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Query: UMLS:C0021311 (Infection)
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The virulence of Pseudomonas aeruginosa is multifactorial and caused by several extracellular enzymes and other substances. The importance of these virulence factors for the pathogenesis of human P. aeruginosa infections is dependent on the type of infection. For acute, systemic infections in immunocompromised patients, exotoxin A, alkaline protease and elastase are essential virulence factors. In localized infections (e. g., cystic fibrosis) they seem to be of minor importance, since they are neutralized by specific antibodies in immune complexes, and in the case of exotoxin A cleavage by proteinases from polymorphonuclear leukocytes occurs. The rhamnolipid of P. aeruginosa which has been detected in sputa of patients with cystic fibrosis evades the host's immune response and has to be regarded as a potential virulence factor together with the phenazine pigments, also in chronic P. aeruginosa infections.
Infection 1987
PMID:[Significance of Pseudomonas aeruginosa virulence factors for acute and chronic Pseudomonas aeruginosa infections]. 311 18

During 1985, 251 respiratory samples from 61 patients were examined at the tuscan cystic fibrosis Center (Florence), and isolated strains were tested against various antimicrobial drugs. Pseudomonas aeruginosa and Staphylococcus aureus were the predominant pathogens isolated. Infections caused by St. aureus were the commonest during the first years of life, whereas those caused by Ps. aeruginosa, occasional at early age, became chronic and the main source of infection with growth. Sensitivity testings against antibiotics confirmed that Ps. aeruginosa isolated from cystic fibrosis patients has a high percentage of resistant strains. The most active drugs were ceftazidime and aztreonam. An increased resistance to aminoglycosides was observed.
 ...
PMID:[Frequency of isolation and drug resistance of bacterial strains isolated from respiratory material in patients with cystic fibrosis]. 311 60

A microbiological analysis of 102 patients suffering from cystic fibrosis was conducted over a 22 month period. 20 microbial species with the following incidence were identified: Pseudomonas aeruginosa: 83.4%; Candida albicans: 29.4%; Staphylococcus aureus: 24.5%; Staphylococcus epidermidis: 11.8%; Haemophilus influenzae: 11.8%; Streptococcus pneumoniae; 6.9%; Pseudomonas maltophilia: 6.8%; Aspergillus fumigatus: 5.9%. Other species were present in less than 5% of the patients. In the majority of specimens with P. aeruginosa, more than one type (up to six) was detectable. These strains were identical in colony appearance, O-serotype and pyocin-type. Quantitative analysis revealed concentrations of colony-forming units of 10(7) to 10(9) for P. aeruginosa, 10(6) to 10(8) for P. maltophilia, 10(4) to 10(7) for S. aureus, 10(4) to 10(6) for S. epidermidis and 10(4) to 10(7) for C. albicans in the majority of specimens. Significant differences were observed in the time periods during which the pathogens persisted in the patients. Maximum persistence was observed for P. aeruginosa. P. maltophilia and A. fumigatus had about similar persistence rates, which were lower than those for P. aeruginosa but above those for S. aureus and H. influenzae. S. epidermidis was eliminated within shorter periods than S. aureus. C. albicans, although the second most frequent microorganism identified, showed a very low persistence rate. The microbiological analysis confirms results from other research centers (high incidence of P. aeruginosa), but reveals significant regional differences as well (Pseudomonas cepacia not detectable, higher incidence of P. maltophilia and C. albicans). This underlines the necessity for detailed qualitative and quantitative microbiological analysis of sputa from cystic fibrosis patients as a prerequisite for rational analysis of etiological, epidemiological and therapeutical aspects of cystic fibrosis.
Infection
PMID:Qualitative and quantitative microbiological analysis of sputa of 102 patients with cystic fibrosis. 311

The identification of respiratory pathogens (e. g. Haemophilus influenzae, Streptococcus pneumoniae) is impaired by the presence of large quantities of Pseudomonas aeruginosa, as is the case in the sputum specimens of cystic fibrosis patients. A procedure has been evaluated whereby the selective inhibition of the proliferation of P. aeruginosa is achieved by a broad spectrum pyocin, whereas the growth of H. influenzae is not influenced. This technique has been tested over a two year period resulting in a significantly augmented rate of identification of H. influenzae.
Infection
PMID:Selective procedure to isolate haemophilus influenzae from sputa with large quantities of Pseudomonas aeruginosa. 311 1

Pseudomonas aeruginosa is currently the major cause of morbidity and mortality in cystic fibrosis. Studies to understand why this particular organism is a problem and why host defenses fail to clear it, are beginning to provide some answers. Implicit in any working hypothesis are the prerequisites that: (i) P. aeruginosa should have a tropism for the respiratory tract; (ii) there should be a physical clearance defect; and (iii) there should be an acquired immune clearance defect. Studies from many laboratories support these contentions. This organism exhibits its tropism by adhering to tracheal cells and to tracheobronchial mucins by means of pili or the mucoid exopolysacharide of mucoid strains. The receptors on both cells and mucins contain sialic acid as the dominant sugar moiety. Many factors contribute to its persistence, chief among which is the failure of phagocytic defenses caused by microbial or host enzymes and even by mucins which inhibit the opsonophagocytosis of P. aeruginosa. Injury to the mucociliary system, again caused by microbial or host factors, is also a prominent factor in the persistence of P. aeruginosa. We hypothesize that this organism is the dominant pathogen because of the existence of receptors in the respiratory tract for it and that it persists because bacteria in stagnant mucus cannot be cleared physically or immunologically. We are doubtful that conventional vaccination approaches will yield a solution to this problem.
Infection
PMID:Why is Pseudomonas the colonizer and why does it persist? 311 2

A Pseudomonas aeruginosa strain was isolated from a patient with cystic fibrosis and was found capable of growing within polymorphonuclear leucocytes. As illustrated by electron microscopy, several mechanisms accounted for the intracellular growth: (a) Cell division occurred within the lysosomes; (b) The fusion of the phagosome with the primary lysosome was inhibited; (c) The phagosomal membrane disintegrated, and the bacteria grew within the cytosol; (d) Cytosolic material was separated from the surroundings by bacterial membranes, and subsequently the bacteria coated with host material were released from the leucocyte. The patient suffered from several severe acute pulmonary exacerbations as long as the intracellularly growing variant was detectable in his sputum. After the strain had been eliminated by antibiotic therapy the patient improved (from stage two to one).
Infection
PMID:Unusual mechanism of pathogenicity of Pseudomonas aeruginosa isolates from patients with cystic fibrosis. 311 5

Data from the literature and the authors' experiences were used to review aspects of antibiotic therapy of patients with cystic fibrosis; attention was paid to in vitro antimicrobial susceptibility tests and assessment of therapy directed against mucoid Pseudomonas aeruginosa. The heterogeneity of P. aeruginosa within single sputa with respect to antibiotic susceptibility is stressed. Quantitative viable counts of bacteria based on an analysis of homogenised sputum is recommended. The mode of in vivo growth of mucoid P. aeruginosa is discussed to explain the survival of hypersusceptible P. aeruginosa in vivo, and the clinical benefit observed in the absence of a significant reduction of the pathogen. The value of ceftazidime in the treatment of exacerbations due to Haemophilus influenzae is emphasised. The social benefits from oral administration of ciprofloxacin also emphasises that the patient's quality of life must also be considered.
Infection
PMID:Rational parameters for antibiotic therapy in patients with cystic fibrosis. 311 4

The medical records of the cystic fibrosis patients at the CF clinic in Hannover are followed up by a computer-assisted on-line documentation. An overview of clinical and bacteriological data is given. During the last few years Pseudomonas aeruginosa has taken the place of Staphylococcus aureus as the major bacterial pathogen in the respiratory tract of CF patients. The chronic colonization with P. aeruginosa for more than three years correlated with excessive under-weight and failure to grow. As an example of a longitudinal study the beneficial effect of long-term aerosol administration of tobramycin on the clinical course of chronically colonized CF patients is demonstrated.
Infection 1987
PMID:Computer-assisted documentation of the clinical course of cystic fibrosis patients. 312 18

Strains of Pseudomonas aeruginosa resistant to clinically relevant antibiotics (beta-lactams, quinolones, aminoglycosides) were detectable in sputa of cystic fibrosis patients. Correlations between in vitro susceptibility and bacteriological results in vivo were demonstrated at a quantitative level. P. aeruginosa strains susceptible prior to antibiotic therapy were observed to become resistant towards each of the compounds used for treatment. We conclude that antibiotic therapy in cystic fibrosis has to be optimized by culture specific selection of the drugs and consecutive bacteriological follow-ups.
Infection 1987
PMID:Bacteriological effects of anti-Pseudomonas aeruginosa chemotherapy in cystic fibrosis. 312 19

We reviewed the records of 23 pediatric patients who had received at least one central venous catheter during a two-year period. Nine patients had acute lymphoblastic leukemia (ALL), nine had other hematologic/oncologic diagnoses, and five had cystic fibrosis. Twenty-nine of 65 febrile episodes in 16 patients were associated with a catheter-related infection. Twenty of 40 catheters were associated with an infection over a period of 7,229 catheter days. For every 1,000 catheter days, four episodes of infections were observed. The number of infections/1,000 catheter days, the average life of a catheter (approximately equal to 180 days), and mean number of days elapsing before the first infection were not significantly different in the three diagnostic groups. Broviac catheters were used most often (24/40), followed by Quinton (9/40) and Port-a-Cath (7/40). Broviac catheters lasted twice as long (224 days, p less than 0.01) as Quinton and Port-a-Cath. Gram-positive cocci were isolated most frequently and Staphylococcus epidermidis was the most common pathogen. No consistent relationship between an absolute neutrophil count of less than 1,000/mm3 and infection with gram-positive cocci was seen. However, seven of eight episodes of gram-negative bacillary infections occurred in patients with an absolute neutrophil count of less than 1,000/m3 (p less than 0.005). Those patients who were not considered terminally ill responded well to antimicrobials. Catheter removal was necessary in only two instances.
Infection
PMID:Central venous catheter infections in pediatric patients--in a community hospital. 316 79


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