Assessment of bacteriocin production by clinical Pseudomonas aeruginosa isolates and their potential as therapeutic agents.

INTRODUCTION: Bacterial infections and the rising antimicrobial resistance pose a significant threat to public health. Pseudomonas aeruginosa produces bacteriocins like pyocins, especially S-type pyocins, which are promising for biological applications. This research focuses on clinical P. aeruginosa isolates to assess their bacteriocin production, inhibitory spectrum, chemical structure, antibacterial agents, and preservative potential. METHODS: The identification of P. aeruginosa was conducted through both phenotypic and molecular approaches. The inhibitory spectrum and antibacterial potential of the isolates were assessed. The kinetics of antibacterial peptide production were investigated, and the activity of bacteriocin was quantified in arbitrary units (AU ml-1). Physico-chemical characterization of the antibacterial peptides was performed. Molecular weight estimation was carried out using SDS-PAGE. qRT-PCR analysis was employed to validate the expression of the selected candidate gene. RESULT: The antibacterial activity of P. aeruginosa was attributed to the secretion of bacteriocin compounds, which belong to the S-type pyocin family. The use of mitomycin C led to a significant 65.74% increase in pyocin production by these isolates. These S-type pyocins exhibited the ability to inhibit the growth of both Gram-negative (P. mirabilis and P. vulgaris) and Gram-positive (S. aureus, S. epidermidis, E. hirae, S. pyogenes, and S. mutans) bacteria. The molecular weight of S-type pyocin was 66 kDa, and its gene expression was confirmed through qRT-PCR. CONCLUSION: These findings suggest that S-type pyocin hold significant potential as therapeutic agents against pathogenic strains. The Physico-chemical resistance of S-type pyocin underscores its potential for broad applications in the pharmaceutical, hygiene, and food industries.

Comparing the Bacteriostatic Effects of Different Metal Nanoparticles Against Proteus vulgaris.

For many years, researchers were looking for new antibacterial substances to deal with hospital infections and especially resistant infections. Nanoparticles attracted much attentions because of their very small size that increases the surface to capacity ratio and consequently increase chemical activity. In this study, the antibacterial effects of silver, copper oxide, nickel oxide, and titanium dioxide nanoparticles were studied on Proteus vulgaris, as a bacterium involved in the resistant hospital infections. The capability of nanoparticles to inhibit the growth of bacteria was assessed via 9 different methods including cylinder, disk, and well-diffusion, spot test, MBC, MIC, liquid inhibitory action test, diffusion, and assessing the effects of nanoparticles on a 24-h culture. Based on the results, copper oxide and silver nanoparticles had high antibacterial effects on P. vulgaris in both liquid and solid cultures, respectively. However, nickel oxide and titanium dioxide nanoparticles only had a weak effect on the inhibition of bacterial growth in the liquid culture. CuO and Ag NPs could release ions and consequently produce free radicals, disturb the equilibrium of electrons between electron donor groups and inactivate enzymes and DNA of the organisms. Moreover, they triggered holes in the bacterial membrane to disturb cellular ion equilibrium. So, they can be used to inhibit the growth of pathogens. Besides, further studies have shown that they could be used as a supplementary treatment and/or in combination with other drugs to cure infections caused by P. vulgaris.

Synergistic bactericidal activity of a naturally isolated phage and ampicillin against urinary tract infecting Escherichia coli O157.

OBJECTIVES: Bacteriophages are infectious replicating entities that are under consideration as antimicrobial bioagents to control bacterial infections. As an alternative or supplement to antibiotics, bacteriophages can be used to circumvent the resistance to existing antibiotics. The aim of this study was to assess the synergistic effect of a naturally isolated phage and ampicillin against Escherichia coli O157. MATERIALS AND METHODS: In the present study, a natural phage against E. coli O157 was isolated, the morphology and molecular characteristics of the phage were identified, and the combination of bacteriophage and antibiotic to combat clinically isolated drug-resistant E. coli O157 was evaluated. RESULTS: The results showed the synergistic action between a naturally isolated phage and ampicillin in solid (disk diffusion test) and liquid culture media. Addition of the isolated phage, gT0E.co-MGY2, to the microbial lawn of bacteria in modified antibiotic disk diffusion test, altered susceptibility pattern of E. coli O157 from resistant to sensitive based on the inhibition zones. Combinations of bacteriophage and ampicillin significantly enhanced the killing of bacterial strains when compared to treatment with ampicillin or phage alone in liquid culture. Moreover, it lasted few hours for ampicillin to reverse the growth of E. coli O157, while the bacteriophage and combination treatment stopped the proliferation of bacteria from the beginning, and this can compensate the delayed onset of antibiotic action. CONCLUSION: The synergistic action of bacteriophages and antibiotics is an alternative that cannot only be effective against bacterial infections but also contribute to the reduction of antibiotic resistance.