The ability of periurethral Escherichia coli to grow in a voiding system is a key for the dominance of E. coli cystitis.
The generally accepted concept of the pathogenesis of cystitis is that bacteria on the periurethra migrate via the urethra to the bladder urine. To explore why Escherichia coli is the dominant organism isolated from cystitis, we examined two potential mechanisms that might account for the dominance of E. coli as the etiologic agent in cystitis in prepubertal, non-sexually active girls. First, the frequency of carriage of aerobic bacteria on the periurethra of two populations-healthy girls and girls after their first episode of cystitis was determined. Second, the survival capability of periurethral bacteria in urine under voiding conditions was examined. Two voids were simulated over 6 h by 10(2) dilution. A control was run in broth instead of urine. We found that Gram-positive bacteria, particularly coagulase-negative staphylococci, were much more common on the periurethra than E. coli. E. coli did grow well in urine in an in vitro voiding system whereas most Gram-positive bacteria did not. Growth in urine despite voiding may be the key reason for the dominance of E. coli in cystitis.
Schlager
T A
TA
Department of Pediatrics, University of Virginia, Charlottesville 22908, USA.
Ashe
K M
KM
Hendley
J O
JO
D002648:Child; D002675:Child, Preschool; D003556:Cystitis / Q000382:microbiology*; D004926:Escherichia coli / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D014521:Urethra / Q000382:microbiology*; D014556:Urine / Q000382:microbiology