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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 susceptibility of 14 strains of Legionella pneumophila to 17 anti-microbial agents were determined. The most active antibiotics were cefoxitin, erythromycin and doxycycline while the least active were cephalothin, cefamandole and cefazolin. Subculturing, type of medium and duration of incubation did not alter the effect of the antimicrobial agents. A change in the inoculum size, from 10(4) to 10(6) cfu, increased MICs two- to sixfold. Erythromycin was not synergistic with gentamicin, tobramycin or amikacin.
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PMID:The effect of inoculum, culture medium and antimicrobial combinations on the in-vitro susceptibilities of Legionella pneumophila. 725 23

Four severe cases of Legionnaires' disease are described. In addition to multilobar pneumonia with respiratory failure, involvement of the central nervous, cardiovascular, renal, hepatic and coagulation systems had occurred. Adult respiratory distress syndrome complicated respiratory management. Early development of acute renal failure was associated with a poor prognosis. Erythromycin was the most commonly used antibiotic. Review of stored pathological material from patients who died from unidentified pneumonias enabled confirmation of the existence of Legionnaires' disease in Australia in 1974.
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PMID:Legionnaires' disease in South Australia. Four case reports. 739 74

Thirty-three isolates of Legionella pneumophila, all except one of which were clinical isolates, were tested against 20 antimicrobial agents by using an agar dilution technique. Erythromycin, rifamp]in, and rosaramycin were the most active agents tested. Aminoglycosides, chloramphenicol, and cefoxitin also inhibited the organisms at low concentrations. Other agents, including moxalactam, cefoperazone, and cephalosporins, exhibited moderate to little activity. Tetracycline, doxycycline and minocyeline were apparently inactivated by charcoal-yeast extract medium. There was slight inoculum dependence noted with most of the antimicrobials tested, particularly the beta-lactam agents. There was no consistent difference in susceptibility between Center for Disease Control-supplied stock strains and recent clinical isolates, but there were marked differences with some agents. Susceptibility testing needs to be standardized in view of the influence of inoculum size, strain variation, and the medium used.
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PMID:Susceptibility of Legionella pneumophila to twenty antimicrobial agents. 742 11

Development of susceptibility tests for Legionella spp. has been difficult because of the specific growth requirements of this organism. The most commonly used media, buffered charcoal-yeast extract (BCYE) agar contains charcoal, which is known to inactivate some antimicrobial agents. This study compared five antimicrobial (erythromycin, clindamycin, ofloxacin, doxycycline, and rifampin) minimum inhibitory concentration (MIC) values as determined by agar dilution using BCYE, agar dilution using this same media without the charcoal [buffered yeast extract (BYE) agar], and the Etest on BCYE media. The MIC50 and MIC90 for this group of Legionella spp. were greater with BCYE than with BYE. Erythromycin and ofloxacin (fourfold change) were the most affected by the charcoal in the medium. The Etest MIC and agar dilution MIC with BYE were comparable. The Etest rifampin results demonstrated that the Legionella spp. strains were very susceptible (< 0.016 micrograms/ml, producing very large zones) requiring use of one half of the Etest strip, a whole test strip on an individual 100-mm plate of BCYE, or use of a new low-MIC-range Etest strip. The Etest on BCYE provides a simple, readily available, and accurate method unaffected by medium components for susceptibility testing of Legionella spp.
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PMID:Application of the Etest to antimicrobial susceptibility testing of Legionella spp. 782 Sep 99

The activities of ceftriaxone, piperacillin, tazobactam, clavulanic acid, and combinations of ceftriaxone or piperacillin with tazobactam against 22 clinical Legionella isolates were measured by broth microdilution and macrodilution methods and in macrophages. The broth microdilution MICs that inhibited 90% of strains tested were 2 and 1 microgram/ml for ceftriaxone and tazobactam, respectively. Broth macrodilution MICs were 8 and 1 microgram/ml, respectively, for the two Legionella pneumophila strains tested with piperacillin and were 0.25 and 0.5 microgram/ml, respectively, for clavulanate. No significant intracellular anti-L. pneumophila activity was observed for ceftriaxone (32 micrograms/ml), piperacillin (32 micrograms/ml), tazobactam alone (16 micrograms/ml), clavulanate alone (2 micrograms/ml), or tazobactam in combination with ceftriaxone (ceftriaxone/tazobactam at 32/4 and 16/16 micrograms/ml) or piperacillin (32/4 micrograms/ml). Erythromycin (1 microgram/ml) was active against intracellular L. pneumophila in the same macrophage model of infection. It is very unlikely that tazobactam or clavulanate, alone or in combination with beta-lactam antimicrobial agents, will be effective for the treatment of Legionnaires' disease in humans.
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PMID:In vitro extracellular and intracellular activities of clavulanic acid and those of piperacillin and ceftriaxone alone and in combination with tazobactam against clinical isolates of Legionella species. 819 43

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

The authors report a case of ARDS following pneumonia caused by Legionella pneumophila, in a thirty year old young man. Mechanical ventilation was maintained for twenty days. The gravity of ARDS and pneumonia, perhaps was caused because infective agent and the efficacious antibiotic were identified too late: twelve days after the comparison of symptoms. In fact, early laboratory diagnosis of Legionella pneumonia, is currently very difficult. A primitive extranocosomial pneumonia with rapid development to ARDS, in a good health young man, is an uncommon event. The exclusion of particular causes of ARDS, such as narcotic over-dose, AIDS, lung cancer, lymphatic carcinomatosis, and the clinical suspicion of Legionella pneumonia presence, can be useful: waiting for the right diagnosis from the laboratory, it will be possible to begin antibiotic therapy with Erythromycin (often used for slight respiratory infections), and to prevent the evolution of illness.
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PMID:[ARDS in a severe case of primary pulmonary infection caused by Legionella pneumophila]. 827 69

Legionella pneumophila is the second most common cause of severe community-acquired pneumonia requiring treatment with intermittent positive pressure ventilation. The prognosis of this condition and its complications have not been well documented. Erythromycin is the first-line antibiotic of choice based on clinical experience. Rifampicin has been recommended as an additional agent, though clinical experience has not been reported. We have retrospectively examined 30 cases of severe community-acquired legionella pneumonia. The mean age of the patients was 53 years, 24 were male and eight died (27%, mean age 57 years). During admission 26 patients received erythromycin (eight died) and 15 received rifampicin in addition (five died); four received neither drug and survived. Mean duration of intermittent positive pressure ventilation was 15.9 days for survivors and 14.1 days for fatal cases. Acute renal failure requiring dialysis developed in 13 (43%), of whom five died (38%). Positive inotropic drugs were used in 10 patients and of these six died. Jaundice occurred in 11 patients and was significantly more common (p = 0.028) in patients who received rifampicin (60%) than in those who did not (17%). Excess bilirubin was largely conjugated when measured and there was no consistent hepatitic or obstructive change in the liver enzymes. Severe community-acquired legionella pneumonia has a relatively good outcome with a mortality of 27%, though prolonged intermittent positive pressure ventilation may be required. Acute renal failure is common but reversible in survivors, and jaundice is more common in those who receive rifampicin.
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PMID:Severe community-acquired legionella pneumonia: treatment, complications and outcome. 832 50

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


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