<i>Allium ursinum</i> and <i>Allium oschaninii</i> against <i>Klebsiella pneumoniae</i> and <i>Candida albicans</i> Mono- and Polymicrobic Biofilms in In Vitro Static and Dynamic Models

• Main Authors: Emilia Galdiero, Valeria Di Onofrio, Angela Maione, Edvige Gambino, Renato Gesuele, Bruno Menale, Martina Ciaravolo, Federica Carraturo, Marco Guida
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Microorganisms
• Subjects: polymicrobial biofilm; cdc biofilm reactor; <i>allium</i> extracts; <i>klebsiella pneumoniae</i>; <i>candida albicans</i>
• Online Access: https://www.mdpi.com/2076-2607/8/3/336

The present study assesses the in vitro antibiofilm potential activity of extracts of wild <i>Allium</i> <i>ursinum </i>and <i>Allium</i> <i>oschaninii</i>. The active ingredients of the extracts were obtained with a technique named Naviglio (rapid solid&#8722;liquid dynamic extraction, RSLDE) which is based on an innovative and green solid&#8722;liquid extraction methodology. The extracts were tested against models of mono- and polymicrobial biofilm structures of clinically antibiotic-resistant pathogens, <i>Klebsiella pneumoniae</i> ATCC 10031 and <i>Candida albicans</i> ATCC 90028. Biofilms were studied using a static and a dynamic model (microtiter plates and a CDC reactor) on three different surfaces reproducing what happens on implantable medical devices. Antimicrobic activities were determined through minimum inhibitory concentration (MIC), while antibiofilm activity was assessed by minimum biofilm eradication concentration (MBEC) using a crystal violet (CV) biofilm assay and colony forming unit (CFU) counts. Results showed that both <i>Allium</i> extracts eradicated biofilms of the tested microorganisms well; biofilms on Teflon were more susceptible to extracts than those on polypropylene and polycarbonate, suggesting that when grown on a complex substrate, biofilms may be more tolerant to antibiotics. Our data provide significant advances on antibiotic susceptibility testing of biofilms grown on biologically relevant materials for future in vitro and in vivo applications.