Interference of Lactobacillus casei with Pseudomonas aeruginosa in the treatment of infected burns in Wistar rats

Abstract

Objectives: Burns are the most common type of trauma with a high mortality rate worldwide. The use of modern and natural medicines, especially probiotic products, has been recently considered for cutaneous wound healing. The present study was designed to investigate the effect of Lactobacillus casei on wound healing caused by Pseudomonas aeruginosa.

Materials and methods: In this study, the anti-adhesion activity of L. casei was examined by the glass slide method, and inhibitory substances in the cell-free supernatant (CFS) were quantified by high-performance liquid chromatography (HPLC). Following the induction of second-degree wounds, multidrug-resistant (MDR) P. aeruginosa was injected subcutaneously and directly on the burn. The animals were divided into four groups. The supernatant of L. casei was sprayed for treatment every day and wound healing was examined.

Results: Based on our findings, the supernatant of L. casei showed considerable anti-adhesion effects on P. aeruginosa. HPLC analysis indicated that the inhibitory effect of this supernatant can be due to four main organic acids including lactic acid, acetic acid, citric acid, and succinic acid. The effect of treatment on fibroblastic cells showed that the treated group by supernatant of L. casei had more fibroblastic cells compared with the non-treated group. Moreover, this supernatant increased the rate of fibroblastic cells, re-epithelialization in the wound area, and the largest thickness of the epidermis and dermis layers.

Conclusion: The present findings showed that L. casei supernatant significantly reduced inflammation and could be used to treat P. aeruginosa infection in second-degree burns.

Keywords: Biofilms; Multidrug-resistant; Probiotics; Pseudomonas infections; Wound healing.

Figure 1

Pseudomonas aeruginosa biofilm formation on the glass slide

Figure 2

Scanning electron microscopy (SEM) of Pseudomonas aeruginosa biofilm cells

Figure 3

Pseudomonas aeruginosa adhesion on the glass slide. 1: Control group (in the absence of Lactobacillus casei supernatant). 2: Experimental group (in the presence of L. casei supernatant)

Figure 4

Presence of different organic acids analyzed by HPLC. LA: lactic acid, AA: acetic acid, CA: citric acid, SA: succinic acid

Figure 5

The appearance of the burn wound area in treated groups with (supernatant of L.casei and Silver sulfadiazine) at Wistar rats on; A. 21 days and B. 28 days

Figure 6

1. H&E staining showing the histological changes of mouse skin in the unburned and burned mice; 6. 1. H&E appearance of unburned and burned mouse skin on the 21^st day; (a. Normal skin b. Negative control group c. Group treated by the supernatant of Lactobacillus casei d. Group treated by silver sulfadiazine), 6. 2. H&E appearance of unburned and burned mouse skin on the 28^th day; (a. Normal skin b. Negative control group c. Group treated by the supernatant of Lactobacillus casei d. Group treated by silver sulfadiazine)