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)

The in vitro activities of several 14-, 15- and 16-membered macrolides were compared with that of erythromycin. In general, 14-membered macrolides such as erythromycin, clarithromycin, and flurithromycin were more active against streptococci and Bordetella pertussis than was the 15-membered macrolide azithromycin, which was more active than 16-membered macrolides such as miocamycin and rokitamycin. Clarithromycin was the most active compound against Streptococcus pyogenes, pneumococci, Listeria monocytogenes, and Corynebacterium species. Legionella pneumophila was most susceptible to miocamycin, clarithromycin, and rokitamycin. Branhamella catarrhalis, Neisseria gonorrhoeae, and Haemophilus influenzae were most susceptible to azithromycin. Azithromycin and dirithromycin were the most active compounds against Campylobacter jejuni. MICs of 16-membered macrolides for strains expressing inducible-type resistance to erythromycin were less than or equal to 1 microgram/ml, whereas none of the compounds had activity against strains expressing constitutive-type resistance. The MICs of roxithromycin, miocamycin, rokitamycin, and josamycin increased in the presence of human serum, whereas MICs of the other compounds either were unchanged or decreased.
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PMID:Comparative in vitro activities of new 14-, 15-, and 16-membered macrolides. 325 53

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

Azithromycin pharmacokinetics in Legionella pneumophila-infected and uninfected guinea pigs were assessed by measuring the drug concentration in whole lungs or the drug content in bronchoalveolar lavage (BAL) fluid in separate experiments. Azithromycin concentrations were measured by using a bioassay. The mean azithromycin content in the BAL fluid of infected guinea pigs was higher than that in controls at 10 h (0.87 versus 0.39 microgram; P = 0.05), 24 h (1.10 versus 0.37 microgram; P = 0.003), and 48 h (1.21 versus 0.28 microgram; P = 0.05) after a single intraperitoneal injection of drug (15 mg/kg). The mean peak lung azithromycin concentration was higher in control animals than in infected animals (15.8 versus 13.4 micrograms/ml). The mean lung azithromycin concentration in infected animals was significantly higher than that in controls 48 h after dosing (12.7 versus 10.4 micrograms/g; P = 0.04). There were no significant differences between infected and uninfected animals in serum azithromycin levels. Complementary experiments assessed intracellular/extracellular concentration ratios of azithromycin and erythromycin in L. pneumophila-infected and control guinea pig alveolar macrophages. Azithromycin was highly concentrated in alveolar macrophages, and the intracellular/extracellular concentration ratios for infected cells were significantly higher (P < 0.0001) than those observed in controls after 4 h (127 versus 119), 24 h (481 versus 361), and 48 h (582 versus 520) of incubation. Erythromycin was also preferentially concentrated in infected cells (P < 0.0001). AZ intracellular concentrations were at least fivefold higher than those measured for erythromycin, and this differential increased with incubation time. Thus, azithromycin recovery from BAL fluid, and from guinea pig lungs at the 48-h time point, was higher in the presence of experimental Legionnaires' disease. This likely results from recruitment of phagocytes, including macrophages, that have an enhanced capacity to highly concentrate the drug.
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PMID:Azithromycin pharmacokinetics and intracellular concentrations in Legionella pneumophila-infected and uninfected guinea pigs and their alveolar macrophages. 819 46

An in vitro infection model was created using a suspension of macrophages, polymorphonuclear leukocytes, lymphocytes, fibroblasts, and human serum to which pathogen and antibiotic were added. Separate intracellular and extracellular antibiotic concentrations and activity against Staphylococcus aureus and Legionella pneumophila were assessed for three antimicrobial agents: amoxicillin, azithromycin and clarithromycin. Amoxicillin was found almost exclusively in extracellular fluid, where it was active; intracellularly, it was ineffective. Azithromycin, in contrast, was primarily concentrated and active intracellularly, with little activity in extracellular fluid. Clarithromycin was present in both compartments and possessed significant activity both intracellularly and extracellularly.
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PMID:A new model examining intracellular and extracellular activity of amoxicillin, azithromycin, and clarithromycin in infected cells. 822 70

Azithromycin is about as active against Legionella spp. in vitro as is erythromycin, with modal MICs approximately 0.5 to 0.125 microgram/ml, depending on the method used. In contrast, azithromycin is much more active against intracellular L. pneumophila than is erythromycin. In a guinea pig model of Legionnaires' disease, azithromycin is much more active than is erythromycin or clarithromycin. Despite the paucity of reports of treatment of Legionnaires' disease with azithromycin, it is likely to be as or more effective than erythromycin.
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PMID:Review of azithromycin activity against Legionella spp. 853 85

A clinical, retrospective and non-comparative study was undertaken to assess the clinical efficacy and tolerability of azithromycin in the treatment of community-acquired pneumonia caused by Legionella pneumophila. A total of 16 patients with a serologically confirmed diagnosis of Legionnaires' diseases were included. Azithromycin was administered orally at a total dose of 1.5 g for either 3 or 5 days. All patients were no side-effects requiring discontinuation of the treatment. Further increase of abnormal baseline liver function was recorded in 2 patients and in 1 patient mild, transient eosinophilia. Equal clinical efficacy and tolerability were observed with the 3- and 5-day dosage regimen. These results indicate that azithromycin given at a standard dose of 1.5 g is effective and well tolerated in the treatment of Legionnaires' disease.
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PMID:Azithromycin for treatment of community acquired pneumonia caused by Legionella pneumophila: a retrospective study. 858 43

One of the chemical features that distinguishes the 15-membered ring azalide azithromycin from the 14-membered ring macrolide compound erythromycin is the former's increased stability at acid pH. Azithromycin also differs pharmacokinetically from erythromycin, an important feature being azithromycin's ability to achieve high tissue concentrations, with the agent being delivered to the sites of infection by direct uptake and by targeted delivery via phagocytes. High tissue concentrations are maintained for prolonged periods because of azithromycin's long half-life, leading to once-daily dosing for 3 or 5 days. Notable microbiological features of azithromycin are in-vitro activity against many pyogenic bacteria (e.g. Neisseria gonorrhoeae and Moraxella catarrhalis), as well as organisms against which beta-lactam antibiotics are usually ineffective (e.g. Legionella and Chlamydia spp.), organisms that are resistant to benzylpenicillin and erythromycin (e.g. Haemophilus influenzae) and organisms for which satisfactory therapy is limited (e.g. Toxoplasma gondii and the Mycobacterium avium-intracellulare complex). These properties of azithromycin suggest that it might be a useful agent for the treatment of a wide range of bacterial infections.
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PMID:Azithromycin--review of key chemical, pharmacokinetic and microbiological features. 881 41

The azalide antibacterial agent azithromycin is a semisynthetic acid-stable erythromycin derivative with an expanded spectrum of activity and improved tissue pharmacokinetic characteristics relative to erythromycin. The drug is noted for its activity against some Gram-negative organisms associated with respiratory tract infections, particularly Haemophilus influenzae. Azithromycin has similar activity to other macrolides against Streptococcus pneumoniae and Moraxella catarrhalis, and is active against atypical pathogens such as Legionella pneumophila, Chlamydia pneumoniae and Mycoplasma pneumoniae. Once-daily administration of azithromycin is made possible by the long elimination half-life of the drug from tissue. Azithromycin is rapidly and highly concentrated in a number of cell types after absorption, including leucocytes, monocytes and macrophages. It undergoes extensive distribution into tissue, from where it is subsequently eliminated slowly. A 3-day oral regimen of once-daily azithromycin has been shown to be as effective as 5- to 10-day courses of other more frequently administered antibacterial agents [such as erythromycin, amoxicillin-clavulanic acid and phenoxymethylpenicillin (penicillin V)] in patients with acute exacerbations of chronic bronchitis, pneumonia, sinusitis, pharyngitis, tonsillitis and otitis media. Adverse effects of azithromycin are mainly gastrointestinal in nature and occur less frequently than with erythromycin. Azithromycin is likely to prove most useful as a 3-day regimen in the empirical management of respiratory tract infections in the community. Its ease of administration and 3-day duration of therapy, together with its good gastrointestinal tolerability, should optimise patient compliance (the highest level of which is achieved with once-daily regimens). Azithromycin is also likely to be useful in the hospital setting, particularly for outpatients and for those unable to tolerate erythromycin.
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PMID:Azithromycin. A review of its pharmacological properties and use as 3-day therapy in respiratory tract infections. 888 83

Erythromycin, the prototypical macrolide, has been widely used since the 1950s in the management of pediatric infections. Erythromycin is the drug of choice for infants and children with Legionnaire's disease, pertussis, diphtheria, lower respiratory tract infections caused by Mycoplasma pneumoniae, Chlamydia pneumoniae and Chlamydia trachomatis and enteritis caused by Campylobacter jejuni. It is also indicated for treatment of syphilis; for streptococcal, staphylococcal and pneumococcal infections; genital infections caused by Ureaplasma urealyticum; and for the prevention of rheumatic fever and endocarditis in patients who are allergic to beta-lactam antibiotics. The new macrolides azithromycin and clarithromycin are also active against Borrelia burgdorferi, Helicobacter pylori, Mycobacterium avium-intracellulare complex, Cryptosporidium spp. and Toxoplasma gondii. Erythromycin is associated with a low risk of serious side effects, although gastric distress occurs in a significant proportion of patients. Drug interactions with theophylline, carbamazepine, warfarin, cyclosporine, terfenadine and digoxin limit erythromycin use. The newer macrolides azithromycin and clarithromycin are more stable, better absorbed and better tolerated than erythromycin. Azithromycin is more active than erythromycin against Haemophilus influenzae. Excellent tissue and intracellular penetration may contribute to their clinical efficacy. In children both azithromycin and clarithromycin are indicated for acute otitis media caused by Streptococcus pneumoniae, H. influenzae and Moraxella catarrhalis and for pharyngitis/tonsillitis caused by Streptococcus pyogenes. (As of December, 1996, azithromycin for oral suspension was approved for community-acquired pneumonia in children caused by C. pneumoniae, H. influenzae, M. pneumoniae and S. pneumoniae.) Claritromycin is also indicated for acute maxillary sinusitis, uncomplicated skin and skin structure infections, pneumonia and disseminated mycobacterial infections. Azithromycin and clarithromycin are associated with a lower incidence of gastrointestinal side effects, a low rate of drug discontinuation caused by side effects and a low potential for interaction with other drugs.
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PMID:History of macrolide use in pediatrics. 910 54

Lower respiratory tract infection (LRTI) is one of the major health problems in developing countries such as Indonesia. According to the National Household Health Survey conducted by the Ministry of Health in 1992, LRTIs still rank fourth as the main cause of death in Indonesia. The problem of LRTIs could be simply managed as long as the causative organism can be identified and the proper antibiotic known. In some occasions, it is not quite so easy to identify the causative micro-organism, especially in lower tract infections. There are several methods of obtaining specimens from LRTIs for cultures. The easiest, most simple way is to collect expectorated sputum. Unfortunately, because of the high rate of contamination by upper respiratory tract flora, this method is not reliable. Recognizing the difficulties with routine expectorated sputum cultures, two alternative approaches have been suggested. One approach is to bypass potential expectorated sputum 'contaminants' in the oropharynx by transtracheal aspiration or transthoracic aspiration. The second approach is to modify the usual technique of processing expectorated sputum by either washing techniques or by quantitative cultures. Azithromycin and clarithromycin are chemically related to macrolide erithromycin. Both antibiotics retain the traditional macrolide spectrum of activity against gram-positive and atypical pneumonia pathogens, while demonstrating improved activity against gram-negative bacteria. The American Thoracic Society (ATS) recommended the use of macrolide for outpatients with community-acquired pneumonia, without comorbidity and 60 years of age or younger. A total of 34 outpatients with acute LRTIs were open-comparative, randomly allocated to treatment with the new macrolide in Persahabatan Hospital, Jakarta, 1996. The purposes of this study were: (i) to identify the causative micro-organisms; and (ii) to evaluate the clinical efficacy of the new macrolide in these infections. Azithromycin 500 mg was given orally once a day for 3 days and was administered 1 h before or 2 h after every meal. Clarithromycin 500 mg was given orally every 12 h for 10 days. The diagnosis of the patients were: 16 with pneumonia, 10 with acute bronchitis and 8 with acute exacerbation of chronic bronchitis. In this study of 34 patients, the sputum specimens were washed with N acetylcysteine before culture and we could only detect micro-organisms in one patient. Before treatment, we found 47 strains in 33 (97.05%) patients and after treatment we found five strains. From serological examination, only four (11.76%) atypical bacterial were detected. The most frequently found microorganisms were 23 strains of Klebsiella pneumoniae (40.42%), 10 of Streptococcus alpha haemolyticus (21.26%), five of Streptococcus pneumoniae (10.63%) and five of Staphylococcus aureus (10.63%). The atypical bacterial were: two Legionella pneumophila, one Mycoplasma pneumoniae and one Chlamydia pneumoniae. The clinical efficacy of new macrolides were 100% and the bacteriological responses with eradication of 94.12% vs 70.59% of isolates in the azithromycin and clarithromycin groups are shown in Table 1. There were no adverse reactions detected in the two treatment groups until the end of the study.
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PMID:The pattern of micro-organisms and the efficacy of new macrolide in acute lower respiratory tract infections. 969 20


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