Isolation and identification of gram -negative bacilli from clinical specimen

Introduction: Gram-Negative Bacilli (GNB) includes numerous organisms but the ones which are known to cause nosocomial infections are Pseudomonas aeruginosa, Acinetobacter baumanii. This study was undertaken to identify various Gram negative bacteria isolated from patients admitted at a hospital, in Meerut, India. Material and Method: A total of 3000 clinical specimens were analyzed. These included 1512(50.4%) urine, 28 (0.9%,) pus, 260(8.6%) blood, 159 (5.3%) Sputum, 45(1.5%) CSF and 38 (1.2%) body fluid samples. These samples were inoculated on blood agar, and MacConkey agar. The plates were then incubated at 37°C for 18-24 hours. The clinical isolates obtained were identified using the conventional biochemical tests as per the standardized protocols. Result: Majority (1366/3000) of the isolates obtained were Gram-negative bacilli clinical accounting for an isolation rate of 45.5%. Among these GNB, Escherichia coli was the most common isolate, accounting for 375 (27.4%) of the total, followed by Klebsiella pneumoniae 292(21.3%), Acinetobacter species 64(12%), Enterobacter species 139 (10%), and Proteus Species 134(9.8%). Conclusion: GNB are emerging as important opportunistic pathogens and are resistant to most commonly used antimicrobials. Therefore early diagnosis and institution of empirical therapy based on local antibiogram of the institute would reduce mortality and improve patient management.