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

Amoxycillin and clavulanic acid show good activity against Legionella pneumophila in vitro, and synergy has been observed between the two agents. However, in tissue culture studies, amoxycillin was inactive against intracellular legionellae, whereas clavulanic acid and amoxycillin plus clavulanic acid were as effective as erythromycin in preventing bacterial growth. These latter findings were reflected in the results of therapy of a L. pneumophila pneumonia in the neutropenic rat. Amoxycillin was ineffective in reducing bacterial counts in the lungs of infected animals, but clavulanic acid and amoxycillin-clavulanic acid produced bactericidal effects similar to those of erythromycin. The data illustrate the bactericidal activity of amoxycillin-clavulanic acid and clavulanic acid against intracellular L. pneumophila in contrast to the lack of activity of amoxycillin.
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PMID:Activity of amoxycillin-clavulanic acid against Legionella pneumophila in vitro and in an experimental respiratory infection model. 136 51

To evaluate the activity of co-amoxiclav (amoxycillin/clavulanic acid) against Legionella pneumophila in vivo, a model of L. pneumophila pneumonia was developed in weanling rats rendered leukopenic by pre-administration of cyclophosphamide. Assessment of therapy was by lung bacterial counts and histological examination. Amoxycillin was ineffective in reducing bacterial counts in the lungs of infected rats, whereas erythromycin, the standard agent, was significantly more effective (P < 0.01). Co-amoxiclav and erythromycin, administered parenterally, produced significant bactericidal effects (P < 0.01), reducing the counts of L. pneumophila strain 1624 at 96 h to 1.2 log10 cfu/lungs compared with counts of 6 log10 cfu/lungs in the untreated animals. Clavulanic acid was also highly effective in preventing development of the infection, and was as efficacious as co-amoxiclav. Because of the significant reduction in bacterial numbers, a marked reduction in inflammation and consolidation of lung tissue was seen in rats treated with erythromycin, clavulanic acid or co-amoxiclav. The activity of co-amoxiclav was no greater than clavulanic acid alone, and no synergy was noted between the two components. When therapy was delayed until 48 h after infection, co-amoxiclav was as effective as erythromycin, with both treatments reducing bacterial numbers to 3.3 and 3.6 log10 cfu/lungs by 96 h, after only two days of therapy, in comparison with non-treated rats (5.6 log10 cfu/lungs). In a prolonged infection, produced by extending the period of leucopenia, co-amoxiclav and erythromycin were equally effective in preventing growth of the organism, with 1.5 and 1.6 log10 cfu/lungs, respectively, present at 96 h, in contrast to the non-treated rats with 5.7 log10 cfu/lungs (P < 0.01). After cessation of therapy, regrowth of L. pneumophila occurred in the erythromycin-treated group to such a degree that by 168 h, lung viable counts from these rats were significantly higher (4.8 log10 cfu/lungs) than in co-amoxiclav-treated rats (2.1 log10 cfu/lungs) (P < 0.05). Oral therapy of this infection with erythromycin or clavulanic acid, either alone or in combination with amoxycillin, resulted in counts of 3.3, 3.6 and 3.5 log10 cfu/lungs at 96 h, respectively. Although oral therapy was significantly less effective than parenteral therapy (P < 0.05), the bacterial counts in the treated groups were significantly lower than in the non-treated animals. The data show that co-amoxiclav displayed bactericidal activity consistently against intracellular L. pneumophila in vivo.
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PMID:Bactericidal effects of co-amoxiclav (amoxycillin clavulanic acid) against a Legionella pneumophila pneumonia in the immunocompromised weanling rat. 149 Sep 22

Amoxycillin/clavulanic acid and clavulanic acid have been previously reported to demonstrate bactericidal activity in tissue culture studies against intracellular Legionella pneumophila. A rat model of legionellosis was therefore developed for the purpose of assessing the efficacy of these agents against L. pneumophila in vivo. Therapy by the subcutaneous route was started 12 h after infection when the majority of the bacteria observed in lavage fluid were residing in alveolar macrophages. Treatment with amoxycillin was ineffective in reducing the bacterial counts of L. pneumophila in lung homogenates whereas amoxycillin/clavulanic acid displayed bactericidal effects of the same order as the control antibiotic, erythromycin. Further in-vivo studies are planned to assess the clinical relevance of these findings.
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PMID:Bactericidal effects of amoxycillin/clavulanic acid against a Legionella pneumophila pneumonia in the weanling rat. 205 May 89

The bactericidal effects of amoxycillin, clavulanic acid and amoxycillin plus clavulanic acid were determined against Legionella pneumophila growing intracellularly in MRC-5 human fetal lung fibroblast cells. The strain of L. pneumophila was shown to be growing within the cells by transmission electron microscopy and this was confirmed by the results of bactericidal tests in which gentamicin was shown to be ineffective in preventing growth of the organism in the tissue culture system. Amoxycillin failed to prevent infection of the cell monolayers and had no effect on the growth of intracellular L. pneumophila. Transmission electron microscopy showed the presence of large numbers of bacteria of normal morphology within the fibroblasts. In contrast, clavulanic acid and amoxycillin/clavulanic acid protected the cell sheets from the effects of infection with L. pneumophila and reduced the numbers of intracellular bacteria to the same extent as erythromycin. Also, bacteria of abnormal morphology were observed within fibroblast cells of the cultures treated with clavulanic acid and the combination. These data demonstrate the penetration of clavulanic acid, when used alone or in the presence of amoxycillin, into cells infected with L. pneumophila and the resulting bactericidal activity of the agents against intracellular bacteria.
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PMID:Bactericidal effects of amoxycillin/clavulanic acid against intracellular Legionella pneumophila in tissue culture studies. 1122 73

The guidelines used in Dutch hospitals for the treatment of pneumonia as described in antibiotic formularies are described. A total of 42 formularies were examined. Amoxycillin was the most frequently used agent in the treatment of community-acquired pneumonia and a wide variety of drugs was used for the treatment of nosocomial pneumonia, of which cefuroxime, alone or in combination with an aminoglycoside, was used most often. Benzylpenicillin was the most frequently used drug in community-acquired aspiration pneumonia; this drug, in combination with an aminoglycoside, was also the drug of choice in hospital-acquired aspiration pneumonia. Treatment of pneumonias with known or presumed pathogens was also surveyed and the most usual drugs of choice were benzylpenicillin for pneumococci, flucloxacillin for staphylococci, amoxycillin for Haemophilus influenzae, cefuroxime for Enterobacteriaceae (cefuroxime), cotrimoxazole for Pneumocystis carinii, doxycycline and erythromycin for Mycoplasma pneumoniae and erythromycin for Legionella pneumophila. Relatively wide variations in dosage guidelines were observed for benzylpenicillin and amoxycillin. Only a few formularies gave guidelines for the duration of treatment.
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PMID:Antibiotic policies in Dutch hospitals for the treatment of pneumonia. 782 19

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

Optimal antibiotic treatment of community-acquired pneumonia (CAP) remains controversial. The clinical impact of S. pneumoniae resistance to macrolides is well documented. By contrast high dosage amoxicillin (1 g tid) remains active against such strains and no failure has been reported. The aim of this paper was to review clinical trials in community-acquired pneumonia, published from January 1, 1999, to December 31, 2005. One hundred seventy-three articles were collected, using Medline, 35 of which were analyzed, and 16 finally used. Telithromycin and pristinamycin may be used in mild to moderate CAP. Anti-pneumococcal fluoroquinolones such as levofloxacin and moxifloxacin may be used in at risk patients, but levofloxacin has only been investigated in patients with severe CAP and patients with Legionnaire's disease. Amoxicillin 1 g tid remains the drug of choice for pneumococcal CAP.
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PMID:[Acute community-acquired pneumonia. A review of clinical trials]. 1687 63