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 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

Intracellular bactericidal activity of ampicillin/sulbactam and erythromycin was determined with a human macrophage-like (U-937) cell line infected with Legionella pneumophila. Cell monolayers inoculated with L. pneumophila were treated with erythromycin, ampicillin, sulbactam, or ampicillin/sulbactam during the logarithmic phase of bacterial growth. Intracellular bacterial counts were determined at 2-h intervals for 8 h from the time that antibiotics were added. The number of viable intracellular bacteria increased during this time by 0.9 x log10 cfu/mL (P < 0.05) in the control culture, did not change significantly in the cultures treated with ampicillin or sulbactam, decreased by 0.8 x log10 cfu/mL (P < 0.05) with erythromycin, and decreased by 1.8 x log10 cfu/mL with ampicillin/sulbactam (P < 0.05). The number of cfu/mL was significantly less after incubation with ampicillin/sulbactam than with erythromycin (P < 0.05). Ampicillin/sulbactam appeared to have greater bactericidal activity against intracellular L. pneumophila than erythromycin in this in-vitro model. The bactericidal action of ampicillin/sulbactam was significantly greater than would be expected from the additive effects of ampicillin plus sulbactam, suggesting synergic bactericidal activity.
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PMID:Comparative study of the bactericidal activity of ampicillin/sulbactam and erythromycin against intracellular Legionella pneumophila. 822 20

Community-acquired pneumonia is common. Most disease is mild but mortality among hospitalized patients is 5-20%. The most common aetiological pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and the 'atypical' organisms, Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia pneumoniae. Less common pathogens account for 10-30% of cases and the aetiology cannot be determined in one-third to one-half of cases. Classification by aetiology and initiation of specific antimicrobial therapy are difficult and treatment is often initiated empirically. Ampicillin (or amoxycillin) or erythromycin are inexpensive and effective for most patients, but their use in combination, the addition of a beta-lactamase inhibitor (e.g. amoxycillin/clavulanate) or the substitution of an expanded spectrum cephalosporin (e.g. cefuroxime) should be considered for patients with more serious illnesses or pathogens likely to be drug-resistant. Fluoroquinolones such as ciprofloxacin or ofloxacin would be acceptable if adequacy for treating pneumococcal infections were likely. New macrolides, such as azithromycin and clarithromycin, and new fluoroquinolones, such as temafloxacin and sparfloxacin, have theoretical advantages over previously available drugs, but superior efficacy has not yet been demonstrated satisfactorily. Pneumococcal resistance in various parts of the world is modifying traditional treatment. Currently, there is no drug of choice for the empirical treatment of community-acquired pneumonia.
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PMID:Aetiology and treatment of community-acquired pneumonia in adults: an historical perspective. 840 96

A class D beta-lactamase determinant was isolated from the genome of Legionella (Fluoribacter) gormanii ATCC 33297(T). The enzyme, named OXA-29, is quite divergent from other class D beta-lactamases, being more similar (33 to 43% amino acid identity) to those of groups III (OXA-1) and IV (OXA-9, OXA-12, OXA-18, and OXA-22) than to other class D enzymes (21 to 24% sequence identity). Phylogenetic analysis confirmed the closer ancestry of OXA-29 with members of the former groups. The OXA-29 enzyme was purified from an Escherichia coli strain overexpressing the gene via a T7-based expression system by a single ion-exchange chromatography step on S-Sepharose. The mature enzyme consists of a 28.5-kDa polypeptide and exhibits an isoelectric pH of >9. Analysis of the kinetic parameters of OXA-29 revealed efficient activity (k(cat)/K(m) ratios of >10(5) M(-1) x s(-1)) for several penam compounds (oxacillin, methicillin, penicillin G, ampicillin, carbenicillin, and piperacillin) and also for cefazolin and nitrocefin. Oxyimino cephalosporins and aztreonam were also hydrolyzed, although less efficiently (k(cat)/K(m) ratios of around 10(3) M(-1) x s(-1)). Carbapenems were neither hydrolyzed nor inhibitory. OXA-29 was inhibited by BRL 42715 (50% inhibitory concentration [IC(50)], 0.44 microM) and by tazobactam (IC(50), 3.2 microM), but not by clavulanate. It was also unusually resistant to chloride ions (IC(50), >100 mM). Unlike OXA-10, OXA-29 was apparently found as a dimer both in diluted solutions and in the presence of EDTA. Its activity was either unaffected or inhibited by divalent cations. OXA-29 is a new class D beta-lactamase that exhibits some unusual properties likely reflecting original structural and mechanistic features.
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PMID:Characterization of OXA-29 from Legionella (Fluoribacter) gormanii: molecular class D beta-lactamase with unusual properties. 1170 32

The aim of this multicenter study was to identify the causative pathogens of community-acquired pneumonia (CAP) in Shanghai, China, and to determine their susceptibility to antimicrobial agents. Pathogens obtained from 389 patients with documented CAP during 2001-2003 were identified by multiple diagnostic tools that included bacterial culture, polymerase chain reaction (PCR), and specific immunological assays. Susceptibility of the bacterial isolates was tested by the broth microdilution method. A specific pathogen was identified in 39.8% (155/389) of the patients: Haemophilus influenzae (n=80), Klebsiella spp. (n=15), Streptococcus pneumoniae (n=12), Staphylococcus aureus (n=6), Moraxella catarrhalis (n=1), other gram-negative organisms (n=9), and atypical pathogens that comprised Mycoplasma pneumoniae (n=42), Chlamydia pneumoniae (n=17), and Legionella pneumophila (n=2). Most H. influenzae isolates were susceptible to ampicillin (88.3%), and all were susceptible to macrolides. Of the S. pneumoniae isolates, 75% (9/12) were susceptible to penicillin, while 25% (3/12) were intermediately susceptible. H. influenzae and atypical pathogens are among the most important pathogens of CAP. Ampicillin, cephalosporins, and the newer fluoroquinolones can be used as empirical therapy for CAP in the Shanghai area. The efficacy of monotherapy with newer macrolides for CAP caused by S. pneumoniae requires further evaluation.
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PMID:Community-acquired pneumonia in Shanghai, China: microbial etiology and implications for empirical therapy in a prospective study of 389 patients. 1676 84