DEMOGRAPHIC, CLINICALAND ANTIBIOTIC SUSCEPTIBILITY ANALYSIS OF PIGMENTED AND NON-PIGMENTED SERRATIA MARCESCENS : A COMPARATIVE STUDY AT A TERTIARY CARE CANCER HOSPITAL

Introduction: Serratia marcescens (S. marcescens) are diminutive, motile, gram-negative bacilli. They are distinguished by their ability to ferment glucose, mannitol, mannose, salicin, and trehalose, producing acid and occasionally gas. They are indole-negative, urease-negative, and can grow on Simon's citrate medium, with certain strains producing a red non-diffusible pigment. Non-pigmented S. marcescens biotypes are also known to occur and cause serious infections. These strains have increased lethality due to cytotoxin synthesis and their resistance to commonly used antibiotics. Methods:Aretrospective investigation was conducted in the Department of Microbiology, at Tata Memorial Hospital to ascertain and analyze the antibiotic susceptibility patterns in non-pigmented isolates of Serratia marcescens and compare it across the pigmented strain. Results: 115 isolates were included in this study, 80 of which were non-pigmented against 30 that were pigmented. Agreater incidence 34.78% (40/115) of infections due to S. marcescens was observed among middle age (51 – 60 years) males, of which majority 62.5% (25/40) were non-pigmented. Conclusion: The non-pigmented strains were more resistant to routinely prescribed antibiotics. The hazards associated with infections due to Serratia marcescens in immunocompromised people are signicant; thus, the early detection, accurate detection and treatment of such infections is of utmost importance.