Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0023241 (Legionella)
6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparison of agar dilution and microdilution susceptibility testing for eight antimicrobial agents, including roxithromycin, was performed against 48 isolates of Legionella pneumophila. For agar dilution tests, charcoal free agar (BSYE) and charcoal supplemented agar (BCYE) were used. In general, BSYE agar produced lower MICs than BCYE agar, except for imipenem. Microdilution testing data fell between the data obtained for the two agar media. The MBCs were two to sixteen fold higher than the MICs. Prolongation of the incubation time from 48 h to 72 h or growth in 5% CO2 did not influence the results. As tested by the microdilution method, an increase in the inoculum from 10(5) to 10(7) was associated with a two-fold increase in the MIC. Roxithromycin and two other investigational macrolides (A-56268 and rosaramicin) demonstrated better in-vitro activity than erythromycin.
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PMID:Susceptibility of Legionella pneumophila to eight antimicrobial agents including four macrolides under different assay conditions. 252 10

A method was developed to grow Legionella pneumophila in continuous culture. A chemostat was used to simulate nutrient-limited, submaximal growth in the natural environmental and to provide a precisely controlled growth regimen. Cultures grew under forced aeration under conditions yielding up to 38% saturation of dissolved oxygen; supplemental CO2 (5%) at the same gas flow rates as ambient air had no effect on culture growth. Pleomorphism was observed during growth under all conditions. Pigment was produced only at D less than 0.03 h-1. Catalase was produced at higher growth rates but not at higher temperatures. The pathogenicity was unaffected by altering either the growth rate or the growth temperature.
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PMID:Growth of Legionella pneumophila in continuous culture. 401 91

The objective of this study was to evaluate by relatively simple metabolic tests the usefulness of buffers and energy sources commonly used in Legionella growth media. Legionella pneumophila serogroups 1 to 6, Legionella micdadei, and Legionella bozemanii were grown in an enriched charcoal-yeast extract diphasic medium. The cells were washed thrice, suspended in various buffers (pH 6.9) with 1 or 5 mM MgSO4, and used immediately or after controlled-rate cryopreservation. CO2 produced and C incorporated into the cold trichloracetic acid-insoluble fractions from 14C-labeled substrates were determine. Potassium phosphate buffer (0.02 M) was as satisfactory as organic buffers for glutamate metabolism, but the addition of KCl or NaCl reduced activity. Metabolic activity for glutamate was not lost upon cryopreservation, and cryopreserved cells were used to test the utilization of other single or paired substrates. Rates of activity for serine, glutamate, threonine, and pyruvate, in this descending order, were high, and those for alpha-ketoglutarate, succinate, and gamma-aminobutyrate were low. Although glutamine was not used as rapidly as glutamate, when added to glutamate it was preferentially metabolized, possibly because of more rapid transport. When glutamate and serine were combined, glutamate furnished more C for CO2 and less for incorporation, whereas the reverse was true of serine. In conclusion, glutamate as an energy source may in some cases spare other amino acids for synthesis. alpha-Ketoglutarate, a common constituent of Legionella media, may reduce oxygen toxicity but is probably not a chief energy source.
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PMID:Substrate utilization by Legionella cells after cryopreservation in phosphate buffer. 614 14

The modes of action of bis(tributyltin)oxide (TBTO) doses between 1 X 10(4) and 6 X 10(7) molecules per cell on a single environmental isolate of Legionella pneumophila were studied by monitoring the following parameters: (i) growth, (ii) cell viability, (iii) 14C-amino acid incorporation, (iv) 14CO2 production from 14C-amino acids, (v) [3H]uridine incorporation, (vi) [3H]thymidine incorporation, (vii) oxygen consumption, (viii) cellular ATP levels, and (ix) adenylate energy charge. The amount of TBTO associated with the cells in these laboratory cultures was also compared with that remaining in the suspending medium. Most of the TBTO (68 to 88%) was found to be associated with the cells. This result explained why the cellular responses which were measured did not correlate with the TBTO concentration, but rather with the dose of TBTO to which the cells were exposed. At the lower TBTO doses tested (10(4) to 10(7) molecules per cell) a log-normal relationship was observed between the reduction in growth rate and the TBTO concentration. At intermediate TBTO doses (ca. 10(7) molecules per cell) growth stasis occurred, with nearly 100% of the cells in these cultures remaining viable for at least 5 h after treatment. The cellular function which seemed to be primarily affected at these levels of TBTO was the energy conversion mechanism, since the decline in the rates of CO2 production, oxygen consumption, and macromolecular synthesis was preceded by an immediate (within 1 min) drop in the intracellular levels of ATP and the adenylate energy charge. At the higher TBTO doses greater than 10(7) molecules per cell) an initial, precipitous, drop in the number of viable cells was observed, which was followed by a further exponential reduction of viable cells in the treated culture. This dramatic increase in bactericidal activity with a slight increase in the TBTO dose indicated that the modes of bacteriostatic and bactericidal action of TBTO were different.
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PMID:Bacteriostatic and bactericidal modes of action of bis(tributyltin)oxide on Legionella pneumophila. 618 98

The genus Legionella, belonging to the family of Legionellaceae, comprises nowadays seven species, among which Legionella pneumophila might be the most important. The identification of the agent is difficult because L. pneumophila is very pretentious requiring peculiar conditions concerning culture medium, temperature, and time. The initial cultivation will succeed the best in an atmosphere enriched with CO2. The demonstration of serum antibodies will succeed by means of indirect immunofluorescence; recently the micro-agglutination test is vastly applied. The clinical picture of Legionellosis is characterized by an atypical pneumonia with a serious course in most cases. The Pontiac Fever is an illness with milder course than the classical form of Legionellosis. Erythromycin and Rifampicin are the chemotherapeutics of choice.
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PMID:[The detection of the agent of Legionnaires' disease--a confirmation of Koch's postulates]. 635 47

Chromatographic separations with a supercritical fluid as the mobile phase were suggested more than 20 years ago. Availability of commercial hardware makes this technique more widely usable today. Many separations by this method are now carried out with supercritical carbon dioxide as the mobile phase and packed liquid-chromatography columns as the stationary phase. Although carbon dioxide has many practical advantages, including its near-ambient critical temperature and minimal interference with spectrometric detection, the use of other supercritical fluids or addition of modifiers to carbon dioxide may extend the applications of this technique. Some mixtures that are difficult to analyze by other chromatographic methods may be susceptible to separation by supercritical fluid chromatography. Mixtures that have been separated with supercritical carbon dioxide include resin acids with the empirical formula C20H30O2 and ubiquinones from bacterial cell wall extracts of Legionella pneumophila.
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PMID:Supercritical fluid chromatography. 641 83

Two patients with adult respiratory distress syndrome (ARDS) caused by Legionnaires' disease were treated with erythromycin lactobionate, and they survived. Sequential pulmonary function studies and chest roentgenograms were obtained in both patients. Despite previous suggestions that severe fibrosis might complicate the recovery of patients with this disease, both patients had normal lung volumes and only minimal reduction in single-breath carbon monoxide diffusing capacity ten weeks after the onset of the disease. Thus, pulmonary function after ARDS caused by Legionnaires' disease seems to be only minimally disturbed.
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PMID:Pulmonary function after adult respiratory distress syndrome associated with Legionnaires' disease pneumonia. 723 82

The optimum temperature for multiplication of legionella strains in culture media is around 37 degrees C. The effect of high temperatures on the growth of strains isolated from various environments is poorly known. We studied the growth (cell multiplication, respiration) of clinical and environmental Legionella pneumophila strains in liquid media at intervals of 0.5 degrees C in the temperature range from 41.6 to 51.6 degrees C using a temperature gradient incubator. Cell multiplication and CO2 production decreased markedly with all the strains at temperatures above 44-45 degrees C. CO2 continued to be produced up to 51.6 degrees C even if cell multiplication generally stopped at around 48.4-50.0 degrees C. Thus, legionella retained its metabolic activity beyond the maximum temperature for cell multiplication. The CO2 production per bacterial cell (metabolic quotient, qCO2) increased with increasing temperature up to 45 degrees C, whereafter it decreased, the turning point being almost at the same at which the rate of cell multiplication decreased. The difference in qCO2 between the strains] may reflect their different physiological capacities for tolerating high temperatures.
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PMID:Growth, respiration and survival of Legionella pneumophila at high temperatures. 889 48

Opsonophagocytic killing of some bacteria (Staphylococcus aureus, Pseudomonas aeruginosa) by phagocytes is enhanced by previous brief exposure of the organism to antibiotics. We studied the regrowth of Legionella pneumophila previously pretreated with levofloxacin, erythromycin and/or rifampicin in human monocytes. The MIC for the L. pneumophila isolate of levofloxacin, erythromycin and rifampicin was 0.03, 0.5 and 0.001 mg/L, respectively. Growth of L. pneumophila from buffered charcoal yeast extract (BCYE) agar for 24 h was subcultured into BYE broth containing from 0 to 4x MIC of levofloxacin, erythromycin or rifampicin. After incubation at 35 degrees C in 5% CO2 for 18 h, the organisms were washed and opsonized with 20% heat inactivated pooled normal human serum. Thereafter, L. pneumophila was exposed to human monocytes (5:1 ratio) previously adhered to wells in tissue culture plates containing RPMI and 10% fetal calf serum. After 0, 24, 48 and 72 h of incubation, quantitative cultures of lysed human monocytes were done on BCYE agar. Our results indicate effective inhibition on L. pneumophila at 0 h regardless of the antibiotic (levofloxacin, rifampicin or erythromycin) or their concentrations (1x, 2x or 4x MIC). At 24, 48 and 72 h, recovery and regrowth of L. pneumophila were both antibiotic- and concentration-dependent. In comparison with controls (no antibiotic pretreatment), peak regrowth of L. pneumophila pretreated with either 1x MIC of levofloxacin or erythromycin was delayed (48 versus 24 h) and reduced (30% of control peak regrowth). Regrowth of L. pneumophila pretreated with 1x MIC of rifampicin continued beyond 72 h. Pretreatment with levofloxacin at 4x MIC caused the greatest degree of growth inhibition (2 log10). In contrast, at 72 h, regrowth of organisms pretreated with 4x MIC of erythromycin or rifampicin was less than peak control (P < 0.01) but greater than that seen with levofloxacin (P < 0.01). The rate and degree of regrowth of L. pneumophila pretreated with combinations of levofloxacin or erythromycin with rifampicin, or levofloxacin with erythromycin (all at 1x MIC) was similar to that seen with single drugs. Thus, significant delay and reduction of regrowth in this phagocytic system occurred with levofloxacin only. Prolonged exposure of the organism at 4x MIC levofloxacin concentrations was effective in suppressing regrowth of pretreated L. pneumophila in human monocytes.
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PMID:Effect of levofloxacin, erythromycin or rifampicin pretreatment on growth of Legionella pneumophila in human monocytes. 942 15

The use of macrolides for treatment of respiratory complaints has been complicated by susceptibility test conditions that adversely effect the in vitro test results and perceived potencies of these compounds. Dirithromycin was studied as to its in vitro activity compared to other macrolides as well as the effects that environmental incubation variations and inoculum concentrations may have on susceptibility results. Dirithromycin was less active than other macrolides tested (azithromycin clarithromycin, erythromycin) against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis with MIC90 values of 16, 32, and 1 microgram/ml, respectively; an activity that was most similar to roxithromycin. This reduced activity may be compensated by the superior pharmacokinetic properties that dirithromycin possesses compared to other members in its class. Method variation studies show that incubation in CO2 environments increase the MIC values for all macrolide compounds and dirithromycin was most effected by pH changes in three in vitro methods tested (Etest [AB BIODISK, Solna, Sweden] broth microdilution, and disk diffusion). Variations in inoculum concentration had minimal effect on dirithromycin potency. In addition the variability (lack of reproducibility) of the test results with dirithromycin were not significant. Dirithromycin is an alternative therapeutic choice among macrolide compounds for treatment of community-acquired respiratory infections caused by various streptococci, Legionella pneumophilia, Mycoplasma pneumoniae and M. catarrhalis, and also possesses a modest in vitro potency versus H. influenzae coupled with excellent pharmacokinetic properties. In vitro tests with dirithromycin will continue to be problematic for H. influenzae because of the adverse effects of recommended CO2 incubation for some standardized methods or commercial products (Etest).
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PMID:Comparative in vitro evaluation of dirithromycin tested against recent clinical isolates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae, including effects of medium supplements and test conditions on MIC results. 1021 55


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