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At least 685 records · Page 38Linked to original sources
PubMed1966

Factors influencing the occurrence of high numbers of iodine-resistant bacteria in iodinated swimming pools.

It has been shown that, although iodinated swimming-pool waters are usually free from coliform bacteria and enterococci, the total counts frequently become relatively high. Pseudomonas alcaligenes and Alcaligenes faecalis have been shown to account for most of these high counts. It was of interest, therefore, to compare the microbial flora of four alternately chlorinated and iodinated swimming pools. By means of the membrane filter method and suitable selective media, examinations were made for total viable counts, coliform bacteria, enterococci, staphylococci, Streptococcus salivarius, and P. aeruginosa. Colonies also were picked from membrane filters incubated on standard plate count agar and identified. The results showed that, although viable counts were significantly higher during the iodinated periods, the specific types of bacteria determined were either fewer than or the same as in chlorinated periods. During chlorination, the predominant microbial flora consisted of staphylococci and members of the genus Bacillus. During iodination, however, the P. alcaligenes-A. faecalis group accounted for 92 to 99% of the microbial flora. The accumulation of high numbers of these bacteria was shown to be due to their iodine resistance and their ability to grow rapidly in pool water in the absence of free iodine.

Alcaligenes↗
PubMed1967

Fluorescein-labeled beta-glucosidase as a bacterial stain.

Fluorescein isothiocyanate-labeled beta-glucosidase was used as a simple staining reagent with selected gram-positive and gram-negative organisms. Staining in situ appeared to be dependent on the presence of accessible glycosidic-type linkages in the bacterial cell wall. Extensive wall damage or lysis did not occur when stained cells were suspended in washing and mounting solutions. The apparent specificity of labeled enzyme for wall substance was tested by blocking reactions, staining of isolated cell walls, and failure to stain substances lacking appropriate glycosidic linkages. Severe cell wall lesions were produced after prolonged contact with labeled enzyme, and this phenomenon may also be related to staining specificity. Gram-negative organisms and spores were poorly stained unless protected glycopeptide substrate was previously exposed by treatment of cells with thioglycolic acid or dilute alkaline sodium hypochlorite solution. A potential for staining tissues and cell lines may also exist. Some possible applications of labeled enzymes are briefly discussed.

Bacillus anthracis↗
PubMed1968

Proteolytic activity of microorganisms isolated from freshwater fish.

A raw fish-juice was prepared and sterilized through the use of (60)Co gamma-irradiation. It was evaluated for suitability in an agar medium for testing the proteolytic activity of bacteria isolated from fish. Microorganism proteolytic activity was also detected by conventional methods with skim milk-agar. We tested 1,145 isolates from fresh and spoiling irradiated (0.0, 0.3, and 0.6 Mrad) yellow perch fillets for proteolytic activity, by the use of both media. Most isolates that showed proteolytic activity exhibited this activity in both media. A few isolates showed proteolytic activity only in one medium or the other. Proteolysis was found mainly among bacteria isolated from nonirradiated perch fillets. Nonproteolytic organisms were slightly more abundant than were proteolytic ones throughout refrigerated storage (6 days); the latter constituted 48% of the total organisms. Irradiation eliminated essentially all proteolytic bacteria when the fillets were stored at 1 C. However, some proteolytic bacteria survived for a few days after irradiation when the fillets were stored at 5 C.

Alcaligenes↗
PubMed1968

Effects in hyperoxia upon microorganisms. I. Membrane culture technique for exposing cells directly to test atmospheres.

A membrane culture technique was developed for directly exposing microorganisms to test atmospheres. Inhibition and killing were calculated from comparisons with air-grown cultures. Direct colony counts were used with low inocula. With mass inocula, plate colony counts and optical-density measurements were made on resuspended filter populations. Bacteria, including Escherichia coli, were more sensitive to oxygen than previously reported. With inocula of a few hundred cells per membrane, five of seven species failed to produce colonies while exposed to oxygen at one atmosphere. Upon reincubation in air, the survival of five species ranged from near 0 to 12% of the cells. Aerobacter aerogenes was neither inhibited nor killed. With this technique, bacteria are in direct contact with the test atmosphere and cells which survive are detected but do not obscure the response of other cells in the population.

Bacillus cereus↗
PubMed1968

Drug resistance as influenced by inactivated sensitivity discs.

Reports of staphylococci resistant to the semisynthetic penicillins stimulated a study of the factors influencing the stability of the drugs in discs. The behavior of penicillin G, methicillin, oxacillin, cloxacillin, and cephalothin discs under different humidity and temperature conditions is described. Humidity was found to be the most significant factor in drug inactivation. Storage of discs in a vacuum desiccator at -20 C provides maximal antibiotic stability.

Bacteriological Techniques↗
PubMed1968

Metabolism of tryptophans by Pseudomonas aureofaciens. VI. Production of pyrrolnitrin by selected Pseudomonas species.

Twenty-nine strains of Pseudomonas, classified as P. fluorescens biotype D or E or as P. multivorans, were examined for the production of pyrrolnitrin, an antifungal agent synthesized in P. aureofaciens. Eight strains were shown to produce pyrrolnitrin in shake-flask fermentation. Four cultures were from the multivorans taxon, and the remaining four were members of the fluorescens group. The antifungal agent produced in these strains was isolated and shown to be pyrrolnitrin by comparison with an authentic sample. The strains differed markedly with respect to the amount of pyrrolnitrin produced and in their utilization of exogenous tryptophan. Secondary metabolites, not related to pyrrolnitrin, were also examined and compared with those synthesized in P. aureofaciens. Marked differences were noted in both phenazine pigments and phenolic metabolites. The results of the study suggest that the production of pyrrolnitrin may be widespread in selected taxonomic groups of Pseudomonas.

Antifungal Agents↗
PubMed1969

Micromethod for assaying serum levels of erythromycin.

A micromethod for assaying serum levels of erythromycin is described. The assay had the following characteristics: detection of 0.03 to 0.035 mug/ml, a long-range curve which minimizes sample dilution, 0.04 ml for a single measurement (0.3 ml required for full coverage), and utility for a variety of body fluids. The method employs radial diffusion from small paper discs which were saturated by capillary action rather than by dipping or pipetting. Although the method was designed to handle serum in which the sample volume is limited, statistical analysis demonstrated that the method has satisfactory precision for routine use. A study of 10 consecutive assays indicates a precision of +/-12% at the 95% confidence limits. The method of least squares was used to calculate the line of best fit, and the statistics were developed on this basis. The assay method is applicable to a variety of antibiotics.

Anti-Bacterial Agents↗
PubMed1969

Motility tracks: technique for quantitative study of bacterial movement.

A method for recording movements of bacteria in time and space on a single photograph is described. Quantitative information on the behavior of various motile organisms may easily be obtained for comparative studies. The method possesses certain advantages over cinematography, and illustrations of applications of the technique are presented.

Bacillus↗
PubMed1969

Characterization of Micrococcaceae isolated from clinical sources.

The characterization of 556 Micrococcaceae isolates from various clinical sources has been presented. The incidence of coagulase-negative mannitol-positive staphylococci was 3.2% and that of coagulase-positive mannitol-negative staphylococci was 1.6%. There appears to be insufficient justification for the routine reporting of staphylococcal variants from a general bacteriology laboratory, and biotyping should be reserved for special circumstances.

Bacteria↗
PubMed1970

Procedures for the assay of carbenicillin in body fluids.

The assay of carbenicillin in clinical specimens is complicated by the fact that carbenicillin also contains a small amount of benzylpenicillin, thereby precluding the use of conventional penicillin assay organisms. This report gives details of a microbiological assay method involving the use of a strain of Pseudomonas aeruginosa which is very sensitive to carbenicillin but insensitive to benzylpenicillin. The outline of a microassay method with this organism is presented, and a method for the assay of specimens containing mixtures of carbenicillin and other antibiotics is described.

Agar↗
PubMed1970

Microbioassay of antimicrobial agents.

A previously described agar-diffusion technique for microbioassay of antimicrobial agents has been modified to increase sensitivity of the technique and to extend the range of antimicrobial agents to which it is applicable. This microtechnique requires only 0.02 ml of an unknown test sample for assay, and is capable of measuring minute concentrations of antibiotics in buffer, serum, and urine. In some cases, up to a 20-fold increase in sensitivity is gained relative to other published standardized methods and the error of this method is less than +/-5%. Buffer standard curves have been established for this technique, concurrently with serum standard curves, yielding information on antimicrobial serum-binding and demonstrating linearity of the data points compared to the estimated regression line for the microconcentration ranges covered by this technique. This microassay technique is particularly well suited for pediatric research and for other investigations where sample volumes are small and quantitative accuracy is desired. Dilution of clinical samples to attain concentrations falling with the range of this assay makes the technique readily adaptable and suitable for general clinical pharmacological studies. The microassay technique has been standardized in buffer solutions and in normal human serum pools for the following antimicrobials: ampicillin, methicillin, penicillin G, oxacillin, cloxacillin, dicloxacillin, cephaloglycin, cephalexin, cephaloridine, cephalothin, erythromycin, rifamycin amino methyl piperazine, kanamycin, neomycin, streptomycin, colistin, polymyxin B, doxycycline, minocycline, oxytetracycline, tetracycline, and chloramphenicol.

Agar↗
PubMed1971

Cephaloglycin and its biologically active metabolite desacetylcephaloglycin.

Chromatographic studies and microbiological assays show that, after oral administration, cephaloglycin is partially converted in man to a biologically active metabolite desacetylcephaloglycin. The antibacterial activity of this metabolite compared to that of cephaloglycin is equivalent against gram-positive organisms but is lower against gram-negative bacilli. Successful therapy of urinary tract infections with cephaloglycin must be mainly attributed to the antibacterial activity of this metabolite. At the present time, it is not possible to assess what influence low amounts of unaltered cephaloglycin have on the outcome of therapy.

Administration, Oral↗
PubMed1971

Specific assay of aminoglycosidic- or polymyxin-type antibiotics present in human sera in combination with cephalosporins.

Monitoring of serum concentrations of aminoglycosidic or polymyxin antibiotics when administered concurrently with cephalosporins or penicillins requires a special assay technique. Selective enzymatic degradation of the beta-lactam antibiotic from the serum specimen allows subsequent assay of the antibiotic being monitored. This report gives details of a simple procedure for laboratory production of a crude enzyme capable of degrading cephalosporins or penicillins. An assay procedure for quantitating aminoglycosidic or polymyxin antibiotics after enzymatic degradation of a coexisting beta-lactam antibiotic is described.

Amidohydrolases↗
PubMed1971

Microorganisms in unamended soil as observed by various forms of microscopy and staining.

A light-diffraction microscope was modified to allow sequential viewing of the microorganisms in a soil smear by transmitted, reflected, and reflected-polarized incandescent light and by reflected ultraviolet light. Observations were also made by conventional incandescent and ultraviolet transmitted-light microscopy. All results for the various forms of bright-field microscopy with stained and unstained soils were in agreement, but they differed from the results obtained for two types of ultraviolet-fluorescence microscopy. The latter proved to be nonspecific for in situ soil microorganisms. Capsule-like areas were noted surrounding many of the resident microbial cells of soil when viewed by the various forms of bright-field microscopy. These areas could not be stained or removed by a variety of treatments, but they apparently often did take up stain after in situ soil growth had been initiated. It was concluded that these areas are not capsules but may represent a structural component of nonmultiplying microbial cells in soil.

Acridines↗