# Can flow cytometry be an alternative method for the detection of antimicrobial resistance?

## TL;DR

This study explores using flow cytometry as a fast and reliable method to detect antibiotic resistance in E. coli and P. aeruginosa.

## Contribution

The study introduces a novel flow cytometry-based approach for rapid detection of ESBL and MDR bacteria.

## Key findings

- Flow cytometry efficiently identified cells with damaged membranes after antibiotic exposure.
- The method detected ESBL E. coli and MDR P. aeruginosa with high accuracy.
- CLA index values above 1.5 indicated resistance in a majority of tested isolates.

## Abstract

The inappropriate use of antibiotics may cause antibiotic resistance, cause side effects, and eventually cause an increase in healthcare costs. This study aimed to determine a flow cytometry-based test to detect ESBL E. coli and MDR P. aeruginosa in a short time.

The study included 25 E.coli isolates and 25 P.aeruginosa isolates identified by Phoenix TM 100 automated system [Becton Dickinson, USA]. In the flow cytometric method, the percentages of death cells exposed to cephalosporin including ceftazidime [CAZ] or cefotaxime [CTX] and clavulanic acid [CLA] combination, were compared with death cells exposed only to a cephalosporin [CAZ or CTX]. CLA index values [CAZ-CLA and CTX-CLA indices] were obtained for CTX and CAZ. Index values that were higher than 1.5 just for one cephalosporin were accepted as positive.

Cell viability was performed after 1-hour exposure to the drugs. When PI staining was applied to ESBL-treated and MDR-treated bacteria, 65% and 85% had nonviable membranes, indicating the method efficiently identified only cells with damaged membranes.

Flow cytometry is a rapid and reliable method for the detection of ESBL and MDR in clinical microbiology laboratories