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Synthesis of thymine and alpha-putrescinylthymine in bacteriophage phi W-14-infected Pseudomonas acidovorans.

Host DNA synthesis stopped about 10 min after the infection of Pseudomonas acidovorans with bacteriophage phi W-14, but host DNA was not degraded to acid-soluble fragments. The synthesis of host but not of phage DNA was inhibited by 5-fluorodeoxyuridine. The nucleotide pools of infected cells did not contain dTTP, and infection resulted in the appearance of dTTPase activity. Although ornithine labeled the alpha-putrescinylthymine residues of phi W-14 DNA, ornithine-labeled nucleotides were not detected in infected cells. A new deoxynucleoside triphosphate did appear in infected cells, but it was not labeled by ornithine. It is concluded that the thymine and alpha-putrescinylthymine in phi W-14 DNA are synthesized at the polynucleotide level.

Bacteriophages↗

The Pseudomonas aeruginosa genome: how do we use it to develop strategies for the treatment of patients with cystic fibrosis and Pseudomonas infections?

In the 2 years since the complete sequence of Pseudomonas aeruginosa strain PAO1 was published, at least 200 papers have been published describing research that made use of the PAO1 genome sequence. Some of this research included genome-wide studies of gene expression or the effect of mutation on bacterial functions such as biofilm formation; this type of global analysis would not have been possible without the availability of the sequence. As a result of these and other, more traditional, research studies, there is a wealth of new knowledge about the physiology of this pathogen. This raises the possibility of new strategies for the treatment of patients with P. aeruginosa infection, either by novel antibiotics or by drugs targeting bacterial functions essential for survival and virulence in the human host.

Biofilms↗

Interaction of purulent material with antibiotics used to treat Pseudomonas infections.

To define factors contributing to the adverse prognosis of patients with gram-negative bacillemia and abscess formation, we studied the interaction between polymyxin B, colistin sulfate, gentamicin, or carbenicillin with purulent material. Carbenicillin activity was not significantly altered by incubation with pus. Equal volumes of antibiotic and purulent sediment decreased the effective concentration of polymyxin B, colistin sulfate, or gentamicin from 100 mug/ml to 3 to 6 mug/ml. One milliliter of purulent sediment bound more than 700 mug of gentamicin and 1,500 mug of polymyxin B or colistin sulfate. This effect occurred rapidly, proceeded at 4 and 37 C, was stable for 24 to 48 h, and was altered, but not abolished, by varying the pH of the solution. Antibiotic activity could be removed from pus by high concentrations of protamine sulfate, heparin, sodium chloride, or potassium chloride, suggesting binding rather than inactivation.

Abscess↗

Ultrastructural observations in an alcoholic patient with post-surgical pseudomonas infection.

Gram negative bacteria were seen in the peripheral blood and within the neutrophils of a patient with bacteremic shock secondary to Pseudomonas aeruginosa infection. By electron microscopy, bacteria were present either in vacuoles or in the cytoplasm of neutrophils. When seen in the cytoplasm, they were surrounded by amorphous material which most probably represented fused lysosomal granules. In both cases, the microorganisms appeared morphologically normal. The presumption is that there was a pre-existing defect of neutrophilic lysosomal formation or function. These findings indicate the importance of studying neutrophil morphology and function in patients with persistent infections.

Adult↗

Safety and efficacy of colistin in Acinetobacter and Pseudomonas infections: a prospective cohort study.

OBJECTIVE: To assess renal dysfunction and outcome in patients treated exclusively with colistin vs. other antibiotics. DESIGN AND SETTING: Prospective cohort study in a mixed ICU in a university-affiliated hospital. PATIENTS: 185 patients infected with Acinetobacter baumannii and Pseudomonas aeruginosa after an ICU stay longer than 48 h: 55 in the colistin group and 130 in the noncolistin group, similar in age, APACHE II, medical status, and SOFA score. MEASUREMENTS AND RESULTS: We recorded data on epidemiology and severity of illness, site of infection, renal function before and after treatment, clinical cure, and mortality. Clinical cure was defined as simultaneous normalization of central temperature (< or = 38 degrees), leukocyte count (< or = 10,000/mm3), and PaO2/FIO2 ratio (>187). Before treatment creatinine was 0.9+/-0.2 in the colistin group and 0.9+/-0.1 in the noncolistin group; after treatment the value was 1.0+/-0.3 in both groups. The most frequent infection was ventilator-associated pneumonia: 53% vs. 66% in colistin and noncolistin groups, respectively, Acinetobacter was the cause in 65% and 60% and Pseudomonas in 35% and 53%. In the noncolistin group 81% of patients were treated with carbapenems. Inadequate empirical antimicrobial treatment was more frequent in the colistin group (100% vs. 8%), but there were no differences in the frequency of clinical cure on day 6 of treatment (15% and 17%) or in mortality (29% and 24%). CONCLUSIONS: Colistin appears to be as safe and as effective as other antimicrobials for treatment of sepsis caused by Acinetobacter and Pseudomonas in critically ill patients.

APACHE↗

Therapy of experimental pseudomonas infections with a nonreplicating genetically modified phage.

Bacteriophage therapy of bacterial infections has received renewed attention owing to the increasing prevalence of antibiotic-resistant pathogens. A side effect of many antibiotics as well as of phage therapy with lytic phage is the release of cell wall components, e.g., endotoxins of gram-negative bacteria, which mediate the general pathological aspects of septicemia. Here we explored an alternative strategy by using genetically engineered nonreplicating, nonlytic phage to combat an experimental Pseudomonas aeruginosa infection. An export protein gene of the P. aeruginosa filamentous phage Pf3 was replaced with a restriction endonuclease gene. This rendered the Pf3 variant (Pf3R) nonreplicative and concomitantly prevented the release of the therapeutic agent from the target cell. The Pf3R phage efficiently killed a wild-type host in vitro, while endotoxin release was kept to a minimum. Treatment of P. aeruginosa infections of mice with Pf3R or with a replicating lytic phage resulted in comparable survival rates upon challenge with a minimal lethal dose of 3. However, the survival rate after phage therapy with Pf3R was significantly higher than that with the lytic phage upon challenge with a minimal lethal dose of 5. This higher survival rate correlated with a reduced inflammatory response elicited by Pf3R treatment relative to that with the lytic phage. Therefore, this study suggests that the increased survival rate of Pf3R-treated mice could result from reduced endotoxin release. Thus, the use of a nonreplicating modified phage for the delivery of genes encoding proteins toxic to bacterial pathogens may open up a new avenue in antimicrobial therapy.

Animals↗

The epidemiology of nosocomial epidemic Pseudomonas cepacia infections.

Pseudomonas cepacia has occasionally been identified as an epidemic and endemic nosocomial pathogen. In outbreaks, usually one clinical site predominates but many may be involved. Detailed investigations have usually implicated a contaminated liquid reservoir or moist environmental surface as the source. Liquid sources have included a number of different classes of antiseptics and disinfectants such as quaternary ammonium chlorides, biguanides, hexachlorophene, and iodophors. Environmental and patient isolates have had multiply resistant antimicrobial susceptibility patterns. The clinical distinction between colonization and infection may be difficult and may challenge the skills of the clinician. Expenditure of resources needed to solve epidemics is justified in view of the potential virulence of this organism and the high likelihood that an unrecognized but easily eliminated liquid environmental reservoir may be the source.

Cross Infection↗

[Effect of erythromycin on neutrophil function in chronic respiratory tract diseases with Pseudomonas infection].

The "low dose and long term" erythromycin (EM) therapy has been reported as effective (or useful) in chronic respiratory tract disease with pseudomonas (P.) infection including diffuse panbronchiolitis (DPB), however the mode of action is still obscure. Therefore in this study we have examined the effect of EM on the interaction between P. aeruginosa and human polymorphonuclear leukocyte (PMN) in vitro. The efficiency of intracellular killing and the ability of superoxide production were employed to evaluate the PMN functions. For the first step, the following results were obtained; 1) Pretreatment of PMN with 20 micrograms/ml EM did not affect the killing ability of PMNs against opsonized P. aeruginosa of standard and clinical isolate from DPB patient. 2) Superoxide production from PMNs was observed by phagocytosis of P. aeruginosa in the presence of serum. This was not affected by exposure of PMNs to 20 micrograms/ml EM even with increased ratios of bacteria to cells. 3) Pretreatment of P. aeruginosa with 20 micrograms/ml EM before opsonization enhanced the killing ability of PMNs in both standard and clinical isolate. 4) Pretreatment of P. aeruginosa with 20 micrograms/ml EM resulted in no effect on superoxide production from PMNs by phagocytosis of the bacteria. These results indicate that EM may modify a certain step of the interaction between bacteria and intracellular host defence mechanisms. Therefore for the second step, we have investigated the susceptibility of EM-exposed bacteria to killing by the cell free (glucose oxidase-glucose) system, which will detect the enzymatic generation of hydrogen peroxide (H2O2). The following results were observed; 1) EM-exposed bacteria was more susceptible to killing than control bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchiolitis↗

Pseudomonas infections of the foot after puncture wounds.

Evaluation of ten children with Pseudomonas bone and joint infections resulting from puncture wounds of the foot identified a definite pattern to sequelae. The longer the symptoms were present before adequate treatment was instituted the greater was the risk of bone and joint destruction along with the development of chronic osteomyelitis. The syndrome usually does not produce systemic signs, but the patterns is characteristic and should be considered after any puncture wound of the foot in which the symptoms worsen instead of improving with time.

Aminoglycosides↗