Cephalothin, a New Cephalosporin with a Broad Antibacterial Spectrum: I. In Vitro Studies Employing the Gradient Plate Technique

Cephalothin is 7-(thiophene-2-acetamido) cephalosporanic acid; it was prepared by N-acylation of the nucleus of cephalosporin C, 7-aminocephalosporanic acid. Cephalothin had a broad spectrum of antibiotic activity that was essentially unaffected by human serum or inoculum level, the activity of penicillinase, or pH variation of the growth medium. In vitro development of resistance by staphylococci could not be demonstrated, but the gram-negative organisms did develop a stepwise type of resistance to the antibiotic. Staphylococci made resistant in vitro to 5-methyl-3-phenyl-4-isoxazole penicillin were also resistant to cephalothin and to 6-(2,6-dimethoxybenzamido) penicillin; however, the mechanism of resistance to each antibiotic may have differed. Some complications involved in the laboratory evaluation methods currently in use in the field of antibiotics are examined.     

Formulation and In Vivo Activity of Liposome-Encapsulated Cephapirin

Abstract

Serum levels, tissue distribution, and in vivo activity in mice of two liposomal formulations of cephapirin were compared with those of free cephapirin. Egg phosphatidylcholine (EPC) liposomes containing cephapirin (drug to lipid ratio approximately 1:15 by weight) were relatively stable in serum and provided prolonged serum levels of cephapirin activity after intravenous (iv) administration. With a 200 mg/kg dosage, serum levels were 10 µg/ml or higher for 24 hr after injection. Free drug at a similar dosage is undetectable in 3-5 hr. EPC-cephapirin liposomes showed a protective effect when administered up to 4 hr before infection of mice with Staphylococcus aureus, whereas free drug had no effect when given prophylactically. Cephapirin liposomes prepared with the tris salt of cholesterol hemisuccinate (CHS-t) were not stable in serum, but provided prolonged serum levels of cephapirin when injected subcutaneously and resulted in a protective effect when given prophylactically to mice infected with S. aureus. Cephapirin activity in the spleen and liver was greatly increased and persisted for at least 24 hr in mice injected intravenously with EPC formulation, but were not increased with the CHS-t formulation given subcutaneously. Only the EPC formulation could prolong survival in mice infected with Salmonella typhimurium.     

大蒜中生理活性物质对致病细菌的体外抑制作用

目的：从鲜蒜中提取蒜氨酸、蒜氨酸酶和蒜素,测定了蒜氨酸、蒜氨酸酶、蒜氨酸＋蒜氨酸酶、蒜素和蒜汁对10种致病细菌的抑菌作用及最低抑菌浓度。方法：采用平板打孔法和液体2倍稀释法。结果：蒜氨酸酶、蒜氨酸＋蒜氨酸酶、蒜素和蒜汁对金黄色葡萄球菌、大肠杆菌、鲍曼不动杆菌等10种菌株的抑菌环直径均大于7mm。蒜氨酸＋蒜氨酸酶对鲍曼不动杆菌的抑菌作用是50mg／mL氨苄青霉素的1．5倍。蒜氨酸＋蒜氨酸酶对金黄色葡萄球菌、类产碱假单胞菌和福氏志贺氏菌的MIC为0．19mg/mL。结论：蒜氨酸酶、蒜氨酸＋蒜氨酸酶、蒜素和蒜汁在体外具有明显的抑菌作用。     

Determination of Untreated Whole-Milk Effects on In Vitro Antibacterial Activity

The effect of fresh whole milk without pasteurization or other pretreatment on in vitro antibacterial activity of selected compounds was determined in broth dilution. The milk was collected by hand directly from dairy goats, or by syringe or cannula from bovine quarters showing low bacterial counts. Antibacterial activity was determined in 50% (v/v) milk-broth medium against sensitive mastitis-etiologic strains of Streptococcus agalactiae and Staphylococcus aureus. The indicator salt 2,3,5-triphenyltetrazolium chloride was incorporated in the milk broth medium to determine inoculum growth. Contaminant interference was circumvented through early as well as late readings and comparisons with uninoculated control tubes, with and without the test compounds. Application of the method with more than 75 compounds, including nitrofurans, antibiotics, and other chemicals uncovered marked degrees of milk interference. The method warrants routine use among preliminary screens to relate in vitro with in vivo observations of antimicrobial activity. Similar procedures may be used with serum, skim milk, or mastitis-milk media for separating effects due to protein, lipid, or other elements in product evaluation.     

Chlorhexidine Salt-Loaded Polyurethane Orthodontic Chains: In Vitro Release and Antibacterial Activity Studies

The widespread use of indwelling medical devices has enormously increased the interest in materials incorporating antibiotics and antimicrobial agents as a means to prevent dangerous device-related infections. Recently, chlorhexidine-loaded polyurethane has been proposed as a material suitable for the production of devices which are able to resist microbial contamination. The aim of the present study was to characterize the in vitro release of chlorhexidine from new polymeric orthodontic chains realized with polyurethane loaded with two different chlorhexidine salts: chlorhexidine diacetate or chlorhexidine digluconate. The orthodontic chains constituted of three layers: a middle polyurethane layer loaded with chlorhexidine salt inserted between two layers of unloaded polymer. In vitro release of chlorhexidine diacetate and digluconate from orthodontic chains loaded with 10% or 20% (w/w) chlorhexidine salt was sustained for 42 days and followed Fickian diffusion. The drug diffusion through the polyurethane was found to be dependent not only on chlorhexidine loading, but also on the type of chlorhexidine salt. The antibacterial activity of 0.2% (w/w) chlorhexidine diacetate-loaded orthodontic chain was successfully tested towards clinically isolated biofilm forming ica-positive Staphylococcus epidermidis via agar diffusion test. In conclusion, the chlorhexidine salt-loaded chains could provide an innovative approach in the prevention of oral infections related to the use of orthodontic devices.KEY WORDS: antibacterial activity, cariogenic treatment, chlorhexidine, in vitro release, orthodontic chains     

抗菌肽体外对结核杆菌的作用初探

将结核杆菌接种于含抗菌肽的苏通氏培养基中 ,在接种后不同时间内取样接种于罗氏培养基上 ,观察结核杆菌在罗氏培养基上的生长情况 ,初步探讨了抗菌肽 (CecropinB)对结核杆菌标准株H3 7RV的作用。结果显示 ,接种 10天后在罗氏培养基上结核杆菌对抗菌肽敏感。说明在体外培养中 ,抗菌肽有一定的抗结核杆菌的作用     

Synthesis and In Vitro Antibacterial Activity of New C-3-Modified Carbapenems

Russian Journal of Bioorganic Chemistry - New C-3 modified carbapenems have been synthesized by the AdNE-substitution of the enol phosphate group of 4-nitrobenzyl...     

Synthesis of Some New N-Substituted Imidazole Derivatives and Their In Vitro Antibacterial Investigation

Russian Journal of Bioorganic Chemistry - Here we reported the synthesis of N-substituted imidazole derivatives (VIa–o) that involves Suzuki coupling reaction between...     

In Vitro Antibacterial Activity of Cysteine Protease Inhibitor from Kiwifruit (Actinidia deliciosa)

The need for replacing traditional pesticides with alternative agents for the management of agricultural pathogens is rising worldwide. In this study, a cysteine proteinase inhibitor (CPI), 11 kDa in size, was purified from green kiwifruit to homogeneity. We examined the growth inhibition of three plant pathogenic Gram-negative bacterial strains by kiwi CPI and attempted to elucidate the potential mechanism of the growth inhibition. CPI influenced the growth of phytopathogenic bacteria Agrobacterium tumefaciens (76.2 % growth inhibition using 15 μM CPI), Burkholderia cepacia (75.6 % growth inhibition) and, to a lesser extent, Erwinia carotovora (44.4 % growth inhibition) by inhibiting proteinases that are excreted by these bacteria. Identification and characterization of natural plant defense molecules is the first step toward creation of improved methods for pest control based on naturally occurring molecules.     

Neurons-on-a-Chip: In Vitro NeuroTools

Neurons-on-a-Chip technology has been developed to provide diverse in vitro neuro-tools to study neuritogenesis, synaptogensis, axon guidance, and network dynamics. The two core enabling technologies are soft-lithography and microelectrode array technology. Soft lithography technology made it possible to fabricate microstamps and microfluidic channel devices with a simple replica molding method in a biological laboratory and innovatively reduced the turn-around time from assay design to chip fabrication, facilitating various experimental designs. To control nerve cell behaviors at the single cell level via chemical cues, surface biofunctionalization methods and micropatterning techniques were developed. Microelectrode chip technology, which provides a functional readout by measuring the electrophysiological signals from individual neurons, has become a popular platform to investigate neural information processing in networks. Due to these key advances, it is possible to study the relationship between the network structure and functions, and they have opened a new era of neurobiology and will become standard tools in the near future.     

In Vitro Antibacterial Activity of 4-Phenyl-1-(2-phenyl-allyl)pyridinium bromide: A Novel Class of Pyridinium Based Antibacterial Compounds

The continuing increase in the incidence of multi drug resistant pathogenic bacteria and shortage of new antimicrobial agents are the prime driver in efforts to identify the novel antimicrobial classes. In vitro antibacterial activity of 4-phenyl-1-(2-phenylallyl) pyridinium bromide was tested against Gram positive Staphylococcus aureus, Streptococcus species, Bacillus subtilis, and Gram negative Klebsiella aerogenes and Escherichia coli using disk diffusion method. Among them S. aureus showed strong antibacterial activity (21.99 ± 0.03 mm) while E. coli showed very little activity (8.97 ± 0.06 mm) towards the compound. The MIC of 4-phenyl-1-(2-phenyl-allyl)-pyridinium bromide for 90% S. aureus was ≤20 μg/ml and was compared with phenoxymethylpenicillin, cloxacillin, erythromycin and vancomycin. When 4-phenyl-1-(2-phenyl-allyl)pyridinium bromide showed MIC at ≤20 μg/ml, all others showed MIC at ≤100 μg/ml. Strong antibacterial activity of 4-phenyl-1-(2-phenyl-allyl)pyridinium bromide against S. aureus indicates that there is a possibility to use it as an effective antibacterial agent.     

青天葵体外抑菌活性研究

目的:研究青天葵水提取液、醇提取液和水醇提取液对金黄色葡萄球菌、大肠杆菌、白色念珠菌、伤寒沙门菌、绿脓杆菌、黑曲霉菌6种菌株的抑菌效果。方法:制备青天葵3种提取液,采用试管两倍稀释法测定3种提取液对金黄色葡萄球菌等6种菌株的最低抑菌浓度(MIC)。结果:青天葵水提取液对伤寒沙门菌的抑菌作用较强(MIC为12.5%),对金黄色葡萄球菌、大肠杆菌、绿脓杆菌和黑曲霉菌的抑菌作用较弱(MIC为50%);醇提取液对伤寒沙门菌和绿脓杆菌都有很强的抑菌作用(MIC为6.25%),对金黄色葡萄球菌也有较强的抑菌活性(MIC为12.5%),对大肠杆菌的抑菌作用较弱(MIC为50%);水醇提取液的抑菌活性与醇提取液相当。结论:青天葵对金黄色葡萄球菌等6种菌株表现出不同程度的抑制活性。     

In Vitro Antibacterial and Antioxidant Studies of Croton roxburghii L., from Similipal Biosphere Reserve

In vitro antibacterial activities of acetone, ethanol, methanol and water extracts of leaves and bark of Croton roxburghii L. studied against ten human pathogenic bacterial strains showed significantly higher activity in acetone extract and least activity in case of aqueous. Minimal inhibitory concentration (MIC) values of all extracts ranged between 0.62 and 10 mg/ml, while minimal bactericidal concentration (MBC) values ranged from 1.25 to values greater than 10 mg/ml. The antioxidant assays viz. DPPH, hydrogen peroxide scavenging, iron reducing and iron chelating assays along with total phenol and ascorbic acid content were carried out with aqueous extracts of leaves and bark. While the total phenol contents in leaves and bark extracts were 0.766 ± 0.014 and 0.735 ± 0.028% respectively their ascorbic acid contents were found to be 0.252 ± 0.019 and 0.431 ± 0.013% respectively. DPPH activities in both (leaves and bark) extracts increased with the increase in concentrations. Iron chelating capacity of leaves extract is significantly higher than that of the bark. Leaves extract showed an increase in percentage of scavenging property with the increase in concentrations. Plant extracts showed low amount of iron reducing property at all concentrations. Hydrogen peroxide scavenging properties of bark was low than that of the leaves.     

Spontaneously Induced Suppressor Cells In Vitro: Nonspecific Suppression of In Vitro Antibody Formation

Nonspecific suppressor cells were induced during in vitro culture of normal mouse spleen cells (SPC) using the Marbrook culture system. The suppressor cells inhibited both the primary and secondary antibody-formation responses antigen nonspecifically in vitro, and both IgM- and IgG-responses were inhibited. The supernatants from suppressive precultured cells were not suppressive. The suppressor cells also inhibited the response of allogeneic SPC beyond H-2 compatibility. The induction of the suppressor cells did not require the presence of antigen but required fetal calf serum (FCS) or both FCS and 2-mercaptoethanol (2-ME). The suppressor cells were generated from the nylon-wool adherent, radiation-sensitive T cell population. On the other hand, the suppressor cells were nylon-wool nonadherent, relatively radiation-sensitive T cells. Actively antibody-producing cells were not affected by the suppressor cells. The suppressor cells inhibited the mitogenic responses of normal SPC to phytohemagglutinin-P (PHA), bacterial lipopolysaccharide (LPS) and concanavalin A (Con A). The suppressor cells themselves inhibited the growth of EL4 cells (T-cell leukemia of C57BL/6 mouse origin) and MOPCll cells (B cells, plasmacytoma of BALB/c mouse origin) even at a low effector-to-target cell ratio (E:T ratio = 1:1), but did not kill these tumor cells. These results indicate that the target cells of the suppressor cells are both T and B cells, and that the mechanism of action of the suppression is either inhibition of proliferation or inhibition of early events in the course of the immune response.     

In Vitro Antibacterial Activity of Minocycline and Effect of Agar Medium Utilized in Its Susceptibility Testing

The in vitro activity of minocycline against 1,028 bacterial strains was determined in parallel in Mueller Hinton Agar and Trypticase Soy Agar. The broad antibacterial effect of minocycline against gram-positive cocci and gram-negative bacilli is confirmed. Minimal inhibitory concentrations for gram-positive bacteria in Mueller Hinton Agar were at least twofold less than in Trypticase Soy Agar. Minimal inhibitory concentrations for gram-negative bacilli in Mueller Hinton Agar were usually fourfold less than in Trypticase Soy Agar.     

In Vitro Antibacterial Evaluation of Terminalia chebula as an Alternative of Antibiotics against Bovine Subclinical Mastitis

The extent of subclinical mastitis in three breeds of cattle, Kankrej, Gir, and Crossbred, was performed at cattle farms in Anand town of Gujarat State, India. The prevalence of subclinical mastitis in crossbred cattle was higher compared to local breed of cattle. Causative agents identified using 16S rDNA polymerase chain reaction (PCR)-based molecular method were Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Bacillus megaterium. In vitro antibacterial activity of ethyl acetate extract of plant Terminalia chebula (Combretaceae) was checked by agar well diffusion method against four isolated and molecularly identified microorganisms. Ethyl acetate extract shows antimicrobial activity with varying magnitudes against all identified isolates. Among the three different concentrations, 500?µg/mL conc. of extract is as effective as that of standard amoxicillin. In vitro results support the use of plant extract from T. chebula as an alternative to antibiotics therapy against bovine subclinical mastitis.     

In Vitro Trypanocidal and Antibacterial Activities of Essential Oils from Four Species of the Family Annonaceae

The objective of this study was to evaluate the chemical composition, and the trypanocidal and antibacterial activities of the essential oils from four species of Annonaceae: Bocageopsis multiflora (Mart .) R.E.Fr ., Duguetia quitarensis Benth ., Fusaea longifolia (Aubl. ) Saff ., and Guatteria punctata (Aubl .) R.A.Howard . The chemical composition of the essential oils from the aerial parts yielded 23, 20, 21 and 23 constituents, respectively, which were identified by GC/MS. The trypanocidal activity was evaluated against the amastigote and trypomastigote forms of T. cruzi. The antibacterial activity was evaluated by the microdilution method against enterohemorrhagic Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, Streptococcus pyogenes, and methicillin‐resistant Staphylococcus aureus. The results of trypanocidal activity showed that the essential oils of the four species were active at the tested concentrations, with G. punctata essential oil being the most active, with IC₅₀=0.029 μg/mL, and selectivity index (SI)=32, being 34 times more active than the reference drug benznidazole. All EOs showed strong antibacterial activity (minimum inhibitory concentrations of 4.68–37.5 μg/mL) against strains of S. mutans.     

Colorimetric Assay to Determine In Vitro Antibacterial Activity Against Clinical Isolates： Enhanced Activity in Damaged Chinese Masson Pine Needles

A colorimetric assay for antibacterial susceptibility testing of clinical isolates (Escherichia coli, Pseudomonas aeruginosa, Shigella dysenteriae, Staphylococcus aureus, Bacillus cereus, and Streptococcus pneumoniae) is described based on the reduction of a novel tetrazolium salt, 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium (MTS), in the presence of phenazine methosulfate (PMS) as an electron‐coupling agent. The combination of 200 μg/mL MTS with 25 μmol/L PMS resulted in production of large amounts of formazan within 1 h of exposure. In this setting, fractions extracted from Chinese Masson pine (Pinus massoniana Lamb.) needles damaged by the pine caterpillar Dendrolimus punctatus Walker were found to have enhanced levels of antibacterial activity. These fractions, which were designated “Master”, “Technique”, and “Strength”, were isolated and identified by reverse‐phase C₁₈ cartridge concentration, gel filtration, and affinity chromatography. Two fractions purified from healthy and undamaged needles were designated H1 and H2, respectively. For all test bacteria species. Technique produced the lowest minimal inhibitory concentrations (MICs), ranging from 2 to 32 μg/mL, and H2 produced the highest values, with four of the six MICs being higher than 128 μg/mL We found that the R_max model fitted the data well in that the r² ranged between 0.87 and 0.96 (median, 0.92) and no statistically significant deviations from the model were found (P= 0.23). The median coefficient of variation of the log RC₅₀ values and the slope m of the fitted model for all six strains among the replicates were 38 and 41%, respectively. In the course of the investigation, the physiological and functional factors involved in pest damage to plants were also explored. In summary, the MTS‐PMS colorimetric assay has advantages over existing methods for the examination of antibacterial activity, and could be developed further such that it would be suitable for screening new antibiotic molecules. (Managing editor: Ping He)