During the exeriments on the biochemical influence of monosodium glutamate on rats, Pseudomonas aeruginosa infections broke out affecting 23 of 95 rats, 45 males and 50 females, after long-term feeding with diets containing 5 to 20 % monosodium glutamate. Of the 23 infected animals, five males and 18 females, two males and 17 females had lesions in the lungs, mainly lung abscesses. Other changes observed were hemorrhagic enteritis, suppurative keratitis, suppurative prostatitis, and cerebellum abscess. Of 23 control rats autopsied, only one male had subcutaneous abscess in the abdominal region. A large number of P. aeruginosa organisms were found in the jejunum of rats with lung infections. P. aeruginosa of two particular pyocine types were most frequently recovered from the lesions and intestines of the diseased rats. The results of pyocine typing suggested auto-infection. The possible relationship between P. aeruginosa infection and MSG feeding, age and sex was discussed.
