MICROBIOLOGICAL SPECTRUM AND DIAGNOSTIC APPROACH IN NEONATAL SEPSIS

Background: Neonatal sepsis is a life-threatening systemic infection caused by bacteria, fungi, or viruses, characterized by hemodynamic instability and variable clinical presentations. Early and accurate diagnosis remains challenging and typically relies on a combination of clinical assessment, laboratory parameters, and microbiological confirmation, most commonly through blood culture. Materials and Methods: A hospital-based prospective cross-sectional study was conducted in the Government Institute of Medical Sciences (GIMS), Greater Noida, from June 1, 2024, to May 31, 2025. A total of 511 blood samples from neonates with suspected sepsis were processed using the automated BACTEC blood culture system. Isolates were identified and antimicrobial susceptibility testing was performed using the VITEK 2 Compact system. Results: Of the 511 suspected cases, 144 (28.2%) were culture-positive. Fungal isolates (budding yeast cells) were the most frequent, accounting for 63 (43.8%) cases, followed by Gram-negative bacilli in 54 (37.5%) cases and Gram-positive cocci in 27 (18.8%) cases. Among fungal pathogens, Candida albicans was predominant (46 isolates; 31.9%), with a higher proportion observed in early-onset sepsis (43.7%) compared to late-onset sepsis (22.8%). Candida pelliculosa was the second most common fungal isolate. Among Gram-negative organisms, Klebsiella pneumoniae (14.6%) was the most frequently isolated, followed by Pseudomonas aeruginosa (6.3%), Escherichia coli (4.9%), Serratia marcescens (4.2%), and Acinetobacter spp. (3.5%). Among Gram-positive cocci, coagulase-negative staphylococci (CONS) were predominant (10.4%). Most bacterial isolates, both Gram-negative and Gram-positive, were associated with late-onset sepsis. Gram-positive organisms demonstrated high susceptibility to linezolid and vancomycin, while Gram-negative isolates showed variable susceptibility patterns, indicating the need for ongoing local antimicrobial surveillance. Conclusion: Timely identification of causative pathogens is critical for the effective management of neonatal sepsis. The use of automated diagnostic systems enhances detection efficiency and reduces turnaround time. However, reliance primarily on culture-based methods may underestimate the true burden of infection due to prior antibiotic exposure, low-level bacteremia, or fastidious organisms. Integration of rapid molecular diagnostics alongside conventional culture methods is recommended to improve diagnostic yield and support targeted antimicrobial stewardship.