolate Was Fusarium (18/34) Followed By Aspergillus (8/34), Curvularia (4/34), Pseudallescheria Boydii (3/34), And Geotrichum (1/34). Among The Gram-Positive Bacterial Isolates ( N = 16), Staphyloccus Species (15/16) Were Isolated In Maximum Number Followed By Streptococcus Pneumoniae (1/16). Among The Gram-Negative Isolates ( N = 13), Pseudomonas Species (8/13) Were Isolated In Maximum Number Of Cases, Followed By Acinetobacter (3/13), Klebsiella Pneumoniae (1/13), And Escherichia Coli (1/13). Conclusion: For Initiating Appropriate Empirical Therapy, The Knowledge Of The Epidemiological Pattern Of Infectious Keratitis Of A Particular Geographical Region Is Crucial.

Recent Perspectives in the Management of Fungal Keratitis

“…Earlier used only in the diagnosis of bacterial organisms, it has now emerged as a tool to identify isolates of fungi, particularly yeasts, and also a few genera of filamentous fungi, including Aspergillus, Penicillium, Fusarium, and Mucorales [49]. A recent study from a tertiary centre [50] in India found that MALDI-TOF MS used to specifically identify the aetiological spectrum of infective keratitis was able to accurately identify in 51% of cases (100% of culture positive), except 2% of polymicrobial growths. These newer modalities can help identify the exact species involved in the infection which in turn helps to commence appropriate treatment and pave the way for appropriate antifungal susceptibility testing [51].…”

From Clinical Suspicion to Diagnosis: A Review of Diagnostic Approaches and Challenges in Fungal Keratitis

“…Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-ToF MS) has emerged as a breakthrough technique and has been successfully applied in recent years in the field of clinical microbiology for the identification of microorganisms. MALDI-ToF MS Z proves to be a valuable method for quickly diagnosing fungal keratitis, especially for cases involving rare or uncommon fungi [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”

Bacterial Keratitis. Part 1. Epidemiology, Etiology, Pathophysiology, Risk Factors, Clinic, Current Aspects of Diagnosis

“…[23,28]. Метод характеризуется высокой диагностической эффективностью, экономической целесообразностью в рутинной практике, быстротой получения результатов идентификации и простотой методологии выполнения исследований [29,30]. Применение ПЦР-методов для идентификации возбудителей БК не рекомендуется, так как результаты могут иметь низкую клиническую значимость.…”