Mucoid Pseudomonas aeruginosa in cystic fibrosis: characterization of muc mutations in clinical isolates and analysis of clearance in a mouse model of respiratory infection
| Autor: | J. C. Boucher, Hongwei D. Yu, M H Mudd, Vojo Deretic |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Cystic Fibrosis
Molecular Sequence Data Immunology medicine.disease_cause Microbiology Cystic fibrosis Mice Bacterial Proteins Sigma factor medicine Animals Pseudomonas Infections Amino Acid Sequence Lung Polymorphism Single-Stranded Conformational Mice Inbred BALB C Mutation Base Sequence biology Tumor Necrosis Factor-alpha Pseudomonas aeruginosa Respiratory infection biology.organism_classification medicine.disease respiratory tract diseases Mice Inbred C57BL Disease Models Animal Infectious Diseases Mice Inbred DBA Urinary Tract Infections Pseudomonadales Parasitology Bacteria Research Article Pseudomonadaceae |
| Zdroj: | Scopus-Elsevier ResearcherID |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.65.9.3838-3846.1997 |
| Popis: | A distinguishing feature of Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients is their mucoid, exopolysaccharide alginate-overproducing phenotype. One mechanism of conversion to mucoidy is based on mutations in the algU mucABCD cluster, encoding the stress sigma factor AlgU and its regulators. However, conversion to mucoidy in laboratory strains can be achieved via mutations in other chromosomal sites. Here, we investigated mechanisms of the emergence of mucoid P. aeruginosa in CF by analyzing the status of mucA in a collection of mucoid P. aeruginosa isolates from 53 CF patients. This negative regulator of algU, when inactivated under laboratory conditions, causes conversion to mucoidy. The overall frequency of mucA alterations in mucoid CF isolates was 84%. Nucleotide sequence analyses revealed that the majority of the alterations caused premature termination of the mucA coding sequence. Comparison of paired nonmucoid and mucoid P. aeruginosa isolates from three CF patients indicated the presence of mucA mutations only in the mucoid strains. Interestingly, mucoid P. aeruginosa isolates from urinary tract infections also had mutations in the mucA gene. Clearance of CF isolates from the murine lung was investigated in an aerosol infection model with C57BL/6J, BALB/c, and DBA/2NHsd mice. Two CF strains, selected for further study based on the dependence of their alginate production on the concentration of salt in the medium, were used to examine the effects of mucoidy on pulmonary clearance. Statistically significant improvement in recovery from the murine lung of viable mucoid P. aeruginosa cells relative to the nonmucoid bacteria was observed in the majority of mouse strains tested. Collectively, the results reported here suggest that mucA is most likely the preferential site for conversion to mucoidy in CF and that alginate overproduction in mucA-mutant P. aeruginosa improves its resistance to the innate clearance mechanisms in the lung. |
| Databáze: | OpenAIRE |
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