Antibacterial and antibiofilm activity of cinnamic acid against Multidrug-resistant bacteria isolated from Ramadi Teaching hospitals, Iraq

Various bacterial pathotypes remain a significant public health concern due to their pathogenicity and antimicrobial resistance. Moreover, the ability of bacteria to form biofilms can hinder host defense and antimicrobial eradication, leading to additional resistance. This study aimed to estimate the cinnamic acid's anti-biofilm activity against biofilms-producing bacteria. From October to November 2023, various clinical isolates were obtained from the Bacteriology Unit, Ramadi Teaching Hospital, Iraq. All isolates were identified using a conventional and automated VITEK-2 compact system. Based on the Clinical and Laboratory Standards Institute (CLSI) guidelines and the European Committee on Antimicrobial Susceptibility Testing (EUCAST), the Kirby- Bauer disk diffusion and AST were performed for antimicrobial susceptibility. Biofilm formation was estimated using a 96-well Enzyme-linked immunosorbent assay (ELISA) reader. Based on the antimicrobial susceptibility test,  all bacterial isolates showed antibiotic resistance, including Kleibsella  pneumonieae, Psuedomonas aeruginosa, Escherichia coli and Staphylococcus aureus. The data showed that MICs of cinnamic acid against bacteria were 125 μg /ml.The biofilms formed by all isolates exhibited strong strength (OD570 : 0.078-0.099). Cinnamic acid demonstrated significant inhibition of biofilm production in Multidrug resistance (MDR) bacteria (P-value = 0.0236). The results indicated that Cinnamic acid could be a promising anti-infective agent based on its ability to inhibit MDR-bacterial infections through biofilm formation.