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PubMed2001

Small molecular weight secretory factors from Pseudomonas aeruginosa have opposite effects on IL-8 and RANTES expression by human airway epithelial cells.

Pseudomonas aeruginosa is an opportunistic human pathogen that causes both an acute lung disease in patients with hospital-acquired pneumonia and a chronic lung disease in individuals with cystic fibrosis. Many of the pathophysiologic effects of P. aeruginosa infection are due to factors secreted by the bacterium. Conditioned media from cultures of P. aeruginosa increased interleukin-8 expression and decreased regulated on activation, normal T cells expressed and secreted (RANTES) expression by human airway epithelial cells. Both of these activities were present in heat-treated, protease-treated, small molecular weight fractions. The activities were not inhibited by polymyxin B and were not extracted into ethyl acetate, suggesting that they were not due to endotoxin or autoinducer. Conversely, results from chloroform extractions and studies with a phenazine-minus mutant suggested that the blue pigment pyocyanin contributes to these activities when present. In addition to the effects of small molecular weight factors on cytokine expression, proteases in bacterial-conditioned media further decreased levels of RANTES. By altering expression, release, and/or activity of inflammatory cytokines, secretory factors from P. aeruginosa could disrupt the delicate balance that constitutes the immune response to bacterial infection and thus could contribute to the lung damage that occurs in P. aeruginosa-infected airways.

Cell Line↗

PubMed1992

Release of mucus glycoconjugates by Pseudomonas aeruginosa rhamnolipid into feline trachea in vivo and human bronchus in vitro.

Pseudomonas aeruginosa colonizes the lower respiratory tracts of patients with severe bronchiectasis, including cystic fibrosis, a condition associated with increased airway mucus output. We have shown that an extract containing chloroform-soluble extracellular products of P. aeruginosa releases glycoconjugates into the cat trachea in vivo. This activity was not related to pyocyanin, a major component of the extract, but was associated with the rhamnolipids. Purified monorhamnolipid (100 micrograms/ml) released radiolabeled and periodic acid-Schiff (PAS)-reactive glycoconjugates (delta 3H = +490 +/- 70%, delta 35S = +170 +/- 40%, delta PAS = +8.6 +/- 1.7 micrograms/min; n = 6, P less than 0.02 for each). Dirhamnolipid (200 micrograms/ml) was also effective (delta 3H = +640 +/- 70%, delta 35S = +130 +/- 20%, delta PAS = +9.3 +/- 1.5 micrograms/min; n = 6, P less than 0.02 for each). Monorhamnolipid (100 micrograms/ml) also released 35S-labeled and PAS-reactive glycoconjugates from human bronchial tissue in vitro (delta 35S = +189 +/- 47%, delta PAS = +26.3 +/- 8.5 micrograms/min; n = 7, P less than 0.001 versus control tissues in which no stimulus was given). The cat tracheal glycoconjugates released by the rhamnolipids differed from those released by pilocarpine 50 microM, in having a higher 3H:35S ratio (P less than 0.001). After gel chromatography on a Sepharose CL-4B column, the void volume fractions of the glycoconjugates also had different profiles in a cesium chloride density gradient. Those released by rhamnolipid banded at 1.62 g/ml, while those released by pilocarpine banded mainly at 1.50 g/ml, with some of the higher density material also present.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2005

Effects of azithromycin on clinical isolates of Pseudomonas aeruginosa from cystic fibrosis patients.

There is considerable interest in the use of azithromycin for the treatment of lung disease in patients with cystic fibrosis (CF). Although its mechanism of action as an inhibitor of bacterial protein synthesis has been well-established, it is less clear how azithromycin ameliorates the lung disease associated with Pseudomonas aeruginosa, which is considered to be resistant to the drug. We tested the effects of azithromycin on clinical isolates (CIs) from CF patients and compared them with laboratory reference strains to establish how this drug might interfere with the production of bacterial virulence factors that are relevant to the pathogenesis of airway disease in CF patients. Azithromycin inhibited P aeruginosa PAO1 protein synthesis by 80%, inhibiting bacterial growth and the expression of immunostimulatory exoproducts such as pyocyanin, as well as the gene products necessary for biofilm formation. In contrast, the effects of azithromycin on CIs of P aeruginosa were much more variable, due in large part to their slow growth and limited exoproduct expression. Culture supernatants for two of three clinical strains induced appreciable CXCL8 expression from cultured epithelial cells. Azithromycin treatment of the organisms inhibited 65 to 70% of this induction; azithromycin had no direct effect on the ability of either normal cells or CF epithelial cells to produce CXCL8. Azithromycin does decrease the P aeruginosa synthesis of immunostimulatory exoproducts and is likely to be most effective against planktonic, actively growing bacteria. This effect is less predictable against CIs than the prototypic strain PAO1.

Anti-Bacterial Agents↗

PubMed1975

[In vitro examination on antibacterial activities of broad-spectrum antibiotics against gram-negative clinical isolates (author's transl)].

In vitro studies were undertaken on clinically isolated strains of various bacteria to examine the antibacterial activity of ampicillin (AB-PC), carbenicillin (CB-PC), sulbenicillin (SB-PC) cephalothin (CET), cefazolin (CEZ) and gentamicin (GM). Fifty three % of Escherichia coli strains 53.3% of Citrobacter sp., 80% of Proteus mirabilis, 42.9% of Morganella and 80% of Bacteroides sp. were susceptible (MIC being not higher than 12.5 mug/ml) to AB-PC. The eight other species were not so susceptible to this penicillin. CB-PC and SB-PC were almost as effective as AB-PC against Escherichia coli and Citrobacter sp. They were less active against Klebsiella sp., but more active against Enterobacter sp., Serratia sp., indole-positive Proteus group and Pseudomonas sp. than AB-PC, SB-PC was more effective than CB-PC against Pseudomonas sp. The strains of Pseudomonas sp. which were resistant to higher concentrations of CB-PC and SB-PC were pyocyanine-negative strains. All strains (100%) of Escherichia coli, Klebsiella sp. and Citrobacter sp. were susceptible to CET and CEZ, while none of Enterobacter sp. , Serratia sp., Proteus vulgaris. Morganella, Rettgerella, Providencia and Pseudomonas sp. were susceptible to these cephalosporins. The MICs of CET and CEZ against Bacteroides sp. were moderately low. Some strains of Providencia and Alkaligenes sp. were resistant of GM but the other 10 species were not resistant to this antibiotic, though it showed comparatively high MICs against Bacteroides sp. When seen from the MIC distribution of each antibiotic, there was a tendency that the strains isolated from the pus were more resistant than those isolated from the other sources (urine, sputum and bile).

Ampicillin↗

PubMed2001

Interspecies biofilms of Pseudomonas aeruginosa and Burkholderia cepacia.

The leading cause of morbidity and mortality in cystic fibrosis (CF) continues to be lung infections with Pseudomonas aeruginosa biofilms. Co-colonization of the lungs with P aeruginosa and Burkholderia cepacia can result in more severe pulmonary disease than P. aeruginosa alone. The interactions between P. aeruginosa biofilms and B. cepacia are not yet understood; one possible association being that mixed species biofilm formation may be part of the interspecies relationship. Using the Calgary Biofilm Device (CBD), members of all genomovars of the B. cepacia complex were shown to form biofilms, including those isolated from CF lungs. Mixed species biofilm formation between CF isolates of P. aeruginosa and B. cepacia was readily achieved using the CBD. Oxidation-fermentation lactose agar was adapted as a differential agar to monitor mixed biofilm composition. Scanning electron micrographs of the biofilms demonstrated that both species readily integrated in close association in the biofilm structure. Pseudomonas aeruginosa laboratory strain PAO1, however, inhibited mixed biofilm formation of both CF isolates and environmental strains of the B. cepacia complex. Characterization of the soluble inhibitor suggested pyocyanin as the active compound.

Biofilms↗

PubMed2002

Incidence of Pseudomonas aeruginosa in recreational and hydrotherapy pools.

Pseudomonas aeruginosa remains an important agent of opportunistic infection in patients, particularly those with respiratory complications and burns. One natural niche of this organism is water and water-associated facilities, hence the aim of this study was to examine specimens from recreational and hydrotherapy pools in Northern Ireland over a two-year period. Water specimens (n = 3,510) were obtained from three amenity categories, namely, 13 hydrotherapy pools (specimen number [n] = 323), 51 Jacuzzis/spas (n = 1,397) and 68 swimming pools (n = 1,790). Specimens (100 ml) were filtered through a cellulose acetate (0.45 micron pore size) gridded filter and the membrane was placed on Pseudomonas CFC agar (Oxoid CM559 + SR103) and incubated at 37 degrees C for 48 +/- 2 h. Colonies that clearly showed pyocyanin production or met other identification criteria were considered P. aeruginosa. Of the amenities examined 4/13 hydrotherapy pools (30.8%), 37/51 Jacuzzis/spas (72.5%) and 26/68 swimming pools (38.2%) were positive for P. aeruginosa. The most heavily contaminated amenity category was the Jacuzzi/spa, where 34.7% and 12% of private and public sites respectively were positive for P. aeruginosa at a level of greater than 1,000 cfu 100 ml-1. Approximately twice as many samples were positive in private Jacuzzis/spas compared to publicly operated facilities. There was a similar trend with respect to public and private hydrotherapy pools, though bacterial counts did not exceed 1,000 cfu 100 ml-1. Recreational and therapeutic amenities involving the use of water may be a potential source of P. aeruginosa for susceptible patient groups, including patients with cystic fibrosis and bronchiectasis. This may vary depending on amenity type and public/private ownership of such amenities.

Humans↗

PubMed1990

Kinetics of haemolytic activity in Proteus strains.

Proteus species produces toxins and constitutes a causative agent of some chronic and recurrent infections. For the study of haemolytic activity and the production and inhibition kinetics, a total of 140 local isolates were diagnosed and examined by the general biochemical methods, and their ability of haemolysis were tested by both direct and indirect methods utilizing the enrichment procedure for all strains. Two antibiotics, erythromycin and keflex (cephalexin), were tested for the study of haemolysis inhibition and its kinetisc. Rof further study, examples of Proteus species were selected; the new approach was based on mixing procedure between P. aeruginosa (also pyocyanine) and Proteus species for inhibition of haemolytic activity. Spectrophotometric analysis were used parallel to these studies to support quantitatively the observed results as all samples show an absorption centre at 542 +/- 1 nm. Results of such analysis of haemolytic activity and inhibition kinetics are presented.

Cephalexin↗

PubMed1988

Bacterial and host factors affecting Pseudomonas aeruginosa colonization versus bacteremia in granulocytopenic patients.

In order to evaluate bacterial factors which might predispose to P. aeruginosa colonization or bacteremia in the granulocytopenic patient, 132 isolates recovered from 44 oncology patients were evaluated for antigenic serotype, iron correctable sensitivity to pooled human serum, antibiotic susceptibility, production of lecithinase, elastase, protease, gelatinase, pyocyanin and pyoverdin. Similarly, potential host factors, primarily total iron binding capacity, were evaluated in a subpopulation of acute leukemia patients composed of 13 control patients without P. aeruginosa cultured during their hospital course, 11 colonization only patients and 15 P. aeruginosa bacteremia patients. No significant differences were observed between strains recovered from bacteremia vs. colonization patients for extracellular enzyme activity, pigment production, serum sensitivity and antigenic serotype. Significant differences were observed between bacteremia and colonizing strains for antibiotic susceptibility to ticarcillin, 40% vs. 76% (P less than 0.002); piperacillin, 44% vs. 86% (P less than 0.006); and cefsulodin, 60% vs. 90% (P less than 0.02). Of the host factors evaluated in the acute leukemia patients, significant differences were observed between the TIBC nadir of control patients and both colonization patients (P less than 0.0002) and bacteremia patients (P less than 0.0004). P. aeruginosa bacteremia was associated with the temporal occurrence of TIBC nadir and the detection of the organism. These data suggest a possible role for beta-lactam antibiotic resistance and host iron binding capacity as determinants and possible predictors of P. aeruginosa sepsis in the granulocytopenic patient.

Adult↗

PubMed1977

[Virulence of human and environmental strains of "pseudomonas aeruginosa" in mice (author's transl)].

The virulence of 21 clinical isolates and 10 environmental strains of Pseudomonas aeruginosa was studied by intraperitoneal challenge in mice. The LD50 values of human strains ranged from 10(7),(0) to 10(8),(5) viable cells per mouse (average: 10(7),(7)(2)). The LD50 of environmental strains ranged from 10(7),(2) to 10(8),(1) (average: 10(7),(59)). These results are not significantly different. Experimental virulence for mice of P. aeruginosa strains found in hospital environment allows no prediction on their level of pathogenicity for in-patients. Furthermore, this study proved no relationship between letal effect of P. aeruginosa for mice and following characters of strains: O serogroup, untypability and productivity of specific pigments, pyocyanin and pyorubrin.

Animals↗

PubMed1983

[Evaluation of the GNF computer-coding system for the identification of non-fermentative Gram-negative bacilli].

In order to evaluate the effectiveness of the GNF computer-coding system for the identification of glucose non-fermenting gram-negative bacilli, we employed 406 strains of bacteria including 367 clinical isolates and 39 standard strains for testing. These strains were inoculated into the following eleven conventional biochemical test media: Triple Sugar Iron Agar, Simmon's Citrate Agar, Christensen's Urea Agar, Sulfide-Indole-Motility Medium, Semisolid Voges-Proskauer Test Medium, Moeller's Ornithine Decarboxylase Test Medium, Pyocyanin Test Medium, Oxidation/Fermentation (O/F) Glucose, O/F Fructose, Nitrate Broth, Moeller's Arginine Dihydrolase Test Medium. The results of these tests plus those from the hanging drop motility test and the oxidase test were converted into bacterial code number and then checked with the GNF computer-coding system. It was found that the first preference of agreement was 75.6%, second 15.3%, third 5.9%, and fourth or more 3.2%. In regard to the speed of bacterial identification by using the GNF system and information from hemolysis pattern and flagella stain, it was indicated that 84.7% would be correctly identified within 36-48 hours after isolation. If more confirmational tests were employed, the accurate identification rate would reach to 98.7% after 4 days of isolation. In addition, the use of the GNF computer-coding system can standardize identification procedures, shorten the identification period, and save cost in terms of materials supply, inoculation time, media preparation and media-storing space. Therefore, we conclude that the GNF computer-coding system is an effective tool in the identification of the glucose non-fermenting gram-negative bacilli.

Computers↗

PubMedDate not supplied

[Pseudomonas aeruginosa III. Identification of strains isolated from blue foxes (Alopex lagopus) in a Danish fur farm (author's transl)].

The technique of determining bacterial strains as Ps. aeruginosa is described. It was attempted to base this technique upon well-defined commercial preparations, so as to afford a possibility for comparative studies. 261 strains presumed to be Ps. aeruginosa were isolated from sick and healthy blue foxes and their watering troughs. 244 of the strains could be subjected to detailed bacteriological study (Table I a, b, c, fig. 1) in addition to the demonstration of pigment (pyocyanin and fluorescin). All 244 proved to be Ps. aeruginosa. Among them 10 non-pigment-producing strains were characterized as "atypical" Ps. aeruginosa strains. The determination of the genus was supported by the results of the sensitivity tests (Table II).

Animals↗

PubMed1997

A study of purified pyorubrin produced by local Pseudomonas aeruginosa.

A study of more than one thousand strains of local P. aeruginosa was performed. These include the strains production of various pigments, methods of extraction and purification, the pigments activity and characteristics. Lately, we have reported a comprehensive study about the purified blue pyocyanine pigment. This paper displays a parallel study of a number of physical and chemical properties of the purified pink pigment, the pyorubrin, that is produced by our local collection of P. aeruginosa strains. This characteristics is useful for production of an active pigment purpose and is necessary in the pigment use as antibiotic, in addition of importance in developing the methods of strains identification. Such studies are important due to the biological significance of pyorubrin activity against other bacteria and in comparison with some known antibiotics; stability tests and MIC (minimum inhibitory concentration) measurements indicate that found isolates were of animal and food origin mainly.

Anti-Bacterial Agents↗

PubMed1994

A novel membrane bioreactor for microbial growth.

A novel membrane bioreactor, previously assessed for its gas transfer characteristics, was used in various size and membrane configurations for the growth of the strictly aerobic bacterium Pseudomonas aeruginosa. The bioreactor was found to readily support growth, and the initial growth rates showed the previously demonstrated enhanced effect in gas O2 mass transfer of the dimpled membrane bioreactor over flat membrane bioreactors. The production of a secondary metabolite by a Pseudomonas sp. following growth was demonstrated, as was the biotransformation of a nitrile by Nocardia rhodochrous with the removal of the biotransformation products across a membrane. The potential of the bioreactor, in terms of other applications in the field of biotechnology, is discussed.

Acrylonitrile↗

PubMed2001

Extracellular electron transfer.

Results from several laboratories indicate that extracellular electron transfer may be a general mechanism whereby microoorganisms generate energy for cell growth and/or maintenance. Specifically, bacteria can use redox-active organic small molecules, generated outside or inside the cells, to shuttle electrons between reduced and oxidized compounds. Electron shuttling has now been reported for several different bacterial species, and exchanges of shuttling compounds may even syntrophically link diverse organisms in nature. Biofilm systems in both geological and clinical settings are likely to be important environments for metabolisms that employ extracellular electron transfer. Both structural and functional analyses suggest that electron shuttles and some virulence factors may be related to one another.

Bacteria↗

PubMed1979