UK-18892, a new aminoglycoside: an in vitro study.
UK-18892 is a new aminoglycoside antibiotic, a derivative of kanamycin A structurally related to amikacin. It was found to be active against a wide range of pathogenic bacteria, including many gentamicin-resistant strains. The spectrum and degree of activity of UK-18892 were similar to those of amikacin, and differences were relatively minor. UK-18892 was about twice as active as amikacin against gentamicin-susceptible strains of Pseudomonas aeruginosa. Both amikacin and UK-18892 were equally active against gentamicin-resistant strains of P. aeruginosa. There were no appreciable differences in the activity of UK-18892 and amikacin against Enterobacteriaceae and Staphylococcus aureus. Cross-resistance between these two antimicrobials was also apparent. (+info)
Modified peptidoglycan transpeptidase activity in a carbenicillin-resistant mutant of Pseudomonas aeruginosa 18s.
A carbenicillin-resistant mutant of Pseudomonas aeruginosa 18s was found to possess peptidoglycan transpeptidase activity significantly more resistant to inhibition by benzyl penicillin, ampicillin, carbenicillin, and cephaloridine than that of the parent strain. The mutant was more resistant than the parent strain to all of the beta-lactam antibiotics tested, and 50% inhibition values for these compounds against membrane-bound model transpeptidase activity paralleled this increase. The resistance of the mutant to kanamycin, streptomycin, and chloramphenicol was unchanged. (+info)
Improved medium for recovery and enumeration of Pseudomonas aeruginosa from water using membrane filters.
A modified mPA medium, designated mPA-C, was shown to recover Pseudomonas aeruginosa from a variety of water sources with results comparable to those with mPA-B and within the confidence limits of a most-probable-number technique. Enumeration of P. aeruginosa on mPA-C was possible after only 24 h of incubation at 41.5 degrees C, compared with 72 h of incubation required for mPA-B and 96 h of incubation for a presumptive most probable number. (+info)
Automated food microbiology: potential for the hydrophobic grid-membrane filter.
Bacterial counts obtained on hydrophobic grid-membrane filters were comparable to conventional plate counts for Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus in homogenates from a range of foods. The wide numerical operating range of the hydrophobic grid-membrane filters allowed sequential diluting to be reduced or even eliminated, making them attractive as components in automated systems of analysis. Food debris could be rinsed completely from the unincubated hydrophobic grid-membrane filter surface without affecting the subsequent count, thus eliminating the possibility of counting food particles, a common source of error in electronic counting systems. (+info)
Denitrifying Pseudomonas aeruginosa: some parameters of growth and active transport.
Optimal cell yield of Pseudomonas aeruginosa grown under denitrifying conditions was obtained with 100 mM nitrate as the terminal electron acceptor, irrespective of the medium used. Nitrite as the terminal electron acceptor supported poor denitrifying growth when concentrations of less than 15 mM, but not higher, were used, apparently owing to toxicity exerted by nitrite. Nitrite accumulated in the medium during early exponential phase when nitrate was the terminal electron acceptor and then decreased to extinction before midexponential phase. The maximal rate of glucose and gluconate transport was supported by 1 mM nitrate or nitrite as the terminal electron acceptor under anaerobic conditions. The transport rate was greater with nitrate than with nitrite as the terminal electron acceptor, but the greatest transport rate was observed under aerobic conditions with oxygen as the terminal electron acceptor. When P. aeruginosa was inoculated into a denitrifying environment, nitrate reductase was detected after 3 h of incubation, nitrite reductase was detected after another 4 h of incubation, and maximal nitrate and nitrite reductase activities peaked together during midexponential phase. The latter coincided with maximal glucose transport activity. (+info)
The Pseudomonas aeruginosa secretory product pyocyanin inactivates alpha1 protease inhibitor: implications for the pathogenesis of cystic fibrosis lung disease.
Alpha1 Protease inhibitor (alpha1PI) modulates serine protease activity in the lung. Reactive oxygen species inactivate alpha1PI, and this process has been implicated in the pathogenesis of a variety of forms of lung injury. An imbalance of protease-antiprotease activity is also detected in the airways of patients with cystic fibrosis-associated lung disease who are infected with Pseudomonas aeruginosa. P. aeruginosa secretes pyocyanin, which, through its ability to redox cycle, induces cells to generate reactive oxygen species. We tested the hypothesis that redox cycling of pyocyanin could lead to inactivation of alpha1PI. When alpha1PI was exposed to NADH and pyocyanin, a combination that results in superoxide production, alpha1PI lost its ability to form an inhibitory complex with both porcine pancreatic elastase (PPE) and trypsin. Similarly, addition of pyocyanin to cultures of human airway epithelial cells to which alpha1PI was also added resulted in a loss of the ability of alpha1PI to form a complex with PPE or trypsin. Neither superoxide dismutase, catalase, nor dimethylthiourea nor depletion of the media of O2 to prevent formation of reactive oxygen species blocked pyocyanin-mediated inactivation of alpha1PI. These data raise the possibility that a direct interaction between reduced pyocyanin and alpha1PI is involved in the process. Consistent with this possibility, pretreatment of alpha1PI with the reducing agent beta-mercaptoethanol also inhibited binding of trypsin to alpha1PI. These data suggest that pyocyanin could contribute to lung injury in the P. aeruginosa-infected airway of cystic fibrosis patients by decreasing the ability of alpha1PI to control the local activity of serine proteases. (+info)
Safety and immunogenicity of a Pseudomonas aeruginosa hybrid outer membrane protein F-I vaccine in human volunteers.
A hybrid protein [Met-Ala-(His)6OprF190-342-OprI21-83] consisting of the mature outer membrane protein I (OprI) and amino acids 190 to 342 of OprF of Pseudomonas aeruginosa was expressed in Escherichia coli and purified by Ni2+ chelate-affinity chromatography. After safety and pyrogenicity evaluations in animals, four groups of eight adult human volunteers were vaccinated intramuscularly three times at 4-week intervals and revaccinated 6 months later with either 500, 100, 50, or 20 microg of OprF-OprI adsorbed onto A1(OH)3. All vaccinations were well tolerated. After the first vaccination, a significant rise of antibody titers against P. aeruginosa OprF and OprI was measured in volunteers receiving the 100- or the 500-microg dose. After the second vaccination, significant antibody titers were measured for all groups. Elevated antibody titers against OprF and OprI could still be measured 6 months after the third vaccination. The capacity of the elicited antibodies to promote complement binding and opsonization could be demonstrated by a C1q-binding assay and by the in vitro opsonophagocytic uptake of P. aeruginosa bacteria. These data support the continued development of an OprF-OprI vaccine for use in humans. (+info)
Lipopolysaccharide (LPS) from Burkholderia cepacia is more active than LPS from Pseudomonas aeruginosa and Stenotrophomonas maltophilia in stimulating tumor necrosis factor alpha from human monocytes.
Whole cells and lipopolysaccharides (LPSs) extracted from Burkholderia cepacia, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Escherichia coli were compared in their ability to stimulate tumor necrosis factor alpha (TNF-alpha) from the human monocyte cell line MonoMac-6. B. cepacia LPS, on a weight-for-weight basis, was found to have TNF-alpha-inducing activity similar to that of LPS from E. coli, which was approximately four- and eightfold greater than the activity of LPSs from P. aeruginosa and S. maltophilia, respectively. The LPS-stimulated TNF-alpha production from monocytes was found to be CD14 dependent. These results suggest that B. cepacia LPS might play a role in the pathogenesis of inflammatory lung disease in cystic fibrosis, and in some patients it might be responsible, at least in part, for the sepsis-like cepacia syndrome. (+info)