Pasteur Institute of Iran

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Introduction: In this study, the chemical composition and antimicrobial activity of essential oil of Ziziphora clinopodiodes and its potential application as a natural preservative in reducing the indigenous microbial population of hamburger were investigated. Method: Essential oil of Ziziphora clinopodiodes cultivated in Iran was obtained by Hydro-distillation method (HDM). Chemical composition of the oil was determined by gas chromatography/mass spectrometry (GC-MS) analysis. Antimicrobial activity of the essential oil was checked against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Salmonella typhi, Listeria monocytogenes, Pseudomonas aeruginosa, by using Agar dilution method (ADM). Minimum Inhibitory Concentration (MIC) values of each active oil concentration were determined and its potential application as a natural preservative in reducing the indigenous microbial population of hamburger was investigated. Results: The major components were carvacrol (54.31%), thymol (12.51%), octadecane (9.51%) and pulegone (4.88%). The results showed a significant activity against the tested strains (gram-positive and gram-negative bacteria). Addition of essential oil in concentration higher than MIC values reduced the microbial population of hamburgers stored at 25°C, 4°C and -12°C. In samples refrigerated at 4°C, differences between the controls and samples treated with essential oil at MIC values (0.20 and 0.4 mg/ml)  were  not  significant  during the first 24 h (p> 0.05), but higher concentration of essential oil resulted in about 2 to 3 log reduction in total microorganisms. Conclusion: This study showed that the Ziziphora clinopodiodes essential oil can be added to the ingredients of foods as the natural antibacterial agent.

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Introduction: Chronic suppurative otitis media (CSOM) is one of the most common middle ear infections leading to extra and intracranial complications if not diagnosed promptly. Early identification and detection of the etiological agents and antibiotic susceptibility patterns assist in preventing complications. Methods: Two hundred twelve ear swabs were collected using sterile cotton swabs. Direct gram staining was done and then inoculated into blood, MacConkey, and Nutrient agar. Bacterial isolates were identified using conventional methods. According to CLSI guidelines, Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method. Minimum inhibitory concentration (MIC) was performed by the agar dilution method. Extended-spectrum beta-lactamases producing bacteria were detected by the phenotypic confirmatory test and then corroborated by uniplex PCR. Results: Out of 212 samples, 157 samples (74.06%) were culture-positive for bacteria. The isolated bacteria included Pseudomonas aeruginosa (46.24%), Staphylococcus aureus (26.59%), Klebsiella pneumoniae (14.45%), coagulase-negative Staphylococcus aureus (5.20%), Proteus mirabilis (4.05%), Enterococcus faecalis (2.89%), and Escherichia coli (0.58%). The P. aeruginosa isolates showed 96.25% and 95% susceptibility to amikacin and ofloxacin, respectively. All Gram-negative bacilli isolates were 100% sensitivite to imipenem. Ten (30.30%) isolates were ESBL producers with the CTX-M-14 gene detected in most of them. Conclusion: Our study found that P. aeruginosa was the most common isolated pathogen bacteria. Knowledge of CSOM causing bacteria and their susceptibility to antibiotics would help choose an appropriate treatment, thereby preventing antibiotic resistance and complications in these cases.

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Introduction: Streptococcus pyogenes remains a significant human pathogen responsible for a spectrum of infections, including severe invasive diseases such as streptococcal toxic shock syndrome, and serious post-infectious sequelae like acute rheumatic fever and glomerulonephritis. Considering the recognized antimicrobial properties of Capsicum annuum L. (C. annuum L.) and the persistent clinical challenge presented by S. pyogenes, this study investigated the in vitro antimicrobial activity of an aqueous extract of Capsicum annuum L., Capsaicin (C₁₈H₂₇NO₃), amoxicillin, and a combination of Capsaicin with amoxicillin against S. pyogenes (ATCC 19615). The primary objective was to evaluate both the inhibitory and bactericidal effects of these agents, specifically exploring the potential for synergistic or additive interactions between a plant-derived compound and a conventional antibiotic to improve therapeutic potential. Methods: The antimicrobial activities were evaluated using broth microdilution to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Time-kill kinetics were assessed spectrophotometrically by monitoring bacterial growth. Additionally, disk diffusion assays were performed to evaluate antimicrobial susceptibility. Statistical analyses were conducted using one-way analysis of variance (ANOVA), followed by Tukey’s post hoc test to determine significant differences between treatment groups. Results: The aqueous extract of C. annuum L. and Capsaicin both demonstrated significant in vitro inhibitory and bactericidal activity against S. pyogenes. Specifically, MIC and MBC of the aqueous extract were determined to be 12 mg/mL and 14 mg/mL, respectively. For Capsaicin, the MIC was 15 μg/mL, and the MBC was 20 μg/mL. Consistent with these findings, disk diffusion assays revealed distinct zones of inhibition for both agents. Notably, the combination of Capsaicin with amoxicillin exhibited enhanced antimicrobial activity, resulting in a statistically significant reduction in the MIC (P < 0.05) and MBC (P < 0.01) compared to each agent alone. Conclusion: The combination of Capsaicin with amoxicillin demonstrated enhanced bactericidal efficacy in a dose-dependent manner. Notably, Capsaicin exhibited bactericidal activity at microgram concentrations, whereas amoxicillin required milligram concentrations to achieve a comparable effect, highlighting the potent antibacterial properties of Capsaicin. These findings suggest that both the aqueous extract of C. annuum L. and Capsaicin hold significant potential as promising candidates for the development of novel antimicrobial therapies against S. pyogenes.