Comparative Evaluation of EUCAST RAST and VITEK 2 AST in Cancer Patients with Bloodstream Infections: A Prospective Observational Study

Abstract Background: Early initiation of targeted antibiotic therapy is essential for effective management of sepsis to reduce morbidity, mortality, cost of treatment and prevent antibiotic resistance. With the available microbiological reporting system, the turnaround time to report a positive blood culture is 48-72 hours. We aim to conduct a study to evaluate EUCAST (European Committee on Antimicrobial Susceptibility Testing) RAST (rapid antimicrobial susceptibility test) method from positive blood cultures in comparison with automated Vitek2 AST system in our cancer set up. Method: This is a prospective study conducted over period of one year. All positively flagged blood culture bottles showing monomicrobial gram negative bacilli or gram positive cocci in gram stain were included in study. Positively flagged blood culture bottles were processed simultaneously as per EUCAST RAST and by routine methodology. Results: The drug bug combinations as per EUCAST RAST was evaluated for 26 Escherichia coli, 17 Klebsiella pneumoniae and 7 Psuedomonas aeruginosa isolates for meropenem, imipenem, piperacillin tazobactam, ceftazidime ,amikacin, levofloxacin, ciprofloxacin, cefepime, cotrimoxazole, gentamicin and ceftriaxone. Overall Categorial Agreement is 92.13% at 6 hours. Overall VME, ME and mE was 1.11%, 3.61% and 5.61% respectively. Conclusions: EUCAST RAST can be implemented in routine work flow to guide clinicians regarding antimicrobial choice at early stage.