Journal Article

Direct identification and antimicrobial susceptibility testing of microorganisms from positive blood culture bottles using a membrane filtration method

Liu, Tsui-Ping, Chang, Pai-Ling, Wu, Hui-Fang

2025

Overview

Background Bloodstream infections (BSIs) are a major cause of morbidity and mortality globally. Rapid and accurate pathogen identification and antimicrobial susceptibility testing (AST) are crucial for timely and effective treatment. Conventional blood culture (BC) workflows are time-consuming, typically requiring 18–48 h. Although integrating matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with direct AST protocols is promising, certain limitations remain. Therefore, we aimed to establish a faster and more reliable method for the direct identification and AST of microorganisms from positive BC bottles using a membrane filtration-based protocol. Results The membrane filtration-based method achieved an overall identification success rate of 76.5%. Rates were highest for Gram-negative bacteria (88.1%), followed by anaerobes (80.0%), Gram-positive cocci (70.2%), and Gram-positive bacilli (43.8%). Yeast identification was unsuccessful. AST results showed strong concordance with those from the conventional method, with essential agreement (EA) exceeding 95% across all groups. For Gram-negative bacteria, EA was 98% and categorical agreement (CA) was 95.4%, with 3.6%, 0.5%, and 0.5% minor, major, and very major errors, respectively. EA and CA were 96.1% and 94.2% for Gram-positive cocci, and 95.5% and 93.4% for Streptococcus spp. Conclusions The membrane filtration-based method, effective for Gram-negative bacteria, reduced turnaround time by 10–12 h compared to conventional workflows. Further optimization can improve accuracy for Gram-positive bacteria and yeast, offering a promising, streamlined workflow to enhance BSI diagnostics and guide targeted antimicrobial therapy.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Anaerobes / Anti-Bacterial Agents - pharmacology / Anti-infective agents / Antimicrobial susceptibility testing / Bacteremia / Bacteremia - diagnosis / Bacteremia - microbiology / Bacteria / Bacteria - classification / Bacteria - drug effects / Bacteria - isolation & purification / Biological Microscopy / Biomedical and Life Sciences / Blood / Blood culture / Blood Culture - methods / Bloodstream infection / Bottles / Care and treatment / Complications and side effects / Diagnosis / Disease susceptibility / Dosage and administration / Filtration / Filtration - methods / Gram-negative bacteria / Gram-Negative Bacteria - drug effects / Gram-Negative Bacteria - isolation & purification / Gram-positive bacilli / Gram-positive bacteria / Gram-positive cocci / Humans / Identification / Ionization / Laboratories / Life Sciences / MALDI-TOF MS / Mass spectrometry / Mass spectroscopy / Medical examination / Membrane filtration / Membrane filtration method / Membrane separation / Membranes / Methods / Microbial Sensitivity Tests - methods / Microbiology / Microorganisms / Morbidity / Mortality / Mycology / Parasitology / Pathogens / Proteins / Rapid identification / Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Success / Testing / Virology / Yeast