PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “enteric bacteria”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1979

Influence of culture medium of the fatty-acid profile in enteric bacteria.

Enteric bacteria having a high content of cyclopropane fatty acids steeply increase their synthesis when grown on insufficiently propitious culture media (meat-peptone agar or modified Drobot'ko synthetic medium) as compared with bacteria grown under more favourable conditions (meat-peptone broth). Simultaneously, a decrease in monounsaturated fatty acids and increase in palmitic acid are observed. One of the main factors underlying the change in the proportion of fatty acids in bacteria grown on synthetic medium is an increase in medium pH in the process of their growth. Enteric bacteria containing minute amounts/or not containing cyclopropane fatty acids at all (under the experimental conditions used) change their fatty-acid profile little if the culture medium is changed. When grown under insufficiently favourable conditions, these bacteria mainly display an enhanced content of palmitic acid and a lowered content of octadacenoic acid as compared with bacteria grown under more favourable conditions. Of the culture media used, meat-peptone broth, which affords the most favourable conditions for eneteric bacteria growth, is the most suitable medium for obtaining data of taxonomic value.

Culture Media↗
PubMed1979

[The increase of resistant enteric bacteria and the role of R plasmids (author's transl)].

As elsewhere in the world, the number of resistant enteric bacteria is rapidly increasing in this country. In a survey made in 1977 on about 40,000 strains of enteric bacteria in Clinical Pathology Laboratory of Hacettepe University Medical School, Ankara, Turkey, 70% to 97% of enteric bacteria were shown to be resistant to conventional antimicrobic agents. Also the rates of multiple-resistant strains of enteric bacteria are increasing quite rapidly. In most of these strains this increase proved to depend on the presence of R plasmids. In this paper, these and related facts were summarized and some precautions were suggested to lessen the increase of resistant strains in this country.

Anti-Bacterial Agents↗
PubMed1976

Degradation of blood group antigens in human colon ecosystems. I. In vitro production of ABH blood group-degrading enzymes by enteric bacteria.

Human feces contain enzymes produced by enteric bacteria that degrade the A, B, and H blood group antigens of gut mucin glycoproteins. We have studied their production in fecal cultures to determine if such cultures can be a source for enzyme purification and to explore how blood group antigen-degrading enzymes are adapted in individual human colon ecosystems. They were present in fecal cultures from each of 27 healthy subjects, including ABH nonsecretors. Heat-sensitive obligate anaerobes are their major source. From 39 to 85% of the total enzyme activity produced by growing cultures was extracellular. Commercial hog gastric mucin and salivary glycoproteins, including Lea saliva which lacks A, B, and H antigens, enhance production of A-, B-, and H-degrading activity in anaerobic fecal cultures irrespective of the glycoprotein's blood group specificity. There is evidence that the host's ABO blood type and secretor status affects the specificity of blood group-degrading enzymes produced by his fecal bacteria in vitro. Thus, fecal inocula from B secretors incubated with hog gastric mucin (A and H specificity) or with Lea saliva produced greater levels of B-degrading than A- or H-degrading activity, and inocula from A secretors in similar media produced greater levels of A-degrading than B- or H-degrading activity. Blood group-degrading enzymes produced in fecal cultures are glycosidases and not proteases. The B-degrading enzyme cleaves the B antigenic determinant alpha-D-galactose from the oligosaccharide side chains of mucin glycoproteins with B specificity. Anaerobic fecal cultures containing blood group substances are a feasible source for purifying blood group antigen-degrading enzymes. Prior adaptation to blood group antigens in the gut mucins of type A and type B secretors affects the specificity of the enzymes produced in vitro.

ABO Blood-Group System↗
PubMed1979

Enterotoxigenic enteric bacteria in foods and outbreaks of food-borne diseases in Sweden.

All of 86 food routinely examined for potentially pathogenic enteric bacteria were found to harbour one or more coliform species. None of the strains isolated produced heat-labile enterotoxin (LT) or showed invasive properties. The suckling mouse test indicated that one strain of Escherichia coli produced heat-stable enterotoxin (ST). Twelve incidents of suspected food poisoning were also investigated. In two of them the foods examined contained LT-producing strains of E. coli and in two there were LT-producing strains of Klebsiella pneumoniae. The counts of viable enterotoxigenic micro-organisms in these foods were 3000-30,000 E. coli/g and 50,000 to 1 million K. pneumoniae/g. The dominant symptom in all the incidents was watery diarrhoea. These seem to be the first reported cases of foodborne enterotoxigenic enteric bacteria in Europe. Though enterotoxigenic E. coli and related gram-negative enterotoxin-producing species are rare in correctly handled food in Sweden, these micro-organisms should be searched for when outbreaks of food poisoning are investigated.

Enterotoxins↗
PubMed1977

The ability of enteric bacteria to catalyze the covalent binding of bile acids and cholesterol to DNA and their in ability to metabolize benzo(a)pyrene to a binding product and to known metabolites.

The capacity of enteric bacteria (E. coli, Salmonella, Pseudomonas, Shigella and Klebsiella) to catalyze the covalent binding of benzo(a)pyrene (BP), cholic acid, deoxycholic acid and cholesterol was investigated. In general, these bacteria were incapable of activating BP to a covalently bound product with calf thymus DNA. Metabolism studies of BP by fluorometric assay failed to indicate any accumulation of BP-3-hydroxy in the incubation medium. Detailed metabolic investigation with high-pressure liquid chromatography indicated that these bacteria did not produce any known metabolites which are formed by mammalian systems. However, radioactivity was detected in all fractions, suggesting that the bacteria were readily metabolizing BP into smaller molecules for energy and carbon sources. Although the enteric bacteria did not metabolize BP into known metabolites, some were capable of activating cholesterol, cholic acid and deoxycholic acid to covalently bound products with DNA. The binding data with cholesterol and bile acids also suggested that the binding process required NADPH as a cofactor because binding level was rather low without NADPH.

Benzopyrenes↗
PubMed1979

Small-colony forms of enteric bacteria after exposure to aminoglycosides.

Small colony forms of enteric bacteria were isolated in vitro after exposure of near-lethal amounts of aminoglycosides. These small-colony forms were several times more resistant to all aminoglycosides than the parent clones. A small form of Escherichia coli was isolated directly from a clinical specimen, along with a more sensitive larger colony.

Aminoglycosides↗
PubMed1979

Enterotoxins of enteric bacteria--a review.

A review of the enterotoxins of enteric bacteria was compiled, taking into account recent developments of the field as well as results of the author's own research work. After characterization of enterotoxins of different origin, their pathogenic role is described, with special attention to the genetic background of these agents. The possible use of enterotoxins for active immunization purposes is also discussed.

Adhesiveness↗
PubMed1992

The evolution of insertion sequences within enteric bacteria.

To identify mechanisms that influence the evolution of bacterial transposons, DNA sequence variation was evaluated among homologs of insertion sequences IS1, IS3 and IS30 from natural strains of Escherichia coli and related enteric bacteria. The nucleotide sequences within each class of IS were highly conserved among E. coli strains, over 99.7% similar to a consensus sequence. When compared to the range of nucleotide divergence among chromosomal genes, these data indicate high turnover and rapid movement of the transposons among clonal lineages of E. coli. In addition, length polymorphism among IS appears to be far less frequent than in eukaryotic transposons, indicating that nonfunctional elements comprise a smaller fraction of bacterial transposon populations than found in eukaryotes. IS present in other species of enteric bacteria are substantially divergent from E. coli elements, indicating that IS are mobilized among bacterial species at a reduced rate. However, homologs of IS1 and IS3 from diverse species provide evidence that recombination events and horizontal transfer of IS among species have both played major roles in the evolution of these elements. IS3 elements from E. coli and Shigella show multiple, nested, intragenic recombinations with a distantly related transposon, and IS1 homologs from diverse taxa reveal a mosaic structure indicative of multiple recombination and horizontal transfer events.

Base Sequence↗
PubMed1978

Genetic mapping of tyramine oxidase and arylsulfatase genes and their regulation in intergeneric hybrids of enteric bacteria.

The genes for arylsulfatase (atsA) and tyramine oxidase (tynA) have been mapped in Klebsiella aerogenes by P1 transduction. They are linked to gdhD and trp in the order atsA-tynA-gdhD-trp-pyrF. Complementation analysis using F' episomes from Escherichia coli suggested an analogous location of these genes in E. coli, although arylsulfatase activity was not detected in E. coli. P1 phage and F' episomes were used to create intergeneric hybrid strains of enteric bacteria by transfer of the ats and tyn genes between K. aerogenes, E. coli, and Salmonella typhimurium. Intergeneric transduction of the tynK gene from K. aerogenes to an E. coli restrictionless strain was one to two orders less frequent than that of the leuK gene. The tyramine oxidase of E. coli and S. typhimurium in regulatory activity resemble very closely the enzyme of K. aerogenes. The atsE gene from E. coli was expressed, and latent arylsulfatase protein was formed in K. aerogenes and S typhimurium. The results of tyramine oxidase and arylsulfatase synthesis in intergeneric hybrids of enteric bacteria suggest that the system for regulation of enzyme synthesis is conserved more than the structure or function of enzyme protein during evolution.

Arylsulfatases↗
PubMed1976

Transduction of chromosomal genes between enteric bacteria by bacteriophage P1.

We have used P1 transduction to create intergeneric hybrid strains of enteric bacteria by moving the genA and hut genes between Klebsiella aerogenes, Escherichia coli and Salmonella typhimurium. The use of E. coli as the recipient in such transductions permits the construction of episomes and specialized transducing phage containing non-E. coli material. The effect of host restriction modification and deoxyribonucleic acid homology on the frequency of intergeneric transduction of these loci has been examined.

Chromosomes, Bacterial↗
PubMed2024

D-galactonate metabolism in enteric bacteria: a molecular and physiological perspective.

D-galactonate, a widely prevalent sugar acid, was first reported as a nutrient source for enteric bacteria in the 1970s. Since then, decades of research enabled a description of the modified Entner-Doudoroff pathway involved in its degradation and reported the structural and biochemical features of its metabolic enzymes, primarily in Escherichia coli K-12. However, only in the last few years, the D-galactonate transporter has been characterized, and the regulation of the dgo operon, encoding the structural genes for the transporter and enzymes of D-galactonate metabolism, has been detailed. Notably, in recent years, multiple evolutionary studies have identified the dgo operon as a dominant target for adaptation of E. coli in the mammalian gut. Despite considerable research on dgo operon, numerous fundamental questions remain to be addressed. The emerging relevance of the dgo operon in host-bacterial interactions further necessitates the study of D-galactonate metabolism in other enterobacterial strains.

Operon↗
PubMed1978

In vitro antibiotic susceptibility of enteric bacteria isolated from commercial broiler chickens.

The in vitro activity of six different antimicrobial agents was evaluated by an agar dilution method against enteric bacteria isolated from broilers. Of 923 isolates, 796 were gram-positive bacteria and 127 were Escherichia coli (E. coli). Thiopeptin at 25 microgram/ml inhibited 75% of lactobacilli. This antibiotic at .78 microgram/ml inhibited 82% of staphylococci and more than 92% of other gram-positive organisms. Bacitracin at 100 microgram or less per ml was active against 42% of staphylococci and 30% of streptococci. At 6.25 microgram or less per ml, 70% of clostridia and 78% of lactobacilli were inhibited. The minimum inhibitory concentrations (MIC) of penicillin G and ampicillin shown as cumulative distribution curves for all isolates were very similar. Both antibiotics showed a wide range of MIC distribution. Streptomycin at 50 microgram or less per ml was active against 87% of lactobacilli and 50% of E. coli. Only 32% of staphylococci were inhibited at these concentrations. At 100 microgram or less per ml, 30% of streptococci and 12% of clostridia were inhibited. Tetracycline at 100 microgram or less per ml inhibited 63% of clostridia. Lactobacilli and E. coli were not inhibited by this antibiotic at 100 microgram or less per ml.

Ampicillin↗
PubMed1976

Tryptophan operon regulation in interspecific hybrids of enteric bacteria.

We examined tryptophan regulation in merodiploid hybrids in which a plasmid carrying the trp operon of Escherichia was introduced into Trp mutants of other enteric genera, or in which a plasmid carrying the trpR+ (repressor) gene of E. coli was transfered into fully constitutive trpR mutants of other genera. In these hybrids the trp operon of one species is controlled by the repressor of a different species. Similar investigations were possible in transduction hybrids in which either the trp operon or the trpR+ locus of Shigella dysenteriae was introduced into E. coli. Our measurements of trp enzymes levels in repressed and nonrepressed cells indicate that Trp regulation is normal, with only minor quantitative variations, in hybrids between E coli and Shigella dysenteriae, Salmonella typhimurium, Klebsiella aerogenes, Serratia marcescens, and Proteus mirabilis. Our results support the idea that a repressor-operator mechanism for regulating trp messenger ribonucleic acid production evolved in a common ancestor of the enteric bacteria, and that this repressor-operator recognition has been conversed during the evolutionary divergence of the Enterobacteriaceae.

Anthranilate Phosphoribosyltransferase↗
PubMed1992

Detergent-shock response in enteric bacteria.

Our work on bacterial detergent resistance started with the realization that bacteria growing in a sink full of soap must be resistant to the detergents in that soap. We chose sodium dodecyl sulphate (SDS) as a model detergent and decided to see how much SDS the bacterium growing in the sink could tolerate. The research program thus initiated has shown that bacteria such as Enterobacter cloacae can grow in up to 25% SDS and that SDS-shock proteins constitute c. 8% of the proteins synthesized by SDS-grown Escherichia coli. It has also provided explanations why enteric bacteria are oxidase negative, and how pyrroloquinoline quinone (PQQ) enters the periplasmic space. Finally, for E. coli, it has provided evidence for an alternate, phosphate-limited, aquatic life style which places greater emphasis on the Entner-Doudoroff pathway. Detergent resistance is important both medically and ecologically, e.g. entry of pathogens via bile-salt-containing intestinal tracts and biodegradation of detergent-like pollutants such as those resulting from oil spills. Our current research is focused on SDS-induced modifications of the cytoplasmic membrane and the presence of SDS in the periplasm.

Detergents↗
PubMed1975

Antibodies against enteric bacteria in brown bullhead catfish (Ictalurus nebulosus, LeSueur) inhabiting contaminated waters.

Brown bullhead catfish were collected from sewage- and acid mine waste-polluted waters in an attempt to detect antibodies against human enteric bacteria in their sera and to investigate the association of antibody response with environmental conditions. Agglutination antigens prepared from isolates obtained from water collected at the same locations as the fish habitats were used to demonstrate such antibodies. The results showed large percentages of reactive sera for common isolates such as Escherichia coli and Enterobacter cloacae as well as lesser incidences of antibodies to other, less common isolates. In general, fish with the highest titres were collected from habitats with higher coliform counts. Acid mine drainage reduced the total coliform counts, but did not appear to affect the titers of sera from fish collected from water so affected. It was concluded that the bottom-feeding catfish might be a better subject for the study of fish as an ecological indicator of fecal pollution in acid-polluted waters.

Acinetobacter↗
PubMed1975

Inhibition of pathogenic enteric bacteria by hyperbaric oxygen: enhanced antibacterial activity in the absence of carbon dioxide.

The antibacterial effects of 24-h exposures to high-pressure oxygen in relation to environmental CO(2) were studied at 3 atm absolute (ata) and at 1 ata. Eight gram-negative, aerobic and facultatively aerobic, pathogenic enteric bacteria (Salmonella typhosa, Salmonella paratyphi, Salmonella schottmuelleri, Shigella dysenteriae, Shigella flexneri, Proteus vulgaris, Pseudomonas aeruginosa, and Escherichia coli) were exposed as shallow-broth cultures and agar surface cultures. Although broths supplemented with 0.2% glucose permitted some growth of Salmonella typhosa, Salmonella schottmuelleri, Shigella dysenteriae, and Shigella flexneri during exposure to high-pressure oxygen in the presence of CO(2), the other species grew only after the exposure, indicating a bacteriostatic effect. Both bacteriostatic and bactericidal effects were demonstrated on the surface of Trypticase soy agar, where killing of Salmonellea typhosa, Proteus vulgaris, and Pseudomonas aeruginosa was significantly greater after exposure to pure O(2) at 3 ata than at 1 ata. At 3 ata, significantly more killing occurred upon exposure of all species (except Shigella dysenteriae and S. flexneri) on an agar surface to 100% O(2) as compared with exposure to a mixture of 95% O(2) + 5% CO(2). Thus, deprivation of CO(2) during exposure to pure O(2) enhanced the bactericidal effect of high-pressure oxygen.

Carbon Dioxide↗
PubMed1975

Rapid detection and identification of enteric bacteria from blood cultures.

The BACTEC radiometric system and Inolex Enteric I card were used in conjunction for the rapid detection and presumptive identification of enteric gram-negative rods in blood cultures. Excellent correlation was obtained between the Inolex card and routine identification techniques when organisms from both artificially inoculated and clinical blood cultures were studied. In many instances, the culture report was available less than 24 hr after receipt of the specimen.

Acinetobacter↗