Pseudomonas aeruginosa Vasculitis and Bacteremia Following Conjunctivitis: A Simple Model of Fatal Pseudomonas Infection in Neutropenia

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Abstract
During attempts to create a realistic model of fatal bacteremia due to Pseudomonas aeruginosa during immunosuppression, it was found that the invasive as well as the disseminated phase of infection could be mimicked by gentle instillation of 108 colony- forming units of P. aeruginosa into the intact conjunctival sac of agranulocytic rabbits. Within 48 hr animals developed conjunctivitis leading to severe necrotizing vasculitis and fatal bacteremia. Twelve of 26 strains from patients with P. aeruginosa infections were virulent, causing death in 50%–100% of animals. Nine (75%) of 12 isolates from blood but only two (15%) of 13 isolates from sputum and urine were highly lethal. Neither proteolytic enzyme production nor serum resistance alone accounted for virulence. No infection developed in animals with normal leukocyte counts or in neutropenic animals given Escherichia coli, Klebsiella pneumoniae, or non-aeruginosa pseudomonads. A rare vasculitic lesion was observed in animals inocblated with Serratia marcescens. This model, which illustrates the distinctive features of P. aeruginosa infection, is so simple and reproducible that it should be useful for evaluation of the efficacy of drugs and immunization against Pseudomonas in the compromised host.