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Chronic colonization of rat airways with Pseudomonas aeruginosa
Abstract:
Colonization of the airways of rats by Pseudomonas aeruginosa was established by treating the animals with hexamethylphosphoramide (HMPA) and inoculating with P. aeruginosa. Male Sprague-Dawley rats were given tap water (controls) or HMPA in the drinking water at 2 or 4 mg/ml. The ciliated cells of the airway epithelium were denuded, and microulcerative lesions in the epithelium were induced in the HMPA-treated rats. After 2 weeks of treatment, the rats were inoculated by transoral intratracheal instillation with 5 X 10(7) CFU of P. aeruginosa obtained from a cystic fibrosis patient. Two weeks after inoculation, P. aeruginosa was cultured from the airways, and scanning and transmission electron microscopy showed bacilli adhering to or invading the injured airway epithelium. P. aeruginosa was present in tracheal and intrapulmonary tissue homogenates of 9% of the P. aeruginosa-inoculated control rats (n = 22) as compared with 61% of the 2-mg/ml (n = 18) and 65% of the 4-mg/ml (n = 20) HMPA-treated rats (P less than 0.05). No dose-response relationship was found between 2 and 4 mg of HMPA per ml and colonization. Contamination of 47% of all of the rats with Mycoplasma pulmonis, as indicated by a positive enzyme-linked immunosorbent assay for immunoglobulin G, had no discernible significant effect on colonization by P. aeruginosa. These results indicate that colonization of the rat airway by P. aeruginosa can be achieved experimentally by treating the animals with HMPA. This research supports the hypothesis that colonization by P. aeruginosa may occur in airways where the ciliated epithelium has been injured and epithelial lesions exist.
Insights
Hexamethylphosphoramide (HMPA) treatment in rats successfully established Pseudomonas aeruginosa airway colonization. This model supports that P. aeruginosa colonizes injured airway epithelium, crucial for cystic fibrosis research.
Area of Science:
- Microbiology
- Pulmonology
- Toxicology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen that frequently colonizes the airways of cystic fibrosis patients.
- Airway injury is hypothesized to facilitate P. aeruginosa colonization, but experimental models are limited.
Purpose of the Study:
- To establish an experimental model for P. aeruginosa airway colonization in rats.
- To investigate the role of airway epithelial injury in P. aeruginosa colonization.
Main Methods:
- Rats were treated with hexamethylphosphoramide (HMPA) to induce airway epithelial injury.
- HMPA-treated and control rats were inoculated with P. aeruginosa.
- Colonization was assessed by bacterial culture and electron microscopy.
Main Results:
- HMPA treatment significantly increased P. aeruginosa colonization rates compared to controls (61-65% vs. 9%).
- Electron microscopy confirmed P. aeruginosa adherence to and invasion of injured airway epithelium.
- Mycoplasma pulmonis co-infection did not significantly affect P. aeruginosa colonization.
Conclusions:
- HMPA treatment provides a viable experimental model for studying P. aeruginosa airway colonization.
- This model supports the hypothesis that airway epithelial injury is a prerequisite for P. aeruginosa colonization.