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At least 19 recordsLinked to original sources
PubMed1979

[Comparison of the antibacterial activity of ticarcillin with other antibacterial agents (author's transl)].

Antibacterial activity of ticarcillin was determined in comparison with that of sulbenicillin, amoxicillin, cefuroxime, clindamycin and metronidazole against anaerobic bacteria which have been isolated from various clinical materials in this hospital. Growth of more than 90% of Gram-negative anaerobic rod bacteria was inhibited by ticarcillin at its concentration of 100 micrograms/ml. Strains resistant to ticarcillin showed cross resistance against both sulbenicillin and amoxicillin. Antibacterial activity of ticarcillin against Gram-positive anaerobic bacteria was found almost equal to sulbenicillin but slightly inferior to amoxicillin. Cefuroxime was found most inferior among the tested six antibiotics when an inoculation level of 10(8)/ml was utilized, but it showed similar activity to ticarcillin when they were tested with 10(6)/ml inoculation. Approximately 10% of bacteroides strains was resistant to clindamycin while all the strains were sensitive to metronidazole.

Amoxicillin↗
PubMed1979

Studies in potential organo-fluorine antibacterial agents. Part 2: Synthesis and antibacterial activity of some new fluorine-containing 3.5-disubstituted isoxazoles.

A series of new fluorine-containing 3,5-disubstituted aryl/alkylisoxazoles has been synthesized by the condensation of hydroxylamine with appropriate beta-diketones in the presence of pyridine and characterized by IR and 1H NMR spectral studies. These isoxazoles have been screened for their antibacterial activity against the gram positive bacteria, Staphylococcus albus, Streptococcus nonhemolyticus and the gram negative bacterium Escherichia coli.

Anti-Bacterial Agents↗
PubMed2026

Exploration of the antibacterial function of the Eutherian LEG1s.

Liver-enriched gene 1 (LEG1) encodes a novel protein family whose functions are not fully explored. LEG1 was first reported and characterized in zebrafish, where it encodes secreted proteins involved in liver development. In contrast, mammalian LEG1s exhibit a different expression pattern. The platypus monotreme lactation protein (platMLP) was uncovered in milk with antibacterial function. Studies in mouse and pig have shown that LEG1s are specifically expressed in the salivary glands; however, their function remains unclear. Evolutionarily, LEG1s are present in vertebrates and form three major clades, LEG1a, LEG1b, and LEG1c. Only a few invertebrates, protists, and bacteria retain LEG1 homologs, making the evolutionary origin of LEG1 obscure. In the current study, we conducted a thorough exploration of prokaryotic reference genomes and found that LEG1 predominantly exists in Actinomycetota. Given that Actinomycetota are well known for producing antibacterial compounds, and that platMLP can inhibit the growth of certain bacteria, we hypothesized that LEG1 is a conserved antibacterial protein. Recombinant LEG1s from each of the three clades were then purified and subjected to antibacterial tests, which showed that pig LEG1c and platMLP have divergent antibacterial activities. These findings support the hypothesis that the antibacterial function of LEG1 is conserved in eutherians but has undergone functional diversification following gene duplication events.

Animals↗
PubMed1976

[Preliminary clinical experience with antibacterial surgical sutures].

Surgical sutures made of Letilan-Lavsan and polyvinyl alcohol fibers with morphocycline and neomycin and filamentous Letilan were applied in 802 patients in the past 4 years. These sutures display considerable antibacterial properties. The antibacterial effect of Letilan-Lavsan sutures is reduced during the healing because of formation of fibrous capsules, the fibers themselves not being deprived of their antibacterial properties for a long period. The Letilan fibers undergo gradual fragmentation and degradation. The antibacterial properties of polyvinyl alcohol fibers added with morphocycline and neomycin are retained for 2 months in the body tissues. The antibacterial Letilan-Lavsan sutures and filamentous Letilan sutures can be sterilized by autoclaving, applying hydrogen peroxide--formic acid mixture, gamma irradiation and ethylene oxide. The unsterilized antibacterial sutures can be used as cutaneous sutures in surgical procedures.

Adolescent↗
PubMed1977

Amniotic fluid antibacterial mechanisms: newer concepts.

In this review the factors present in human amniotic fluid that may function to inhibit bacterial growth have been examined. It appears that several potential antibacterial systems are present. Lysozyme and B-lysin may significantly contribute to the killing of gram-positive bacteria. Whether or not the remaining antibacterial systems function to inhibit gram-positive organisms remains to be determined. The phosphate-sensitive bacterial inhibitor recently described in our laboratory may represent the primary defense mechanism against gram-negative bacteria in amniotic fluid. Studies are warranted to ascertain whether this antibacterial system also inhibits gram-positive bacteria. The phosphate-sensitive bacterial inhibitor is quite different from other bacterial inhibitors in at least three respects. The system is very sensitive to the ubiquitous phosphate anion. The reason for this sensitivity is unknown and is difficult to explain phylogenetically, since phosphates are present virtually everywhere. To our knowledge this is the first antibacterial system of human origin which has been shown to require a metal cation as an integral part of the bactericidal effect. The peptide component of the phosphate-sensitive bacterial inhibitor is also unique in that it is of the molecular size of antibiotics or hormones. Additionally, the peptide does not appear to contain any unusual amino acids to explain its antibacterial activity. The mechanism of bacterial destruction of the phosphate-sensitive bacterial inhibitor, and its relation to the other antibacterial systems in amniotic fluid, remain to be elucidated.

Amniotic Fluid↗
PubMed1975

[Comparison of the antibacterial activity of amikacin (BB-K8) with other aminoglycosides against pathogens recently isolated from clinical materials (author's transl) ].

We determined the antibacterial activity of amikacin against 1,277 strains of pathogenic bacteria isolated from clinical materials during 1974, including beta hemolytic streptococci, pneumococci, enterococci, Staphylococcus aureus, Staph. epidermidis, Escherichia coli, Klebsiella, Enterobacter, Citrobacter, Serratia, Proteus morganii and Pseudomonas aeruginosa, and compared the minimum inhibitory concentration (MIC) of this drug with gentamicin, dibekacin, tobramycin and kanamycin. 1)Antibacterial activity of amikacin against beta hemolytic streptococci, pneumococci and enterococci was as weak as the other four aminoglycosides, but against Staph. aureus, Staph. epidermidis, various groups of Enterobacteriaceae and Pseudomonas aeruginosa showed amikacin the good antibacterial activity as gentamicin, dibedacin and tobramycin, and also showed the good activity against kanamycin resistant strains. 2) Amikacin has the similar antibacterial spectrum as gentamicin, dibekacin or tobramycin, but its antibacterial activity is generally weakest among these four drugs. 3) On many strains tested the cross resistance is observed between amikacin and one of gentamicin, dibekacin and tobramycin, but several strains of Proteus morganii and Pseudomonas aeruginosa which have rather large MIC against gentamicin, dibekacin or tobramycin showed rather small MIC against amikacin.

Amikacin↗
PubMedDate not supplied

Mutagenicity and antibacterial activity of mycotoxins produced by Penicillium islandicum Sopp and Penicillium rugulosum.

Twelve mycotoxins produced by Penicillium islandicum Sopp and Penicillium rugulosum in solid-state fermentation on grains were purified and tested for mutagenicity and antibacterial activity in Salmonella/mammalian microsome assays. The mutations studied were reversions of histidine auxotrophs to prototrophy in strains TA98 and TA100 and forward mutations to 8-azaguanine resistance (8AGR) in strain TM677. Rubroskyrin, (+)rugulosin, lumiluteoskyrin [a photoproduct of (-)luteoskyrin], and simatoxin [a new water-soluble metabolite of unknown structure] induced 8AGR mutations in strain TM677 but not histidine reversions in strains TA98 and TA100. Mutagenic potency was reduced by rat-liver microsomes. The carcinogens (-)luteoskyrin and cyclochlorotine were antibacterial but not mutagenic. (+)Rugulosin, rubroskyrin, lumiluteoskyrin, and high concentrations of simotoxin were also antibacterial. Antibacterial activity but not mutagenicity was observed with pibasterol and skyrin. Chrysophanol, islandicin, iridoskyrin, and emodin were inactive as mutagens or as antibacterial agents.

Animals↗
PubMed1975

Antibacterial activity of antisera against homologous and heterologous Escherichia coli of porcine origin.

Fourteen enteropathogenic and five nonenterotoxigenic Escherichia coli strains isolated from pigs were used for producing antisera in rabbits and pigs. These antisera were used in an vitro test system for antibacterial activity against homologous and heterologous porcine E. coli strains. Antibacterial titres were determined against the homologous strains and the percent reduction in CFU/ml caused by a 1/200 dilution of the sera against heterologous strains was determined. The results indicated that following immunization the antibacterial activity of serum against homologous and heterologous strains was significantly increased. This activity did not appear to be influenced by O and K antigen relationships among the organisms or by enterotoxigenicity of the vaccine strains. When antiserum produced against a combination of three enteropathogenic E. coli was tested against 20 strains a wider spectrum of heterologous antibacterial activity was obtained than with antiserum produced against any individual strain. The results indicate the existence in E. coli strains of porcine origin of common antigenic determinants not related to the serological formula and that a selected combination of strains can be expected to induce antibacterial acitivity against a wide variety of serological types of porcine enteropathogenic E. coli.

Absorption↗
PubMed2025

Broad-spectrum antibacterial and antibiofilm activity of dandelion endophytic bacteria against multidrug-resistant bacteria.

Microbial secondary metabolites have long served as a key source of natural product-based drugs. This study evaluates the antibacterial, antibiofilm, and antioxidant activities of endophytic bacteria derived from dandelion, focusing on their effects against multidrug-resistant (MDR) clinical isolates. In total, 33 endophytic bacteria strains were isolated from Taraxacum ohwianum, representing 15 genera. Among these, 13 exhibited antibacterial activity, with 6 demonstrating efficacy against MDR clinical isolates. The endogenous strain Bacillus velezensis DR8 showed strong antibacterial activity against all three MDR strains tested and exerted inhibitory effects on the biofilm formation and dispersal of methicillin-resistant Staphylococcus aureus. Genome sequencing and antibiotics and secondary metabolite analysis shell analysis revealed that this strain harbors 12 biosynthetic gene clusters (BGCs) associated with secondary metabolite production. Of these, seven BGCs exhibited ≥ 80% similarity to known clusters, suggesting the potential to synthesize surfactin, difficidin, fengycin, bacillaene, macrolactin H, bacilysin, and bacillibactin. Overall, these findings indicate that endophytic bacteria from dandelion are a potential source of antibacterial compounds and biofilm formation inhibitors.

Endophytes↗
PubMed1979

Comparative antibacterial activity of azlocillin, mezlocillin, carbenicillin and ticarcillin and relative stability to beta-lactamases of pseudomonas aeruginosa and klebsiella aerogenes.

The antibacterial activities of two ureidopenicillins, azlocillin and mezlocillin, were compared with those of the alpha-carboxypenicillins, carbenicillin and ticarcillin, against a large number of gram-positive and gram-negative bacteria. All four penicillins were active against a wide range of bacteria including Pseudomonas aeruginosa, but there were differences in the antibacterial spectra and in the antibacterial effects demonstrated by the two classes of penicillins. In particular, the minimum inhibitory concentrations of azlocillin and mezlocillin against Klebsiella aerogenes and against P. aeruginosa were greatly influenced by the size of bacterial inoculum tested whereas there was no significant inoculum effect with carbenicillin and ticarcillin. In stability tests, the ureidopenicillins were inactivated rapidly by the beta-lactamases of K. aerogenes and P. aeruginosa whereas the alpha-carboxypenicillins were stable. It seems probable that the inoculum effect seen with azlocillin and mezlocillin in antibacterial tests with K. aerogenes and P. aeruginosa is associated with the instability of the compounds to the beta-lactamases of these bacteria.

Carbenicillin↗
PubMed2026

Antibacterial activity and mechanistic insights of Lucilia illustris antimicrobial peptide Cecropin A2 against Pseudomonas aeruginosa.

Pseudomonas aeruginosa (P. aeruginosa) poses a serious public health threat due to multidrug resistance and biofilm formation. This study investigated the antibacterial mechanisms of the antimicrobial peptide, Cecropin A2 (CA2), against P. aeruginosa. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CA2 against P. aeruginosa ATCC 9027 (PA ATCC 9027) were determined by broth microdilution. Antibacterial activity was evaluated using growth curves and time-kill assays. The mechanism was explored by assessing membrane integrity (outer/inner membrane permeability, SEM, and fluorescence microscopy), and intracellular responses (ATP, SDH activity, and ROS). Biofilm effects were assessed by crystal violet staining (biomass) and viable cell counting (biofilm-embedded bacteria). The MIC and MBC of CA2 against PA ATCC 9027 were 37.34 μM and 74.68 μM, respectively. CA2 exhibited moderate antibacterial activity against PA ATCC 9027. Scanning electron microscopy (SEM) revealed marked morphological damage after treatment. CA2 affected intracellular metabolism, potentially interacted with genomic DNA, and reduced biofilm biomass. Cecropin A2 exhibits concentration-dependent in vitro antibacterial activity against P. aeruginosa ATCC 9027, providing mechanistic insights and a theoretical basis for the development of alternative antimicrobial strategies.

Antimicrobial activity↗
PubMed1979

Antibody-dependent cell-mediated antibacterial activity of human mononuclear cells. I. K lymphocytes and monocytes are effective against meningococi in cooperation with human imune sera.

In cooperation with human heat-inactivated antisera from adults immunized with group C meningococcal polysaccharide, normal human peripheral blood mononuclear cells significantly decreased the viability of group C meningococci (Mgc) in vitro. K lymphocytes (Null cells) and monocytes, (but not T or B lymphocytes) were capable of effecting antibody-dependent cell-mediated (ADC) antibacterial activity in this system. The degree to which meningococcal viability was decreased was a function of the length of the test incubation, the concentration of effector cells, and the amount of antiserum used in the assay. When specific antibodies directed against Mgc were adsorbed from the antiserum, cell-mediated antibacterial activity was abolished. ADC antibacterial activity was also abrogated by performing the assay at 4 degrees C or by heating effector cells to 46 degrees C for 15 min before the assay, Similarities between the ADC antibacterial system and previously described ADCC assays are discussed. The data suggest the K cells (as well as monocytes) may play a role in host immune defense against pathogenic bacteria.

Antibodies, Bacterial↗
PubMedDate not supplied

Interactions between antibacterial drugs below the minimal inhibitory concentration.

Interaction between antibacterial agents is often assessed in chessboard titrations, in which bacteriostatic synergy is detected as a mutual reduction in the minimal inhibitory concentrations (MICs) of the agents being tested. If MIC titrations are continually monitored turbidimetrically, the conventionally determined "end point" is seen to reflect the final outcome of a series of events that have occurred during the incubation period. One factor that influences the end point is the emergence, during overnight incubation, of a bacterial population with slightly increased drug resistance. A frequent component of the synergy recorded in chessboard titrations is the mutual suppression of such adaptive resistance. Synergy can also be expressed in terms of the minimal antibiotic concentration (MAC), i.e., the lowest concentration needed to produce an observable antibacterial effect. Antibacterial agents that exhibit true biochemical synergy interact to cause a mutual reduction in the MAC, but the degree of synergy recorded in this way is substantially lower than that determined by conventional chessboard titration. The benefits of antibacterial synergy in therapy cannot be predicted based on chessboard titrations alone. Dramatic synergy of the trimethoprim-sulfamethoxazole type may be of limited clinical use, whereas other drug combinations may be more useful than the results of cross-titration suggest.

Anti-Bacterial Agents↗
PubMed1978

Comparison of the in vivo and in vitro antibacterial properties of providone iodine and chlorhexidine gluconate mouthrinses.

Clinical and laboratory studies were carried out to compare the antibacterial properties of two antiseptic mouthwashes, namely 1% povidone iodine and 0.2% chlorhexidine gluconate. In a group of 10 subjects after a single rinse with povidone iodine, an immediate mean fall in total salivary aerobes and anaerobes occurred, followed by a return to normal levels by 1-hour postrinsing. With chlorhexidine gluconate a similar but greater reduction in salivary bacterial counts was observed, which was still present up to the 7-h postrinsing period. Saliva samples obtained from the subjects 2 min after rinsing with providone iodine produced little or no inhibition to the growth of a test organism in vitro, whereas following chlorhexidine gluconate, antibacterial activity was present in the saliva specimens up to the 3-h sampling time. Using culture media containing comparable levels of soluble protein to saliva, the minimum inhibitory concentrations of povidone iodine against several standard test organisms were much higher than those of chlorhexidine gluconate. The results suggest that povidone iodine, as a mouthwash, exerts only an immediate antibacterial effect and unlike chlorhexidine, is not retained at antibacterial levels within the oral cavity after expectoration. This lack of prolonged action of povidone iodine in the oral cavity would appear to be relevant to its reported lack of antiplaque activity.

Anti-Infective Agents, Local↗
PubMed1977

The relationship between nicotinamide adenine dinucleotide concentration and antibacterial activity of isoniazid in Mycobacterium tuberculosis.

The relationship between the antibacterial effect of isoniazid and the intracellular concentration of nicotinamide adenine dinucleotide (NAD) was investigated in Mycobacterium tuberculosis strain H37Rv given continuous and pulsed exposures to the drug. Depletion of NAD to a plateau value occurred rapidly during exposure, and recovery after a pulse of isoniazid was also rapid. It seemed unlikely that NAD depletion was the direct cause of the antibacterial activity because (1) insufficient depletion occurred at low isoniazid concentrations; (2) antibacterial activity, but not NAD depletion, was proportional to the product of isoniazid concentration and the exposure period; and (3) NAD depletion was not related to antibacterial activity in cultures of differing physiologic state.

Isoniazid↗