Relationship of iron and extracellular virulence factors to Pseudomonas aeruginosa lung infections.
The iron concentration in the culture medium used to prepare the inocula influenced the virulence of Pseudomonas aeruginosa in a chronic pulmonary infection model in rats. Groups of rats were given transtracheal inocula of agar beads in which were embedded c.10(4) cfu of P. aeruginosa strain PAO and the mutants of strain PAO, Fe5 and Fe18. When strain PAO was grown in low-iron medium before infection, it caused severe parenchymal changes including a dense mononuclear cell infiltration in the alveolar spaces, as well as intra- and peribronchial inflammation. When strain PAO was grown in high-iron medium, the pathological changes in lungs were restricted to intra- and peribronchial inflammation. Strain Fe5, in which the effect of iron on yields of elastase is deregulated, produced similar pathological changes regardless of whether it was grown in low- or high-iron media. All rats infected with strain Fe18, in which the effect of iron on yields of toxin A is deregulated, died within 48 h after infection. These data indicate that the iron concentration of the culture medium can influence the pathogenesis of P. aeruginosa in a chronic respiratory infection. These studies also suggest that the regulation of extracellular virulence factors by iron is important in the determination of P. aeruginosa virulence.
D000818:Animals; D003470:Culture Media; D007501:Iron / Q000494:pharmacology*; D008297:Male; D011014:Pneumonia / Q000382:microbiology* / Q000473:pathology; D011552:Pseudomonas Infections / Q000382:microbiology* / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000472:pathogenicity*; D051381:Rats; D011919:Rats, Inbred Strains; D014774:Virulence / Q000187:drug effects
D003470:Culture Media; D007501:Iron