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Ribotype stability of serial pulmonary isolates of Pseudomonas cepacia
J J LiPuma1, M C Fisher, S E Dasen
1Department of Pediatrics, Medical College of Pennsylvania, Philadelphia 19129.
Abstract:
Eighty-three isolates of Pseudomonas capacia were recovered from respiratory secretions from 12 chronically colonized cystic fibrosis patients and examined by ribotype analysis. In 9 patients, the ribotype of the cultured P. cepacia remained unchanged throughout the entire period of observation, indicating chronic pulmonary colonization with a single strain. In each of the remaining 3 patients, two genetically distinct strains were detected among serial P. cepacia isolates. No significant change in clinical condition was correlated with the change in identity of the colonizing strain. In control experiments, the stability of strain ribotype was demonstrated among isolated that had been subcultured 100 times in vitro and among isolates recovered from chronically colonized mice. These data demonstrate the utility of ribotype analysis and indicate that most chronically colonized cystic fibrosis patients harbor a single strain of P. cepacia for prolonged periods.
Insights
Most cystic fibrosis patients with chronic Pseudomonas cepacia lung infections are colonized by a single bacterial strain. Ribotype analysis confirms strain stability over time, highlighting its utility in tracking infections.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Genetics
Background:
- Chronic pulmonary colonization by Pseudomonas cepacia is a significant concern in cystic fibrosis (CF) patients.
- Understanding the genetic diversity and stability of P. cepacia strains within CF patients is crucial for effective management.
Purpose of the Study:
- To investigate the genetic stability and diversity of Pseudomonas cepacia strains colonizing the lungs of cystic fibrosis patients.
- To evaluate the utility of ribotype analysis in tracking chronic P. cepacia infections in CF.
Main Methods:
- Ribotype analysis was performed on 83 isolates of P. cepacia from respiratory secretions of 12 CF patients.
- Strain stability was assessed through serial isolates from patients and in vitro/in vivo control experiments.
Main Results:
- In 9 out of 12 patients, a single P. cepacia strain persisted throughout the observation period, confirmed by stable ribotypes.
- Three patients harbored two genetically distinct P. cepacia strains.
- No clinical changes correlated with shifts in colonizing P. cepacia strains.
- Control experiments demonstrated the stability of P. cepacia ribotypes after extensive subculturing and in a mouse model.
Conclusions:
- Ribotype analysis is a reliable method for assessing P. cepacia strain stability in CF patients.
- Most chronically colonized CF patients maintain a single P. cepacia strain for extended durations.
- The genetic stability of P. cepacia suggests limited strain replacement in established pulmonary infections.