TY - JOUR
T1 - Capsular K1 polysaccharide of Escherichia coli
T2 - Relationship to virulence in newborn rats and resistance to phagocytosis
AU - Bortolussi, R.
AU - Ferrieri, P.
AU - Bjorksten, B.
AU - Quie, P. G.
PY - 1979
Y1 - 1979
N2 - The virulence of Escherichia coli strains for newborn rats was related to opsonic requirements of the strains, sensitivity to the bactericidal activity of serum, and K1 capsular polysaccharide content. K1 E. coli strains were more virulent than non-K1 strains after intraperitoneal injection in newborn rats (P< 0.05) and were more resistant to phagocytosis than non-K1 strains when the classical complement pathway was blocked with Mg-ethyleneglycoltetraacetic acid (P<0.0005). Sensitivity to the bactericidal activity of serum was similar among K1 and non-K1 E. coli strains. Two groups of K1 E. coli strains were defined on the basis of opsonic requirements. Group I strains were efficiently opsonized by the alternative complement pathway, while group II strains required the classical complement pathway for opsonization. Group I strains had less detectable K1 polysaccharide in the washed whole cell fraction than group II strains (10.3 versus 18.9 μg of K1 polysaccharide per 1010 colony-forming units) and were less virulent than group II strains (mortality, 44 versus 77%, P<0.05). The K1 capsular polysaccharide appears to play an important role in determining virulence in newborn rats and opsonic requirements of these strains, but does not contribute to the sensitivity of strains to the bactericidal activity of serum.
AB - The virulence of Escherichia coli strains for newborn rats was related to opsonic requirements of the strains, sensitivity to the bactericidal activity of serum, and K1 capsular polysaccharide content. K1 E. coli strains were more virulent than non-K1 strains after intraperitoneal injection in newborn rats (P< 0.05) and were more resistant to phagocytosis than non-K1 strains when the classical complement pathway was blocked with Mg-ethyleneglycoltetraacetic acid (P<0.0005). Sensitivity to the bactericidal activity of serum was similar among K1 and non-K1 E. coli strains. Two groups of K1 E. coli strains were defined on the basis of opsonic requirements. Group I strains were efficiently opsonized by the alternative complement pathway, while group II strains required the classical complement pathway for opsonization. Group I strains had less detectable K1 polysaccharide in the washed whole cell fraction than group II strains (10.3 versus 18.9 μg of K1 polysaccharide per 1010 colony-forming units) and were less virulent than group II strains (mortality, 44 versus 77%, P<0.05). The K1 capsular polysaccharide appears to play an important role in determining virulence in newborn rats and opsonic requirements of these strains, but does not contribute to the sensitivity of strains to the bactericidal activity of serum.
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U2 - 10.1128/iai.25.1.293-298.1979
DO - 10.1128/iai.25.1.293-298.1979
M3 - Article
C2 - 383617
AN - SCOPUS:0018763663
SN - 0019-9567
VL - 25
SP - 293
EP - 298
JO - Infection and immunity
JF - Infection and immunity
IS - 1
ER -