Effect of Mannan from Baker's Yeast Saccharomyces cerevisiae on Multidrug-Resistant (MDR) Gram-Negative Bacteria Isolated from Urinary Stones

Mannan is a complex polysaccharide composed of Mannose monosaccharide units that linked by α-(1→6) bonds with branching at α-(1→2) and/or α-(1→3) positions, which expresses diverse biological properties and potential applications. In the current study, a total of 30 stones samples were collected from patients aged 20-50 years suffering from signs and symptoms of urinary tract infections. Results showed that the highest percentage of G-ve bacterial isolates was Escherichia coli (43.3%), followed by Klebsiella pneumoniae (33.3%), The lowest incidence include Pseudomonas aeruginosa (16.7%) and Proteus mirabilis (6.7%). Clinical isolates were examined to ascertain their antibiotic susceptibility profiles and biofilm formation. High resistance rates were observed against ciprofloxacin (100%), gentamicin (69.2%), doxycycline (76.2%) in E. coli isolates, and trimethoprim-sulfamethoxazole (70%), amikacin (70%) in K. pneumoniae. 80% of P. aeruginosa isolates were resistant to ceftriaxone. The biofilm production results demonstrated that out of E. coli isolates 61.5% were identified as a biofilm producers, 50% from K. pneumoniae isolates were biofilm producers, and 60% of P.aeruginosa isolates were biofilm producer. Mannan was extracted and purified from the yeast Saccharomyces cerevisiae and then analyzed using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM). A micro-dilution method was used to test the antibacterial activity of mannan. The results showed that the minimum inhibitory concentration (MIC) of mannan ranged from 12.5 to 50 mg/ml. The activity of mannan on the biofilm formed by grit isolates was also investigated. The results showed that mannan was able to disrupt the biofilm formed by these isolates.