Zinc as an agent for the prevention of biofilm formation by pathogenic bacteria

Abstract

Aims: Biofilm formation is important for the persistence of bacteria in hostile environments. Bacteria in a biofilm are usually more resistant to antibiotics and disinfectants than planktonic bacteria. Our laboratory previously reported that low concentrations of zinc inhibit biofilm formation of Actinobacillus pleuropneumoniae. The aim of this study is to evaluate the effect of zinc on growth and biofilm formation of other bacterial swine pathogens. Methods and Results: To determine the effect of zinc on biofilm formation, biofilms were grown with or without zinc in 96-well plates and stained with crystal violet. At micromolar concentrations (0-250 l mol l À1 ), zinc weakly inhibited bacterial growth and it effectively blocked biofilm formation by A. pleuropneumoniae, Salmonella Typhymurium and Haemophilus parasuis in a dose-dependent manner. Additionally, biofilm formation of Escherichia coli, Staphylococcus aureus and Streptococcus suis was slightly inhibited by zinc. However, zinc did not disperse preformed biofilms. To determine whether zinc inhibits biofilm formation when poly-N-acetylglucosamine (PGA) is present, PGA was detected with the lectin wheat germ agglutinin. Only A. pleuropneumoniae and Staph. aureus biofilms were found to contain PGA. Conclusion: Zinc used at nonbactericidal concentrations can inhibit biofilm formation by several Gram-negative and Gram-positive bacterial swine pathogens. Significance and Impact of Study: The antibiofilm activity of zinc could provide a tool to fight biofilms, and the nonspecific inhibitory effect may well extend to other important human and animal bacterial pathogens.

Increased Zinc Availability Enhances Initial Aggregation and Biofilm Formation of Streptococcus pneumoniae

“…Interestingly, evidence shows the importance of zinc for surface protein interactions that contribute to aggregation and biofilm formation of Staphylococcus aureus , another significant human pathogen (Conrady et al, 2008; Formosa-Dague et al, 2016). However, in contrast, high concentrations of zinc have also been shown to inhibit biofilm formation in the Gram-positive organism Streptococcus suis (Wu et al, 2013). …”

Deletion of the znuA virulence factor attenuates Actinobacillus pleuropneumoniae and confers protection against homologous or heterologous strain challenge

“…This may be explained by the ability of DznuA to acquire Zn 2+ by the ABC transporter, and through other processes, such as peptide uptake and degradation in vivo. In addition, there is some evidence that zinc inhibits biofilm formation by many respiratory pathogens, such as A. pleuropneumoniae (Wu et al, 2013). However, it remains to be confirmed that the attenuation * This pig was not challenged and was euthanised at the same time as the other surviving pigs for use as a negative control.…”

High-Throughput Microfluidic Method To Study Biofilm Formation and Host-Pathogen Interactions in Pathogenic Escherichia coli

“…The assay of biofilm formation in microtiter plates was adapted from the work of Wu et al (16) and is sum- 1. Briefly, colonies of E. coli on LB agar were resuspended in 5 ml of fresh LB and were incubated at 37°C with shaking (180 rpm) for 16 h. These cultures were then diluted (1:100) in 5 ml of M9 medium with glucose (0.4%, wt/vol) and were incubated at 37°C with shaking (180 rpm) for 24 h. A 1-ml volume was transferred to a 1.5-ml Eppendorf tube, and the bacteria were collected by centrifugation (14,000 ϫ g, 2 min).…”