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

The susceptibilities of 11 strains representing the five recognized species of Legionella were determined by agar dilution testing on buffered charcoal-yeast extract agar. All of the legionellae tested were susceptible to rifampin, erythromycin, rosaramycin, chloramphenicol, and the aminoglycosides and were resistant to clindamycin and vancomycin. Susceptibilities to penicillins and cephalosporins were variable. Legionella micdadei, Legionella bozemanii, and Legionella gormanii were susceptible to these agents, but minimal inhibitory concentrations for each species were different. Legionella dumoffii resembled Legionella pneumophila in being resistant to penicillin, cephalothin, and cephamandole and susceptible to moxalactam and cefoxitin. All species except L. micdadei produced beta-lactamase.
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PMID:Susceptibility of Pittsburgh pneumonia agent (Legionella micdadei) and other newly recognized members of the genus Legionella to nineteen antimicrobial agents. 732 45

Acute bronchitis is usually a viral infection which, unless there is a special disposition, does not require antibiotic therapy. For the initial oral chemotherapy of bacterial infections of the lower respiratory tract (chronic bronchitis, pneumonia) the effective and well tolerated cephalosporins, macrolides and amoxicillin plus beta-lactamase-inhibitor are recommended. In complicated cases with severe underlying disease, longer history or frequent exacerbations, quinolones should be given if Gram-negative infections are suspected or if initial therapy with other substances has failed. If Legionella, Mycoplasma or Chlamydia spp., so-called 'atypical' pathogens, are involved, macrolide antibiotics are the therapy of first choice. Special attention should be given to the increase in resistance against cotrimoxazole (trimethoprim-sulfamethoxazole) and tetracyclines. In hospitals where primary pneumonias are treated preferentially by intravenous medication, therapy should be switched to oral antibiotics as soon as feasible (follow-up therapy). For severely ill patients with secondary pneumonia and underlying disease, second generation cephalosporins with aminoglycosides, or monotherapy with third generation cephalosporins are recommended. In very severe, high-risk cases, third generation cephalosporins, combinations with high-dosage quinolones or ureidopenicillins plus beta-lactamase-inhibitors are suitable. Future development in the antibiotic treatment of respiratory infections will follow the current trend of lower dosages, with the clear objective of shortening treatment periods and achieving earlier discharge from hospital.
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PMID:A guide to the treatment of lower respiratory tract infections. 758 90

Cefdinir (FK482), a new oral cephalosporin with enhanced beta-lactamase stability, was tested by microbroth dilution against respiratory, urogenital, and skin and skin-structure bacterial pathogens. Included were beta-lactamase (beta LAC)-producing and -nonproducing isolates. Activity was compared with that of other orally administered beta-lactams. Cefdinir minimum inhibitory concentrations for 90% of isolates MIC90s (microgram/ml) were < or = 0.5 versus beta LAC+/oxacillin-susceptible Staphylococcus, aureus, S. epidermidis, and S. saprophyticus; < or = 0.06 versus Streptococcus groups A and B, and Neisseria gonorrhoeae beta LAC+; 0.125 versus S. pneumoniae penicillin-susceptible and Proteus mirabilis beta LAC+; 0.25 versus beta LAC+ versus strains of Moraxella catarrhalis, Escherichia coli, Klebsiella pneumoniae, and K. oxytoca; 0.5 versus Haemophilus influenzae beta LAC-; 1 versus H. influenzae beta LAC+; 4 versus Legionella pneumophila beta LAC+; and 8 versus Enterococcus faecalis beta LAC-strains. Cefdinir was equally effective against both standard and high inocula of S. aureus strains producing A, B, C, or D beta LAC types. MICs were also generated versus quality-control reference strains.
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PMID:In vitro evaluation of cefdinir (FK482), a new oral cephalosporin with enhanced antistaphylococcal activity and beta-lactamase stability. 802 55

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

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

Respiratory tract infections (RTIs) are among the most frequent infections in man and lower tract infections account substantially for the overall mortality in hospitals. Regarding the etiology of pneumonias, one has to consider different pathogenic mechanisms, age of the patients, underlying diseases, concomitant medications, symptomatologies, seasonal influences, and clinical conditions, e.g. intensive care environment and mechanical ventilation. To optimize the rational management of respiratory infections, identification of the etiologic agent would be desirable. The decision of how to treat is often based on epidemiologic, clinical, and radiological assessments. Epidemiologic studies have shown a pronounced difference in the etiologic spectrum between community- and hospital-acquired RTIs. In community-acquired pneumonias, pneumococci, Haemophilus influenzae, Legionella, Mycoplasma and viruses predominate, whereas in nosocomially acquired pneumonias, Enterobacteriaceae, e.g. Klebsiella, Proteus, Enterobacter as well as Pseudomonas and staphylococci comprise the most frequent isolates. Empirical therapy has to cover all possible etiologic pathogens which most likely cause the infection. In addition, an adequate kinetic profile, e.g. once or twice daily dosing, sufficient pulmonary tissue or fluid penetration, and acceptable tolerance and costs are prerequisites for optimal therapy. Drugs of choice for the treatment of community-acquired pneumonia are aminobenzylpenicillins or macrolides. Oral cephalosporins exhibit excellent activity against many bacterial pathogens of typical community-acquired pneumonia, and are active against beta-lactamase-producing H. influenzae.
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PMID:Clinical requirements in the treatment of today's respiratory tract infections. 848 87

Pneumonia in the community affects between 1 and 5 per 1000 per year. The microbial aetiology is diverse and influenced by preexisting disease, seasonality, as well as animate and inanimate environmental sources; pneumococci, Legionella spp., Mycoplasma pneumoniae, and more recently Chlamydia pneumoniae are the predominant bacterial pathogens. Gram-negative enteric bacteria although less common are particularly virulent. Antibiotic resistance is well established for Haemophilus influenzae and Gram-negative bacillary infections, but has been a recent phenomenon in the case of Streptococcus pneumoniae, which is numerically the leading pathogen. Despite the concerns raised by this reduced susceptibility to penicillin, evidence that this has been translated into increased clinical failures is currently difficult to establish. Macrolide and tetracycline resistance among pneumococci is more common. beta-Lactamase production by H. influenzae has now reached levels where, in those with severe pneumonia, beta-lactamase stable agents are preferred. Consensus Guidelines on the treatment of community acquired pneumonia have been published by the British Thoracic Society, the American Thoracic Society, and from Expert Panels in Canada and France. These emphasize severity assessment and differentiate management in the community or hospital setting. The recommended regimens are compared and contrasted. In conclusion, mild/moderate pneumonia, when pneumococcal in nature, is likely to still respond to amoxycillin or penicillin G, but in higher dosages where pneumococcal resistance is documented. However, in severe infection where pneumococcal resistance, other beta-lactamase-producing pathogens, or an atypical infection could be operating, it is important that initial empirical therapy be broad spectrum and promptly administered. Treating multiresistant pneumococcal disease in those allergic to beta-lactams presents a particular dilemma. Glycopeptides are currently preferred.
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PMID:Pneumonia: the impact of antibiotic resistance on its management. 915 49

Clarithromycin is a broad spectrum macrolide antibacterial agent active in vitro and effective in vivo against the major pathogens responsible for respiratory tract infections in immunocompetent patients. It is highly active in vitro against pathogens causing atypical pneumonia (Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella spp.) and has similar activity to other macrolides against Staphylococcus aureus. Streptococcus pyogenes, Moraxella catarrhalis and Streptococcus pneumoniae. Haemophilus influenzae is susceptible or intermediately susceptible to clarithromycin alone, but activity is enhanced when the parent drug and metabolite are combined in vitro. Absorption of clarithromycin is unaffected by food. More than half of an oral dose is systemically available as the parent drug and the active 14-hydroxy metabolite. Pharmacokinetics are nonlinear, with plasma concentrations increasing in more than proportion to the dosage. First-pass metabolism results in the rapid appearance of the active metabolite 14-hydroxy-clarithromycin in plasma. Clarithromycin and its active metabolite are found in greater concentrations in the tissues and fluids of the respiratory tract than in plasma. Dosage adjustments are required for patients with severe renal failure, but not for elderly patients or those with hepatic impairment. Drug interactions related to the cytochrome P450 system may occur with clarithromycin use. In addition to the standard immediate-release formulation for administration twice daily, a modified-release formulation of clarithromycin is now available for use once daily. In dosages of 500 to 1000 mg/day for 5 to 14 days, clarithromycin was as effective in the treatment of community-acquired upper and lower respiratory tract infections in hospital and community settings as beta-lactam agents (with or without a beta-lactamase inhibitor), cephalosporins and most other macrolides. Clarithromycin was similar in efficacy to azithromycin in comparative studies and is as effective as and better tolerated than erythromycin. Adverse events are primarily gastrointestinal in nature, but result in fewer withdrawals from therapy than are seen with erythromycin. Clarithromycin provides similar clinical and bacteriological efficacy to that seen with beta-lactam agents, cephalosporins and other macrolides. It offers a cost-saving alternative to intravenous erythromycin use in US hospitals and is available in both once-daily and twice-daily formulations. The spectrum of activity of clarithromycin against common and emerging respiratory tract pathogens may make it suitable for use in the community as empirical therapy of respiratory tract infections in both children and adults.
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PMID:Clarithromycin. A review of its efficacy in the treatment of respiratory tract infections in immunocompetent patients. 917 28

In France the current consensus for the treatment of community-acquired pneumonia is based on the French Society for Infectious Diseases 1991 guidelines. In healthy adults without signs of severe disease, oral amoxicillin is recommended at the dose of 3 g per day for 8 to 10 days. This empirical choice is warranted by the prevalence of pneumococcal infections, found as causal agents in half to two-thirds of the bacteriologically proven cases. The 3 g dose is recommended due to the increasing risk of penicillin-resistant S. pneumoniae with MIC > 1 microgram/ml and exceptionally > 2 micrograms/ml. Clinical experience has shown that with a threshold at 2 micrograms/ml, 3 g of amoxicillin is a safe and sure choice. The duration is undoubtedly too long for most patients, but is a prudent measure due to the lack of clinical signs distinguishing between patent infection and its prolongation by inflammatory processes. Indiscriminate prescription of amoxicillin alone is however unacceptable as aminopenicillin is not effective against all microbial agents responsible for community-acquired pneumonia. The risk of selecting resistant strains is very real. Use of a large spectrum antibiotic could be indicated as first line treatment in patients with risk factors (underlying chronic disease, institutionalization, exposure to Gram negatives or S. aureus). For such patients, combination with a beta-lactamase inhibitor (coamoxiclav) or a cephalosporin with a MIC similar to that for penicillin G (cefpodoxime proxetil, cefuroxime axetil) could be recommended. In case of severe disease, Legionella pneumophila must be taken into consideration, implicating adjuction of a macrolide. Wide spectrum fluoroquinolones such as the soon to be available trovafloxacin offer a safe alternative, covering the main microorganisms responsible for community acquired pneumonia. Widespread use would however increase the risk of microbial resistance. In the current epidemiological situation in France, prescription of an aminopenicillin alone for alveolar community-acquired pneumonia in healthy adults remains the gold standard for first line therapy.
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PMID:[Can aminopenicillin be prescribed as monotherapy in case of community-acquired pneumonia?]. 981 92

A metallo-beta-lactamase determinant was cloned from a genomic library of Legionella (Fluoribacter) gormanii ATCC 33297(T) constructed in the plasmid vector pACYC184 and transformed into Escherichia coli DH5alpha, by screening for clones showing a reduced susceptibility to imipenem. The product of the cloned determinant, named FEZ-1, contains a 30-kDa polypeptide and exhibits an isoelectric pH of 7.6. Sequencing revealed that FEZ-1 is a molecular-class B beta-lactamase which shares the closest structural similarity (29.7% of identical residues) with the L1 enzyme of Stenotrophomonas maltophilia, being a new member of the highly divergent subclass B3 lineage. All the residues that in L1 are known to be directly or indirectly involved in coordination of the zinc ions were found to be conserved also in FEZ-1, suggesting that the geometry of zinc coordination in the active site of the latter enzyme is identical to that of L1. Unlike L1, however, FEZ-1 appeared to be monomeric in gel permeation chromatography experiments and exhibited a distinctive substrate specificity with a marked preference for cephalosporins and meropenem. The properties of FEZ-1 overall resembled those of a beta-lactamase previously purified from the same strain of L. gormanii (T. Fujii, K. Sato, K. Miyata, M. Inoue, and S. Mitsuhashi, Antimicrob. Agents Chemother. 29:925-926, 1986) and are as yet unique among class B enzymes, reinforcing the notion that considerable functional heterogeneity can be encountered among members of this class. A system for overexpression of the bla(FEZ-1) gene in E. coli, based on the T7 phage promoter, was also developed.
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PMID:The Legionella (Fluoribacter) gormanii metallo-beta-lactamase: a new member of the highly divergent lineage of molecular-subclass B3 beta-lactamases. 1081 5


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