Introduction: The biofilm formation by Pseudomonas aeruginosa seems to protect the bacteria from antibiotics since these entities are highly resistant to such antimicrobial agents. The aim of this study was to investigate the role of Lactobacillus salivarus, Lactobacillus plantarum supernatants and CuII Schiff base complex in eliminating planktonic cells and biofilm of P. aeruginosa.
Methods: One hundred specimens of blood, urine, cerebrospinal fluid, respiratory samples, and wound swabs were collected from patients attending three hospitals in Mashhad. All specimens were identified by biochemical tests. The susceptibility of the isolates to the conventional antibiotics was assessed using disk diffusion method. The biofilm formation ability of P. aeruginosa isolates was evaluated by crystal violet assay and confirmed using PCR. The anti-planktonic and antibiofilm ability of L. salivarus, L. plantarum supernatants and CuII Schiff base complex was evaluated separately in P. aeruginosa isolates.
Results: The highest and lowest resistance rates were detected in Cefazoline (95%) and cefepime (23%), respectively. The thickest biofilm was produced by 8% of P. aeruginosa isolates, 9% and 83% of the isolates were considered as moderate and weak biofilm producers, respectively. The rhlR and lasR genes were reported in 100% of the isolates, but the algD gene existed in 92% of them.
Conclusion: Particularly, the CuII Schiff base complex could affect both planktonic and biofilm cells by the lowest concentration in comparison of probiotic supernatants. L. plantarum supernatant inhibited planktonic cells at a lower concentration than L. salivarius. Also, L. salivarius showed better antibiofilm activity than another probiotic in lower doses of supernatant. Unlike that, these compounds have not completely eliminated biofilm cells, but only reduced the biofilm formation.
Metal Schiff base complex and Lactobacillus supernatants is a potent antimicrobial agent against Pseudomonas aeruginosa biofilm cells.
Keywords: Pseudomonas aeruginosa, biofilm, probiotic, CuII Schiff base, resistance, antimicrobial agent.