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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.
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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.
The antimicrobial activity of three antioxydants, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) and ethoxyquin (ETO) was studied. In vitro assays showed that when these antioxydants are added to the culture media at concentrations lower or equal to that used in nutrition, they inhibit or decrease the growth of certain microorganisms. BHT showed the most marked effect, affecting Gram-positive bacteria at a higher degree than the Gram-negative bacteria belonging to the family Enterobacteriaceae. Inactivation study of different bacterial species by BHT revealed differences in sensitivity among a single genus and between strains of the same species. The association of ETO with BHT results in an increase of the inhibitory activity. The increased sensitivity to BHT resulting from the osmotic shock of Escherichia coli cells suggests that the resistance to BHT of the Gram-negative bacteria belonging to the family Enterobacteriaceae might be due in part to the structure of their cell wall.
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.
Some 1-(hydroxyphenyl)-1-nonen-3-ones, the corresponding Mannich bases, and O-benzoyl esters were synthesized. Evaluation of these derivatives against murine P-388 lymphocytic leukemia indicated that, while the hydroxyphenyl styryl ketones and related esters were devoid of significant anticancer activities, etherification of the nuclear hydroxyl group gave compounds with a discernible increase in mean survival time. The hydroxyphenyl styryl ketones showed marked potencies against two pathogenic fungi and one, yeast, while the corresponding ethers had diminished activities and the related esters were virtually devoid of antimicrobial activities. Two Mannich bases showed similar spectra of antimicrobial activities as the phenols and, in particular, were active against Trichophyton mentagrophytes and Saccharomyces uvarum.
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.
The antimicrobial activities of a number of cytotoxic C-benzylated flavonoids from Uvaria chamae have been determined. The minimum inhibitory concentration values of these flavonoids and certain of their derivatives against Straphylococcus aureus, Bacillus subtilis, and Mycobacterium smegmatis compare favorably with those of streptomycin sulfate.
The in vitro antimicrobial activity of the antieczematic Bay f 4797 was studied. This combination drug contains the three active components acidamfenicol, clotrimazole and dexamethasone (prospective trade name: Baycuten). Various bacterial and fungal species of importance in dermatology served as test organisms. All the bacterial strains examined were found to be moderately susceptible to acidamfenicol; clotrimazole showed good inhibitory values agaisnt all the fungal species and the gram-positive bacterial strains. Additionally it was checked whether a synergistic or antagonistic interaction occurs with respect to the antimicrobial activity. An interference which could lead to impairment of the therapeutic activity was not observed.
Sixty-one amniotic fluid samples from women in their second and third trimesters of pregnancy were examined for antimicrobial activity. Seventy per cent of the fluids were found to be active. The factor or factors responsible for this activity were present in low concentrations. The presence of spermine in the fluids accounted for some of the antimicrobial activity.
In the scope of our research about the antimicrobial activity of amin-aldehyde-condensates a number of azomethins was synthesized by the condensation of primary aliphatic and aromatic amins with aliphatic aldehydes. Structures and physical constants are listed in table 1 and 2. - The antimicrobial activity of these azomethins is demonstrated by the results of the disk-test (table 3), of the minimal inhibition concentration test (MIC, table 4), and the suspension test (table 5) following the method of the DGHM. - The different water-solubility of the azomethins was equalized by using the standard solution described earlier. - It may be shown that the azomethins have both bacterio- and fungistatic activity which resembles that of the corresponding aldehydes (table 4). The fungistatic activity against Trichophyton mentragrophytes shown by the results of the disk-test is remarkable. - The bactericidal power of the azomethins versus Klebsiella pneumoniae, Pseudomonas aeruginosa and Proteus vulgaris is quiet stronger than that of the corresponding aldehydes.
In the scope of our research about the antimicrobial activity of amin-aldehyde-condensates a number of benzylidene-amines (azomethins of benzyldehyde) was synthesized by condensation of primary amines with benzaldehyde. Structures and physical constants are shown in table 1 and 2. The antimicrobial activity of these benzylidene-amines is demonstrated by the results of the disk-test (table 3), of the minimal inhibition concentration test (MIC, table 4) and the suspension test (table 5) following the method of the DGHM. The different hydrophilic behaviour was equalized by using the standard solution described earlier with 3% dioxane. The results show, that the germistatic activity of the benzylideneamines resembles or exceeds in some cases that of benzaldehyde (table 4). Some compounds show good fungistatic activity versus Trichophyton mentagrophytes (table 3). The bactericidal power versus Klebsiella pneumoniae, Pseudomonas aeruginosa and Proteus vulgaris is remarkable and quiet stronger than that of the benzaldehyde.
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.