جستجوی مقالات مرتبط با کلیدواژه "mrsa" در نشریات گروه "زیست شناسی"

This study aimed to evaluate the antibacterial and antioxidant activities of methanol and ethyl acetate extracts of the roots and aerial parts of Salvia abrotanoides obtained at different phenological stages (vegetative, flowering, and seeding) and to determine their total phenol and flavonoid content. Disc diffusion and micro-dilution methods evaluated antibacterial activity against eight bacterial strains. Folin-Ciocalteu and aluminum chloride colorimetric methods were used to determine the content of total phenol and flavonoids, respectively. The antioxidant potential of the extracts was measured using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Staphylococcus aureus and Pseudomonas aeruginosa were the most sensitive and resistant bacteria to the extracts, respectively. The strongest antibacterial activity against multi drug resistant bacteria was recorded for methicillin-resistant Staphylococcus aureus treated with ethyl acetate extract of the root at the seeding stage, in which MIC and MBC values were 30.33 and 40.00 mg/mL, respectively. The highest content of total phenol (557.51 mg GAE/g DW) and flavonoids (236.40 mg QE/g DW) was found in the ethyl acetate extract of the aerial parts in the seeding phase. The aerial parts had more total phenolic and flavonoid content at different phenological stages than the root. The antioxidant capacity of the aerial part was also better that of the roots. The ethyl acetate extract of the aerial part at the seeding phase presented the highest DPPH scavenging activity (92.51 ± 1.25 %). The results showed that S. abrotanoides extracts, especially at the seeding phase, have good potential as a source of antioxidant, antibacterial, and bioactive compounds and can be considered good candidates in the development of new drugs or as the main source of food preservative compounds.

The unique ecosystem of the Persian Gulf has made it a rich source of natural antimicrobial compounds produced by various microorganisms, especially bacteria, which can be used in the treatment of infectious diseases, especially those of drug-resistant microbes. This study aimed to identify antimicrobial compounds in the bacteria isolated from the northern region of the Persian Gulf in Abadan (Chavibdeh port), Iran, for the first time.  Sampling was performed in the fall on November 15, 2019, from 10 different stations (water and sediment samples). The secondary metabolites of all isolates were extracted, and their antimicrobial effects were investigated. 16S ribosomal ribonucleic acid sequencing was used for the identification of the strains that showed the best inhibition against selected pathogens, and growth conditions were optimized for them. A fermentation medium in a volume of 5000 mL was prepared to produce the antimicrobial compound by the superior strain. The extracted antimicrobial compounds were identified using the gas chromatography-mass spectrometry technique. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for the superior strain. The effects of salinity, pH, and temperature on the production of antimicrobial compounds were determined by measuring the inhibitory region (mm) of methicillin-resistant Staphylococcus aureus (MRSA). Four new strains with antimicrobial properties (i.e., Halomonas sp. strain Persiangulf TA1, Bacillus aquimarisstrain Persiangulf TA2, Salinicoccus roseus strain Persiangulf TA4, and Exiguobacterium profundum strain Persiangulf TA9) were identified. The optimum growth temperatures were determined at 37-30, 37, and 40 °C for TA1 and TA2, TA4, and TA9 strains, respectively. The optimum pH values for the four strains were 7, 6-7, 7.5, and 6.5-7.5, respectively. The optimal salt concentrations for the four strains were 15%, 2.5-5%, 7.5%, and 5%, respectively. The ethyl acetate extract of strain Persiangulf TA2 showed extensive antimicrobial activity against human pathogens (75%) and MRSA. The most abundant compound identified in TA2 extract was the new compound 4-fluoro-2-trifluoromethyl imidazole. The MBC and MIC for the ethyl acetate extract of strain TA2 were 20 and 5 mg. mL-1 (Staphylococcus aureus), 40 and 20 mg. mL-1(MRSA, Escherichia coli, and Enterococcus faecalis), 40 and 10 mg. mL-1 Acinetobacter baumannii), and 80 and 40 mg. mL-1 (Staphylococcus epidermidis, Shigella sp., Bacillus cereus, and Klebsiella pneumoniae), respectively. The optimal conditions for antibiotic production by TA2 strain were 5% salt concentration, pH of 7, and temperature of 35 °C.  Newly detected natural compounds in TA2 strain due to superior antimicrobial activity even against MRSA strain can be clinically valuable in pharmacy and treatment.

Staphylococcus aureus is gram-positive cocci, which is consistently one of the four causes of hospital infections. S. aureus is a member of the normal nasal and intestinal flora in 30-50% of the population. But this organism is carried in almost 90% of the clinical staff of hospitals. S. aureus is an important cause of a wide variety of infectious diseases in humans. This bacterium often causes infections such as endocarditis, bacteremia, and pneumonia. S. aureus species are typically resistant to a large number of drugs. These bacteria are able to sustain and grow properly in the hospital environment and are easily transmitted to people who have weak immune systems. So far, methicillin-resistant S. aureus  (MRSA) has been limited to hospitals, but with the increase in skin and soft tissue infections and necrotizing pneumonia in younger patients, methicillin-resistant staphylococci in the community (CA-MRSA) has spread throughout the world.

Interspecies interaction of actinomycetes will express new gene clusters and may therefore affect the pigmentation, sporulation and production of secondary metabolites. Actinomycetes strains were isolated from Howze Soltan Salt Lake. Binary actinomycete interaction assay was conducted to evaluate its effect on colony morphology and antibiotic production. The molecular identification of the induced strains was performed. A total of 18% of isolates induced antibiotic production of 22% of the other strains against methicillin resistance Staphylococcus aureus (MRSA) and 44 % of them inhibited that of 31 % of antibiotic production in other actinomycete strains. The extract of the selected strains had an inhibitory effect on the pathogen growth. Based on molecular identification, the selected isolates, called act 32, shared 98% similarity with Streptomyces peucetius. It is expected that by screening of actinomycetes from untouched environments and co-culture method, new metabolites can be found to treat antibiotic-resistant infectious diseases.