Antagonistic Activities of Cell-Free Supernatants of Lactobacilli Against Extended-Spectrum β-Lactamase Producing Klebsiella pneumoniae and Pseudomonas aeruginosa

Abstract

Aim

This study aimed to describe the inhibitory activity of cell-free supernatants (CFS) of lactobacilli against extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae (K pneumoniae) and Pseudomonas aeruginosa (P aeruginosa).

Material and Methods

Pathogenic clinical strains of K pneumoniae and P aeruginosa were isolated from urine samples and selected for investigation. Anti-bacterial activities of the CFS of lactobacilli were assessed by agar well diffusion, MTT assay, as well as time-kill tests. In addition, the antibiofilm characteristics were analyzed by the microplate method against fresh and 24 h-old biofilms. The ability of CFS to interfere with bacterial invasion was analyzed by flow cytometry.

Results

Although all tested strains were ESBL producers and showed a multidrug-resistant phenotype, the CFS displayed a high anti-ESBL activity with inhibition zone diameters greater than 13 mm in the agar well diffusion assays against both pathogens. The growth kinetics of K pneumoniae and P aeruginosa were dramatically decreased in the presence of the CFS. The CFS not only inhibited the biofilm formation by these pathogens but also was able to remove the 24-h formed biofilms. The invasion abilities of FITC-labelled K pneumoniae decreased from 30.3%±7 to 15.4%±5 and invasion of FITC-labelled P aeruginosa was reduced from 36.9%±7 to 25.2%±5.

Conclusion

CFS of lactobacilli exhibit anti-ESBL activities, which suggests its potential application for controlling or preventing colonization of infections caused by ESBL-producing bacteria.

Keywords:

• lactobacilli
• antibiofilm
• ESBL
• K pneumoniae
• P aeruginosa

Acknowledgment

We would like to thank the Drug Research Xenter and the Medical Research Center at Assiut University for providing the necessary research equipment.

Abbreviations

ESBL, extended-spectrum β-lactamase; CFS, cell-free supernatants.

Disclosure

The authors report no conflicts of interest in this work.