220D-F2 from Rubus ulmifolius Kills Streptococcus pneumoniae Planktonic Cells and Pneumococcal Biofilms

Abstract

Streptococcus pneumoniae (pneumococcus) forms organized biofilms to persist in the human nasopharynx. This persistence allows the pneumococcus to produce severe diseases such as pneumonia, otitis media, bacteremia and meningitis that kill nearly a million children every year. While bacteremia and meningitis are mediated by planktonic pneumococci, biofilm structures are present during pneumonia and otitis media. The global emergence of S. pneumoniae strains resistant to most commonly prescribed antibiotics warrants further discovery of alternative therapeutics. The present study assessed the antimicrobial potential of a plant extract, 220D-F2, rich in ellagic acid, and ellagic acid derivatives, against S. pneumoniae planktonic cells and biofilm structures. Our studies first demonstrate that, when inoculated together with planktonic cultures, 220D-F2 inhibited the formation of pneumococcal biofilms in a dose-dependent manner. As measured by bacterial counts and a LIVE/DEAD bacterial viability assay, 100 and 200 µg/ml of 220D-F2 had significant bactericidal activity against pneumococcal planktonic cultures as early as 3 h post-inoculation. Quantitative MIC’s, whether quantified by qPCR or dilution and plating, showed that 80 µg/ml of 220D-F2 completely eradicated overnight cultures of planktonic pneumococci, including antibiotic resistant strains. When preformed pneumococcal biofilms were challenged with 220D-F2, it significantly reduced the population of biofilms 3 h post-inoculation. Minimum biofilm inhibitory concentration (MBIC)50 was obtained incubating biofilms with 100 µg/ml of 220D-F2 for 3 h and 6 h of incubation. 220D-F2 also significantly reduced the population of pneumococcal biofilms formed on human pharyngeal cells. Our results demonstrate potential therapeutic applications of 220D-F2 to both kill planktonic pneumococcal cells and disrupt pneumococcal biofilms.

The Small Molecule DAM Inhibitor, Pyrimidinedione, Disrupts Streptococcus pneumoniae Biofilm Growth In Vitro

“…Moreover, the emergence of antibiotic resistant pneumococcal strains necessitates the identification of alternative drug targets and new antimicrobial compounds that could be effective against pneumococcal biofilms. Effective anti-biofilm strategies could inhibit initial bacterial attachment and colonization, interfere with signaling pathways important for biofilm development, or disrupt the biofilm matrix [ 19 , 20 , 21 ].…”

Pneumococcal Biofilms and Their Intervention Strategies

“…In another study of the plant extract of Rubus ulmifolius Schott., rich in ellagic acid, and ellagic acid derivatives, inhibited the formation of pneumococcal biofilms in a dose-dependent manner. As measured by viability assay, 100 and 200 mg/ml of 220D-F2 had significant bactericidal activity against pneumococcal planktonic cultures as early as 3 h post-inoculation having MIC's 80 mg/ml of 220D-F2 which completely eradicated overnight cultures of planktonic Pneumococci [39].…”

Otitis media pathogens – A life entrapped in biofilm communities

“…For instance, bacterial autolysin LytA and the and phage lysozymes Cpl-1 and Cpl-7 reduced around 80%, 70% and 55%, respectively (Domenech et al 2011). Other proposed alternative or adjuvant antimicrobial therapies to fight pneumococcal biofilms include xylitol (Kurola et al 2011), HAMLET (a natural complex from human milk) (Laura R. , plant extracts or essential oils (Yadav et al 2013;Talekar et al 2014;Minami et al 2017), ceragenins (Moscoso et al 2014), nitric oxide (Allan et al Allan et al 2017), zinc oxide nanoparticles (Bhattacharyya et al 2018), flavonoids (Wang et al 2018), and even human amniotic/chorionic membrane extracts (Yadav et al 2017), among others.…”