ObjectiveStaphylococcus aureus is considered an important pathogen with a variety of virulence factors in communities and hospitals all around the world. Prophage typing is a practical technique for categorizing this bacterium. In this study, we focused on the detection of prophage patterns in methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains based on their virulence factors, antimicrobial resistance patterns, and molecular typing by rep-PCR.ResultsOut of 126 S. aureus isolates, 45 (35.7%) were identified as MRSA. In total, 17 different prophage types were detected and 112 strains out of 126 strains contained at least one prophage. There was a statistically significant relationship between hld, hlg, eta and SGA, SGA, and SGFb, respectively. The results of the rep-PCR analysis revealed 14 different patterns among the MRSA and MSSA isolates. In conclusion, the presence of different prophage-encoded virulence factors and antibiotic-resistant genes among MRSA strains enables them to produce a broad range of diseases. Thus, diverse MRSA strains which have these prophages can be considered as a potential threat to the patient’s health in either the hospital or the community.

The clinical significance of vancomycin-intermediate S. aureus (VISA) infections is intensified by its tendency to develop resistance to antimicrobials and persistent infections. The decreasing effectiveness of the antimicrobials available is now seriously compromised; thus, there is an emergent need to invent new classes of antimicrobial agents that can rapidly and efficiently eradicate infections. Fe3O4@SiO2@chitosan (CS) nanocomposites were successfully synthesized and then decorated with nisin to gain Fe3O4/SiO2/CS/nisin-based magnetic nanostructures (Fe3O4@SiO2@CS-NISIN). The nanomaterials were characterized comparatively via FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), FE-SEM (field emission scanning electron microscopes), DLS (dynamic light scattering), and VSM (vibrating sample magnetometer) methods. The methyl thiazol tetrazolium (MTT) assay was performed to determine the inhibitory effects of antibacterial agents on the cell viability. The in vitro bactericidal effect of all compounds was characterized using the microdilution assay. Finally, the topical antibacterial efficacy of free nisin, Fe3O4@SiO2@CS, and Fe3O4@SiO2@CS-NISIN nanocomposites against murine superficial wound infection models was determined. The functionalized nanocomposites were more efficient in suppressing bacterial growth in vitro and in vivo compared to the same quantities of untargeted nanocomposites. MTT results showed acceptable biocompatibility of all nanoformulations, and no substantial difference in the cell viability was recorded between treated cells and untreated control. These results suggest that Fe3O4@SiO2@CS-NISIN nanocomposites can be served as an alternative antimicrobial agent in innovative and emerging technologies to treat a variety of staphylococcal infections.

Background and Objectives: Staphylococcus aureus is one of the most common causes of food poisoning. This study aimed to identify S. aureus isolated from pastries, the virulence factors, antimicrobial resistance patterns, biofilm formation, and then classification based on SCCmec types, phage types, and also Rep types. Materials and Methods: In this study, 370 creamy and dried pastry samples have been randomly collected from different confectioneries in Hamadan city. The S. aureus isolates were identified by conventional microbiological methods and nuc gene amplification. The virulence factors and prophage genes were detected. After that, the biofilm production and antibiotic susceptibility assay of S. aureus isolates were examined. Finally, the isolates were classified by rep-PCR typing. Results: Among 370 samples, 97 creamy (34.64%) and 3 dried (3.33%) pastry samples were contaminated with S. aureus. Antibiotic sensitivity results showed the highest resistance to penicillin (90%) but none of them were MRSA. According to biofilm formation assay, 14 strains (45%) were strongly adhesive. The dominant phage among isolates was SGF, especially SGFa subgroup. About half of the isolates carried SCCmec Types I and III. Analysis of the genetic linkage between isolates by rep-PCR showed ≥80% genetic similarity and also different rep-types of S. aureus isolates. Conclusion: The presence of different prophage encoded virulence factors and antibiotic resistance enable S. aureus strains to produce a broad range of diseases. Thus, consumption of creamy pastries increases the risk of infection with S. aureus and it is a serious warning to the health system.

Objectives Staphylococcus aureus and Pseudomonas aeruginosa were the most common bacteria in nosocomial infections. Different bacteriocins are currently being studied as antibiotics or in conjunction with antibiotics as potential strategies to treat resistant infectious agents. The study aimed to determine nisin's effect on the biofilm production, antimicrobial susceptibility, and biofilm formation of S. aureus and P. aeruginosa. Materials and methods The experimental research tested two antibiotic-resistant isolates of S. aureus and P. aeruginosa strains. The experimental study tested two antibiotic-resistant isolates of S. aureus and P. aeruginosa strains. The MIC of bacteriocin nisin was determined using the micro broth dilution method, and crystal violet was used to assess the effect of bacteriocin on the biofilm. In addition, L929 cell culture was used to determine the effectiveness of bacteriocin on the isolate under similar cell conditions. Moreover, the MTT assay was used to and evaluate bacteriocin toxicity. In this study, the software Prism version 9 and Graph pad software were utilized. Results The results of this study reveal that the nisin has different activities at different doses and is considered dose-dependent. At various times and doses, nisin inhibits biofilm formation in S. aureus, and P. aeruginosa isolates. Nisin also showed a decreasing survival of the isolates. Antibiotic-resistant bacteria can be made more vulnerable by nisin. Furthermore, nisin treatment affected the production of virulence factors such as hemolysins in S. aureus and had little or a negative effect on P. aeruginosa virulence factors. This medication stops S. aureus and P. aeruginosa from growing and causes bacterial cell damage. Conclusions Antibacterial properties of nicin against S. aureus and P. aeruginosa were successfully studied. This bacteriocin stops S. aureus and P. aeruginosa from growing and causes bacterial cell damage or death. Damage to the membrane among the fundamental causes is reduced membrane potential and enzyme inactivation.