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

Foodborne illnesses caused by <i>Salmonella</i> represent a global one health challenge, with biofilm-forming strains exhibiting enhanced public health risks due to their ability to persist due to resistance to antimicrobial agents, disinfectants, and environmental stresses. While food-safety and public health investigation primarily focus on <i>Salmonella</i> identification and source tracing, they often overlook the biofilm-forming capacity of isolates, limiting their predictive value for risks posed by biofilm producing <i>Salmonella</i>. This study assessed fourier transform infrared (FTIR) biotyping for rapid serotype-independent differentiatial detection of biofilm-positive (BFP) from biofilm-negative (BFN) <i>Salmonella</i>. A total of 270 <i>Salmonella</i> strains representing 12 common serotypes were classified using three conventional biofilm assays (congo red and coomassie brilliant blue agar test, calcofluor test, and tube test) into true BFP (<i>n</i> = 80), true BFN (<i>n</i> = 64), and uncertain (<i>n</i> = 59) biofilm producers. Biofilm production for each group was also assessed with a microtiter plate assay. FTIR biotyping was applied to a subset of 115 strains (61 BFP, 54 BFN). Using spectral windows of 1180-1050 cm^-1 and 1400-1200 cm^-1, FTIR biotyping accurately differentiated BFP from BFN strains with 93.4 % sensitivity, 83.3 % specificity, and 88.6 % overall accuracy. FTIR biotyping differentiated 59 strains with uncertain biofilm status into BFN (<i>n</i> = 45) and BFP (<i>n</i> = 14). FTIR biotyping provides a rapid, sensitive and specific method for detection of biofilm-forming <i>Salmonella</i> strains. Incorporating FTIR biotyping for biofilm detection in current <i>Salmonella</i> surveillance and source-tracing protocols can enhance food safety risk assessments and improve <i>Salmonella</i> outbreak prevention.