Bacteriological profile of gram negative nosocomial isolates from intensive care units and their antibiogram in a tertiary care hospital of South India

Introduction: Nosocomial infection is a key factor in determining clinical outcomes among patients admitted in intensive care units .Studies on nosocomial infections in ICUs found that respiratory tract infections, blood stream infections, urinary tract infections and soft tissue infections are the common nosocomial infections in ICUs. These infections are more commonly caused by Gram negative isolates. These organisms isolated are highly resistant to antibiotics. Early recognition of bacteria and appropriate antimicrobial therapy are essential for controlling infection, preventing the morbidity and improve the quality of life. Objectives: To find out the profile of Gram negative bacteria causing nosocomial infection in patients admitted in intensive care units. To know the antibiotic susceptibility pattern of the nosocomial isolates. Materials and Methods: A total of 192 culture positive samples were taken from various clinical specimens. The organisms were identified by Gram staining, cultural characteristics and a battery of biochemical tests. Drug susceptibility was performed on the isolates by Kirby Bauer's disk diffusion method. Results: A total of 202 organisms were isolated from 192 various clinical samples. Respiratory tract infection 76( 39.6%) was the most common infection in Intensive care units .The number of Gram positive isolates was 60 (29.7% ) .142 (70.3%) Gram negative organisms were isolated. Among the Gram negative isolates Escherichia coli 46 (22.8%) was the most frequently isolated organism followed by Klebsiella species 34(16.8%). Highest occurrence of nosocomial infections was observed in CCU 52( 27.1% ) followed by ICCU 48 ( 25%).Among Gram negative bacilli minimum resistance was seen against imipenem (26.8%)followed by piperacillin – tazobactam (45.1%) and amikacin ( 47.9%). Conclusion: This study shows that Gram negative bacteria were the major cause of infections in intensive care units. The most common isolates were E.coli followed by Klebsiella sp, and Acinetobacter sp. For Gram negative isolates the most effective antibiotics were imipenem followed by piperacillin – tazobactam and amikacin .Appropriate antibiotic utilization in Intensive Care Units is crucial not only in ensuring an optimal outcome but also in preventing multidrug resistant bacteria.