Rationalising empirical antibiotics for bloodstream infections: A retrospective study at a South African district-level hospital

Abstract

Background. Incorrect empirical antibiotic therapy is one of the factors that contribute to poor clinical outcomes and the development of antimicrobial resistance. Knowledge of the local infectious disease burden and antibiotic resistance patterns can assist with development of strategies, updating of guidelines and subsequent improvement in initial empirical therapy. Objectives. To determine whether the empirical antibiotic choice for treatment of septic episodes at a district-level hospital was appropriate according to national guidelines, and to describe the epidemiological features of the septic episode population being studied and depict their antibiotic susceptibility profile. Methods. This was a retrospective, descriptive study of adult inpatients with bloodstream infections at Karl Bremer Hospital, Cape Town, South Africa. Laboratory and clinical data were obtained and analysed for the period 1 July 2017 - 30 June 2018. Septic episodes were subdivided into community-acquired bloodstream infection (CABSI) and hospital-acquired bloodstream infection (HABSI) study populations, and empirical antibiotics for both groups were assessed and compared with the adult Standard Treatment Guidelines and Essential Medicines List for South Africa, Hospital Level Care, 2015 edition (STG and EML). Results. Our study sample consisted of 184 septic episodes, isolated from 176 patients. Nearly half of the septic episodes (49.5%) were hospital acquired. Overall guideline adherence in the CABSI population was 88%, compared with 58% in the HABSI population. The reasons for guideline non-adherence in the CABSI population were lack of source-appropriate empirical antibiotics (n=7) and septic episodes where empirical antibiotics were indicated but not prescribed (n=4), while in the HABSI group the main reason was that the patients were treated by community-acquired standards (n=30; 33.0%). The in-hospital mortality rate for a septic episode in this study was 38%. Considering the typical first-line antibiotics used, 77.3% of CABSIs were found to be susceptible to co-amoxiclav (n=75) and 59.8% to ceftriaxone (n=58). With the exclusion of methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii isolates as confounders, HABSIs had a susceptibility of 86% to the piperacillin/tazobactam plus amikacin combination, 81% to ertapenem, 90% to imipenem and 93% to meropenem. Conclusions. This study demonstrates poor guideline adherence in HABSIs, emphasising the importance of distinguishing between CABSIs and HABSIs. The empirical antibiotics advised by the STG and EML were found to be appropriate in the majority of septic episodes. Future revision and improvement of prescribing practices can assist in rationalising empirical antibiotic decisions.