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Auxotrophy of Pseudomonas aeruginosa in cystic fibrosis
R F Taylor1, M E Hodson, T L Pitt
1Royal Brompton and National Heart Hospital, London, UK.
Abstract:
Seventy-four of 403 (18.4%) sputum isolates of Pseudomonas aeruginosa from 49 of 136 (36.0%) adults with cystic fibrosis (CF) were auxotrophic mutants. Two of 11 (18.2%) isolates of P. aeruginosa taken from patients with non-CF bronchiectasis were also auxotrophic. All 99 strains taken from non-bronchiectatic sources were prototrophic. Forty-six of 55 (83.6%) CF auxotrophs required one or more of 36 growth factors tested; the requirements for the remaining 9 isolates were not identified. Methionine was the sole factor required by 17 of 22 (77.3%) isolated which depended on a single factor. We conclude that auxotrophy is a feature of P. aeruginosa infection in cystic fibrosis.
Insights
Auxotrophy, a growth deficiency, is common in Pseudomonas aeruginosa infections in cystic fibrosis (CF) patients. This finding suggests a link between CF and P. aeruginosa auxotrophic mutations.
Area of Science:
- Microbiology
- Genetics
- Pulmonology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen frequently found in cystic fibrosis (CF) patients.
- Auxotrophy, the inability to synthesize essential organic compounds, can impact bacterial fitness and virulence.
Purpose of the Study:
- To investigate the prevalence of auxotrophic Pseudomonas aeruginosa strains in patients with cystic fibrosis.
- To compare auxotrophy rates in P. aeruginosa from CF patients versus those with non-CF bronchiectasis and healthy individuals.
Main Methods:
- Sputum isolates of P. aeruginosa were collected from adult patients with CF and non-CF bronchiectasis.
- Bacterial strains were screened for auxotrophy (growth factor requirements).
- Growth factor requirements for auxotrophic strains were identified.
Main Results:
- 18.4% of P. aeruginosa isolates from CF patients were auxotrophic.
- 18.2% of P. aeruginosa isolates from non-CF bronchiectasis patients were auxotrophic.
- All P. aeruginosa strains from non-bronchiectatic sources were prototrophic (lacked growth factor requirements).
- Methionine was the most common single growth factor required by CF auxotrophs.
Conclusions:
- Auxotrophy is a significant characteristic of P. aeruginosa infections in cystic fibrosis.
- The high prevalence of auxotrophy in CF suggests a potential role in disease progression or adaptation within the CF lung environment.