UK-18892, a new aminoglycoside: an in vitro study.
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UK-18892 is a new aminoglycoside antibiotic, a derivative of kanamycin A structurally related to amikacin. It was found to be active against a wide range of pathogenic bacteria, including many gentamicin-resistant strains. The spectrum and degree of activity of UK-18892 were similar to those of amikacin, and differences were relatively minor. UK-18892 was about twice as active as amikacin against gentamicin-susceptible strains of Pseudomonas aeruginosa. Both amikacin and UK-18892 were equally active against gentamicin-resistant strains of P. aeruginosa. There were no appreciable differences in the activity of UK-18892 and amikacin against Enterobacteriaceae and Staphylococcus aureus. Cross-resistance between these two antimicrobials was also apparent. (+info)
Ciprofloxacin decreases the rate of ethanol elimination in humans.
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BACKGROUND: Extrahepatic ethanol metabolism is postulated to take place via microbial oxidation in the colon, mediated by aerobic and facultative anaerobic bacteria. AIMS: To evaluate the role of microbial ethanol oxidation in the total elimination rate of ethanol in humans by reducing gut flora with ciprofloxacin. METHODS: Ethanol was administered intravenously at the beginning and end of a one week period to eight male volunteers. Between ethanol doses volunteers received 750 mg ciprofloxacin twice daily. RESULTS: A highly significant (p=0.001) reduction in the ethanol elimination rate (EER) was detected after ciprofloxacin medication. Mean (SEM) EER was 107.0 (5.3) and 96.9 (4.8) mg/kg/h before and after ciprofloxacin, respectively. Faecal Enterobacteriaceae and Enterococcus sp. were totally absent after medication, and faecal acetaldehyde production capacity was significantly (p<0.05) decreased from 0.91 (0.15) to 0.39 (0.08) nmol/min/mg protein. Mean faecal alcohol dehydrogenase (ADH) activity was significantly (p<0. 05) decreased after medication, but ciprofloxacin did not inhibit human hepatic ADH activity in vitro. CONCLUSIONS: Ciprofloxacin treatment decreased the ethanol elimination rate by 9.4%, with a concomitant decrease in intestinal aerobic and facultative anaerobic bacteria, faecal ADH activity, and acetaldehyde production. As ciprofloxacin has no effect on liver blood flow, hepatic ADH activity, or cytochrome CYP2E1 activity, these effects are probably caused by the reduction in intestinal flora. (+info)
Sodalis gen. nov. and Sodalis glossinidius sp. nov., a microaerophilic secondary endosymbiont of the tsetse fly Glossina morsitans morsitans.
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A secondary intracellular symbiotic bacterium was isolated from the haemolymph of the tsetse fly Glossina morsitans morsitans and cultured in Aedes albopictus cell line C6/36. Pure-culture isolation of this bacterium was achieved through the use of solid-phase culture under a microaerobic atmosphere. After isolation of strain M1T, a range of tests was performed to determine the phenotypic properties of this bacterium. Considering the results of these tests, along with the phylogenetic position of this micro-organism, it is proposed that this intracellular symbiont from G. m. morsitans should be classified in a new genus Sodalis gen. nov., as Sodalis glossinidius gen. nov., sp. nov. Strain M1T is the type strain for this new species. (+info)
High turnover rate of Escherichia coli strains in the intestinal flora of infants in Pakistan.
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The Escherichia coli flora of infants in developed countries is dominated by one or a few strains which persist for prolonged periods of time, but no longitudinal studies have been performed in developing countries. To this end, we studied the rectal enterobacterial flora in 22 home-delivered Pakistani infants during their first 6 months of life. Three colonies were isolated and species typed on each of 11 sampling occasions. E. coli isolates were strain typed using electromorphic typing of cytoplasmic enzymes, and their O serogroups were determined. There was a very rapid turnover of enterobacterial strains in the rectal flora of individual infants. On average, 8.5 different E. coli strains were found per infant, and several biotypes of other enterobacteria. Less than 50% of the infants were colonized with E. coli from their mothers, but strains of maternal origin were four times more likely to persists in the infants' flora than other E. coli strains. Enterobacteria other than E. coli were always of non-maternal origin, and Enterobacter cloacae and Klebsiella pneumoniae biotypes recovered from contaminated feeds were later identified in the infants' rectal flora. An early colonization with klebsiella or enterobacter was significantly associated with diarrhoea during the neonatal period, although these bacteria were not likely to be the cause of the disease. The results suggest that poor hygienic conditions result in an unstable and diverse enterobacterial flora, which may influence infant health. (+info)
The influence of a diet rich in wheat fibre on the human faecal flora.
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The effect on the faecal flora of adding wheat fibre to a controlled diet in four healthy volunteers for a 3-week period has been observed. No change in the concentration of the bacteria in the bacterial groups counted was found, although there was a slight increase in total output associated with increased faecal weight. The predominant organisms in all subjects were non-sporing anaerobes, but the dominant species in each subject was different and was unaffected by changing the diet. Similarly, the concentration of faecal beta-glucuronidase detected in two subjects was unaltered and the concentration of clostridia able to dehydrogenate the steroid nucleus found in one subject was unaltered. It is suggested that the faecal microflora is not primarily controlled by the presence of undigested food residues in the large bowel. (+info)
Use of an isogenic Escherichia coli panel to design tests for discrimination of beta-lactamase functional groups of Enterobacteriaceae.
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A study was designed to determine if an isogenic panel of Escherichia coli strains containing many different beta-lactamases could be used for the preliminary screening of a large number of beta-lactam agents to identify which might be most useful in the development of a definitive test for specific beta-lactamases found among the members of family Enterobacteriaceae. The susceptibilities of 46 strains, comprising the isogenic panel, to expanded-spectrum cephalosporins, cephamycins, and aztreonam were determined in the presence and absence of beta-lactamase inhibitors in broth microdilution tests. The results indicated that strains producing extended-spectrum beta-lactamases (ESBLs) could be distinguished from strains producing other Bush-Jacoby-Medeiros functional group 2 or group 1 beta-lactamases. For strains producing group 1 beta-lactamases, cefpodoxime and ceftazidime MICs were > or = 4 micrograms/ml and addition of clavulanate did not reduce the MICs more than fourfold. For strains producing group 2 enzymes other than ESBLs, cefpodoxime and ceftazidime MICs were < or = 2 micrograms/ml. With a single exception (ceftazidime for the strain producing SHV-3), among strains producing ESBLs, cefpodoxime and ceftazidime MICs were > or = 4 micrograms/ml and addition of clavulanate reduced the MICs by more than eightfold. Cephamycins could also be used to discriminate between strains producing group 1 beta-lactamases and ESBLs, since only the former required cefotetan concentrations as high as 8 micrograms/ml or cefoxitin concentrations of > 16 micrograms/ml for inhibition. Other cephalosporins provided some discrimination between the various beta-lactamase producers, although they were not as reliable as either cefpodoxime or ceftazidime. These results indicate the utility of an isogenic panel for identification of candidate drugs among many for further testing with clinical isolates of the family Enterobacteriaceae to determine the best agents for detection of specific beta-lactamases in this family. (+info)
Many class I integrons comprise distinct stable structures occurring in different species of Enterobacteriaceae isolated from widespread geographic regions in Europe.
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Three sizes of inserted regions of DNA (800, 1,000, and 1,500 bp) were shown to be common among class I integrons in unrelated clinical isolates of Enterobacteriaceae from different European hospitals. Sequencing showed that 800-bp inserted regions comprised identical sequences including aacA4, that 1,000-bp inserted regions included aadA, and that 1,500-bp inserted regions included dfrI and aadA1, irrespective of host species and geographic origin. In addition promoter sequences were mostly identical for each size class. These data suggest that inserted gene cassettes and promoter regions of integrons are conserved and stable, with resistance genes transferred more often as part of the entire integron structure than as individual gene cassettes. (+info)
Functional importance and local environments of the cysteines in the tetracycline resistance protein encoded by plasmid pBR322.
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The properties of the cysteines in the pBR322-encoded tetracycline resistance protein have been examined. Cysteines are important but not essential for tetracycline transport activity. None of the cysteines reacted with biotin maleimide, suggesting that they are shielded from the aqueous phase or reside in a negatively charged local environment. (+info)