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)

The activity of six intracellular antibiotics, doxycycline, erythromycin, clarithromycin, azithromycin, rifampicin and ciprofloxacin, was tested against 60 strains of Legionella pneumophila (21 of human and 39 of environmental origin). MIC50, MIC90, and MBC values were determined by a microdilution method. Inhibitory and bactericidal activity against human and environmental isolates were similar except for rifampicin, which was 100-fold less active for human strains than for environmental strains, particularly in terms of bactericidal activity. Nevertheless, in general, rifampicin was found to be the most active drug. Among the macrolides tested, clarithromycin showed the greatest activity in MIC assays and erythromycin was the least bactericidal. Azithromycin showed higher MICs and MBCs than the two macrolides, and doxycycline was the least active. The most important factors influencing in-vivo activity of antibiotics are discussed. Even if the in-vitro results cannot be fully extrapolated to activity in vivo, these results indicate the susceptibility of L. pneumophila strains in Italy as a basis for treatment of atypical pneumonia that may be due to Legionella spp.
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PMID:In-vitro activity of six intracellular antibiotics against Legionella pneumophila strains of human and environmental origin. 805 94

We evaluated the in vitro activity of piperacillin alone or in combination with the beta-lactamase inhibitor tazobactam against clinical isolates of Legionella species. At an inoculum of approximately 10(4) CFU, tazobactam, piperacillin, and the 8:1 combination had equivalent activities against Legionella spp. At an approximately 10-fold higher inoculum, the following results were obtained, expressed as MICs for 50 and 90% of strains tested (MIC range): piperacillin, 4 and 16 (0.25 to 32) micrograms/ml; tazobactam, 0.5 and 1 (0.125 to 2) micrograms/ml; and piperacillin-tazobactam (expressed in terms of MIC of piperacillin) 0.5 and 1 (0.03 to 2) micrograms/ml. Tazobactam alone and the combination with piperacillin were more active than piperacillin alone at the higher inoculum.
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PMID:Comparative activities of piperacillin and tazobactam against clinical isolates of Legionella spp. 814 70

BAY Y3118 was highly active against Moraxella catarrhalis, Haemophilus influenzae, Legionella pneumophila, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus (except quinolone-resistant, methicillin-resistant S. aureus), Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae (MIC for 90% of strains tested [MIC90], 0.063 micrograms/ml). For Enterococcus faecalis and Corynebacterium jeikeium, MIC90s were 4 and 2 micrograms/ml, respectively. BAY Y3118 was as active as ciprofloxacin against Pseudomonas aeruginosa (MIC90, 0.5 micrograms/ml) and had potent activity against Bacteroides fragilis (MIC90, 0.5 micrograms/ml).
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PMID:In vitro activities of BAY Y3118, ciprofloxacin, ofloxacin, and fleroxacin against gram-positive and gram-negative pathogens from respiratory tract and soft tissue infections. 823 24

We have investigated the effect of methylprednisolone on the intracellular activity of erythromycin and clindamycin in vitro. An assay system was developed for the determination of intracellular activity of antibiotics against Legionella pneumophila using guinea pig resident alveolar macrophages. Erythromycin at a concentration of 0.625 mg/L (5 x MIC) and clindamycin at a concentration of 8 mg/L (MIC) inhibited the growth of a single strain of L. pneumophila in macrophages, whilst ceftizoxime at a concentration of 0.625 mg/L (5 x MIC) did not. Methylprednisolone at therapeutic concentrations did not affect the intracellular antibacterial activity of either erythromycin or clindamycin against L. pneumophila. We found no direct effect of methylprednisolone on the intracellular antibacterial activity of either erythromycin or clindamycin.
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PMID:Influence of methylprednisolone on the intracellular antimicrobial activity of erythromycin and clindamycin against Legionella pneumophila. 836 Jan 27

Thirty-five clinical isolates of Legionella species were tested against 7 antimicrobial agents using an agar dilution technique. Results obtained on charcoal-supplemented (BCYE) and charcoal-free agar (BSYE) were compared. On BCYE, the most active agent was rifampicin; the minimal inhibitory concentration inhibiting 90% of the strains (MIC90) was 0.008 mg/L. Imipenem was the next most active in vitro (MIC90 0.06 mg/L). The macrolide antibiotics and ciprofloxacin also inhibited the organisms at low concentrations (MIC90 < or = 2 mg/L). In general, MIC's obtained on BCYE agar were at least twofold higher than on BSYE agar except for that of imipenem. BSYE agar is a suitable alternative medium for susceptibility testing of most Legionella species. Erythromycin and rifampicin continue to demonstrate good in vitro activity against legionellae in Australia. On the basis of in vitro susceptibility tests, the other macrolides and ciprofloxacin are likely to be suitable alternatives for the treatment of legionellosis.
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PMID:Susceptibility of Legionella species to antimicrobial agents. 836 99

An agar dilution technique was used to compare the antimicrobial activities of lomefloxacin, norfloxacin, ofloxacin, ciprofloxacin and enoxacin against 544 strains of bacterial isolates. Among the five quinolone agents tested, ciprofloxacin was the most active. Enoxacin was the most active after ciprofloxacin against Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, Shigella spp., Yersinia enterocolitica, and Haemophilus influenzae with an MIC90 of < or = 0.25 micrograms/ml. Ofloxacin was the most active agent after ciprofloxacin against Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter diversus, and Legionella pneumophila with an MIC of < or = 0.25 micrograms/ml. Ciprofloxacin inhibited Staphylococcus spp. and Streptococcus spp., at < or = 0.5 micrograms/ml and 2 micrograms/ml, respectively. Norfloxacin and enoxacin had the same antimicrobial activity (MIC90) against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus agalactiae and some other Gram-positive species, but these activities were weak when compared with ciprofloxacin. The results of this in vitro study show that ciprofloxacin is very active against Gram-negative and Gram-positive species.
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PMID:Comparative antimicrobial activity of lomefloxacin, norfloxacin, ofloxacin, ciprofloxacin and enoxacin against > 500 bacterial isolates. 839 96

Dirithromycin is a semisynthetic derivative of erythromycin, a 14-membered ring macrolide antibiotic. The drug is converted during absorption and distribution, to an active metabolite 9-(S)-erythromycylamine, which is the predominant compound found in plasma and extravascular tissues. High tissue concentration of erythromycylamine is achieved after oral doses of dirithromycin, with slow release back into the circulation. The mechanism of action of dirithromycin is like that of erythromycin and other macrolides. These compounds inhibit RNA-dependent protein synthesis. It has recently been suggested that all macrolides stimulate dissociation of peptidyl-tRNA from ribosomes during the elongation phase, leading to inhibited protein synthesis. The antimicrobial spectrum of dirithromycin is similar to that of erythromycin, although the drug offers no significant advantage with regard to MIC values. In vitro against Gram-positive isolates, dirithromycin exhibits similar potency to that of clarithromycin, erythromycin, roxithromycin, and clindamycin. In vivo, dirithromycin is active against penicillin-susceptible Staphylococcus aureus, beta-hemolytic streptococci, and Streptococcus pneumoniae. Dirithromycin is as effective as penicillin VK against streptococcal pharyngitis and tonsilitis, and as effective as erythromycin against acute superimposed chronic bronchitis and skin and soft-tissue infections. In comparison with other newer macrolides, dirithromycin has shown similar or lesser in vitro activity. In particular, Haemophilus influenzae, Bacteroides spp., Peptococcus-Peptostreprococcus spp., Clostridium perfringens, Legionella spp., Neisseria gonorrhoeae, and Chlamydia trachomatis were all less sensitive to dirithromycin than azithromycin or clarithromycin. Once-daily oral administration of dirithromycin (500 mg) has been demonstrated to be similar in efficacy to erythromycin (250 mg, 4 times daily), each for approximately 7 days, in the treatment of acute bronchitis or acute-exacerbations of chronic bronchitis in controlled studies. Proven or presumed pathogen eradication rates were 83 and 86% for acute bronchitis patients treated with dirithromycin and erythromycin, respectively. Corresponding bacteriological response rates in acute exacerbations of chronic bronchitis were 75 to 84% with dirithromycin and 75 to 82% with erythromycin. Both agents achieved clinical cure or improvement in over 85% of the patients with either condition. The main advantage of dirithromycin over erythromycin appears to be once-daily administration. Lilly launched dirithromycin in September 1993, in Spain, received approval from FDA in August 1995, and launched it during October 1995.
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PMID:New drugs--reports of new drugs recently approved by the FDA. Dirithromycin. 873 38

The activity of six antibiotics directed against intracellularly multiplying Legionella pneumophilia was examined in tissue cultures with J774 macrophages. The drugs tested were the new quinolones, BAY Y 3118 and clinafloxacin, and ciprofloxacin, erythromycin, gentamicin and ampicillin served as reference drugs. Additionally, the MICs of these drugs against L. pneumophila were determined in vitro by broth microdilution. Despite their low MIC values, ampicillin and gentamicin did not inhibit intracellular multiplication of L. pneumophila in J774 macrophages. In contrast, an inhibition of intracellular growth could be demonstrated for the four other antibiotics. The new quinolones BAY Y 3118 and clinafloxacin showed the highest activity against intracellular L. pneumophila. At a concentration of 0.00078 mg/L already, a marked reduction in bacterial counts was seen for both drugs in comparison to the growth control without antibiotics. The corresponding effective concentrations were 0.0125 mg/L for ciprofloxacin and 0.2 mg/L for erythromycin. It may be concluded that new quinolone derivatives might become an alternative to erythromycin and rifampicin which at present are the drugs of primary choice for the treatment of legionnaires' disease.
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PMID:Excellent activity of newer quinolones on Legionella pneumophila in J774 macrophages. 908 16

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 activity of grepafloxacin, a new orally active fluoroquinolone, was compared with the activities of ofloxacin, clarithromycin and doxycycline against Chlamydia pneumoniae, Chlamydia trachomatis, Mycoplasma pneumoniae, Mycoplasma hominis and Ureaplasma urealyticum, and with the activities of ofloxacin, clarithromycin and rifampicin against Legionella spp. Grepafloxacin (MIC range 0.06-0.12 mg/L) was some 8-16 times more active than ofloxacin against the chlamydiae, showing activity similar to that of doxycycline, and equal or two- to four-fold less active than clarithromycin. Grepafloxacin was four-fold more active than ofloxacin against M. pneumoniae (MIC 0.06-0.5 mg/L) and U. urealyticum (MIC 0.12-1.0 mg/L), but 16 times more active against M. hominis (MIC 0.015-0.05 mg/L). Grepafloxacin was highly active against Legionella spp. (MIC 0.008-0.03 mg/L), showing equivalent activity to ofloxacin, clarithromycin and rifampicin.
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PMID:The in-vitro activity of grepafloxacin against Chlamydia spp., Mycoplasma spp., Ureaplasma urealyticum and Legionella spp. 948 71


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