Gram negative organisms isolated from Blood Cultures and their Susceptibility Pattern

Abstract

Background: Bloodstream infections (BSIs) are an important frequent health problem in terms of their high incidence and lethal outcomes. The bacteria that frequently cause bacteremia are Staphylococcus, Streptococcus, Enterococcus, Escherichia coli, Klebsiella, Enterobacter, Pseudomonas, Neisseria and Haemophilus. Gram negative rods constitute a significant bulk in BSIs. The bloodstream infections due to multidrug resistant pathogens are on the rise globally making treatment more challenging. Aim: To identify the gram negative organisms causing blood stream infections and assess their susceptibility pattern so as to provide guidance for the empirical treatment hoping for better clinical outcome. Methodology: A retrospective, cross-sectional descriptive study carried out in Pathology Laboratory of Sharif City Hospital, Lahore. All the blood culture samples received in Microbiology laboratory between June 2017 to June 2019 were included in the study by non-probability consecutive sampling. Blood cultures were proceeded by subculturing on 1st and 5th day on MacConkey and Blood agar. The colonies obtained were identified through gram staining and biochemical profile. API20E was used for Enterobacteriaceae. Antibiotic susceptibility testing of the pathogens was by Kirby Bauer disc diffusion method. Results: In the current study 663 blood cultures were analyzed. Only 11.9% exhibited positive microbial growth. 55.7% of the positive cultures revealed gram negative bacteria. Among the pathogens isolated, E.coli was found to be responsible for BSIs in 22.7% cases, followed by Salmonella Typhi 20.4% and Klebsiella pneumoniae 18.1%.The gram negative rods exhibited a very high resistance for penicillins, cephalosporins and fluoroquinolones. The efficacy of aminoglycosides and results for carbapenems susceptibility were hopeful. Conclusion: The study shows that the Gram negative bacteria causing BSIs have shown unsatisfactory susceptibility to most of the commonly prescribed antimicrobials. The rising drug resistance has a major impact on the selection and prescription of antibiotics and calls for judicious use of antibiotics. Keywords: Gram Negative Organisms, Blood Culture, Antimicrobial Susceptibility Pattern