Identification and Antibacterial Activity Study of a Terrestrial Strain of Brevibacterium aureus 431

This study isolated and purified strain 431 from an animal probiotic product.Through staining and microscopic examination,colony morphology analysis,biochemical reaction tests,and 16S rDNA sequence alignment,the strain was identified and named Brevibacterium aureus 431.The study focused on the production of biosurfactants by strain 431,and antibacterial activity tests were conducted on the strain and its secondary metabolites.The results showed that strain 431 exhibited no resistance to 10 commonly used drugs,and its concentrated secondary metabolites were highly sensitive to the indicator bacterium Escherichia coli.Oral administration of strain 431 to BALB/c mice resulted in normal mental state,diet,and bowel movements,with no signs of illness or death,indicating that strain 431 is highly safe and non-pathogenic to mice.The study suggests that Brevibacterium aureus 431 has significant research value as a new source of actinomycetes and that its secondary metabolites have potential application value in the development of antibacterial drugs.

Antibacterial Activity of Herbal Preparations against Staphylococcus aureus and Streptococcus agalactiae in Cow Mastitis

[Objective] This study aimed to analyze the antibacterial activity of herbal preparations against Staphylococcus aureus and Streptococcus agalactiae in cow mastitis. [Method] The crude drug solutions of four different prescriptions for Zengrujianniusan were prepared through reflux extraction. Their antibacterial activity in vitro against Staphylococcus aureus and Streptococcus agalactiae in cow mastitis were investigated. [Result] All the four different prescriptions exhibited antibacterial activity against S. aureus and S. agalactiae. Among them, prescription Ⅲ was extremely sensitive, and had the best bactericidal effect. The other three prescriptions were highly sensitive. [Conclusion] This study provides a theoretical basis for the development of herbal preparations for the treatment of cow mastitis.

Antibacterial activity of the essential oils from the leaves of Eucalyptus globulus against Escherichia coli and Staphylococcus aureus

Objective:To examine the in vitro antimicrobial activities of essential oil of the leaves of Eucalyptus globulus(E.globulus).Methods:The essential oils of this plant were obtained by the hydrodistillation method.The inhibitory effects of this essential oil were tested against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)by using agar disc diffusion and dilution broth methods.Results:The results obtained showed that essential oil of the leaves of E.globulus has antimicrobial activity against gram negative bacteria(E.coli)as well as gram positive bacteria(S.aureus).Conclusion:The encouraging results indicate the essential oil of E.globulus leaves might be exploited as natural antibiotic for the treatment of several infectious diseases caused by these two germs,and could be useful in understanding the relations between traditional cures and current medicines.

Antibacterial activity of eight Iranian plant extracts against methicillin and cefixime restistant Staphylococcous aureus strains

Objective:To assess the antibacterial activity of eight Iranian plant extracts against Staphylococcus aureus(S.aureus) strains which were isolated from infected patients.Methods: The studied strains were isolated from urine,stool,blood and wound of infected patients and identified by biochemical tests.In further,the antibacterial activity of 8 ethanolic local plant extracts including Querqus brantii(Q.brantii),Ziziphus spina-christi(Z.spina-christi),Peganum harmala(P.harmala),Oliveira decumbens(O.decumbens),Galium tricornutum(G.tricornutum), Vitex pseudo negundo(Vi.pseudo negundo),Salvia officinalis(S.officinalis),Vaccaria pyramidata (V.pyramidata) were then evaluated using agar disc diffusion method.Results:A total of 9 isolates were isolated and identified as S.aureus.Antibacterial profile of the strains showed that the strains were resistant to methicillin and cefixime.The highest antibacterial activity against the studied strains were belong to Q.brantii,P.harmala,Z.spina-christi and O.decumbens vent extracts with 11-40 mm,15-28 mm,8-26 mm and 10-20 mm of diameters,respectively. Intermediate antibacterial activity was exhibited by G.tricornutum and Vi.pseudo negundo against some of the studied strains with 7-20 mm and 7-13 mm of diameters,respectively. Noteworthy,out of 9 studied strains;6 and 2 of them were resistant to the G.tricornutum and Vi. pseudo negundo extracts,respectively.The S.officinalis and Va.pyramidata,however,showed no antibacterial activity against the studied strains.Conclusions:The Q.brantii,P.harmala,Z. spina-christi and O.decumbens extracts were shown to possess strong antibacterial activity against methicillin and cefixime resistant S.aureus strains and can be considered as the promising natural antibiotics for treating the studied strains.

Antibacterial activity of various honey types of Algeria against Staphylococcus aureus and Streptococcus pyogenes

Objective:To assess the in vitro antibacterial activity of honey from different geographical location on Gram negative organismes.Methods:Different concentrations(Undiluted honey,10%, 30%,50%and 70%wt/vol) of honey were studied in vitro using Staphylococcus aureus(S.aureus) and Streptococcus pyogenes(S.pyogenes),briefly,two-fold dilutions of honey solutions were tested to determine the minimum inhibitory concentration(MIC) against each type of microorganism,followed by more assays within a narrower dilution range to obtain more precise MIC values.MICs were determined by both visual inspection and spectrophotometric assay at 620 nm.These honey samples were compared with standard antibiotics like ampicillin,penicillin G,amoxicillin,gentamycin,tobramycin,erythromycin and chloramphenicol was determined by the disc diffusion method.Results:The diameter of zone of the inhibition(ZDI) of honey has various concentrations tested for the isolates ranged 0-46 mm for S.aureus,0-44 mm for S.pyogenes.While the MIC(%) ranged 12%-95%,25%-73%respectively.Conclusions:Algeria honey,in-vitro,possess antibacterial activity.

Antibacterial activity of nanostructured Ti-45S5 bioglass-Ag composite against Streptococcus mutans and Staphylococcus aureus

Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti-10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti-45S5 bioglass-Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.

Antibacterial Activity of Exogenous Glutathione and Its Synergism on Antibiotics in Methicillin-Associated Multidrug Resistant Clinical Isolates of Staphylococcus aureus

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most problematic human pathogens. Antibiotic treatment of MRSA often associated with resistance to multiple classes of antibiotics is extremely challenging and urgently demands action to treat MRSA. Glutathione (GSH) is a biogenic thiol-compound that maintains an optimal intracellular redox-potential required for various normal cellular processes. Antibacterial activity of exogenous GSH has been reported in some bacterial pathogens but is largely unknown in MRSA. Aim: This study aimed to understand antibacterial activity of GSH, its role in antibiotic susceptibility, and a potential antibacterial mechanism in clinical isolates of S. aureus. Materials and Methods: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), checkerboard, time-killing, and bacterial killing assays were performed for 14 clinical isolates of S. aureus including 10 MRSA and two type strains (ATCC 700699 and 35556). Results: MIC and MBC levels for the clinical and type strains were 15 - 20 mM and 25 - 40 mM of GSH, respectively. Subinhibitory concentrations of GSH synergistically enhanced susceptibility of all tested-antibiotics, resulting in sensitizing all-tested S. aureus. Bacterial-killing produced by GSH-mediated acidity was significantly higher than that by hydrochloric acid-mediated acidity. Conclusion: Overall results concluded that GSH exhibited antibacterial activity on S. aureus regardless of antibiotic susceptibility and synergistically enhanced antibiotic susceptibility. Additionally, GSH-mediated acidity was one of the antibacterial mechanisms. These findings suggest that GSH may be a potential antimicrobial agent or adjuvant for the conventional anti-MRSA regimens.

Ultrastructural Analysis of Chitosan Antibacterial Activity against Clinical Isolates of <i>Staphylococcus aureus</i>and <i>Escherichia coli</i>

The continuous search for an antimicrobial agent led to the identification of potential antimicrobial biomaterials based on polymers naturals, such as chitosan (CS). However, the mechanism of action of antibacterial activity of CS for gram-positive and gram-negative bacteria was not completely elucidated. The aim of this work is to report the antibacterial activity of CS through ultrastructural analyses of the clinical isolates Staphylococcus aureus and Escherichia coli by Transmission Electron Microscopy. The CS has a bactericidal action against S. aureus and E. coli which alters its cellular ultrastructure, such as with collapsed cell walls, condensed chromatin and the increase of intracellulares structures like vacuoles and cell debris. In this way, the CS represents a potential model for the future design of antibacterial in order to control bacterial resistance of patients in hospital settings.

Effect of BEDGEN 40 on Growth, Anti-Oxidant Activity and Resistance against Aeromonas Hydrophila Infection in Tilapia （Oreochromis niloticus x O. aureus）

The globe artichoke has become important as a medicinal herb in recent years following the discovery of cynarin. This bitter-tasting compound, which is found in the leaves, improves liver and gall bladder function, stimulates the secretion of digestive juices, especially bile, and lowers blood cholesterol levels. The leaves are anticholesterolemic, antirheumatic, cholagogue, digestive, diuretic, hypoglycaemic and lithontripic. BEDGEN 40 , a compound made with Cynara scolymus L. （artichoke） extract and choline chloride was evaluated for growth performance and anti-oxidant activity in tilapia. There were four treatment groups; group 1 was fed only with a basal diet and served as the control, group 2 - 4 were experimental groups that received 150, 300, or 600 mg/kg BEDGEN 40 , respectively, added to the basal diet and fed for 8 weeks. The results showed signifi- cant differences for weight gain, feed conversion, and protein efficiency in fish diets containing 150, 300, or 600 mg/kg BEDGEN 40 compared to the control. Generally, BEDGEN 40 improved the body condition factor and hepatosomatic index of tilapia, and reduced liver fat content. Fish consum- ing BEDGEN 40 also exhibited improved liver antioxidant status. BEDGEN 40 （300, or 600 mg/kg） was also found to significantly reduce the mortality of tilapia subsequently challenged with Aeromonas hydrophila.

In vitro control of Staphylococcus aureus (NCTC 6571) and Escherichia coli (ATCC 25922) by Ricinus communis L.

Objective:To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L(R.communis)against Staphylococcus aureus(S.aureus)(NCTC 6571)and Escherichia coli(E.coli)(ATCC 25922).Methods:Leaf powder of R.communis L.was extracted with hot(in Soxhlet)and cold ethanol and methanol,separately.The antibacterial activity of the extracts was determined by agar well diffusion and macro broth dilution methods.The extracts were also subjected to phytochemical analysis.Results:All the four test extracts showed inhibition on both S.aureus and E.coli.Hot and cold ethanol extracts revealed significantly(P<0.05)higher inhibition on S.aureus than methanol extracts,and the hot ethanol extract had the lowest minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)values(5 mg/mL and 10 mg/mL,respectively).E.coli was highly inhibited by hot extracts of both ethanol and methanol with the MIC and MBC of 40 mg/mL and 80 mg/mL,respectively.Phytochemical analysis revealed the presence of saponins,cardiac glycosides,tannins,flavonoids and terpenoids in all test extracts.Conclusions:This study demonstrates that the hot and cold methanol and ethanol extracts are potential sources for control of S.aureus and E.coli.Especially,the hot and cold extracts of ethanol are more inhibitive against 5.aureus even at lower concentration.Further study is needed to identify the specific bioactive compounds,their mode of action and their nontoxic nature in vivo condition.

Effect of Nano - Titanium Dioxide with Different Antibiotics against Methicillin-Resistant Staphylococcus Aureus

The different investigation has been carried out on the biological activities of titanium dioxide nanoparticle but the effect of this nano product on the antibacterial activity of different antibiotics has not been yet demonstrated. In this study the nano size TiO2 is synthesized using citric acid and alpha dextrose and the enhancement effect of TiO2 nanoparticle on the antibacterial activity of different antibiotics was evaluated against Methicillin-resistant Staphylococcus aureus (MRSA). During the present study, different concentrations of nano-scale TiO2 were tested to find out the best concentration that can have the most effective antibacterial property against the MRSA culture. Disk diffusion method was used to determine the antibacterial activity of these antibiotics in the absence and presence of sub inhibitory concentration of TiO2 nano particle. A clinical isolate of MRSA, isolated from Intensive Care Unit (ICU) was used as test strain. In the presence of sub-inhibitory concentration of TiO2 nanoparticle (20 μg/disc) the antibacterial activities of all antibiotics have been increased against test strain with minimum 2 mm to maximum 10mm. The highest increase in inhibitory zone for MRSA was observed against pencillin G and amikacin (each 10 mm). Conversely, in case of nalidixic acid, TiO2 nanoparticle showed a Synergic effect on the antibacterial activity of this antibiotic against test strain. These results signify that the TiO2 nanoparticle potentate the antimicrobial action of beta lactums, cephalosporins, aminoglycosides, glycopeptides, macrolids and lincosamides, tetracycline a possible utilization of nano compound in combination effect against MRSA.

Synergistic Effect between Fucoidan and Antibiotics against Clinic Methicillin-Resistant <i>Staphylococcus aureus</i>

Fucoidan is a sulfated polysaccharide that is primarily extracted from brown seaweeds which has been broadly studied in recent years due to its numerous biological properties, including anticoagulant, antithrombotic, antitumor, and antiviral activities. In this study, fucoidan was evaluated against clinic isolated methicillin-resistant Staphylococcus aureus (MRSA) 1 - 20, either alone or with antibiotics, via broth dilution method and checkerboard and time kill assay. Minimum inhibitory concentrations (MICs)/Minimum bactericidal concentrations (MBCs) values for the fucoidan against all the tested bacteria ranged between 64 - 512/256 - 2048 microg/mL, for ampicillin 32 - 1024/64 - 1024 microg/mL and for oxacillin 8 - 64/16 - 256 microg/mL respectively. Furthermore, the MIC and MBC were reduced to one half-eighth as a result of the combination of the fucoidan with antibiotics. 2 - 6 hours of treatment with 1/2 MIC of fucoidan with 1/2 MIC of antibiotics resulted from an increase of the rate of killing in units of CFU/mL to a greater degree than was observed with alone. These results suggest that fucoidan could be employed as a natural antibacterial agent against multi-drug bacteria.

Inhibition of the emergence of multi drug resistant Staphylococcus aureus by Withania somnifera root extracts

Objective:To search systematically for an alternative therapy with compounds particularly from plant origin.Methods:Efficacy test of different root extracts of Withania somnifera(W. somnifera)(L) Dunal against multi drug resistant(MDR) Staphylococcus aureus(S.aureus) variants was performed following the agar well diffusion method.Evaluation of susceptibility pattern of the isolates was carried out by employing disk diffusion method using standard antibiotic disks. Results:In vitro study with W.somnifera root extracts was found to be effective against all the MDR S.aureus strains isolated from local and patient sources.Different root extracts of WS showed different degree of effectiveness against the isolates.Conclusions:The major active principles responsible for the antibacterial efficacy were mainly present in methanol(MeOH) extract and ethanol(EtOH) extracts as well as in butanol(BuOH) extract fraction.Amongst all the extracts the BuOH fraction was found to be most active against all the isolates but aqueous extract was the least active one.Finally it may be concluded that the antimicrobials from W.somnifera may raise an alternative therapy for MDR staphylococcal infections in near future.

Structure - Antimicrobial Activity Relationship Investigation of Some Butadiene and Chalcone Derivatives

The biological activity against Staphylococcus aureus, and Eschericia coil were investigated implementing three series, the first series was l-phenyl-2-（4＇-X-phenyl）-4-（2,4-dichlorophenyl）-1,3-butadiene, where X = H, CH3, OCH3, NH2, C1, F, NO2 and COOEt; the second was 3,4-dichlorochalcone series namely 3-（3,4-dichlorophenyl）-l-（4＇-X-phenyl）-2-propen-l-one, where X = H, CH3, OCH3, NH2, CI, F, NO2 and CN; and the third one was 2,4-dichlorochalcone series namely 3-（2,4-dichlorophenyl）-l- （4＇-X-phenyl）-2-propen-l-one, where X = H, CH3, OCH3, NH2, C1, F, NO2 and COOEt. MIC, MBC and the percentage of inhibition （activity） at 20 ~tg/mL, 15 μg/mL and 10μg/mL against Eschericia coli, and at 7.5 lag/mL, 5 μg/mL and 2.5 μg/mL against Staphylococcus aureus, were determined for each compound in the three series. Highest MIC activity against E. coli and S. aureus were given by 2,4-dichlorochalcone series. Butadiene series was similar in behavior to 2,4-dichlorochalcone series in MIC activity against S. aureus. Results of MBC revealed that compounds in the three series exerted high activity against both types of bacteria. Compounds substituted with nitro or nitril exhibited higher activity than other compounds in the three series. Percentage of inhibition of halogenated compounds （4＇-C1 and 4＇-F） was almost equal in every series. Compounds with substituents （4＇-H and 4＇-CH3） showed fluctuation in activity according to the nature of each series.

Tubastraea coccinea: A Non-Indigenous Coral (Cnidaria, Scleractinia) Collected at Arvoredo Island, South of Brazil with Potential MRSA and VRE Antimicrobial Activity

Bacterial infection is considered to be one of the most critical health issues of the world. It is essential to overcome this problem by the development of new drugs. Marine organisms as corals, sponges, seaweeds, and other are an incredible source of novel pharmacologically active compounds. Herein, the antimicrobial activity (extract/fractions) of the invasive stony coralTubastraea coccinea was evaluated by the disk diffusion method against 21 microbial strains (ATCC and clinical strains). Micro broth dilution was used to determinate the MIC of the fractions that showed antimicrobial activity by the disk diffusion method. Bioautography assay was also performed. Our results showed that the n-butanol (BF) and aqueous fractions (AF) showed activity against ATCC strains Staphylococcus aureus (MIC 31.25 and 250 μg/mL),Salmonella typhimurium (MIC 125 and 500 μg/mL), Escherichia coli (MIC 62.5 and 500 μg/mL) and Pseudomonas aeruginosa (MIC 62.5 and 500 μg/mL), respectively. Moreover, BF fraction was also effective against the clinical strains S. aureus(MIC 62.5 μg/mL), Klebsiella pneumoniae Carbapenemase—KPC (MIC 125 μg/mL), Methicillin-Resistant Staphylococcus aureus—MRSA (MIC 125 μg/mL) and Vancomycin-Resistant Enterococcus faecalis—VRE (MIC 62.5 μg/mL). The ratio MBC/MIC reinforces the bactericidal profile of BF fraction. The bioautography assay of BF fraction showed the presence of antimicrobial components at Rf0.55.

ANTIBACTERIAL ACTIVITY OF SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS GRAFTED ON "GEL-TYPE" STYRENE-DIVINYLBENZENE COPOLYMERS

A systematic study on the synthesis and antibacterial activity of the quaternary "onium" salts grafted on an insoluble "gel-type" styrene-7% divinylbenzene copolymer by polymer-analogous reactions is showed. Antibacterial activity of quaternary ammonium and/or phosphonium salts grafted on polymer-supports has been studied against Staphylococcus aureus and Escherichia coli. A wide variety of "onium" salts bound to macromolecular supports with different quaternary groups and different quaternary chain length substituents were examined. The antibacterial activity of mixed "onium" salts increases as a consequence of the association of ammonium and phosphonium salts grafted on the same polymeric support.

Free Radical Scavenging, Enzyme Inhibitory and Anti-<i>Staphylococcus aureus</i>Properties of the Fruiting Bodies of <i>Ganoderma lucidum</i>, Lingzhi Mushroom

The current study evaluated the antioxidant, α-amylase inhibitory and anti-Staphylococcus aureus activities of the fruiting bodies of Ganoderma lucidum. Methanolic extract of G. lucidum (MEGL) was investigated for its in vitro antioxidant activity using 1,1-diphenyl 2-picrylhydrazyl (DPPH) assay and EC50 value was determined. α-Amylase inhibitory and anti-S. aureus activities were carried out by conventional methods. The mushroom extract showed maximum free radical scavenging activity at a dose of 500 μg/mL with EC50 value of 22.1399 μg/mL. EC50 value for the inhibition of α-amylase activity was found 22.6011 μg/mL. G. lucidum extracts exhibited a concentration-dependent Anti-S. aureus activity. The vast differences of this inhibition between lower and higher doses were assessed significantly (p < 0.05). This study shows that the fruiting body of G. lucidum has moderate antioxidant, α-amylase inhibitory, and anti-S. aureus activities. Thus this mushroom may be the alternative plant source for the antioxidant, anti-diabetic and antibacterial agents and further in vivo studies and isolation of bioactive compounds are required.

耐药葡萄球菌对眼科常用抗菌药物的体外敏感性研究

目的了解外伤性眼内炎中病原菌分布特点及主要致病耐药葡萄球菌对眼科常用抗菌药物的体外敏感性。方法收集2018年7月—2023年7月于绵阳市中心医院外伤性眼内炎患者样本中检测的136株细菌,进行细菌培养、细菌鉴定和药敏试验。结果136株细菌由革兰阳性菌(n=81)、革兰阴性菌(n=49)和真菌(n=6)组成。主要感染病原菌为金黄色葡萄球菌42株、表皮葡萄球菌18株;2种耐药葡萄球菌对左氧氟沙星、头孢唑林钠、妥布霉素和夫西地酸的最小抑菌浓度(MIC)差异较小(0.7~7.5μg·mL^(-1)),对克林霉素的MIC差异较大(2.5~500μg·mL^(-1))。耐药葡萄球菌对5种抗生素的敏感性均差异无统计学意义(均P>0.05)。5种眼用抗生素对耐药葡萄球菌的敏感率差异有统计学意义(P<0.05),其中头孢唑林钠和夫西地酸对耐药葡萄球菌的敏感率显著高于克林霉素、左氧氟沙星和妥布霉素。结论耐药葡萄球菌是外伤性眼内炎患者的主要感染病原菌,夫西地酸、头孢唑林钠对耐药葡萄球菌的抗菌活性优于妥布霉素、左氧氟沙星、克林霉素。

新疆南疆地区乳源金黄色葡萄球菌的分离鉴定及对氟苯尼考纳米凝胶的药物敏感性研究

为了研究氟苯尼考纳米凝胶对新疆南疆地区乳源金黄色葡萄球菌的抑菌效果,试验从新疆南疆地区某奶牛场的乳房炎患病奶牛乳样中分离纯化金黄色葡萄球菌,采用生化试验、PCR扩增及测序等方法进行细菌鉴定,并通过比较氟苯尼考原料药、氟苯尼考纳米凝胶和氟苯尼考注射液对金黄色葡萄球菌分离株的抑菌圈直径(DIZ)、最小抑菌浓度(MIC)和抑菌曲线分析氟苯尼考纳米凝胶对金黄色葡萄球菌分离株的抑菌效果。结果表明:从乳样中分离到一株细菌,该分离株革兰氏染色、镜检后呈蓝紫色并排列成葡萄串状,触酶、血浆凝固酶和甘露醇发酵试验结果均为阳性,其基因组DNA中能扩增出金黄色葡萄球菌耐热核酸酶(nuc)基因,16S rDNA基因序列与金黄色葡萄球菌的相似性为99.7%,判断该分离菌为金黄色葡萄球菌。氟苯尼考原料药、氟苯尼考纳米凝胶和氟苯尼考注射液对金黄色葡萄球菌分离株和金黄色葡萄球菌ATCC 29213株均产生抑菌作用,DIZ大小为氟苯尼考纳米凝胶>氟苯尼考注射液>氟苯尼考原料药,均表现为高度敏感,其中氟苯尼考纳米凝胶对金黄色葡萄球菌分离株和金黄色葡萄球菌ATCC 29213株的DIZ均显著高于氟苯尼考原料药和氟苯尼考注射液(P<0.05)。3种药物对金黄色葡萄球菌分离株的MIC分别为4μg/mL、2μg/mL和4μg/mL。1μg/mL氟苯尼考纳米凝胶对金黄色葡萄球菌分离株的抑菌效果与2μg/mL氟苯尼考原料药和氟苯尼考注射液相当,当氟苯尼考纳米凝胶的浓度为4μg/mL时金黄色葡萄球菌分离株不再生长。说明从新疆南疆地区成功分离出一株乳源金黄色葡萄球菌;相比于氟苯尼考原料药和氟苯尼考注射液,氟苯尼考纳米凝胶对该分离株具有较好的抑菌效果。

新型R型噬菌体尾样细菌素对MRSA的抗菌活性研究

目的探索阴沟肠杆菌SHAMU191747所分泌的新型R型噬菌体尾样细菌素(phage tail-like bacteriocin,PTLB)对耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)的抗菌活性。方法琼脂平板拮抗试验和肉汤微量发酵试验,检测阴沟肠杆菌SHAMU191747对MRSA的拮抗活性。超高速离心法和密度梯度离心法,制备阴沟肠杆菌SHAMU191747发酵上清液粗提物。使用透射电镜检测粗提物中有无新型R型PTLB。琼脂平板点种法,验证粗提物对MRSA的抗菌活性。采用SDS-PAGE电泳检测新型R型PTLB的分子量。结果阴沟肠杆菌SHAMU191747分泌新型R型PTLB,对MRSA具有强拮抗效应。新型R型PTLB的分子量约35 ku,能够高效杀伤MRSA;尾鞘未收缩的功能性分子的物理尺寸为(142.7±4.3)×(13.8±0.6)nm,尾鞘收缩的非功能性分子的物理尺寸为(57.7±1.2)×(20.8±1.5)nm。结论阴沟肠杆菌SHAMU191747产生的新型R型PTLB能够高效杀伤MRSA,具有开发成新型抗菌药物的潜力,临床应用前景很大。