Organisms causing community-acquired bloodstream infection in medical department: A single centre retrospective observational study.

Introduction: Community acquired bloodstream infection (CA-BSI) is positive blood culture obtained within 48 hours of hospital admission. Bloodstream infections need to be treated with antibiotics. Inappropriate choice of antibiotics will lead to antimicrobial resistance. This is an observational retrospective study to look at the antimicrobial resistance of organisms causing bloodstream infections in patients admitted to the medical wards in our centre. The aim of the study is to determine the appropriate choice of empirical antibiotics for suspected CA-BSI in our hospital.

Materials and methods: All patients admitted to medical wards with blood stream infection during the period January 2021 to June 2021 were enrolled. Identification of organisms and antimicrobial susceptibility testing were obtained. Information regarding the severity of the bacteremia was collected by assessing if the patient needed inotropes, mechanical ventilation or renal replacement therapy. Data on comorbidities which were the presence of end-stage renal failure, diabetic mellitus and immunosuppression were collected.

Results: Total of 269 cases were screened. Out of these 104 communities acquired cases were included. The pathogens frequently isolated were gram negative organisms most commonly Escherichia coli (43%) and Klebsiella species (30%). Staphylococcus aureus accounts for the majority of gram-positive organisms. Only two out of 20 Staphylococcus aureus were methicillin resistant. Bulkholderia pseudomallei accounts for 7.8% cases. All Burkholderia pseudomallei isolates were sensitive to cotrimoxazole. Escherichia coli (46%) isolates demonstrated a higher resistance pattern to Augmentin compared to klebsiella species (17.4%). The overall mortality rate was 22%, with higher rates for those critically ill (39%). Patients with Enterobacteriaceae infection showed no difference in outcome between the groups of patients according to sensitivity to Augmentin and cefotaxime. These groups of patients who were critically ill did not demonstrate any significant difference in terms of resistance pattern to Augmentin (p = 0.3) and cefotaxime (p = 0.7). Patients who are aged 65 or older have a significantly more resistant pattern to Augmentin and cefotaxime.

Conclusion: Antibiogram serves as a guide for clinicians to choose appropriate choices of antibiotics based on local data. Empirical antibiotics of choice for patients with sepsis should be narrow-spectrum beta lactam/beta lactamase inhibitors. Broad spectrum beta lactam/beta lactamase inhibitors such as piperacillin tazobactam should be reserved for patients who are critically ill and elderly patients over 65 years. The antibiotics should be deescalated once the organisms and sensitivity of the antibiotics are known.