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At least 523 records · Page 29Linked to original sources
PubMed1993

The effects of Acacia arabica gum on the in vitro growth and protease activities of periodontopathic bacteria.

The antibacterial activity of acacia gum was assessed using fresh isolates and reference strains of Actinobacillus actinomycetemcomitans, Capnocytophaga spp., Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola. A fine aqueous suspension of gum was produced by sonication and then a soluble fraction isolated by centrifugation and membrane filtration. These preparations were incorporated into columbia agar at doubling concentrations. Growth of P. gingivalis and P. intermedia cultures on the agar was inhibited by whole gum sonicate at concentrations of 0.5-1.0% w/v. Both species showed reduced susceptibility when horse blood was present in the agar. The gum soluble fraction did not inhibit growth of any bacterial culture. The effect of acacia on bacterial proteases was examined with cell sonicates from log phase broth cultures. Enzyme activities were determined by fluorimetric assay with various synthetic peptide substrates. Most protease activities reduced in the presence of 0.5% w/v gum sonicate, with the trypsin-like activities of P. gingivalis and P. intermedia proving most sensitive. The gum soluble fraction was nearly always less inhibitory than the sonicate. The action of acacia gum against suspected periodontal pathogens and their enzymes suggests that it may be of clinical value.

Aggregatibacter actinomycetemcomitans↗
PubMed1983

Susceptibility of bacterial pathogens to cefotetan judged by MIC and disc tests.

The activity of cefotetan was tested against 683 bacterial strains by measuring the minimum inhibitory concentrations. Comparisons were made with cefoxitin, cefotaxime, moxalactam, cefoperazone and piperacillin. In addition, a regression line analysis was made with cefotetan discs (30 micrograms) using the ICS technique. Cefotetan was noted to have a broader spectrum of activity than cefoxitin and its antibacterial activity was comparable to that of cefotaxime and moxalactam. According to the regression line analysis a cefotetan inhibition zone diameter of greater than or equal 19 mm is interpreted as sensitive in agar diffusion tests.

Anti-Bacterial Agents↗
PubMedDate not supplied

Comparative evaluation of the MRS test. A 4 to 6 hour screening test for detecting oxacillin-resistant staphylococci.

A total of 131 strains of S. aureus and 25 strains of unspeciated coagulase-negative staphylococci (CNS) initially tested by automated methods for susceptibility to oxacillin were concurrently retested using standardized disk diffusion, reference 2% NaCl-supplemented broth microdilution, oxacillin salt agar, and the MRS test (a commercially prepared broth screening method). Compared to the reference broth microdilution test results, the MRS test was 97% sensitive for S. aureus, 95% sensitive for CNS, and 100% specific for all staphylococci. Results were available in 4 hr for S. aureus and less than 6 hr for CNS. The oxacillin salt agar screen had sensitivities of 93 to 99% with a specificity of 100%. Although the disk diffusion method was the most sensitive method (100%), it was the least specific (83% for S. aureus and 80% for CNS). Differences in manufacturers' agar affected results with most discrepancies resulting in a false-resistant interpretation. Although inoculum standardization was important for accurate susceptibility test results, overinoculation alone could not account for the 30 isolates falsely-resistant to oxacillin by the Vitek AMS or Abbott MS-2. Contaminants or card-fill problems may have also have been responsible for some of the discrepancies. The MRS test was considered to be an acceptable alternative screen or a supplement to other methods for same-day testing for ORS.

Humans↗
PubMed1975

In vitro antibacterial activity of amikacin, a new aminoglycoside, against clinical bacterial isolates from children.

Four hundred and fifty-eight clinical bacterial isolates from a children's hospital were examined for antibiotic susceptibility to amikacin (BB-KS) in comparison with a number of other antibiotics by the disk diffusion and agar dilution methods. The wide spectrum of activity of amikacin against Gram-negative bacteria was confirmed; it included E. coli, Proteus species, Enterobacter species, and Pseudomonas aeruginosa. Staphylococci were highly sensitive, but other Gram-positive bacteria tested were resistant. A disk zone diameter of 10 mm effectively separated resistant form sensitive bacteria in a standard disk diffusion test.

Amikacin↗
PubMed2006

Cytotoxic thio-malate is transported by both an aluminum-responsive malate efflux pathway in wheat and the MAE1 malate permease in Schizosaccharomyces pombe.

Aluminum (Al) tolerance in wheat (Triticum aestivum L.) is mainly achieved by malate efflux, which is regulated by the expression of the recently identified gene, presumably encoding an Al-activated malate efflux transporter (ALMT1). However, the transport mechanism is not fully understood, partly as a result of the rapid turnover of its substrate. We developed a tool to study malate transport in wheat by screening biological compounds using the well-characterized Schizosaccharomyces pombe malate transporter (SpMAE1). Expression of SpMAE1 in both S. pombe and Saccharomyces cerevisiae, which has no SpMAE1 homologue, caused hypersensitivity to thio-malic acid. This hypersensitivity was prominent at pH 3.5, but not pH 4.5, and was accompanied by an increase in thiol content, indicating that SpMAE1 mediates the uptake of thio-malic acid at a specific low pH. In wheat, root apices were able to accumulate thio-malic acid without growth reduction at pH values above 4.2. Pretreatment of root apices with thio-malic acid followed by Al treatment induced thio-malate efflux. Al-induced thio-malate efflux was much higher in Al-resistant cultivars/genotypes than in Al-sensitive ones, and was accompanied by a decrease in thiol-content. Thio-malate efflux in the Al-resistant cultivar was slightly activated by lanthanum or ytterbium ion. Thio-malic acid did not alleviate the Al-induced inhibition of root elongation in wheat. Taken together, our results suggest that thio-malate acts as an analogue for malate in malate transport systems in wheat and yeast, and that it may be a useful tool for the analysis of malate transport involved in Al-tolerance and of other organic ion transport processes.

Aluminum↗
PubMed1971

Characterization of an unusual strain of proteus rettgeri associated with an outbreak of nosocomial urinary-tract infection.

An outbreak of nosocomial urinary-tract infection was caused by a strain of Proteus rettgeri that fermented lactose overnight and was resistant to all antimicrobial drugs tested. The nonmotile isolates shared an O (somatic) antigen that differed from those of wild-type P. rettgeri. The organisms proved markedly serum-sensitive. In rats, the isolates elicited an acute interstitial nephritis with associated transient bacteriuria. Attempts to transfer the lac(+) trait and drug-resistance markers to recipient strains of Escherichia coli K-12 failed; exposure of the isolates to acridine orange yielded small numbers of non-lactose-fermenting variants which, however, were still as drug-resistant as before. Epidemiological studies failed to uncover the source of this unique strain and appeared to indicate exogenous spread of infection.

Acridines↗