The Inhibition Effect of Lactobacilli Against Growth and Biofilm Formation of Pseudomonas aeruginosa

Abstract

The emergence of antibiotic-resistant and food-spoilage microorganisms has renewed efforts to identify safe and natural alternative agents of antibiotics such as probiotics. The aim of this study was the isolation of lactobacilli as potential probiotics from local dairy products with broad antibacterial and anti-biofilm activities against antibiotic-resistant strains of Pseudomonas aeruginosa and determination of their inhibition mechanism. Antibiotic susceptibility and classification of acquired resistance profiles of 80 P. aeruginosa strains were determined based on Centers for Disease Control and Prevention (CDC) new definition as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) followed by antibacterial assessment of lactobacilli against them by different methods. Among the 80 P. aeruginosa strains, 1 (1.3%), 50 (62.5%), and 78 (97.5%) were PDR, XDR, and MDR, respectively, and effective antibiotics against them were fosfomycin and polymyxins. Among 57 isolated lactobacillus strains, two strains which were identified as Lactobacillus fermentum using biochemical and 16S rDNA methods showed broad inhibition/killing and anti-biofilm effects against all P. aeruginosa strains. They formed strong biofilms and had bile salts and low pH tolerance. Although investigation of inhibition mechanism of these strains showed no bacteriocin production, results obtained by high-performance liquid chromatography (HPLC) analysis indicated that their inhibitory effect was the result of production of three main organic acids including lactic acid, acetic acid, and formic acid. Considering the broad activity of these two L. fermentum strains, they can potentially be used in bio-control of drug-resistant strains of P. aeruginosa.

Effective treatment and decolonization of a dog infected with carbapenemase (VIM‐2)‐producing Pseudomonas aeruginosa using probiotic and photodynamic therapies

“…In summary, this report describes a therapeutic strategy using probiotics and aPDT for the treatment of external ear canal infection and gut decolonization of a high‐risk clone of VIM‐2‐producing P. aeruginosa in a dog. These findings support the results of previous studies that have shown lactobacilli‐based probiotics to be effective against planktonic and biofilm modes of growth of MDR P. aeruginosa clinical isolates …”

“…have been investigated as candidates to reduce gut colonization by multidrug‐resistant (MDR) pathogens. Probiotics can act as microbial barriers through competitive inhibition of pathogen binding sites and prevention of the production of virulence factors, and have shown promising results in laboratory mice . In addition, the use of prebiotics (nutritional ingredients) combined with probiotics could be a tool against MDR‐related colonization, reestablishing the normal gut microbiota …”

<p>Antagonistic Activities of Cell-Free Supernatants of Lactobacilli Against Extended-Spectrum β-Lactamase Producing <em>Klebsiella pneumoniae</em> and <em>Pseudomonas aeruginosa</em></p>

“…The inhibitory compounds produced by lactobacilli include organic acids such as lactic acid, acetic acid, and formic acid or bacteriocins. 8,9 Through these antimicrobial mechanisms, lactobacilli have demonstrated antagonistic activates against different pathogenic bacteria, including carbapenem-resistant Enterobacteriaceae, 10 Escherichia coli, 11 Helicobacter pylori, 12 Salmonella, 13 Shigella, 14 P aeruginosa, 15 and Staphylococcus aureus. 16 However, no previous studies have assessed the antimicrobial activity of lactobacillus against ESBL-producing K pneumoniae or P aeruginosa.…”

Anti-Biofilm Activity of Lactic Acid Bacteria Isolated from Kefir Against Multidrug-Resistant Klebsiella pneumoniae

“…Several studies have screened beneficial bacteria for the natural competitors of pathogenic bacteria in order to prevent colonization or biofilm formation by the latter. Lactobacilli have been extensively studied in this regard because of their remarkable ability to inhibit the growth of pathogenic bacteria by producing bactericidal compounds such as lactic acid as a metabolic by-product, which also includes hydrogen peroxide, diacetyl, and bacteriocin 7,8 . Lactobacillus acidophilus and Lactobacillus fermentum produce antimicrobial compounds that not only inhibit bacterial growth but also inhibit biofilm formation of K. pneumoniae 9 .…”