Abstract
Serratia marcescens is an opportunistic nosocomial pathogen and causes wound and burn infections. It shows high resistance to antibiotics and its pathogenicity is mediated by an arsenal of virulence factors. Another therapeutic option to such infections is targeting quorum sensing (QS), which controls the expression of different S. marcescens virulence factors. Prevention of QS can deprive S. marcescens from its bacterial virulence without applying stress on the bacterial growth and facilitates the eradication of the bacteria by immunity. The objective of the current study is to explore the antimicrobial and antivirulence activities of xylitol against S. marcescens. Xylitol could inhibit the growth of S. marcescens. Sub-inhibitory concentrations of xylitol could inhibit biofilm formation, reduce prodigiosin production, and completely block protease activity. Moreover, xylitol decreased swimming motility, swarming motility and increased the sensitivity to hydrogen peroxide. The expression of rsmA, pigP, flhC, flhD fimA, fimC, shlA bsmB, and rssB genes that regulate virulence factor production was significantly downregulated by xylitol. In silico study showed that xylitol could bind with the SmaR receptor by hydrophobic interaction and hydrogen bonding, and interfere with the binding of the natural ligand with SmaR receptor. An in vivo mice survival test confirmed the ability of xylitol to protect mice against the virulence of S. marcescens. In conclusion, xylitol is a growth and virulence inhibitor in S. marcescens and can be employed for the treatment of S. marcescens wound and burn infections.
Highlights
Serratia marcescens is an environmental rod-shaped gram-negative bacterium that belongs to the Enterobacteriaceae family
The S. marcescens clinical isolate used in the current study was obtained from a patient that was admitted to the Intensive Care Unit at Zagazig University Hospital from a surgical wound infection
Xylitol could inhibit the growth of S. marcescens isolate at 400 mg/mL (40% concentration)
Summary
Serratia marcescens is an environmental rod-shaped gram-negative bacterium that belongs to the Enterobacteriaceae family. S. marcescens is an opportunistic microbe that. Microorganisms 2021, 9, 1083 can cause several nosocomial infections [1]. S. marcescens can cause wound and soft tissue infections [2]. S. marcescens is responsible for 11% of open burnrelated surgical wound infections [3], and is one of the gram-negative bacteria that causes invasive burn wound infections [4]. S. marcescens’ pathogenicity is attributed to its arsenal of virulence factors including protease, nuclease, lipase and hemolysin in addition to its ability to swarm and swim and to form biofilm [5]. S. marcescens produces a red pigment, prodigiosin, which possesses different activities against fungi, bacteria and protozoa [6,7]
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