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At least 307 records · Page 17Linked to original sources
PubMed1998

Antibiotic resistance in Pseudomonas aeruginosa: an Italian survey.

In order to assess the current level of resistance to widely used antipseudomonal antibiotics in clinical isolates of Pseudomonas aeruginosa, a national survey was undertaken. Fifteen hospitals throughout Italy participated in the study. The University of Catania tested the antibiotic susceptibility of 1005 consecutive clinically significant P. aeruginosa collected from March to June 1995. Lack of susceptibility, according to NCCLS breakpoints, was at the following rates: meropenem, 9.1%; imipenem, 19.3%; ceftazidime, 13.4%; carbenicillin, 27.3%; piperacillin, 12%; ticarcillin/clavulanic acid, 22.8%; amikacin, 10.6%; and ciprofloxacin, 31.9%. About half of the isolates (44.4%) were not susceptible to at least one of the antibiotics tested.

Amikacin↗
PubMed2005

Recognition of host immune activation by Pseudomonas aeruginosa.

It is generally reasoned that lethal infections caused by opportunistic pathogens develop permissively by invading a host that is both physiologically stressed and immunologically compromised. However, an alternative hypothesis might be that opportunistic pathogens actively sense alterations in host immune function and respond by enhancing their virulence phenotype. We demonstrate that interferon-gamma binds to an outer membrane protein in Pseudomonas aeruginosa, OprF, resulting in the expression of a quorum-sensing dependent virulence determinant, the PA-I lectin. These observations provide details of the mechanisms by which prokaryotic organisms are directly signaled by immune activation in their eukaryotic host.

Adhesins, Bacterial↗
PubMed1998

Influence of the MexAB-OprM multidrug efflux system on quorum sensing in Pseudomonas aeruginosa.

Pseudomonas aeruginosa nalB mutants which hyperexpress the MexAB-OprM multidrug efflux system produce reduced levels of several extracellular virulence factors known to be regulated by quorum sensing. Such mutants also produce less acylated homoserine lactone autoinducer PAI-1, consistent with an observed reduction in lasI expression. These data suggest that PAI-1 is a substrate for MexAB-OprM, and its resulting exclusion from cells hyperexpressing MexAB-OprM limits PAI-1-dependent activation of lasI and the virulence genes.

4-Butyrolactone↗
PubMed2000

Regulation of quorum sensing by RpoS in Pseudomonas aeruginosa.

The LasR-LasI and RhlR-RhlI quorum-sensing systems are global regulators of gene expression in the opportunistic pathogen Pseudomonas aeruginosa. Previous studies suggest that the RhlR-RhlI system activates expression of rpoS. We constructed merodiploid strains of P. aeruginosa containing the native rpoS gene and an rpoS-lacZ fusion. Studies of lacZ transcription in these strains indicated that rpoS was not regulated by RhlR-RhlI. We also generated an rpoS null mutant. This rpoS mutant showed elevated levels of rhlI (but not rhlR) transcription, elevated levels of the RhlI-generated acylhomoserine lactone quorum-sensing signal, and elevated levels of RhlR-RhlI-regulated gene transcription. These findings indicate that there is a relationship between RpoS and quorum sensing, but rather than the RhlR-RhlI system influencing the expression of rpoS, it appears that RpoS regulates rhlI.

Bacterial Proteins↗
PubMed1977

Similar C-phycocyanins from two strains of thermotolerant cyanophyte Mastigocladus laminousus.

C-phycocyanin from two strains of the thermotolerant blue-green alga, Mastigocladus laminosus (NZ-DB2-m and I-30-m), that grow within different temperature ranges have been characterized with respect to aggregation, immunologic properties, subunit composition, and thermodenaturation. The critical thermal-denaturation temperature for phycocyanin from both strains of M. laminosus phycocyanin is 60 degrees C which is higher than that for mesophilic phyococyanin. Immunodiffusion studied have shown that these two strains of M. laminosus exhibit no antigenic differences and are closely related to the mesophilic Plectonema calothricoides and the thermophilic Synechococcus lividus (strains 3). Neither phenol nor alpha-naphthol has any effect on phycocyanin aggregation in these two strains of M. laminosus. There is also no enhancement of formation of large aggregates at their elevated temperature of cultivation. Furthermore, the phycocyanin of both strains of M. laminosus does not demonstrate any large amount of 19S or higher aggregates at any pH value. These observations suggest that the mode of adaptation of M. laminosus phycocyanin to high temperature is differnet from the previously encountered. It is also important to note that phycocyanin is essentially unchanged whether it is extracted from the same strain, M. laminosus (NZ-DBS-m), grown at either 50 degrees C or 37 degrees C.

Adaptation, Biological↗
PubMedDate not supplied

The mucociliary activity of the respiratory tract. I. Inhibitory effects of products of Pseudomonas aeruginosa on rabbit trachea in vitro.

Bacteriological filtrates of three strains of Pseudomonas aeruginosa were compared with respect to inhibitory effect on ciliary movements and a quantitative difference was established between them. The cilia inhibitory effect was strictly concentration-dependent and was resistant to heating. The ciliotoxic effect disappeared from filtrates after chloroform extraction. The chloroform-extracted sediment ws dissolved in physiological saline and the solution revealed an inhibitory effect on cilia. Involvement of endotoxin is not probable, since E. coli endotoxin in a high concentration was not toxic. Partially purified Pseudomonas aeruginosa phenazine pigment as well as haemolysin inhibited ciliary activity and the effect was standardized in the present experimental system.

Animals↗
PubMed1979

Epidemiological markers for Pseudomonas aeruginosa. VII. Nosocomial occurrence in urological ward. Comparison of two phage typing sets, pyocine typing, and serogrouping.

A comparison of two pyocine typing methods with serogrouping, and two phage typing sets has been made. In one instance, a contaminated bladder irrigation fluid of 0.05% silver nitrate solution caused a series of urinary tract infections. By all systems, fewer of the presentstrains were typable than usual. Among the phage typing sets the one developed by LINDBERG et al. typed only 66% whereas that selected by BERGAN typed 83%, both less than observed previously. The set of LINDBERG et al. also rendered longer pattern codes, and yielded more variable results with related strains. A set of pyocine indicator strains, selected among the strains to be typed, was more suitable than one developed elsewhere. Comparison of five different methods of epidemiological typing of Ps. aeruginosa indicated that phage typing alone is not entirely satisfactory for this species and should therefore always be combined with serogrouping.

Bacteriophage Typing↗