Pseudomonas aeruginosa in Otitis Externa: A Particular Variety of the Bacteria?

Sundström, Jim; Jacobson, Kerstin; Munck‐Wikland, Eva; Ringertz, Signe

doi:10.1001/archotol.1996.01890200023004

Cited by 22 publications

(15 citation statements)

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“…The authors conclude that P. aeruginosa strains causing human external otitis can be considered as having a particular phenotype. Third, strain selection may be at the level of the P. aeruginosa reservoir, i.e., strain adaptation to a water environment, as suggested by Sundström et al (29). In contrast to our results for canine ear isolates, however, Sundström et al (28) found no apparent difference in elastolysis between human external otitis, leg ulcer, and urinary tract infection isolates.…”

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confidence: 56%

“…In particular, Hamood et al (8) found that elevated exoenzyme S production from wound and urinary tract infection isolates was subsequently reduced by continuous in vitro subculturing. Second, as suggested by Sundström et al (29), a subset of P. aeruginosa strains may colonize particular infection sites: strains isolated from human external otitis exhibited distinctive biochemical profiles and pigmentation compared to those isolated from varicose ulcers and urinary tract infections. In addition, Sundström et al (28) found that the adhesion of P. aeruginosa external otitis isolates to guinea pig epithelial cells was significantly increased compared to that of isolates from leg ulcers or urinary tract infections.…”

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confidence: 93%

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Elastase Deficiency Phenotype ofPseudomonas aeruginosaCanine Otitis Externa Isolates

Petermann¹,

Doetkott

Rust³

2001

Clin Diagn Lab Immunol

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Pseudomonas aeruginosa veterinary isolates were assayed for elastase and total matrix protease activity. The elastase activity of canine ear isolates was much less than that of strain PAO1 and that of all other veterinary isolates (P < 0.0001). The results indicate that canine ear isolates have a distinct elastase phenotype.Pseudomonas aeruginosa secretes several toxins and enzymes that enhance its virulence. Among the enzymes are three wellcharacterized proteases: two elastases (LasA and LasB) and an alkaline protease (AprA) (for reviews, see references 18 and 23). Two additional proteases have been reported: LasD (21) and protease IV (6). Each of these proteases has broad substrate specificity; in addition, the proteases often act synergistically to cleave connective tissues and immune system components. Connective tissues degraded by P. aeruginosa proteases include elastin, mediated by LasA and LasB, and collagen, mediated by alkaline protease and elastases (18,23). Proteases, either individually or synergistically, mediate Hageman factor activation (11), immunoglobulin and complement degradation (5, 9, 13, 25), cytokine inactivation (22), and host protease activation (32).The contribution of P. aeruginosa proteases to the pathogenesis of acute infections is well documented (for a review, see reference 19). In particular, Tang et al. (31) found that a genetically defined, protease-deficient strain was virtually avirulent compared to the parental strain in a mouse model of acute pneumonia. Interestingly, the protease-deficient strain and the parental strain colonized similar numbers of mice in this study (31).The contribution of proteases to chronic infection is more controversial. The role of P. aeruginosa proteases in chronic infection is best studied in cystic fibrosis (for reviews, see references 3, 4, 10, 16, and 30). P. aeruginosa proteases and lasB and lasA mRNA have been detected in cystic fibrosis lung sputa (14, 27); however, other studies implicate host neutrophil elastase over bacterial elastases in cystic fibrosis lung pathology (2, 33).Reflecting the relative contribution of proteases to virulence, P. aeruginosa strains express levels of proteases that vary with isolation site and disease (34). The mucoid strains that characterize cystic fibrosis isolates are known to secrete less elastase than nonmucoid strains (20,34). Woods et al. (34) found that the frequency of protease production from cystic fibrosis isolates was significantly lower than that from isolates from other sites. In contrast, the levels of protease activity from blood isolates and elastase from acute pneumonia sputum isolates were significantly higher than levels from other infection sites (34).Most of the research regarding P. aeruginosa virulence factor production in disease has focused on human serology, isolates, or samples. In contrast, little is known about the virulence phenotypes of animal isolates. In this study, we surveyed animal intestinal and fecal P. aeruginosa isolates for protease activity. In addition, we soug...

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confidence: 93%

Elastase Deficiency Phenotype ofPseudomonas aeruginosaCanine Otitis Externa Isolates

Petermann¹,

Doetkott

Rust³

2001

Clin Diagn Lab Immunol

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“…However, we did use a bacterial strain of P. aeruginosa harvested from the EAC of a patient suffering from EO. Other investigators [13], using P. aeruginosa strains obtained from various human sources, have shown that the P. aeruginosa strain causing EO is of a specific phenotype. One may conclude that, although the host in the present study was not human, an appropriate bacterium was at least used.…”

Section: Discussionmentioning

confidence: 99%

External otitis caused by infection with Pseudomonas aeruginosa or Candida albicans cured by use of a topical group III steroid, without any antibiotics

Emgård¹,

Hellström²,

Holm³

2005

Acta Oto-Laryngologica

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“…However, to mimic the clinical situation more closely [2,14], microrganisms such as Pseudomonas aeruginosa and Candida albicans should also be included in these treatment experiments. Such a study is already in progress.…”

Section: Discussionmentioning

confidence: 99%

A topical steroid without an antibiotic cures external otitis efficiently: a study in an animal model

Emgård

Hellström

2001

European Archives of Oto-Rhino-Laryngology

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In an animal external otitis model, inflammatory reactions were evoked by mechanical stimulation of the rat ear canal skin. The rats were in four groups: group A treated with a group III steroid, betamethasone dipropionate; group B treated with hydrocortisone combined with oxytetracycline; group C treated with hydrocortisone with oxytetracycline and polymyxin B added; Group D, the controls, treated with saline. All rats were observed otomicroscopically daily during the first 7 days after treatment and then on days 10 and 20. A standardized scoring system was used to evaluate colour, swelling and effusion of the ear canal. Histological specimens were collected on days 3, 7, 10 and 20. The most rapid improvement in the ear canal status occurred in the animals treated with betamethasone dipropionate. The inflammatory reaction of the ear canal skin caused by mechanical stimulation was characterized by oedema of the stroma but few inflammatory cells were present. The surface of the epithelium towards the connective tissue layer was smooth in the group III-treated animals (group A) whereas other groups had irregularities of the basal membrane. From this study it is inferred that the group III steroid betamethasone dipropionate alone heals experimentally induced external otitis more rapidly than hydrocortisone with oxytetracycline, with or without polymyxin B. These findings should be considered in future clinical trials of external otitis.

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Pseudomonas aeruginosa in Otitis Externa: A Particular Variety of the Bacteria?

Cited by 22 publications

References 4 publications

Elastase Deficiency Phenotype ofPseudomonas aeruginosaCanine Otitis Externa Isolates

Elastase Deficiency Phenotype ofPseudomonas aeruginosaCanine Otitis Externa Isolates

External otitis caused by infection with Pseudomonas aeruginosa or Candida albicans cured by use of a topical group III steroid, without any antibiotics

A topical steroid without an antibiotic cures external otitis efficiently: a study in an animal model

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