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

Recent evidence indicates that certain antibiotics affect bacterial adherence and phagocyte-micro-organism interactions. These interactions are important in the early stages of bacterial pathogenesis, that is, attachment to mucosal surfaces and invasion. Among the antibiotics of interest in this field are the fluoroquinolones. Sub-MICs of pefloxacin can alter the ability of Gram-positive cocci (Staphylococcus aureus, Enterococcus faecalis) and Gram-negative bacilli (Escherichia coli) to adhere to different eukaryotic cells (uroepithelial and buccal cells) and to fibrin-platelet matrices. The mechanism by which pefloxacin reduces adhesion is not completely understood. However in the case of Esch. coli, the inhibition of haemagglutination and adherence corresponds to: (1) a decrease in production of fimbriae; (2) changes in the composition of outer membrane proteins; and (3) an effect on partition coefficient (carried out with the PEG/dextran system) which can be attributed to changes in electric and/or hydrophobic properties of the Esch. coli surface. The first step of phagocytosis is represented by adherence of opsonized bacteria to the membrane receptors of phagocytes. Consequently, the action of pefloxacin on phagocytosis is also of importance. Pretreatment of bacteria (Staph. aureus, Ent. faecalis, Esch. coli and Legionella pneumophila) with 1/4 the MIC of pefloxacin leads to an increase in uptake of the different strains by phagocytes (polymorphonuclear leucocytes and macrophages). Exposure of the phagocytes to 10 mg/l of pefloxacin enhances phagocytosis of strains that have not been pretreated. Finally, entry of antibiotics into phagocytic cells is a prerequisite for activity against intracellular organisms. The concentration of pefloxacin by polymorphs and macrophages is high (intracellular concentration/extracellular concentration = 5-10). Such findings correlate well with the intracellular activity of pefloxacin, demonstrated with guinea pig macrophages and different bacteria (Staph. aureus, L. pneumophila).
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PMID:Effect of pefloxacin on microorganism: host cell interaction. 225 45

The response of Legionella pneumophila to antibiotics that inhibit cell-wall, protein and DNA synthesis was examined by electronmicroscopy, MIC estimations and viable counts. Ampicillin, cefotaxime, methicillin, erythromycin, rifampicin and ciprofloxacin, each used separately at 20 times their respective MIC values, showed activity against L. pneumophila in these studies. The inhibitors of cell-wall synthesis--ampicillin, cefotaxime and methicillin--effected the greatest bactericidal activity and induced the most extensive morphological changes, which included the formation of membranous lesions through which cytoplasmic contents were lost. In terms of ultrastructural damage and loss of viability, the inhibitors of protein and DNA synthesis were less effective than the antibiotics that acted on the microbial cell wall. Erythromycin- and rifampicin-treated cells possessed irregular membranes and were partially or fully lysed, whereas ciprofloxacin induced abnormally elongated organisms with intermittently lysed and detached inner membranes. These results illustrated the ability of antibiotics of putative clinical value, with diverse modes of action, to affect the ultrastructural cytology as well as the viability of L. pneumophila in vitro.
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PMID:The effect of antibiotics that inhibit cell-wall, protein, and DNA synthesis on the growth and morphology of Legionella pneumophila. 229 40

The in vitro activity of WIN 57273, a new fluoroquinolone antimicrobial agent, was evaluated against approximately 600 bacterial isolates. The new drug was 4- to 128-fold more active than ciprofloxacin against a broad range of gram-positive organisms, with the new drug inhibiting 90% of strains of each species except Enterococcus faecium at concentrations of less than or equal to 0.25 microgram/ml. WIN 57273 was four- to eightfold less active than ciprofloxacin against many members of the family Enterobacteriaceae, but the MICs of the new drug for 90% of strains tested (MIC90s) were less than or equal to 8 micrograms/ml (range, 0.25 to 8 micrograms/ml) for all species. Branhamella catarrhalis, Haemophilus influenzae, Neisseria gonorrhoeae, and Legionella spp. were highly susceptible (MIC90s, less than or equal to 0.06 microgram/ml). WIN 57273 demonstrated excellent activity against anaerobes (MIC90s, less than or equal to 0.25 microgram/ml), and the drug was also more active than ciprofloxacin against 30 strains of Mycobacterium avium-M. intracellulare (MIC, 0.1 to 1.0 microgram/ml). The activity of WIN 57273 against gram-positive organisms was minimally affected by pH and increased at low pH (5.4) against gram-negative organisms. The bactericidal activity of WIN 57273 was demonstrated by time-kill techniques against selected organisms. The frequencies of spontaneous resistance to the new agent were low, but resistant colonies could be selected after serial passage of initially susceptible organisms through incremental concentrations of the drug.
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PMID:Comparative in vitro activity of WIN 57273, a new fluoroquinolone antimicrobial agent. 239 75

The macrolide antibiotic azithromycin (CP-62,993; 9-deoxo-9a-methyl-9a-aza-9a-homoerythromycin A; also designated XZ-450 [Pliva Pharmaceuticals, Zagreb, Yugoslavia]) showed a significant improvement in potency against gram-negative organisms compared with erythromycin while retaining the classic erythromycin spectrum. It was up to four times more potent than erythromycin against Haemophilus influenzae and Neisseria gonorrhoeae and twofold more potent against Branhamella catarrhalis, Campylobacter species, and Legionella species. It had activity similar to that of erythromycin against Chlamydia spp. Azithromycin was significantly more potent versus many genera of the family Enterobacteriaceae; its MIC for 90% of strains of Escherichia, Salmonella, Shigella, and Yersinia was less than or equal to 4 micrograms/ml, compared with 16 to 128 micrograms/ml for erythromycin. Azithromycin inhibited the majority of gram-positive organisms at less than or equal to 1 micrograms/ml. It displayed cross-resistance to erythromycin-resistant Staphylococcus and Streptococcus isolates. It had moderate activity against Bacteroides fragilis and was comparable to erythromycin against other anaerobic species. Azithromycin also demonstrated improved bactericidal activity in comparison with erythromycin. The mechanism of action of azithromycin was similar to that of erythromycin since azithromycin competed effectively for [14C]erythromycin ribosomebinding sites.
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PMID:Spectrum and mode of action of azithromycin (CP-62,993), a new 15-membered-ring macrolide with improved potency against gram-negative organisms. 244 65

The coumamidines are novel antibiotics with activity against a wide spectrum of aerobic Gram-positive and Gram-negative bacteria. All microbiological studies were performed on coumamidine gamma 1. The MIC90s (micrograms/ml) of coumamidine are as follows: Staphylococcus aureus 1.0, Streptococcus pyogenes 8, Enterobacteriaceae 2.0, Pseudomonas aeruginosa 8, Campylobacter jejuni and Campylobacter coli 1, Legionella pneumophila 8, Haemophilus influenzae 0.5, Neisseria gonorrhoeae 0.5. Coumamidine had MICs ranging from 8 to greater 0.5, Neisseria gonorrhoeae 0.5. Coumamidine had MICs ranging from 8 to greater than 64 for most anaerobes, except some Peptostreptococcus strains. The aminoglycoside super-sensitive strain, P. aeruginosa BMH 10, was also super-sensitive to coumamidine (MIC 0.2 micrograms/ml). Coumamidine was rapidly bactericidal for S. aureus. The viable bacterial count in logarithmic phase cultures was reduced to less than 10 cfu within 2 hours after exposure to 4 times the MIC (3.12 micrograms/ml) of coumamidine. The frequency of resistance development was less than 1 X 10(-9) for Escherichia coli and S. aureus when selected at 4 and 8 times the MIC. The Cmax in mouse serum after a single subcutaneous dose of 25 mg/kg of coumamidine was 4.5 micrograms/ml and t1/2 was 1 hour. Coumamidine is stable in serum. In mouse protection tests against S. aureus NCTC 10649 the ED50 was less than 0.6 mg/kg/day when it was administered subcutaneously at 1 and 5 hours after infection. Coumamidine was not absorbed after oral administration. The antibacterial spectrum, bactericidal activity, stability in serum and low frequency of resistance make this an interesting new class of antibiotics.
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PMID:Coumamidines, new broad spectrum antibiotics of the cinodine type. III. Microbiologic activity of coumamidine gamma 1. 249 68

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

The activity of AT-4140, a new fluoroquinolone, was evaluated against a wide range of clinical bacterial isolates and compared with those of existing analogs. AT-4140 had a broad spectrum and a potent activity against gram-positive and -negative bacteria, including Legionella spp. and Bacteroides fragilis. The activity of AT-4140 against gram-positive and -negative cocci, including Acinetobacter calcoaceticus, was higher than those of ciprofloxacin, ofloxacin, and norfloxacin. Its activity against gram-negative rods was generally comparable to that of ciprofloxacin. Some isolates of methicillin-resistant Staphylococcus aureus (MIC of methicillin, greater than or equal to 12.5 micrograms/ml) were resistant to existing quinolones, but many of them were still susceptible to AT-4140 at concentrations below 0.39 micrograms/ml. The MICs of AT-4140, ciprofloxacin, ofloxacin, and norfloxacin for 90% of clinical isolates of methicillin-resistant S. aureus were 0.2, 12.5, 6.25, and 100 micrograms/ml, respectively. AT-4140 was bactericidal for each of 20 clinical isolates of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas aeruginosa at concentrations near the MICs. AT-4140 inhibited the supercoiling activity of DNA gyrase from E. coli.
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PMID:In vitro activity of AT-4140 against clinical bacterial isolates. 255 17

This paper discusses the evaluation of new macrolides and new quinolones for the treatment of Legionnaires' disease in in vitro susceptibility test, penetration to polynuclear leukocytes and treatment in an animal model. Some kinds of biological response modifier (BRMs) such as granulocyte colony stimulating factor (GCSF), monocyte CSF (M-CSF), GM-CSF, recombinant interleukin-1 (IL-1) and IL-2 were also evaluated. The antimicrobial activity (MIC) of new macrolides to Legionella pneumophila (45 strains) showed the highest activity in TE-031 (Taisho Pharmaceutical Co., Tokyo, Japan) and then rokitamycin (RKM), RU-28965 (Roussel, France), erythromycin (EM), josamycin (JM) in decreasing order of activity. According to the results of the data of cell-penetration and survival rate after treatment of guinea pigs with experimental Legionella pneumonia, the new macrolides such as TE-031, RKM and RU-28965 are expected to be more effective in the treatment of Legionnaires' disease than EM. New quinolones such as ciprofloxatin (CPFX), NY-198 (Hokuriku Pharmaceutical Co., Japan) or T-3262 (Toyama Kagaku Pharmaceutical Co., Toyama Japan) were compared to ofloxacin (OFLX), enoxacin (ENX) or rifampin (RFP) for evaluation. These drugs showed excellent activity against L. pneumophila and good penetration to polynuclear leukocytes. Regarding the treatment of guinea pig with legionella pneumonia, OFLX was the most effective, and NY-198 or T-3262 were more effective than EM treatment. The highest survival rate was obtained with IL-2 in infected guinea pigs. We also observed the efficacy of combined use of IL-2 and HR-8 10 (Horchst FRG) which is a newly developed cephem antibiotic.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Treatment of severe respiratory infection. Legionella pneumonia]. 261 84

This ether oxim derivative of erythromycin A is an easy to absorb oral antimicrobial somewhat less effective in vitro than erythromycin. At relatively low MIC's it is active against staphylococci, streptococci, pneumococci, branhnamella and chlamydiae, higher concentrations are needed against enterococci and some strains of H. influenzae. Roxithromycin is also reported to have a very good effect on campylobacters, many anaerobic bacteria, Toxoplasma gondii, Treponema pallidum, Mycoplasma pneumoniae and Legionella pneumophilla. Its half-life in the serum of healthy individuals ranges from 9 to 16 hours. Maximum serum concentrations at 2 oral doses of 150 mg a day are reached at 3 to 4 days and vary from 5.5 to 11.1 mg/l. The distribution of roxithromycin in body tissues is excellent. In a group of 57 patients treated for various infections of clear etiology the positive therapeutic effects resulting in the state of bacteriological negativity was reached in 86% of cases. Roxithromycin can be recommended as a drug of choice in mild or less severe cases of infection caused by agents sensitive to this antimicrobial. Its excellent tolerance makes it especially well suited for use in pediatric practice.
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PMID:Roxithromycin--a new macrolide derivative. 269 62

The antibacterial activities of amoxycillin, clavulanic acid and the combination of both agents against Legionella spp. were compared in serial-dilution tests, time-kill curve studies and in turbidimetric studies in a continuous recording biophotometer. Both beta-lactam compounds showed high levels of activity against L. pneumophila in serial dilution tests, clavulanic acid (MIC 0.1-0.25 mg/l) being two-fold more active than amoxycillin. The combination of amoxycillin and clavulanic acid was more effective than either of the constituents and was two to four times more active than erythromycin. Clavulanic acid was shown to reduce the extent of inactivation of amoxycillin by L. pneumophila and amoxycillin/clavulanic acid was rapidly bactericidal against the organism in tests in which amoxycillin was ineffective. Microscopical examination showed distinctive morphological effects produced by amoxycillin and by clavulanic acid and synergy between the compounds could be attributed to beta-lactamase inhibition, or by binding to different penicillin binding proteins, or both. These results warrant further studies in vitro and in vivo to elaborate the bactericidal effects demonstrated by amoxycillin and clavulanic acid against Legionella spp.
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PMID:Bactericidal effects of amoxycillin/clavulanic acid against Legionella pneumophila. 274 55


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