ABSTRACT
        Background and objectives: Synthesis and characterization of several metal complexes (metal ions: Co2+, Ti4+ and Ce3+) of macroacyclic Schiff base ligand have been reported. The Schiff base ligand is prepared from the condensation reaction of 1, 4-di-(4-fluoro-2-aminophenoxy) butane with salicylaldehyde in ethanol. In addition, antibacterial activity of metal ions, Schiff base ligand and their complexes have been investigated. Recent studies show that many Schiff base complexes have antibacterial activity against Gram-positive and Gram-negative bacteria. Therefore, we aimed to synthesize new Schiff base complexes and evaluate their antibacterial activity against a number of Gram-positive and Gram-negative bacteria.
         Methods: Schiff base ligand and their complexes were characterized by mass spectrometry and IR, H-NMR and C-NMR spectroscopy. The in vitro antibacterial activity of the Schiff base ligand, metal ions and their complexes were evaluated against some Gram-positive and Gram-negative bacteria by disk diffusion method and determining minimum inhibitory concentration.
          Results: In this study, the Schiff base complexes had good antibacterial activity, but the Schiff base ligand and metal ions did not show any antibacterial effect. In some cases, the antibacterial effect of the complexes was higher than that of the standard antibiotics tetracycline and gentamycin. The titanium complex showed the highest antibacterial activity in both methods. This complex created the largest growth inhibition zone (diameter: 100mm) against Staphylococcus aureus, and had the lowest minimum inhibitory concentration against Bacillus subtilis (6.75 mg/ml).
          Conclusion: The compounds synthesized in our study have strong antibacterial activity.
          Keywords: Schiff base complex, Schiff base ligand, antibacterial activity, Staphylococcus aureus, Bacillus subtilis.

ABSTRACT
       Background and Objectives: Mastitis caused by Staphylococcus aureus is a widely distributed disease in cattle, goats and sheep. The infection is often subclinical in cattle, leading to reduced milk production and quality, but acute catarrhal or even gangrenous inflammation may also occur. The aim of this study was to investigate resistance of S. aureus isolates from bovine subclinical mastitis to a number of antibiotics.
          Methods: Milk samples were collected from 120 cows in different regions of Tabriz, Iran. Milk samples were cultured and bacteriological identification was performed. Antimicrobial susceptibility of the isolates was assessed by determining minimum inhibitory concentration. Plasmid DNA was extracted by an alkaline lysis method. 
         Results: The highest frequency of resistance was observed against gentamicin (100%) and β- lactam antibiotics including amoxicillin (96%), ampicillin (40%) and penicillin (96%). The isolates mostly contained large plasmids, which might harbor acquired antibiotic resistance.
         Conclusion: The results confirm the high frequency of antibiotic resistance among staphylococci isolated from bovine subclinical mastitis.
           Keywords: Anti-infective Agents, Cattle, Staphylococcus Aureus, Mastitis, Plasmids.

ABSTRACT
        Background and Objectives: Several virulence factors are involved in the pathogenesis of Staphylococcus aureus. Surface proteins such as collagen binding proteins (Cna) and fibronectin-binding proteins (FnBP) are important factors in adhesion and invasion of S. aureus. The aim of this study was to evaluate the frequency of adherence genes cna, fnbA and fnbB S. aureus isolates from traditional cheese.
        Methods: All 22 isolates tested were identified as S. aureus. The isolates were tested for the presence of adherence genes cna, fnbA and fnbB using specific primers in polymerase chain reaction assay. 
        Results: Six isolates (27.27%) were positive for the can gene. Of the 22 isolates studied, one isolate was positive for fnbA and one was positive for the fnbB. Co-presence of the genes examined was not observed in any of the isolates.
        Conclusion: The results indicate the weak biofilm formation ability of the S. aureus isolates from traditional cheese.
        Keywords: Staphylococcus aureus, Biofilm, Genes, Cheese. 

ABSTRACT
          Background and Objectives: Determining the genetic relationship between S. aureus isolates is important for epidemiological surveillance and control of infections caused by this bacterium. The present study was conducted to determine polymorphisms of coagulase gene (coa) among S. aureus isolates from pastry and cheese samples using restriction fragment length polymorphism (RFLP) analysis.
         Methods: Overall, 65 S. aureus isolated from pastry (n=45) and cheese (n=20) samples were examined for the coa gene by polymerase chain reaction (PCR). PCR products were digested with AluI enzyme and the products were assessed using gel electrophoresis.
          Results: Except for two isolates, all isolates were positive in coa-PCR and produced four different PCR products, with molecular sizes ranging from 570 to 970 bp. Overall; five distinct RFLP patterns were detected (I-V). Although pattern types I and III were present in isolates from both samples, types I and IV were mainly present in isolates from cheese and pastry samples, respectively.
        Conclusion: PCR-RFLP analysis of the coa gene indicates that S. aureus isolates from pastry and cheese samples may be originated from different sources. However, as one pattern type was predominant in each group, it can be concluded that majority of the isolates may have the same origin.
          Keywords: Staphylococcus aureus, PCR-RFLP, Coagulase, Pastry, Cheese.

ABSTRACT
         Background and Objectives: Silver nanoparticles (AgNPs) have physical and surface properties that could threaten human and environmental health. AgNPs are classified as ‘very toxic’ to eukaryotic organisms and are less toxic to bacteria. The aim of the present study was to study the effects of different sub-minimum inhibitory concentrations (MICs) of AgNPs on some virulence factors of Staphylococcus aureus as a pathogenic bacterial model.
         Methods: Tube double serial dilution method was used to determine MIC of AgNPs against standard strain and ten field isolates of S. aureus. Tube cultures of isolates in LB broth were supplemented with different concentrations of AgNPs and were incubated at 37 °C with constant shaking under aerobic conditions. Samples from each tube were streaked on blood agar plates and assay for hemolysins, coagulase and DNase production were performed.
         Results: The MIC of AgNPs against all examined isolates was determined as 50 µg/mL. The results showed that 1/2, 1/4 and 1/8 MIC of AgNPs had no negative effect on DNase and coagulase production but inhibited alpha- and beta-hemolysin production in most isolates (64-91%). In addition, production of delta-hemolysin was inhibited by 1/2 MIC of AgNPs.
         Conclusion: The effects of sub-MIC of AgNPs on bacterial growth appear at 4-8 hours post-exposure and then the bacteria follow a normal growth trend. This toxic effect may affect ecosystems species.
         Keywords: Silver particles, Minimum inhibitory concentration, Virulence factors, Staphylococcus aureus.

ABSTRACT
             Background and Objectives: In recent years, infections caused by antibiotic-resistant strains of Staphylococcus aureus have become a major health issue. It has been suggested that the extract or essential oil of cinnamon tree has antibacterial properties. In this study, we investigated the antibacterial effects of polyurethane-cinnamon nanofibers against clinical isolates of S. aureus.
             Methods: Polyurethane-Cinnamomum zeylanicum nanofiber scaffolds were synthesized. Polyurethane nanofiber and cinnamon polymers were also used to prepare the scaffold under the electrospinning process. Infrared spectroscopy, electron microscopy and mechanical tensile test were utilized to assess the scaffolds. Minimum inhibitory concentration of the nanofiber against the bacteria was determined using the broth dilution method according to the Clinical & Laboratory Standards Institute guidelines.
Results: The results of antibiogram test showed that all tested disks were susceptible to S. aureus. Diameter of growth inhibition zone for polyurethane-cinnamon 10% was 41 mm. Minimum inhibitory concentration of the nanofiber against S. aureus isolates was 0.02 μg/mL.
             Conclusion: We demonstrated that the polyurethane-cinnamon nanofiber has favorable antibacterial effects against clinical isolates of S. aureus. It is recommended to conduct further studies on the antibacterial effects of this nanofiber on other bacteria.
             Keywords: Staphylococcus aureus, Cinnamon, Nano fiber.

ABSTRACT
            Background and Objectives: Schiff base ligands are prepared via the condensation reaction of 1, 10- dimethyl–phenantroline aldehyde derivative with some nitrogen donor ligands, such as benzene ring that have different functional groups (-OH, -SH, -OCH₃,-CH₂OH, -Br) in acetonitrile. Recent studies suggest that Schiff bases might have antibacterial activity. Therefore, we aimed to synthesize new Schiff base complexes and evaluate their antibacterial activity against a number of Gram-positive and Gram-negative bacteria.
            Methods: Schiff base ligands and their complexes were characterized by mass spectrometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The in vitro antibacterial activity of the Schiff base ligands and metal ions against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by determining minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) using the broth dilution method.
            Results: All synthesized Schiff bases exhibited favorable antibacterial activity against the tested microorganism, but the antibacterial effect of compounds 3OH and 3SH was more significant than that of other compounds.
            Conclusion: Compound 3EOH has favorable antibacterial activity against the tested bacteria.
            Keywords: Schiff bases, antibacterial effect, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa.

          Background and Objectives: Staphylococcus aureus is a common cause of nosocomial infections. The ability of S. aureus to form biofilm and acquire antimicrobial resistance has made this organism a major health problem. In this study, we investigate the biofilm-forming ability of S. aureus isolates from clinical samples.
          Methods: Sixty S. aureus isolates from clinical specimens were collected from the 5th Azar Hospital of Gorgan (Iran) in 2018. The isolates were identified using conventional methods including Gram staining and biochemical tests (catalase and coagulase). Biofilm formation by S. aureus isolates was evaluated using a microplate-based method.
          Results: Of 60 S. aureus isolates, 47 (78.3%) strains were identified as biofilm-forming and 13 (21.7%) strains were non-biofilm-forming.
          Conclusion: The high prevalence of biofilm-producing S. aureus isolates in the 5^th Azar hospital of Gorgan could pose a major health challenge with serious consequences for hospitalized patients. Therefore, it is crucial to disinfect and sterilize hospital surfaces and equipment effectively to minimize the risk of contamination and spread of bacteria in the hospital settings.
          Keywords: Biofilms, Staphylococcus aureus, sample.

Background: Staphylococcus aureus is one of the most common agents of nosocomial infection worldwide. Methicillin-resistant and biofilm-associated infections of this bacterium have become a clinical concern in patients. This research aimed to identify biofilm-forming ability and accessory gene regulator (Agr) - specific group of clinical isolates of methicillin-resistant S. aureus (MRSA) in Northern Iran.
Methods: In 2021, a total of 200 clinical isolates were identified as S. aureus by biochemical tests. The disk diffusion method was used to examine the antibiotic resistance of isolates and the microplate method was applied to investigate the biofilm production capability. In addition, the PCR method was used to determine the frequency of biofilm-associated genes and Agr typing of MRSA isolates. P £ 0.05 was considered significant.
Results: Overall, 62.5% of isolates were methicillin-resistant and 75% were multiple antibiotic-resistant. Biofilm-forming ability was detected in 99 (79.2%) methicillin-resistant isolates in which icaA and icaD were found in 85% and 78% of biofilm-producing isolates, respectively. Type 1 of the Agr gene was the most common type among methicillin-resistant isolates. The frequency of biofilm-associated genes showed a significant association with MDR phenotype and the presence of Agr locus (P £ 0.05).
Conclusion: The present findings indicate a high frequency of biofilm and antibacterial resistance in methicillin-resistant S. aureus isolates in Guilan Province. These findings suggest reliable and rapid identification of biofilm-forming MRSA strains to prevent the spread of these bacteria.
 

Background: Staphylococcus aureus (S. aureus) is a virulent bacterium responsible for a spectrum of infections, from superficial dermatological issues to severe, life-threatening sepsis. The emergence of methicillin-resistant S. aureus (MRSA) strains, encompassing both hospital-acquired (HA) and community-acquired (CA) variants, presents significant challenges to effective treatment, especially in pediatric sepsis cases. This research endeavored to characterize S. aureus sepsis in pediatric patients, differentiate between cases caused by CA S. aureus (CA-SA) and HA S. aureus (HA-SA), and evaluate patterns of antibiotic resistance.
Methods: This study, conducted between January 2021 and December 2022 at the Postgraduate Department of Pediatrics, Children’s Hospital, Srinagar, Kashmir, J&K, investigated patients aged 1 month to 18 years with suspected S. aureus sepsis or disseminated disease. Standard methods (BacT Alert and Vitek II Compact) were employed for culturing various samples. Continuous data are presented as mean ± standard deviation (SD), while categorical variables are expressed as proportions.
Results: Out of 56 patients, CA-SA was observed in 66.1% of cases, while HA-SA accounted for the remaining 33.9%. The cohort primarily consisted of males (62.5%) and individuals residing in rural areas (71.43%). Localized musculoskeletal symptoms were a prominent feature, present in 91.9% of patients (P ≤ 0.05). Pleuropulmonary disease showed an association with HA-SA, whereas necrotizing soft tissue infections were linked to CA-SA. Common clinical manifestations included pneumonia and abscesses. Complications (such as septic shock, respiratory failure, and multi-organ dysfunction) were more frequently encountered in patients with HA-SA. Among 50 culture-confirmed cases, 96% were identified as methicillin-resistant S. aureus (MRSA). Survival rates differed between the two groups, with 94.6% for CA-SA patients and 89.5% for HA-SA patients.
Conclusion: The current study reveals a high prevalence of MRSA in pediatric sepsis, emphasizing the critical need for urgent antimicrobial stewardship. The observed distinct clinical profiles of CA-SA and HA-SA further underscore the necessity for tailored management strategies, particularly in resource-limited environments.
 

Background: Lactic acid bacteria (LAB) are promising platforms for mucosal vaccine development. Staphylococcus aureus enterotoxin B (SEB), a potent superantigen, is associated with food poisoning and toxic shock syndrome. Similarly, cholera toxin is the primary to widespread virulence factor in Vibrio cholerae infections, with its B subunit (CTB) serving as a well-established immune adjuvant that enhances antigen-specific responses in recombinant vaccines. This study aimed to engineer recombinant Lactobacillus plantarum as a dual-purpose vaccine candidate targeting V. cholerae and S. aureus by expressing CTB and SEB antigens.
Methods: A modified gene sequence encoding SEB (Lacking superantigenic activity) and CTB was successfully designed, synthesized, and cloned for secretory expression in L. plantarum. The resulting recombinant protein, tagged with His, was purified using Ni-NTA agarose ion-exchange chromatography and confirmed with Western blot analysis.
Results: Enzyme digestion and PCR analysis confirmed successful cloning of the SEB-CTB fusion gene into the pBlueScript II SK (+) and pNZ7021 expression vectors, as evidenced by the expected band on agarose gel. SDS-PAGE revealed a ~49 kDa protein band, indicating expression of the recombinant rSEB-CTB protein, which was further validated by Western blot using an anti-His tag antibody.
Conclusion: The construct LP-pNZ7021–SP-seb-ctxB may be a promising candidate for recombinant vaccine development targeting V. cholerae (Cholera toxin-producing) and S. aureus (SEB-producing), providing dual protection against both pathogens.