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At least 19 recordsLinked to original sources
PubMed1975

[The effect of antibiotic supplementation on antibiotic resistance, transferable antibiotic resistance, morbidity, and growth in calves (author's transl)].

112 calves, divided into four groups, were given milk substitutes containing tetracycline (high-dosage feed), zinc bacitracin or Lactosat (control) and concentratesw with or without zinc bacitracin (Table I). We have investigated the incidence of antibiotic resistance and transferable antibiotic resistance in E. coli strains isolated from the faces of these calves and checked the growth and state of health in the four groups. Growth was also studies in a further ten feeding series comprising a total of 258 calves. Half this number received zinc bacitracin in milk substitute, the other half were fed milk substitute containing Lactosat, instead of antibiotics (Fig. 8). Tetracycline led to a quick increase of antibiotic-resistant straing (Fig. 4--6). This increase is significant in comparison with the other groups. Significant increases of resistance were also noted to ampicillin and chloramphenicol (Fig. 7), althoug these drugs were not used. A significant increase of the transferable resistance was also observed in the group of calves given tetracycline (Fig. 7) and to 65% at about 31/2 months after the end to 38% within 12 days (Fig. 7) and to 65% at about 31/2 months after the end of tetracycline feeding (Fig. 7). A marked increase of en-bloc transfer was also noted after completion of tetracycline feeding (Fig. 2). Up to slaughter, at the age of 6 months, no better growth was obtained with zinc-bacitracin supplement than with milk substitute without antibiotics but containing Lactosat. During the milking period the results varied between the different feeding series. In some series the mean growth in the zinc-bacitracin group was better than, in some no different from, and in other s poorer than that in the Lactosat group (TableII, Fig. 8). The only demonstrable positive effect of tetracycline supplement was a tendency twwards better health during the period of administration of the drug (Table II...

Ampicillin↗
PubMed1976

Isolation of a new antibiotic 333-25, related to antibiotic EM 49. (Studies on antibiotics from the genus Bacillus. XI).

A new antibiotic, 333-25, active against Gram-positive and Gram-negative bacteria, was isolated from the culture broth of Bacillus circulans 333-25. The antibiotic is a basic acylpeptide containing 2,4-diaminobutyric acid (5), leucine (2), phenylalanine (1) and a fatty acid. It is closely related to antibiotic EM 49, but can be differentiated by chromatographic behaviour.

Animals↗
PubMed1979

Neo-enactin, a new antifungal antibiotic potentiating polyene antifungal antibiotics. II. Taxonomic studies of the producing microorganism and simultaneous production of bleomycin group and streptothricin-like antibiotics.

A new antifungal antibiotic, named neo-enactin, was produced mainly in the mycelia of strain H 829-MY 10. Strain H 829-MY 10 was identified as a Streptoverticillium, determined to be nonchromogenic, and fits in the white color-series. Although Streptoverticillium olivoreticuli is known to be chromogenic, strain H 829-MY 10 is most related to that species. Thus, strain H 829-MY 10 is named as Streptoverticillium olivoreticuli subsp. neoenacticus. Besides neo-enactin, two bleomycin-group antibiotics and two streptothricin-like antibiotics were simultaneously produced by strain H 829-MY 10.

Anti-Bacterial Agents↗
PubMed2026

Occurrence of antibiotic-resistant E. coli and antibiotic resistance genes from culturable bacteria in drinking water sources along the Upper Mahaweli River, Sri Lanka.

Antibiotic-resistant Escherichia coli (AR-E. coli) and antibiotic resistance genes (ARGs) in aquatic environments pose a serious threat to public health. However, their presence in river water in South Asian countries is not well established. The present study investigated AR-E. coli and ARGs from culturable bacteria in drinking water sources from 14 drinking water treatment plants situated along the Upper Mahaweli River, a tropical central hill-country river system in Sri Lanka. A total of 167 E. coli isolates were tested against ten antibiotics using the Kirby-Bauer method, and genomic DNA from culturable bacteria in 45 water samples were screened for 11 ARGs using PCR. Overall, 60.48% E. coli isolates exhibited resistance to at least one antibiotic and multidrug resistance was detected in 27.54%. Highest resistance was for amoxicillin (47.31%), tetracycline (26.95%), and co-trimoxazole (24.55%) and four antibiotics showed seasonal variation. ARGs, dominated by blaTEM (80.0%), tetA (66.67%), and tetM and qnrS (62.22%) were detected in 42.42% PCR assays (n = 210). Multiple antibiotic resistance index varied from 0.00 to 0.80, with 44.91% exceeding the 0.2 threshold value, and the antibiotic resistance index varied from 0.00 to 0.32, with eight above the threshold (≥ 0.2). Hierarchical cluster analysis grouped majority of drinking water sources into the intermediate category while few were categorized under low (Kotagala and Thalawakelle-Galkanda) and high (Haragama, Paradeka, and Nawalapitiya), reflecting the variability of anthropogenic interference. Results highlight the risk associated with AR-E. coli and ARGs from culturable bacteria in one of Sri Lanka's key drinking water sources. Proactive interventions ensuring long-term safety of drinking water sources are urgently needed to safeguard public health.

Sri Lanka↗
PubMed2024

The fate of antibiotics and antibiotic resistance genes in Large-Scale chicken farm Environments: Preliminary view of the performance of National veterinary Antimicrobial use reduction Action in Guangdong, China.

In 2018, China implemented the Veterinary Antimicrobial Use Reduction Action to curb the rapid development of antibiotic resistance (AR). However, the AR-related pollutions in animal farms after the reduction policy has been poorly investigated. Here, we performed a comprehensive investigation combining UPLC-MS/MS, metagenomic, and bacterial genomic analyses in eight representative large-scale chicken farms in Guangdong, China. Our results showed that antibiotics and ARGs contaminations were more severe in broiler farms than in layer farms. Notably, diverse tet(X) variants were prevalent in the chicken farms. These tet(X)s was carried by diverse E. coli lineages and obviously correlated with ISCR2 and IS1B transposases. The resistomes in chicken farms was significantly correlated with microbial community, and multiple factor analyses indicated that the joint effect of antibiotics-microbial community-MGEs was the most dominant driver of ARGs. Host tracking identified a variety of ARG bacterial hosts and the co-occurrence of ARGs-MRGs-MGEs. Source tracking indicated that the inherent component represented the main feature of resistomes in different hosts, while ARG transfer between the chicken gut and farm environments were frequent. A multiperspective evaluation of AR risk revealed that the early effect of antibiotic reduction was exhibited by the mitigation of maximum level of risky ARGs, prevalence of environmental AR pathogens, and HGT potential of ARGs mediated by phage structures. Overall, our findings provide insights into the antibiotic and ARG profiles in large-scale chicken farms with different rearing strategies and demonstrate a preliminary view of the performance of antibiotic reduction actions in China.

Chickens↗
PubMed1975

Antibiotic A-16316-C, a new water-soluble basic antibiotic.

A new water-soluble basic antibiotic named antibiotic A-16316-C was isolated together with antibiotic A-396-I and hygromycin B from a streptomyces strain identified as Streptoverticullium eurocidicus. The properties of the antibiotic A-16316-C were similar to those of destomycin B. But it was found that the antibiotic A-16316-C was not identical with destomycin B on the basis of NMR analysis. On acidic degradation antibiotic A-16136-C gave N, N'-dimethyl-2-deoxystreptamine, destomic acid and D-mannose. The gross structure for antibiotic A-16136-C was deduced from chemical reactions and spectral data.

Aminoglycosides↗
PubMed1975

Mode of action of the macrolide-type antibiotic, chlorothricin. Effect of the antibiotic on the catalytic activity and some structural parameters of pyruvate carboxylases purified from rat and chicken liver.

The macrolide-type antibiotic chlorothricin inhibits pyruvate carboxylases purified from rat liver, chicken liver and Azotobacter vinelandii. Under standard assay conditions the concentration of chlorothricin required for half-maximal inhibition of oxalacetate synthesis is 0.26 mM (rat liver), 0.12 mM (chicken liver), and 0.5 mM (Azobacter vinelandii). Inhibition by chlorothricin appears non-competitive in character when measured as a function of the concentration of the substrates of the pyruvate carboxylase reaction as well as of CoASAc and Mg2+. This pattern of inhibition suggests that this antibiotic interacts at unique sites on chicken and rat liver pyruvate carboxylase which are distinct from both the catalytic and activator sites. Interaction of chlorothricin with the two vertebrate liver pyruvate carboxylases differs from the effect exerted by this antibiotic on pyruvate carboxylase purified from Azotobacter vinelandii. A sigmoidal relationship between initial velocity and inhibitor concentration is observed for the vertebrate enzymes under most conditions whereas a hyperbolic profile characterizes the concentration dependence of inhibition of the Azotobacter vinelandii enzyme by chlorothricin. In the case of rat liver pyruvate carboxylase chlorothricin does not alter the extent of cooperativity in the relationship between initial rate and CoASAc concentration. However, a small but significant increase of the Hill coefficient from a value of 2.7 in the absence of antibiotic to that of 3.3 in the presence of 0.5 mM chlorothricin is observed for chicken liver pyruvate carboxylase. Chlorothricin decreases the rate of inactivation observed when rat liver pyruvate carboxylase is incubated with trinitrobenzenesulfonate and when chicken liver pyruvate carboxylase is incubated at 2 degrees C. The maximal decrease in inactivation observed in the presence of saturating concentrations of antibiotic is 50% for cold inactivation of the chicken liver enzyme and 60% for inactivation of the enzyme from rat liver by trinitrobenzenesulfonate. In both cases a sigmoidal relationship is observed between inactivation rate and chlorothricin concentration. These data as well as the initial rate studies suggest that multiple interacting sites for this antibiotic are present on the vertebrate liver pyruvate carboxylases. The occupancy of these sites appears to cause significant distortion of both the catalytic and the activator sites.

Adenosine Triphosphate↗
PubMed2025

Sequential antibiotic exposure restores antibiotic susceptibility.

BACKGROUND: The prevalence of antibiotic resistance continues to rise, rendering many valuable antimicrobial drugs ineffective. Pairwise cyclic antibiotic therapy, where treatment is rapidly switched between two antibiotics, has been demonstrated in vitro to limit the evolution of antibiotic resistance. However, what happens when resistance inevitably evolves to one of the drugs? METHODS: In this study, we perform over 450 evolution experiments to test the resilience of four proposed cyclic therapies. We use soft agar gradient evolution and 'flat plates' to identify resistance trade-offs that are resilient to compensatory mitigation. Resensitizations were detected by antimicrobial susceptibility assays, and their mechanistic underpinnings were elucidated via genomic and phenotypic analyses. RESULTS: Resistance evolves readily and collateral sensitivity (CS) (where resistance to drug A leads to hypersensitivity to drug B) does not hinder the evolution of multidrug resistance and does not predict or promote resensitization. However, if resistance to drug B increases susceptibility to A, a phenomenon we term backward CS, resistance to A can be reduced or even reversed. For example, we show that Escherichia coli cells frequently become hypersensitive to β-lactams upon aminoglycoside resistance acquisition, due to conflicting modifications to the proton motive force and efflux pumps. We also find for the first time that polymyxin B resistance can be entirely reversed by exposure to tigecycline, through the acquisition of compensatory mutations that reduce the fitness penalty of tigecycline resistance. CONCLUSIONS: The longevity of drug cycling protocols can be significantly improved by leveraging backwards CS to resensitize cells as antibiotic resistance evolves.

Anti-Bacterial Agents↗
PubMed1979

Morphology of experimental antibiotic-associated enterocolitis in the hamster: a model for human pseudomembranous colitis and antibiotic-associated diarrhoea.

The morphology of antibiotic-associated enterocolitis in the hamster is described and compared with human antibiotic-associated pseudomembranous colitis. It is shown to be a caecal disease with proliferative mucosal changes and in this respect unlike the human counterpart. The bacteriology and toxicology, however, are identical. In addition, mucosal changes are described in animals on antibiotics but without established enterocolitis. As a result we suggest that there may be a spectrum of human disease ranging from mild antibiotic-associated diarrhoea to established pseudomembranous colitis. Therefore, despite the morphological variation, the hamster remains a good model for investigating the pathogenesis of pseudomembranous colitis and antibiotic-associated enteropathy in general.

Animals↗
PubMed1976

Antiviral antibiotic S15-1. Taxonomy of the producing strain and study of conditions for production of the antibiotic.

Strain S15-1 which produces antiviral antibiotic S15-1 belonging to the streptothricin group of antibiotics was isolated from a soil sample. Cell analysis, colony morphology, the absence of sporangia-like vesicles, the formation of spores in chains of the Rectus Flexibilis type, and the ability to produce melanoid pigment, indicate that this strain belongs to the genus Streptomyces Waksman and Henrici. A comparison of the characteristics of strain S15-1 with related Streptomyces show that it should be identified as Streptomyces purpeofuscus Yamaguchi and Saburi. The investigation of cultural conditions show that soluble starch and meat extract are the most suitable carbon and organic nitrogen sources for the production of antibiotic S15-1. Strain S15-1 grew poorly on media with no organic nitrogen sources, and did not produce the antibiotic. Antiviral antibiotic S15-1 is accumulated at the highest level after 3 or 4 days growth of the producing organism.

Anti-Bacterial Agents↗
PubMed1979

Neo-enactin, a new antifungal antibiotic potentiating polyene antifungal antibiotics. I. Fermentation, extraction, purification and physico-chemical and biological properties.

A new antifungal antibiotic, named neo-enactin, was isolated from the cultured mycelia of Strain H 829-MY 10, identified as a new subspecies of Streptoverticillium and named Streptoverticillium olivoreticuli subsp. neoenacticus. The antibiotic was produced with a tetraene antifungal antibiotic, found mainly in the cultured mycelia of Strain H 829-MY 10 and it was extracted with methanol. The antibiotic is of a basic nature and it can be extracted with ethyl acetate at alkaline pH. Purification of neo-enactin was carried out by partition chromatography on cellulose and elution with ethyl acetate bufferized with phosphate buffer (pH 8.0). Neo-enactin shows strong antifungal activity and potentiates the antifungal activity of polyene antifungal antibiotics.

Antifungal Agents↗
PubMed1975

[Antibiotic resistance and transferable antibiotic resistance of Escherichia coli isolated from Swedish calves 5 and 30 days old].

E. coli strains isolated from 5-day-old and 30-day-old healthy calves were tested for antibiotic resistance and H-factor mediated antibiotic resistance. An average of 1.6 antibiotic-resistant strains and 1.1 strains with transferable antibiotic resistance were isolated from each of the investigated calves. In comparison with the 30-day-old calves, the 5-day-old calves had significantly more strains with transferable antibiotic resistance (95.8 percent as against 63.4 percent). The R+ strains isolated from the younger calves transferred significantly more en bloc (43.5 percent as against 10.0 percent) and double plus multiple resistance (5292 percent as against 24.4 percent) than did those isolated from the older calves. The most common resistance was to sulphonamide and tetracycline and the most common transferred resistance was to sulphonamide.

Age Factors↗
PubMed1975

Nationwide survey of antibiotic resistance by means of a computer. An introduction into the analysis of multiple antibiotic resistance.

One-year surveillance of single and multiple antibiotic resistance of 8 species of so-called "Problem Bacteria" by computer analysis of data obtained from 18 Public Health Laboratories in Slovakia in 1973 enables to establish the most frequently occuring spectra of multiple drug resistance which would point to the spread of typical R plasmids among the Problem bacteria investigated. As an introduction, we surveyed the mode of testing of Problem bacteria in individual PHLs against antibiotics - drugs of choice. Iw was important to find out whether strains belonging to Problem bacteria investigated are tested against sufficient number of antibacterial drugs. Our study shows that the percentage of bi- and multiple drug resistance in almost all bacterial species investigated depend on the number of antibiotics used in tests in vitro as single discs. The more antibiotic discs are used to test the strains, the more chance the laboratory has to register the true picture of multiresistance to antibiotics. Our study also shows that the testing in the PHLs associated to the computer study in this respect is inadequate. Moreover, the increasing complexity and proportion of multiple drug resistance in Problem Bacteria - with a notable exception of Salmonellae - forces the PHLs to use more and more discs so that using two Petri dishes full of discs - 12 to 15 discs - begins to be necessary in testing of most of the Problem bacteria under investigation.

Anti-Bacterial Agents↗
PubMed1978

Oral antibiotic therapy for skeletal infections of children. I. Antibiotic concentrations in suppurative synovial fluid.

To evaluate the feasibility of oral antibiotic treatment for pyogenic arthritis, one or more oral doses of antibiotics were substituted for the drugs being used for parenteral therapy. Synovial fluid and serum specimens obtained at randomized times after an oral dose of ampicillin, cephalexin, cloxacillin, dicloxacillin, or penicillin G were assayed for antibiotic content and antibacterial activity. Seventy specimens from 21 infants and children were studied. Peak synovial fluid concentrations were greater than 60% of peak serum concentrations with all drugs tested and there was adequate inhibitory activity against bacteria commonly causing arthritis. The degree of antibiotic binding to serum protein had no apparent effect on the degree of penetration into pyogenic synovial fluid.

Administration, Oral↗
PubMed1977

Aminoglycoside-modifying enzyme of an antibiotic-producing bacterium acts as a determinant of antibiotic resistance in Escherichia coli.

Bacillus circulans NRRL B-3312, a nonpathogenic bacterium that produces the aminoglycoside antibiotic butirosin, is known to contain an aminoglycoside phosphotransferase that is similar to the neomycin phosphotransferases of clinically isolated antibiotic-resistant bacteria. Purified DNAs from B. circulans and the plasmid ColE1-ApR were digested with EcoRI endonuclease and the resulting fragments covalently joined with polynucleotide ligase. The recombined DNA was used to transform E. coli and ampicillin-neomycin resistant colonies were selected. Analysis of several clones indicated that neomycin resistance in the E. coli transformants was due to the presence of the B. circulans phosphotransferase gene. This observation is consistent with the notion that anitbiotic-modifying enzymes from antibiotic-producing organisms may be the sources of antibiotic resistance in plasmid-containing bacteria.

Bacillus↗
PubMed1976

Use of sodium polyanethol sulfonate to selectively inhibit aminoglycoside and polymyxin antibiotics in a rapid blood level antibiotic assay.

Sodium polyanethol sulfonate inhibits aminoglycoside and polymyxin classes of antibiotics in direct proportion to its concentration. Aminoglycoside and polymyxin class antibiotics are selectively inactivated; penicillin, including the semisynthetic penicillins, cephalothin, chloramphenicol, clindamycin, tetracycline, erythromycin, and vancomycin are not inhibited. By incorporating sodium polyanethol sulfonate directly into the test medium it is possible, in a 4-h antibiotic blood level assay, to selectively obviate the activity of the aminoglycosides and polymyxins to determine the concentration of other antibiotics present in the same serum sample.

Aminoglycosides↗