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)

Microbial phosphatases are known or suspected to play a role in the pathogenesis of several intracellular pathogens, including Legionella micdadei. Legionella pneumophila also possess phosphatase activities, but their possible roles in cellular infection are unknown. We generated mutants of a serogroup 1 isolate of L. pneumophila that lack the major phosphatase. Isolation of a Pho- mutant after random mutagenesis with transposon MudII4041 allowed us to dissociate the major alkaline phosphatase (pH optimum approximately 8) from a minor acid phosphatase activity. Both activities were concentrated in the bacterial periplasm. The gene encoding the major alkaline phosphatase (pho) was cloned by expression in E. coli and used to generate a site directed mutation in two L. pneumophila strains. Each parent-mutant pair was compared in a U937 cell tissue culture assay for capacity to infect, lyse, and grow within mammalian cells. Although the parental stains differed in their U937 cell cytopathicity, neither was significantly more infective than its Pho- derivative, suggesting that the alkaline phosphatase activity is not essential for cellular infection. Because they are not attenuated, Pho- mutants can be used to generate gene fusions with E. coli alkaline phosphatase to study and secretion and cellular infectivity in L. pneumophila.
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PMID:Phosphatase-negative mutants of Legionella pneumophila and their behavior in mammalian cell infection. 786 53

Legionella usually causes pneumonia, but occasionally is in the differential diagnosis of "culture negative endocarditis" which sometimes involves prosthetic heart valves. Legionella prosthetic valve endocarditis is nearly always due to Legionella pneumophila and its clinical presentation is indistinguishable from other causes of prosthetic valve endocarditis. Diagnosis of Legionella prosthetic valve endocarditis is by recovery of the organism from the blood, demonstration or isolation of the organism from the prosthetic heart valve, or by persistently high Legionella titers which are extremely elevated in prosthetic valve endocarditis compared to Legionella pneumonia. We believe this is the first case reported of prosthetic valve endocarditis caused by Legionella micdadei, and the first case of Legionella prosthetic valve endocarditis with microscopic hematuria.
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PMID:Legionella micdadei prosthetic valve endocarditis. 792 21

The biochemical reactions, carbohydrate content, and 16S-rRNA sequences of Tatlockia (Legionella) maceachernii and Tatlockia micdadei strains were studied. Except for catalase activity, Tatlockia strains were relatively inert in the biochemical tests commonly used in clinical laboratories. Phenotypically, the two Tatlockia species could be distinguished from other legionellae by the presence of yersiniose A, by their inability to hydrolyze hippurate or starch, by the absence of colony or media fluorescence, and by the absence of distinct browning of tyrosine-containing medium. These two species differed from one another by the production of acetoin by T. micdadei but not by T. maceachernii. Gelatinase activity, which had been reported in T. maceachernii, was observed in only one of the four strains studied. The 16S-rRNA sequences and carbohydrate profiles of T. maceachernii and T. micdadei were essentially identical. In preparing the RNA for study, it was noted that the 23S rRNA was fragmented in all T. maceachernii strains tested, while the 23S rRNA of T. micdadei strains was intact. Among the legionellae studied, T. maceachernii was most closely related to T. micdadei.
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PMID:Properties of the genus Tatlockia. Differentiation of Tatlockia (Legionella) maceachernii and micdadei from each other and from other legionellae. 833 Feb 60

Some epidemiological and clinical characteristics of Pityriasis rosea Gibert has led us to hypothesize that this disease may be the clinical manifestation of an infection caused by legionellas. We have thus tested the sera of 36 patients ill with Pityriasis rosea and 19 controls for Legionella pneumophila serogroup 1-6 and Legionella micdadei antibodies. These, who had the same age and sex distribution as study patients, were receiving treatment for other diseases in the same ward. Also tested were 200 sera from the voluntary blood donors from the same region as study patients. Legionella micdadei antibodies were detected in 12 (33.3%) Pityriasis rosea cases and in one (5.2%) control. They were significantly more common in Pityriasis rosea cases than in either controls or voluntary blood donor population. The findings to date encourage continued research into the causative relationship between the Legionella micddadei infection and the onset of Pityriasis rosea Gibert.
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PMID:Pityriasis rosea Gibert: detection of Legionella micdadei antibodies in patients. 854 15

We describe a case of lung abscess caused by sporadic infection with Legionella micdadei in a patient with AIDS. L micdadei infection can be very difficult to diagnose because the organism stains only weakly Gram negative, requires special culture media, and is not detectable with some direct fluorescent antibody tests that are directed only at Legionella pneumophila. Since it can stain acid fast, it may be confused with mycobacteria. The abscess was successfully treated using antibiotics and percutaneous catheter drainage.
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PMID:Lung abscess caused by Legionella micdadei. 951 73

Legionella micdadei (Pittsburgh pneumonia agent) is the second most common cause of Legionella pneumonia, and occurs predominantly in immunocompromised hosts. L micdadei is the cause of nosocomial pneumonia in renal transplant recipients, but has not been described in other adult solid organ transplant recipients. This report describes the first case of L micdadei pneumonia in an adult liver transplant recipient on immunosuppressive therapy. Importantly, this case highlights the difficulties in establishing the diagnosis, as the Legionella urinary antigen is negative, and special culture conditions are required. Furthermore, this case illustrates several atypical clinical features of L micdadei pneumonia in a transplant recipient, including a community acquired mode of transmission, occurrence several years after organ transplantation, and lung abcess formation. The patient was successfully treated with limited surgical resection and quinolone antimicrobial monotherapy.
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PMID:Lung abcess complicating Legionella micdadei pneumonia in an adult liver transplant recipient: case report and review. 972 18

Quinupristin/dalfopristin displays in-vitro bacteriostatic activity against all Legionella spp. (MICs = 0.06-2 mg/L), with Legionella pneumophila usually being at least two-fold more sensitive to quinupristin/dalfopristin than Legionella bozemanii, Legionella dumoffii, Legionella gormanii and Legionella micdadei (MIC = 0.06-2 vs 1-2 mg/L, respectively). Against Legionella spp., quinupristin/dalfopristin was at least as active as erythromycin. Quinupristin/dalfopristin was active in vitro against all Mycoplasma spp. tested (MIC = 0.05-2 mg/L), with Mycoplasma hominis being less susceptible than other species. Quinupristin/dalfopristin was active against erythromycin-resistant strains of Mycoplasma fermentans and M. hominis (MIC90 = 0.5 and 2 mg/L, respectively), and doxycycline-resistant strains of Ureaplasma urealyticum (MIC90 = 1 mg/L). The in-vitro bacteriostatic activity against Mycoplasma pneumoniae and Mycoplasma genitalium (MIC90 = 0.1 and 0.05 mg/L, respectively) was similar to that of erythromycin and doxycycline. Quinupristin/dalfopristin was actively taken up by murine macrophages, and incubation of the drug (2.5 mg/L) with macrophages containing ingested Staphylococcus aureus resulted in the death of 70% of intracellular bacteria within 120 min. Intracellular concentrations of quinupristin/dalfopristin reached 50 and 30 times the extracellular concentration, respectively, showing that these compounds readily penetrate into cells. The intracellular activity of quinupristin/dalfopristin may make it suitable for use in some, presently difficult-to-treat, infections caused by intracellular organisms.
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PMID:A review of the in-vitro activity of quinupristin/dalfopristin against intracellular pathogens and mycoplasmas. 951 Oct 64

We evaluated a human monocyte cell line (HL-60) as a model for testing the intracellular activity of anti-Legionella antibiotics; 1.5 x 10(6) HL-60 cells/well were differentiated into adherent cells and infected with 1.5 x 10(7) cfu of Legionella pneumophila. The most active agents against L. pneumophila as judged by broth dilution MICs were (in order of activity) azithromycin, clarithromycin, roxithromycin, quinupristin/dalfopristin, erythromycin and dirithromycin. The most active inhibitors of L. pneumophila intracellular multiplication were (in order of activity) azithromycin, erythromycin, quinupristin/dalfopristin, roxithromycin, dirithromycin and clarithromycin. All the agents were highly active against Legionella micdadei and Legionella bozemanii when compared with L. pneumophila.
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PMID:Activity of azithromycin, clarithromycin, roxithromycin, dirithromycin, quinupristin/dalfopristin and erythromycin against Legionella species by intracellular susceptibility testing in HL-60 cells. 953 75

We investigated an outbreak of fever, most likely due to a contaminated whirlpool, among nine adults and six children residing in a summerhouse. The outbreak was characterized by a high attack rate, short incubation periods, influenza-like symptoms, and rapid recoveries, all features typical of Pontiac fever. However, the children had less-characteristic symptoms than the adults, and they did not have any sequelae. Findings on the children's chest radiographs were unremarkable, and none of the children had leukocytosis. Evidence of Legionella pneumophila infection was found in six cases: in one case by isolation of L. pneumophila serogroup 1 and detection of legionellae by PCR, and in five cases by seroconversion to the clinical isolate. Six additional cases had presumptive evidence of legionella infection, with seroconversion to Legionella micdadei antigen; a PCR assay was also positive for legionellae for one of these cases. In contrast, two adult nonusers of the whirlpool had no symptoms and no serological evidence of infection. Serological testing and cultures for other pathogens, as well as cultures of all environmental samples, were negative. This investigation demonstrates the differences between adults and children with respect to the clinical picture of Pontiac fever; furthermore, it shows that culture and PCR assay of tracheal aspirates for legionellae can be performed in a hospital setting for rapid diagnosis, although the sensitivities of these methods are low.
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PMID:An outbreak of Pontiac fever among children following use of a whirlpool. 963 66

Based on comparative sequence analysis, we have designed an oligonucleotide probe complementary to a region of 16S rRNA of Legionella pneumophila which allows the differentiation of L. pneumophila from other Legionella species without cultivation. The specificity of the new probe, LEGPNE1, was tested by in situ hybridization to a total of four serogroups of six strains of L. pneumophila, five different Legionella spp. and three nonlegionella species as reference strains. Furthermore, L. pneumophila cells could be easily distinguished from Legionella micdadei and Pseudomonas aeruginosa cells by using in situ hybridization with probes LEGPNE1, LEG705, and EUB338 after infection of the protozoan Acanthamoeba castellanii.
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PMID:Specific detection of Legionella pneumophila: construction of a new 16S rRNA-targeted oligonucleotide probe. 964 49


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