A clinical pilot study for the detection of sphingomyelinase in leptospirosis patient's urine at tertiary care hospital

Purpose: Leptospirosis is a perplexing mystification for many clinicians. Clinically often under-diagnosed due to lack of a rapid, sensitive, and specific diagnostic test. Currently available diagnostic tests have their own limitations; therefore, monitoring biomarkers that contribute an essential role in pathogenesis is crucial. Herein, a pilot study was conducted to detect the presence of sphingomyelinase in urine of leptospirosis patients.Methods: Blood and urine samples were collected from 140 patients having febrile illness. Samples were analyzed through culturing, dark-field microscopy, detecting anti-leptospiral antibodies by MAT, IgM ELISA, Leptocheck-WB and screening for sphingomyelinase using a sphingomyelinase assay kit.Results: Out of 140 febrile illness patients, 22.14 % were tested leptospirosis, 33.57 % were dengue, 25 % scrub typhus, 18.57 % malaria and 0.71 % co-infection (dengue-leptospirosis). MAT seropositivity of 19.28 % (27/140) was confirmed with the highest agglutinant determined against serovar Icterohaemorrhagiae RGA followed by Autumnalis, Australis, and Pyrogens. IgM ELISA and Leptocheck-WB positivity was 16.42 % and 13.57 % respectively. Whereas culture and dark-field microscopy showed a sensitivity of 4.28 % and 2.1 %, respectively. Out of 31 confirmed cases of leptospirosis, sphingomyelinase was detected in the urine of 25 (80.64 %) patients, MAT positivity was seen in 87.09 % and culture positivity was seen in 12.90 % of cases.Conclusion: Detection of sphingomyelinase in the urine of a leptospirosis patient and its absence in other febrile illnesses like dengue, malaria and scrub typhus establish evidence of secretion of sphingomyelinase in urine during leptospiral infection. Hence, sphingomyelinase could be used as a potential diagnostic biomarker to detect leptospirosis in a non-invasive way.