SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Antimicrobial activity of hydroperoxides and cyclic peroxides has been studied. 2,4-Dihydroperoxy-2,4-dimethylpentane (1) and 2,5-dihydroperoxy-2,5-dimethylhexane (2) were active against microorganism, but 1 showed a large specially against C. albicans, M. luteus and B. subtilis with a MIC value of 31.5 mcg/ml.
Explore the source record for details and available documents.
The environmental bacterium Pseudomonas protegens PBL3 has antagonistic activity against the plant pathogenic bacterium Burkholderia glumae, an important pathogen in rice. The antimicrobial activity of P. protegens PBL3 was found in the bacteria-free secreted fraction (secretome), but the specific molecules, as well as the genetic basis of that activity, have not been identified. In this study, we integrated genomic information with antimicrobial assays on P. protegens PBL3 and additional six Pseudomonas spp. strains, to identify putative genomic regions in P. protegens PBL3 associated with antimicrobial activity. We hypothesized that Pseudomonas spp. strains with antimicrobial activity against B. glumae have conserved genes with P. protegens PBL3 that are absent in strains lacking activity. Comparative genomics analyses with anvi'o and progressiveMauve, and using P. protegens PBL3 as the reference genome, revealed 188 genes uniquely present in antimicrobial-producing strains. Seven of those genes were annotated as biosynthetic gene clusters predicted to encode secondary metabolites; additional genes were grouped into 25 contiguous clusters with functions annotated as secretion, signal transduction, regulation, transport/efflux, carbohydrate metabolism and one with an additional uncharacterized function. Altogether, this study uncovered a complex and multi-functional network of candidate genes, suggesting that the antimicrobial activity in P. protegens PBL3 is not limited to biosynthetic pathways but also involves additional regulatory, metabolic and export modules to synthesize and deploy antimicrobials.
The antimicrobial activity of metronidazole was investigated in anaerobic bacteria by use of time-viability studies. This antimicrobial agent has a rapid onset of bactericidal activity under proper reducing conditions. The bactericidal rates were not affected by inoculum size or nutritional requirements, nor by inhibition of growth and protein synthesis by chloramphenicol. Using supernatant fractions of actively growing cultures of susceptible organisms, we observed a disappearance of metronidazole and a loss of biological activity, but there was no significant change in preparations from resistant bacteria. The decrease in drug concentration with susceptible cells occurred during the time that its bactericidal action was being exerted. Extracts from susceptible organisms rapidly reduced the concentration of metronidazole, confirming previous observations which suggest that the drug acts as a terminal electron acceptor. Radioisotope experiments with [14C]metronidazole revealed that the compound was taken up by both resistant and susceptible bacteria, although there was a difference in rate and extent of accumulation. These studies demonstrate that metronidazole's antimicrobial activity against anaerobic bacteria is bactericidal and independent of growth rate, and that it involves the uptake and metabolism of the compound.
The effect of solid dispersion techniques on the antimicrobial activity of chloramphenicol has been studied and it was proven that the antimicrobial activity of chloramphenicol is not affected when the drug is present as a coprecipitate with carbowaxes (4.000, 6.000, 12.000), and PVP 11.000 and 40.000) also in fusion systems with these polymers. In contrast, the antimicrobial activity of the drug is enhanced when it is present in the from of a solid dispersion system.
Mathematical models were investigated for the distribution and antimicrobial activity of chlorocresol in solubilized and emulsified systems stabilized with a nonionic surfactant. The concentration of free preservative in the solubilized systems was described adequately by an equation widely used to describe the binding of small molecules to macromolecules. For the emulsions, this equation was combined with an expression for the partitioning of the preservative between the oil and water phases. It was confirmed that short-term antimicrobial activity can be related to the free (unbound) preservative concentration in the aqueous phase and that preservative solubilized within the surfactant micelles or partitioned into the oil phase does not contribute to short-term preservation.
An in vitro test system was used to compare the antimicrobial activity of erythromycin, amoxicillin and ampicillin against respiratory tract pathogens isolated from man. The minimum inhibitory concentrations (MICs) of fresh clinical isolates of Streptoccus pyogenes, Streptocuccus pneumoniae, Staphylococcus aureus and Haemophilus influenzae to the macrolide and penicillins ranged between 0.01 and 0.9 microgram/ml. The microbes were exposed to each antibiotic for approximately 3 h at 1x,2x and 5x the relevant MIC. Irreversible surface defects and intracellular lesions were resolved by scanning and transmission electron microscopy in all antibiotic-treated bacterial species, irrespective of the antimicrobial used. In each case, inhibition of growth was recorded by turbometric assay; no significant difference was observed among the declining slopes of post-dosing growth curves for either erythromycin-, amoxicillin- or ampicillin-treated pathogens. The experimental observations show that the onset of antimicrobial activity and the bactericidal effectiveness of equipotent concentrations of erythromycin, amoxicillin and ampicillin were comparable in this study. The results complement previous clinical, bacteriologic and ultrastructure studies in vivo and demonstrate the contribution of the combined in vivo/in vitro study design for better understanding of antimicrobial activity in human respiratory tract infections.
Antimicrobial activity of N-alkyl-N-dodecylpiperidinium bromides and N-ethyl-N-dodecylheterocycloalkyl ammonium bromides (pyrrolidine, morpholine, perhydroazepine) determined on grampositive and gramnegative bacteria, yeasts and moulds, presented as minimum inhibition concentration (MIC). Comparison of the effect of change of structure: lengthening of alkyl chain, change of heterocyclic ring. Change in the length of alkyl chain markedly affects the antimicrobial activity, change of heterocyclic ring has no substantial effect. The most active compounds were N-heptyl-and N-hexyl-N-dodecylpiperidinium bromides.
Cell free peritoneal fluids from 23 normal women had antimicrobial activity which was directed against gram-positive and gram-negative bacteria and also against yeasts. The activity was bacteriostatic or bactericidal and seemed to be due to the presence of a variety of factors which varied in their heat stability and dependence on complement. Lysozyme was present in the fluids but was not responsible for all the antimicrobial activity.
A radiochemical study for antimicrobial activity of chlormerodrin was performed using some commonly occurring nonpathogenic and pathogenic microorganisms. Chlormerodrin concentrations of 15-35 and 20-45 microgram/ml of the culture medium were microbiostatic and microbicidal, respectively. The microbiostatic effect was reversible in the presence of cysteine, an amino acid containing a sulfhydryl group.
In the scope of our research about the antimicrobial activity of aldehyde-amin-condenates a number of partly new aminals was synthesized by reaction of formaldehyde with various secondary amines. Structures and physically constants are shown in the tables 1 and 2. The antimicrobial activity is demonstrated by the results of the disk-test (table 3), of the minimal inhibition concentration (MIC, talbe 4) and the suspension and area disinfecting test following the method of the DGHM (tables 5 and 6). Standardized formulations were developed to eliminate the different solubility effects of the various aminals. These formulations do not influence the test results. It may be shown, that aminals have both germistatic activity mainly versus Staphylococcus aureus, Bacillus subtilis, Aspergillus niger and Penicillium glaucum and germicidal activity especially versus Pseudomonas aeruginosa, Trichophyton mentagrophytes and Microsporium gypseum.
In the scope of our research about the antimicrobial activity of amin-aldehydecondensates a number of substituted benzaldehyde azomethines was synthesized by condensation of suitable benzaldehydes with primary amines (aminoethanol and n-butylamine). Structures and physical constants are shown in the table 1. The antimicrobial activity is demonstrated by the results of the disk-test (table 2 and 3), of the minimal inhibition concentration test (MIC, table 4) and of the suspension-disinfecting test following the method of the DGHM (table 5). It may be shown that both the germistatic and the germicidal activity depends on the substituents of the aromatic ring. Bactericidal activity show the test compounds mainly versus the gram-negative bacteria.
Comparative antimicrobial activity studies for certain new classes of soft N-chloramines derived from alpha-aminiisobutyric acid and 2-amino-2-methyl-1-propanol were examined using the minimum inhibitory concentration (MIC) and/or the contact germicidal efficiency (CGE) procedures. Several factors significantly aliphatic chain length in a homologous series, (b) the degree of chlorination of thenitrogen atom, (c) the solution pH, (d) the presence of a denaturant, and (e) the nature of a positive charge.
In the scope of our research about the antimicrobial activity of aldehyde-amin-condensates a number of partly new unsymmetrically substituted animals was synthesized by reaction of formaldehyde with different secondary amines. Structures and physically constants are shown in the tables 1 and 2. The antimicrobial activity is demonstrated by the results of the disktest (table 3), of the minimal inhibition concentration (MIC, table 4) and the suspension and area disinfecting tests following the method of the DGHM (tables 5 and 6). For this testing a standardized formulation was used to eliminate the different solubility effects of the various animals. This formulation does not influence the test results. It may be shown, that unsymmetrically substituted animals have both germistatic activity mainly versus Staphylococcus aureus and Bacillus subtilis and germicidal activity especially versus Pseudomonas aeruginosa, Proteus vulgaris, Trichophyton mentagrophytes and Micosporum gypseum.
The antimicrobial activity of urine collected from adult male paraplegics ingesting methenamine mandelate (MM) was evaluated. The in vitro bacterial growth in urine from these patients was inhibited when the free formaldehyde (HCHO) concentration was 10 to 22 microgram per ml. When the HCHO concentration was in the region of 28 microgram per ml or greater, bactericidal effect became apparent. Urine containing 1323 microgram of MM per ml with a pH of 5.9 when freshly voided had sufficient HCHO to be bacteriostatic. Urine containing at least 1740 microgram of MM per ml with a pH of 5.1 or less when freshly voided was bactericidal. The latter concentration of MM in urine was usually achieved when the patient ingested 4 g of MM per day in divided doses and the intake of fluid was not excessive. Under some circumstances an individual receiving MM without an additional acidifying agent may produce urine with a pH low enough to release sufficient HCHO to exert a useful antibacterial effect. However, supplementary acidification with ammonium chloride produced marked lowering of the urinary pH in all patients receiving MM, resulting in bactericidal levels of HCHO.
The effect of N-alkyl derivatives of saturated heterocyclic amine oxides on the growth and metabolism of microorganisms has been studied. 4-Dodecylmorpholine-N-oxide inhibited the differentiation and growth of Bacillus cereus, of different species of filamentous fungi, and of the yeast Saccharomyces cerevisiae. For vegetative cells, the effect of 4-dodecylmorpholine-N-oxide was lethal. Cells of S. cerevisiae, after interaction with 4-dodecylmorpholine-N-oxide, released intracellular K(+) and were unable to oxidize or ferment glucose. The functions of isolated yeast mitochondria were also impaired. 4-Dodecylmorpholine-N-oxide at growth-inhibiting concentrations induced rapid lysis of osmotically stabilized yeast protoplasts, with the rate of lysis a function of temperature and of amine oxide concentration. A study of the relationships between structure, antimicrobial activity, and cytolytic activity was made with a group of structurally different amine oxides involving a series of homologous 4-alkylmorpholine-N-oxides, 1-alkylpiperidine-N-oxides, 1-dodecylpyrrolidine-N-oxide, 1-dodecylperhydroasepine-N-oxide, and N,N-dimethyldodecylamine oxide. Disorganization of the membrane structure after interaction of cells with the tested amine oxides was primarily responsible for the antimicrobial activity of the amine oxides. This activity was found to be dependent on the chain length of the hydrophobic alkyl group and was only moderately influenced by other substituents of the polarized N-oxide group.
PS-5, a new beta-lactam antibiotic, has relatively potent antimicrobial activity against Gram-positive and Gram-negative bacteria, especially the Enterobacter groups, Serratia marcescens, the Proteus groups and Klebsiella pneumoniae. The activity of PS-5 against many beta-lactamase-producing organisms is greater than that of cefoxitin or cefazolin. PS-5 has good therapeutic activity in mice infected with Staphylococcus aureus Smith or Enterobacter cloacae 45.
It is proposed to determine the antimicrobial activity of propolys alcohol extracts by the method of subsequent dilutions in solid nutrient media. Dilution of the extracts immediately in hot agar eliminated the inhibiting effect of the extragent on the microbial growth. Opalesence appearing in the agar did not prevent estimation of the results in contrast to the method of subsequent dilutions in liquid nutrient media.