Miniaturized volatile organic compound sensor platform for the real-time monitoring of bacterial growth and...

Rapid and accurate determination of bacterial antibiotic susceptibility is essential for effective therapy and prevention of antimicrobial resistance. However, conventional culture-based assays are time-consuming (≥24 h) and labor-intensive, requiring centralized infrastructure. While rapid approaches such as microfluidics and mass spectrometry have been developed, they are often limited by high cost, complex instrumentation, or poor portability, underscoring the need for simple, field-deployable alternatives.

We developed a miniaturized platform integrating a volatile organic compound (VOC) sensor with thermal regulation and onboard agitation to monitor bacterial growth and antibiotic susceptibility in real time. Optimization of glucose concentration and agitation allowed E. coli O157:H7 to be incubated in sealed vials, with VOC emissions recorded every second. Lag-phase analysis of VOC curves, modeled using a modified Gompertz function, quantitatively estimated bacterial concentration. Antibiotic exposure caused dose-dependent delays or complete suppression of VOC signals, producing MICs of ∼1 μg/mL for enrofloxacin, 8 μg/mL for gentamicin, and 0.7 μg/mL for cefoperazone. Susceptible and resistant phenotypes were correctly classified within 12 h. The platform maintained performance in opaque matrices such as milk without preprocessing and was validated with non-pathogenic E. coli and Salmonella typhimurium, demonstrating accurate detection and strain-specific susceptibility profiles.

This VOC-based miniaturized AST platform enables rapid, label-free assessment of bacterial growth and susceptibility in under 12 h without optics, plating, or extensive sample processing. Its portability and compatibility with diverse pathogens, antibiotics, and opaque samples position it as a promising tool for decentralized diagnostics, point-of-care testing, and food-safety monitoring.