The Journal of Medical Microbiology, Vol 27, Issue 1 11-15, Copyright © 1988 by Society for General Microbiology
Bactericidal activity of human serum against strains of Klebsiella from different sources
G. R. Benge
Public Health Laboratory, Central Middlesex Hospital, London.
One hundred and eighty strains of Klebsiella were tested for sensitivity to
pooled normal human serum, capsular type and faecal coliform reaction.
Strains of K. pneumoniae isolated from clinical infections were more likely
to be serum resistant than those from the gut flora or environmental
sources. For K. oxytoca strains, there was no significant correlation
between serum sensitivity and source of isolation. Of 60 strains of K.
oxytoca tested, 19 (32%) were serum resistant, as were 27 (23%) of 120
strains of K. pneumoniae. Strains of K. pneumoniae from human sources gave
positive reactions in the faecal coliform test more frequently than strains
from environmental sources. There was no correlation between a positive
faecal coliform reaction and resistance to the bactericidal effect of human
serum. Strains of capsular type K21 were isolated more frequently from
clinical infections and were more often serum resistant than other strains.
Serum resistance appears to be a virulence factor in strains of K.
pneumoniae but does not account for the difference in pathogenicity between
K. pneumoniae and K. oxytoca.
