Survey on the Inpatient’s Antibiogram Affected by Sampling Day Difference

Abstract

Objective: Antibiogram preparation is important for the proper selection of antimicrobial agent in empiric therapy. It is recommended to prepare the antibiogram separately for inpatients and outpatients. However, the antimicrobial agent susceptibility of bacteria detected from an inpatient is thought to be different when detected at an early date after admission and after a certain period after admission.

Methods: In this study, we defined the bacteria detected from an inpatient within 3 days after admission as “brought bacteria” and those over 3 days after admission as “bacteria detected after admission.” Antimicrobial agent susceptibilities of brought bacteria and bacteria detected after admission in our hospital between April 2018 and March 2019 were compared for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa.

Results: The occurrence rate of Escherichia coli producing an extended β-lactamase of bacteria detected after admission was found to be significantly higher compared with that of brought bacteria. The sulbactam/ampicillin susceptibility rate of bacteria detected after admission was significantly lower than that of brought bacteria. The occurrence rate of the two drug-resistant Pseudomonas aeruginosa detected after admission tends to be higher compared with that of brought bacteria.

Conclusion: Our findings showed that the susceptibility rate of some drugs differed substantially between brought bacteria and bacteria detected after admission. Therefore, the inpatient’s antibiogram is thought to be prepared by separating bacteria detected at an early date after admission and after a certain period after admission, leading to the proper selection of antimicrobial agent in empiric therapy tailored to a patient’s number of days in the hospital.