Rapid serotype-independent differential detection of biofilm-positive and biofilm-negative Salmonella using Fourier transform infrared biotyping

Abstract

Foodborne illnesses caused by Salmonella represent a significant public health threat globally, with biofilm-forming strains exhibiting enhanced food safety risks due to their ability to persist due to resistance to antimicrobial agents, disinfectants, and environmental stresses. While conventional Salmonella detection methods are effective for identification and source tracing, they often overlook the biofilm-forming capacity of isolates, limiting their predictive value for food safety risks. This study assessed Fourier Transform Infrared (FTIR) biotyping system, for its ability to rapidly differentiate biofilm-positive (BFP) from biofilm-negative (BFN) Salmonella strains, independent of serotype. A total of 270 Salmonella strains were classified using three conventional biofilm assays (Congo Red and Coomassie Brilliant Blue agar test, calcofluor test, and tube test) into true BFP ( n = 80), true BFN ( n = 64), and uncertain ( n = 59) biofilm producers. Biofilm production for each group was confirmed with a microtiter plate assay. FTIR biotyping was then applied to a subset of 115 strains (61 BFP, 54 BFN) representing 12 common serotypes. Using spectral windows of 1180–1050 cm −1 and 1400–1200 cm −1 , FTIR biotyping accurately differentiated BFP from BFN strains. Hierarchical clustering achieved 93.4 % sensitivity, 83.3 % specificity, and 88.6 % overall accuracy. FTIR biotyping differentiated 59 strains with uncertain biofilm status into BFN ( n = 45) and BFP ( n = 14). FTIR biotyping provides a rapid, objective, and cost-effective method for distinguishing biofilm-forming Salmonella strains, addressing a critical gap in current surveillance methods. Its application could enhance food safety risk assessments and improve outbreak prevention by incorporating testing of biofilm production into pathogen detection. • Salmonella -induced foodborne illnesses are a global one health concern causing millions of infections and deaths annually. • Biofilm-forming Salmonella strains pose greater food safety and public health risks due to their enhanced resistance to disinfectants, antimicrobials, and environmental stresses. • FTIR biotyping offers a rapid, reliable method for differentiating between biofilm-positive and biofilm-negative Salmonella strains. • Integrating FTIR-based biofilm detection into Salmonella surveillance could enhance food safety risk assessments and strengthen outbreak prevention strategies.

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