Search

The pathogenesis of Citrobacter diversus meningitis and brain abscess was studied in infant rats. Two-day-old rats were inoculated intraperitoneally and intranasally with C. diversus. C. diversus strain 4277, lacking the 32,000-molecular-weight outer membrane protein that appears to be a marker for strains causing meningitis in human neonates, was more likely to produce bacteremia, meningitis, and death in rats than was strain 4036, which possesses this outer membrane protein. Strain 4036 was, however, more likely than strain 4277 to produce ventriculitis and brain abscess. In the infant rat, central nervous system involvement by C. diversus begins with bacteremia and leptomeningitis, followed by ventriculitis and direct extension of infection into periventricular brain parenchyma. Large numbers of bacteria persist inside inflammatory cells, an observation suggesting resistance to intraphagocytic killing. Bacterial strain differences, possibly related to the presence of a 32,000-molecular-weight outer membrane protein, may account for histopathologic differences in the brains of infant rats with C. diversus meningitis. [ABSTRACT FROM AUTHOR]

We studied 17 strains of Citrobacter diversus isolated from the cerebrospinal fluid of infants with meningitis and compared these strains with 21 strains isolated from other body sites. The two groups of strains were similar with respect to biotype, piliation, hemolysin production, and resistance to the killing effects of serum. By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we found that 14 (82%) of 17 strains from cerebrospinal fluid, but only two (10%) of 21 strains isolated from other body sites, possessed a minor outer membrane protein with a molecular weight of 32,000 (P less than .0001). This protein may serve as a marker for strains of C. diversus that are likely to cause meningitis or brain abscess in human neonates. [ABSTRACT FROM AUTHOR]

The pathogenesis of labyrinthitis associated with bacterial meningitis was studied by histopathologic examination of inner ears of 114 rats with Haemophilus influenzae type b meningitis produced by ip inoculation of one of 13 clinical isolates. Findings consisted of inflammation of the perilymphatic spaces of the cochlea and semicircular canals with sparing of the endolymphatic space, cochlear nerve fibers, and middle ear. The degree of inflammation peaked at 48 hr after inoculation, then declined by 96 to 144 hr. No interstrain differences in type or degree of pathology were observed. Immunofluorescent staining of cochleae from 15 animals demonstrated that bacteria were present in areas of inflammation and also in the endolymphatic space and organ of Corti. One isolate displayed a tendency to accumulate in the perilymphatic spaces in larger numbers than those seen with three other isolates. These findings suggest that, in this model, inflammation reaches the inner ear by spreading from the subarachnoid space. Bacterial invasion of the organ of Corti may be one mechanism by which deafness occurs in bacterial meningitis. [ABSTRACT FROM AUTHOR]